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Neuropsychological evaluation aims at describing a child’s weaknesses and strengths to set an appropriate rehabilitation and education programme, as well as to better educate the school and family about the child’s needs. This chapter presents the most commonly used neuropsychological tests, as well as their limits and caveats in the understanding of the cognitive profile of children. It looks at selected cognitive and intelligence tests used in neuropsychological practice, including WWPSI-IV, K-ABC and NEPSY. It also looks at specific tests for attention, memory, visual and spatial cognition, visuo-motor co‑ordination and executive functions. The chapter ends with a discussion about intra- and inter-variability during neuropsychological evaluation and dissociation within an intelligence test; intelligence, neuropsychological assessment and learning abilities; and sources of performance differences between children and robots.

Research suggested the possibility that temporal cognition may be different in autistic spectrum disorder (ASD). Although there are some empirical studies examining timing ability in these individuals, to our knowledge, no one directly assessed the ability to predict when an event will occur. Here, we report a study on implicit temporal preparation in individuals with ASD as indexed by the variable foreperiod (FP) effect. We compared a group of adult ASD participants to a group of typically-developed (TD) controls, for their respective abilities to utilize implicit temporal information in a simple detection task with three different preparatory intervals (FP, short, middle and long). Participants were given a warning tone to signal an imminent stimulus, and asked to press a key as quickly as they could upon detection of the stimulus. Both groups were able to use implicit temporal information, as revealed by both the variable-FP effect (i.e., faster response for targets appearing after a long FP) and asymmetric sequential effects (i.e., slower response in short-FP trials following a previous long-FP trial). The TD group exhibited a faster response in a long-FP trial that was preceded by short-FP one, whereas the ASD group did not, as reflected in their higher percentage of response omissions for a target that appeared later than in the previous trial. The reduced ability of ASD participants to modulate their responses under these conditions might reflect a difficulty in time-based monitoring of stimulus occurrence. LAY SUMMARY: Time-processing may be different in autistic spectrum disorder (ASD). This study addressed the ability to anticipate a relevant stimulus's onset according to predictable interstimulus intervals comparing adults with ASD and typically developed controls. We found that ASD participants did not benefit from temporal preparation when stimulus appeared later than previously attended. This suggests a reduced ability in detecting implicit temporal regularities between events.

International audience; Medical advances in neonatology have improved the survival rate of premature infants, as well as children who are born under difficult neurological conditions. As a result, the prevalence of cerebral dysfunctions, whether minimal or more severe, is increasing in all industrialized countries and in some developing nations. Whereas in the past, ophthalmological diseases were considered principally responsible for severe visual impairment, today, all recent epidemiological studies show that the primary cause of blindness and severe visual impairment in children in industrialized countries is now neurological, with lesions acquired around the time of birth currently comprising the commonest contributor. The resulting cortical or cerebral visual impairments (CVIs) have long been ignored, or have been confused either with other ophthalmological disorders causing low vision, or with a range of learning disabilities. We present here the deleterious consequences that CVI can have upon learning and social interaction, and how these can be given behavioral labels without the underlying visual causes being considered. We discuss the need to train and inform clinicians in the identification and diagnosis of CVI, and how to distinguish the diagnosis of CVI from amongst other visual disorders, including the specific learning disorders. This is important because the range of approaches needed to enhance the development of children with CVI is specific to each child’s unique visual needs, making incorrect labeling or diagnosis potentially detrimental to affected children because these needs are not met.

Aims Patients with homonymous hemianopia may present a subtle ipsilesional deficit, recently referred to as ‘sightblindness’ in addition to the contralesional visual field defect. We recently demonstrated that this deficit could be worse in right brain-damaged patients with left hemianopia than in left brain-damaged patients with right hemianopia, confirming right hemisphere dominance for visuo-spatial and attentional capacities. In the present study we investigate whether this ipsilesional deficit could be attentional in nature and to what extent it is comparable in right brain-damaged (RBD) patients with left hemianopia and in RBD patients with left neglect. The study was also conducted in RBD patients with neither left hemianopia nor left neglect signs in order to test if a right hemisphere lesion per se could be responsible for subtle ipsilesional attentional deficit. To reach this aim, we tested selective attentional capacities in both visual fields of 10 right brain-damaged patients with left neglect (LN), 8 right brain-damaged patients with left homonymous hemianopia (LHH), 8 right brain-damaged patients with no signs of left neglect or left hemianopia (RBD controls), and 17 healthy age-matched participants (Normal controls). Method A lateralized letter-detection task was used to test if right-brain damaged patients with LN or LH may present a deficit of selective attention in their right, ipsilesional visual field, in comparison to Normal and RBD controls. Participants were asked to detect a target letter in either a single large stimulus (low attentional load) or a small stimulus surrounded by flankers (high attentional load). Stimuli were displayed either in the left or in the right visual field. Accuracy and reaction times were recorded. Results Results on accuracy showed that both LN and LH patients exhibited lower correct responses than Normal controls in their ipsilesional right visual field, suggesting an attentional deficit in their ipsilesional, supposed healthy visual field. More specifically, LH patients exhibited a specific deficit for processing single large stimuli, but not for processing flanked stimuli, relative to normal controls. LN patients exhibited lower correct responses for processing all types of stimulus than normal controls, but also than right brain damaged controls, in both visual fields suggesting a non-lateralized deficit not only due to the right hemisphere lesion. Furthermore, this deficit is more pronounced for flanked small stimuli, requiring higher attentional load. Conclusions The present results bring further evidence that patients with left homonymous hemianopia or left unilateral neglect both present a weaker but significant ipsilesional deficit in addition to their well-known massive contralesional deficit. The presence of a specific attentional deficit in the right ipsilesional visual field of left hemianopic and left neglect patients is discussed regarding the hypothesis of hemispheric specialization for selective spatial attention and may have clinical implications for both conditions.

International audience; Neurodevelopmental disorders are frequent in the general population and are often lifelong conditions despite sometimes being masked by conscious or unconscious compensation and avoidance mechanisms. These conditions are often unknown or underestimated in adults, even when diagnosed in childhood. Neurodevelopmental disorders share similarities with and frequently interact in a complex way with neurodegenerative disorders. Considering these aspects during memory clinic assessments can provide a new perspective on lifelong neurocognitive trajectories. Assessing both neurodevelopmental and neurodegenerative dimensions is challenging but should improve diagnostic accuracy. It is therefore necessary to understand the lifelong specific neurocognitive trajectory of each patient in order to develop personalized and focused cognitive medicine and care.

International audience; The role of melatonin has been extensively investigated in pathophysiological conditions, including autism spectrum disorder (ASD). Reduced melatonin secretion has been reported in ASD and led to many clinical trials using immediate-release and prolonged-release oral formulations of melatonin. However, melatonin’s effects in ASD and the choice of formulation type require further study. Therapeutic benefits of melatonin on sleep disorders in ASD were observed, notably on sleep latency and sleep quality. Importantly, melatonin may also have a role in improving autistic behavioral impairments. The objective of this article is to review factors influencing treatment response and possible side effects following melatonin administration. It appears that the effects of exposure to exogenous melatonin are dependent on age, sex, route and time of administration, formulation type, dose, and association with several substances (such as tobacco or contraceptive pills). In addition, no major melatonin-related adverse effect was described in typical development and ASD. In conclusion, melatonin represents currently a well-validated and tolerated treatment for sleep disorders in children and adolescents with ASD. A more thorough consideration of factors influencing melatonin pharmacokinetics could illuminate the best use of melatonin in this population. Future studies are required in ASD to explore further dose-effect relationships of melatonin on sleep problems and autistic behavioral impairments.

International audience; Autism spectrum disorder (ASD) is characterized by difficulties in the social domain, but also by hyper-and hypo-reactivity. Atypical visual behaviours and processing have often been observed. Nevertheless, several similar signs are also identified in other clinical conditions including cerebral visual impairments (CVI). In the present study, we investigated emotional face categorization in groups of children with ASD and CVI by comparing each group to typically developing individuals (TD) in two tasks. Stimuli were either non-filtered or filtered by low-and high-spatial frequencies (LSF and HSF). All participants completed the autism spectrum quotient score (AQ) and a complete neurovisual evaluation. The results show that while both clinical groups presented difficulties in the emotional face recognition tasks and atypical processing of filtered stimuli, they did not differ from one another. Additionally, autistic traits were observed in the CVI group and symmetrically, some visual disturbances were present in the ASD group as measured via the AQ score and a neurovisual evaluation, respectively. The present study suggests the relevance of comparing ASD to CVI by showing that emotional face categorization difficulties should not be solely considered as autism-specific but merit investigation for potential dysfunction of the visual processing neural network. These results are of interest in both clinical and research perspectives, indicating that systematic visual examination is warranted for individuals with ASD. Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by (1) impairments in the social and communication domain and by (2) stereotyped and repetitive behaviours as well as by sensory hypo-and hyper-responsiveness (APA, 2013).

The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby patients are blind to the contralesional visual field of each eye. Homonymous hemianopia has been studied in terms of its deleterious consequences on perceptual, cognitive and motor tasks as well as because it represents an interesting model of vision loss after a unilateral lesion of the occipital lobe. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, HH patients can also exhibit dissociations between perception and awareness. Firstly, HH patients suffering from anosognosia may be unaware of their visual field defect. Secondly, HH patients can present with unconscious visual abilities in the blind hemifield, a phenomenon referred to as blindsight. Thirdly, recent reports demonstrate that HH patients can suffer from a subtle deficit in their ipsilesional visual field that they are unaware of, a condition called sightblindness (i.e. the reverse case of 'blindsight'). Finally, HH patients may also exhibit visual hallucinations in their blind field; however, such patients are not systematically aware that their perceptions are unreal. In this review, we provide an overview of the visual-field losses in HH patients after a left or right unilateral occipital lesion. Furthermore, we explore the implications of these four phenomena for models of visual processing and rehabilitation of visual field defects in HH patients. Finally, in contrast to the traditional view that HH is solely a visual-field defect, we discuss why this deficit is an interesting model for studying the dissociation between perception and awareness.

Purpose: To evaluate the role of the ophthalmologist in the management of children with arterial stroke, at presentation and during follow-up. Methods: This retrospective case series comprised children with arterial stroke who were followed for at least 12 months in a tertiary pediatric medical center in 2005-2016. Demographic data and findings on radiological neuroimaging and ophthalmological and neurological examination were retrieved from the medical files. Results: The cohort included 26 children with stroke. Underlying disorders included metabolic syndrome (n = 5, 19.2%), cardiac anomaly or Fontan repair (n = 3 each, 11.5%), vascular anomaly (n = 3, 11.5%), head trauma with traumatic dissection (n = 3, 11.5%), and hypercoagulability (n = 1, 3.8%); in eight patients (30.8%), no apparent cause was found. Eleven patients (42.3%) had a non-ophthalmological neurological deficit as a result of the stroke. Eye examination was performed in nine patients (34.6%) during follow-up. Ophthalmological manifestations included hemianopic visual field defect in seven patients (7.7%) and complete blindness and poor visual acuity in one patient each (3.8%). At the last visit, no change in visual function was detected. Conclusion: The variable etiology and presentation of pediatric stroke may mask specific visual signs. Children with arterial stroke should be referred for early ophthalmological evaluation and visual rehabilitation.

International audience; From birth, vision guides our movement, facilitates social interaction and accords recognition and understanding of the environment. In children, vision underpins development of these skills, and is crucial for typical development. Deficits in visual processing may lead to impairment of cognitive, motor, and social development, placing children at risk of developing features of autism. Severe early onset visual dysfunction accords the greatest risk. Cerebral Visual Impairment (CVI) can lead to disorders of cognitive and social development that resemble Autism Spectrum Disorder (ASD). Similarly, children who appear primarily affected by cognitive and social developmental disorders, can manifest a range of visual and perceptual deficits that may be contributory to their disorder. This dual perspective highlights the need for links between impaired vision and neurodevelopmental disorders to be identified and acted upon by means of applying appropriate social and educational strategies. There is good evidence to show that targeted systematic screening for visual and perceptual impairments, and implementation of long-term management approaches, is now required for all at risk children.

ObjectivesHomonymous hemianopia (HH) is the most frequent visual-field defect after a stroke. Some of these patients also have visual hallucinations, the origin and frequency of which remain largely unknown. The aims of this work were to determine the occurrence of visual hallucinations among poststroke hemianopic patients in function of the location (Brodmann areas) of the brain lesion, as determined by MRI, and to study the neuroanatomic correlates of these hallucinations by nature, frequency, and type.MethodsOne hundred sixteen patients with HH who had had a stroke in the posterior region, including the occipital lobe, participated in the study. We evaluated the frequency and nature of visual hallucinations with the Questionnaire for Hallucinations in Homonymous Hemianopia. The volume of each patient's brain lesion was modeled in 3 dimensions.ResultsOf 116 patients with an HH from a cortical infarction, 85 were excluded due to confounding factors associated with hallucinations. In the final cohort of 31 patients matched for lesion location and etiology, 58% had experienced hallucinations. A significant inverse correlation between lesion size and the frequency of visual hallucinations emerged. The presence of visual hallucinations in poststroke hemianopic patients requires a relatively small lesion that includes, at the very least, loss of the striate cortex but that spares Brodmann area 19, 20, and 37.ConclusionOur results suggest that visual hallucinations might be due to complex interactions between damaged areas and intact areas of the visual cortex. We discuss these findings regarding models of perception and of visual recognition. Our results also have implications for the clinical care of patients with HH who have had a stroke.

We have been sensitized to children with high intellectual potential (HIP) having difficulties given the number of children consulting in our outpatient medico-psychological centres for scholastic problems (possibly leading to school failure), anxiety disorders or behavioral disorders such as attention deficit/hyperactivity disorder (ADHD), and in which a high intellectual potential was discovered during psychological assessments. It is the contrast, and more precisely the paradox, between the high intellectual potential of these children and their scholastic difficulties (including school failure), and the psychic suffering expressed by some of them, which led us to question, challenge and propose therapeutic and educational care adapted to these children. It is in this context that we created in December 2005 the CNAHP (National Center for Assistance to High Potential children and adolescents) which is a public centre integrated into the hospital-university department of child and adolescent psychiatry at Rennes. It is noteworthy that not all children with HIP have difficulties, and children with school failure or behavioral problems are not always children with HIP. However, it is necessary not to minimize the problem raised by children with HIP with difficulties by ignoring its frequency or by considering that these children are "intelligent" enough to manage by themselves and do not need to be helped, whereas some of them can show school failure and even be de-scholarized. Indeed, based on the definition of the World Health Organization (WHO) of an intellectual Quotient (IQ) above 130 (level corresponding to a statistical threshold), the frequency of children with HIP represents 2.3% of the population of schoolchildren aged 6 to 16. The frequency is therefore not so rare. However, it remains to be determined by French epidemiological studies what is the actual frequency of children with difficulties within a population of children with HIP. The analysis of the CNAHP research data from a clinical population (children with HIP consulting for difficulties) highlights that children with HIP can show major school problems (including school failure, defined here as having or foreseeing repetition of a grade), which corresponds to 7.5% of 611 children with HIP consulting at the CNAHP) and socioemotional problems (emotional regulation disorders) in relation to their high intellectual potential. In particular, anxiety disorders were the most frequent psychiatric disorders observed in this population (40.5%) and were significantly associated with high verbal potential. This significant association requires further studies to avoid establishing a simplistic unidirectional and reductive linear cause-effect relationships. Indeed, a high verbal potential can elicit and/or reinforce anxiety-producing representations, but anxiety disorders may also lead to a defensive over investment of verbal language. The results are discussed in this article and suggest that scholastic and/or psychological difficulties encountered by some children with HIP can be related to their high intellectual potential. It is necessary to develop therapeutic and educational care adapted to these children from a better understanding, based on research results, of their possible difficulties but also cognitive abilities. Even when children with HIP have scholastic and/or psychological difficulties, some of their cognitive skills can be preserved contrary to appearances, with for example, as seen in the CNAHP results, excellent attentional capacities shown by cognitive tests contrasting with behavioral attention deficit reported by parents. These skills are important to identify as they are resources which support the therapeutic and educational project. It is probably through an articulation among professionals from national education, health and research, in alliance with the family (parents, child, and siblings), that advances will be made. In the same way that professionals have been interested in children with intellectual disabilities, it is important to be concerned by children with HIP and difficulties located at the other end of the continuum. It is a question of ethics which concerns both caregivers and teachers. It is also a societal issue that concerns all of us given that the expression of high intellectual and creative potential in children may be essential to the societal development of innovative strategies and each nation's future. Finally, the discussion can be extended to all children, independent of their potential. What we learn from children with HIP and difficulties can be applied to each child: it is important at family, school and societal levels to facilitate the expression of the potential of children, to value their skills, and to help them to remove possible inhibitions of their potential based on individualized projects. The acceptance of singularity and differences in children can contribute to tolerance and the development of creativity, in the interest of the subject and of society.

Coarse information of a visual stimulus is conveyed by Low Spatial Frequencies (LSF) and is thought to be rapidly extracted to generate predictions. This may guide fast recognition with the subsequent integration of fine information, conveyed by High Spatial Frequencies (HSF). In autism, emotional face recognition is challenging, and might be related to alterations in LSF predictive processes. We analyzed the data of 27 autistic and 34 non autistic (NA) adults on an emotional Stroop task (i.e., emotional face with congruent or incongruent emotional word) with spatially filtered primes (HSF vs. LSF). We hypothesized that LSF primes would generate predictions leading to faster categorization of the target face compared to HSF primes, in the NA group but not in autism. Surprisingly, HSF primes led to faster categorization than LSF primes in both groups. Moreover, the advantage of HSF vs. LSF primes was stronger for angry than happy faces in NA, but was stronger for happy than angry faces in autistic participants. Drift diffusion modelling confirmed HSF advantage and showed a longer non-decision time (e.g., encoding) in autism. Despite LSF predictive impairments in autism was not corroborated, our analyses suggest low level processing specificities in autism.

Background Occipital arteriovenous malformations (AVMs) carry a high risk of postoperative morbidity because of their anatomic relation to the visual cortex and optic radiations. Data regarding endovascular management of these lesions are scant. Objective To report our single-center experience with occipital AVMs, most of which were treated endovascularly, with a special interest for postoperative visual impairment. Methods From a prospective database, we assessed the clinical and radiological data of all patients with an occipital AVM managed between 1997 and 2018. The extension of the nidus to the primary visual cortex was assessed and correlated to the pre- and postintervention visual symptomatology. Modified Rankin Scale and visual fields (VFs) were assessed pre- and post-treatment and at the last follow-up. Results A total of 83 patients (47 males [56.6%]) with an occipital AVM were included in the study. Mean age at presentation was 33.5 ± 15.0 yr (min-max = 7-76). A total of 34 patients (41%) presented with hemorrhage related to the AVM. A total of 57 patients (68.7%) underwent endovascular treatment (EVT) alone, 20 (24.1%) underwent embolization and surgery, 3 (3.6%) underwent embolization and radiosurgery, and 3 (3.6%) were conservatively managed. A complete obliteration of the AVM was achieved in 53 patients (66.3%). A post-treatment worsening of the VF was found in 24 of the treated patients (30%), 3 patients (9%) for ruptured AVMs, and in 21 patients (46%) for unruptured AVMs. Morbidity rate was 3.7% and mortality rate was 2.5%. Conclusion EVT of occipital AVM carries a non-negligible rate of complications, especially regarding visual functions.

Background In the nineteenth century, Jean Martin Charcot explained functional neurological disorder (formerly called conversion disorder) as a “psychodynamic” lesion. Numerous advances in neuroimaging have permitted identification of the neural underpinnings of this disorder. Case presentation Herein we describe a case of functional neurological disorder (FND) with initial left sensorimotor deficit, in-coordinated limb movements, neglect, clouded consciousness, slurred speech and a semiology of visual impairment. A single photon emission computed tomography (SPECT) showed a right thalamic hypoperfusion, which is rather concordant with the initial semiology. Later, the semiology changed, presenting with a predominantly neurovisual complex presentation. The second SPECT showed no more thalamic abnormalities but an hypoperfusion in the right temporo-occipital junction, right inferior parietal lobe and left superior frontal lobe, which is also rather concordant with the changing semiology. Conclusions This case illustrates the evolving neuroimaging patterns of FND but also the concordance between semiology and neuroimaging findings in FND supporting Charcot's theory of “dynamic lesion”.

International audience; Cerebral (cortical) visual impairment (CVI) is the primary cause of visual impairment in children in high-income countries. It is increasing globally due to improved life-saving measures for premature and full-term infants. Yet the consequences of this condition are only beginning to be understood and addressed. In contrast to visual impairment due to refractive error and disorders of the eye, there is limited public awareness of CVI, and the consequent impairment of a variety of visual capabilities may go unidentified, adversely affecting cognitive, motor, and social development. CVI refers to visual perception deficits not related to the peripheral (i.e., prechiasmatic) system disorder, but rather, to injury to brain areas serving assimilation, integration, and interpretation of visual information. According to the topography, site, and the extent of the pathology, the deficit may variably concern central visual functions, the visual field, perception of movement, visual analysis, visual exploration and attention, or visual memory, as well as visual guidance of movement. Each affected child has a unique clinical picture, which needs to be identified and individually profiled. This is probably the underlying reason that CVI is commonly underdiagnosed, especially in children, and, as a consequence, the full range of potential behavioral outcomes are not identified and adequately addressed. The present paper shows how the use of multiple methods of assessment can improve the understanding of children with CVI.

After a post-chiasmatic lesion, some patients may retain unconscious visual function, known as blindsight, in their contralesional visual field. Despite the importance of blindsight in the study of consciousness, little is known about the nature of patients' experience in their hemianopic field. To address this knowledge gap, we measured blindsight, and assessed the perceptual experience in the contralesional visual field, of seventeen homonymous hemianopic (HH) patients. To ensure that the stimuli were shown in a "blind" sector of the visual field, we selected a subgroup of eight complete-HH patients, as determined by automatic perimetry. Firstly, we measured blindsight through a forced-choice task in which the patients had to identify letters displayed on a screen. Secondly, we compared the patients' binary responses ("Something was presented" vs "Nothing was presented") to responses on a new, five-level scale, the Sensation Awareness Scale (SAS), which we designed to include visual as well as non-visual answers (e.g., "I felt something"). Interestingly, only one of the eight complete-HH patients met the criteria for blindsight. More importantly, our SAS enabled us to identify a previously unreported dissociation, which we have named blindsense, in four of the eight complete-HH patients. Specifically, these four patients exhibited better-than-chance sensitivity to the presence of a stimulus on the subjective scale, despite being unable to identify the stimulus during the forced-choice task. Our findings highlight the importance of awareness-assessment methods to investigate perceptual experiences in the contralesional visual field and suggest a low incidence of blindsight in post-stroke HH patients.

In age-related macular degeneration (AMD), the processing of fine details in a visual scene, based on a high spatial frequency processing, is impaired, while the processing of global shapes, based on a low spatial frequency processing, is relatively well preserved. The present fMRI study aimed to investigate the residual abilities and functional brain changes of spatial frequency processing in visual scenes in AMD patients. AMD patients and normally sighted elderly participants performed a categorization task using large black and white photographs of scenes (indoors vs. outdoors) filtered in low and high spatial frequencies, and nonfiltered. The study also explored the effect of luminance contrast on the processing of high spatial frequencies. The contrast across scenes was either unmodified or equalized using a root-mean-square contrast normalization in order to increase contrast in high-pass filtered scenes. Performance was lower for high-pass filtered scenes than for low-pass and nonfiltered scenes, for both AMD patients and controls. The deficit for processing high spatial frequencies was more pronounced in AMD patients than in controls and was associated with lower activity for patients than controls not only in the occipital areas dedicated to central and peripheral visual fields but also in a distant cerebral region specialized for scene perception, the parahippocampal place area. Increasing the contrast improved the processing of high spatial frequency content and spurred activation of the occipital cortex for AMD patients. These findings may lead to new perspectives for rehabilitation procedures for AMD patients.

Resume La cecite corticale est une perte de sensation visuelle liee a des lesions atteignant les voies optiques en arriere du corps genouille lateral et plus particulierement les cortex visuels primaires. Les connaissances sur le fonctionnement visuel ont connu une progression considerable ces vingt dernieres annees, en partie grâce a l’amelioration des techniques d’investigation mais surtout grâce a la convergence des donnees provenant des differentes approches: psychophysique, psychologie cognitive, neurophysiologie, et neuropsychologie. Cet enrichissement mutuel induit une meilleure comprehension des troubles neurovisuels complexes tels que la cecite corticale chez l’enfant et chez l’adulte, permet de mettre au point de nouvelles techniques de reeducation et d’en suivre la recuperation grâce aux progres de l’imagerie cerebrale fonctionnelle. En parallele, l’etude de ces troubles, et la facon dont les processus visuels se desorganisent a la suite d’une lesion occipitale nous informent sur les processus cognitifs impliques dans la perception visuelle a l’etat normal.

Using large natural scenes filtered in spatial frequencies, we aimed to demonstrate that spatial frequency processing could not only be retinotopically mapped but could also be lateralized in both hemispheres. For this purpose, participants performed a categorization task using large black and white photographs of natural scenes (indoors vs. outdoors, with a visual angle of 24° × 18°) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and nonfiltered scenes, in block-designed fMRI recording sessions. At the group level, the comparison between the spatial frequency content of scenes revealed first that, compared with HSF, LSF scene categorization elicited activation in the anterior half of the calcarine fissures linked to the peripheral visual field, whereas, compared with LSF, HSF scene categorization elicited activation in the posterior part of the occipital lobes, which are linked to the fovea, according to the retinotopic property of visual areas. At the individual level, functional activations projected on retinotopic maps revealed that LSF processing was mapped in the anterior part of V1, whereas HSF processing was mapped in the posterior and ventral part of V2, V3, and V4. Moreover, at the group level, direct interhemispheric comparisons performed on the same fMRI data highlighted a right-sided occipito-temporal predominance for LSF processing and a left-sided temporal cortex predominance for HSF processing, in accordance with hemispheric specialization theories. By using suitable method of analysis on the same data, our results enabled us to demonstrate for the first time that spatial frequencies processing is mapped retinotopically and lateralized in human occipital cortex.

International audience; Background: Melatonin synchronizes central but also peripheral oscillators (fetal adrenal gland, pancreas, liver, kidney, heart, lung, fat, gut, etc.), allowing temporal organization of biological functions through circadian rhythms (24-hour cycles) in relation to periodic environmental changes and therefore adaptation of the individual to his/her internal and external environment. Measures of melatonin are considered the best peripheral indices of human circadian timing based on an internal 24-hour clock. Methods: First, the pharmacology of melatonin (biosynthesis and circadian rhythms, pharmacokinetics and mechanisms of action) is described, allowing a better understanding of the short and long term effects of melatonin following its immediate or prolonged release. Then, research related to the physiological effects of melatonin is reviewed. Results: The physiological effects of melatonin are various and include detoxification of free radicals and antioxidant actions, bone formation and protection, reproduction, and cardiovascular, immune or body mass regulation. Also, protective and therapeutic effects of melatonin are reported, especially with regard to brain or gastrointestinal protection, psychiatric disorders, cardiovascular diseases and oncostatic effects. Conclusion: This review highlights the high number and diversity of major melatonin effects and opens important perspectives for measuring melatonin as a biomarker (biomarker of early identification of certain disorders and also biomarker of their follow-up) and using melatonin with clinical preventive and therapeutic applications in newborns, children and adults based on its physiological regulatory effects.

International audience; Age-related macular degeneration (AMD) is characterized by a central vision loss. Here, we investigated the ability of AMD patients to process the spatial frequency content of scenes in their residual vision, depending of the luminance contrast level. AMD patients and normally-sighted elderly participants (controls) performed a categorization task involving large scenes (outdoors vs. indoors) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and non-filtered scenes (NF). Luminance contrast of scenes was equalized between stimuli using a root-mean square (RMS) contrast normalization. In Experiment 1, we applied an RMS contrast of 0.1 (for luminance values between 0 and 1), a value situated between the mean contrast of LSF and HSF scenes in natural conditions. In Experiment 2, we applied an RMS contrast of 0.3, corresponding to the mean contrast of HSF scenes in natural conditions. In Experiment 3, we manipulated four levels of linearly-increasing RMS contrasts (0.05, 0.10, 0.15, and 0.20) for HSF scenes only. Compared to controls, AMD patients gave more non-responses in the categorization of HSF than NF or LSF scenes, irrespective of the contrast level of scenes. Performances improved as contrast increased in HSF scenes. Controls were not differentially affected by the spatial frequency content of scenes. Overall, results suggest that LSF processing is well preserved in AMD patients and allows efficient scene categorization in their parafoveal residual vision. The HSF processing deficit could be partially restored by enhancing luminance contrast.

Cerebral visual impairment (CVI) has become the primary cause of visual impairment and blindness in children in industrialized countries. Its prevalence has increased sharply, due to increased survival rates of children who sustain severe neurological conditions during the perinatal period. Improved diagnosis has probably contributed to this increase. As in adults, the nature and severity of CVI in children relate to the cause, location and extent of damage to the brain. In the present paper, we define CVI and how this impacts on visual function. We then define developmental coordination disorder (DCD) and discuss the link between CVI and DCD. The neuroanatomical correlates and aetiologies of DCD are also presented in relationship with CVI as well as the consequences of perinatal asphyxia (PA) and preterm birth on the occurrence and nature of DCD and CVI. This paper underlines why there are both clinical and theoretical reasons to disentangle CVI and DCD, and to categorize the features with more precision. In order to offer the most appropriate rehabilitation, we propose a systematic and rapid evaluation of visual function in at-risk children who have survived preterm birth or PA whether or not they have been diagnosed with cerebral palsy or DCD.

International audience; The most common visual defect to follow a lesion of the retrochiasmal pathwaysishomonymous hemianopia(HH), whereby, in each eye, patients are blind to thecontralesional visual field. From a behavioral perspective, in addition to exhibitinga severe deficit in their contralesional visual field, hemianopic patients can alsopresent implicit residual capacities, now usually referred to collectively asblindsight.It was recently demonstrated that HH patients can also suffer from a subtle deficitin their ipsilesional visual field, calledsightblindness(the reverse case of blindsight).Furthermore, the nature of the visual deficit in the contralesional and ipsilesional visual fields, as well as the pattern of functional reorganization in the occipital lobe of HH patients after stroke, all appear to depend on the lesion side. In addition to their contralesional and ipsilesional visual deficits, and to their residual capacities, HH patients can also experience visual hallucinations in their blind field, the physiopathological mechanisms of which remain poorly understood. Herein we review blindsight in terms of its better-known aspects as well as its less-studied clinical signs such as sightblindness, hemispheric specialization and visual hallucinations. We also discuss the implications of recent experimental findings for rehabilitation of visual field defects in hemianopic patients.

Objective: Visual Evoked Potentials (VEPs) following optic neuritis (ON) remain chronically prolonged, although standard visual tests indicate full recovery. We hypothesized that dynamic visual processes, such as motion perception, may be more vulnerable to slowed conduction in the optic nerve, and consequently be better associated with projection rates. Methods: Twenty-one patients with acute unilateral, first-ever ON were studied during 1 year. Static visual functions (visual acuity, color perception, visual field, and contrast sensitivity), dynamic visual functions (motion perception), and VEPs were assessed repeatedly. Results: Visual and electrophysiological measurements reached maximal performance 4 months following the acute phase, with no subsequent improvement. Whereas VEP amplitude and static visual functions recovered, VEP latency remained significantly prolonged, and motion perception remained impaired throughout the 12-month period. A strong correlation was found between VEP latencies and motion perception. Visual performance at 1 month was strongly predictive of visual outcome. For static functions, patients who showed partial recovery at 1 month subsequently achieved full recovery. For dynamic functions, the rate of improvement was constant across patients, independent of the initial deficit level. Interpretation: Conduction velocity in the visual pathways correlated closely with dynamic visual functions, implicating the need for rapid transmission of visual input to perceive motion. Motion perception level may serve as a tool to assess the magnitude of myelination in the visual pathways. The constancy across patients may serve as a baseline to assess the efficacy of currently developing neuroprotective and regenerative therapeutic strategies, targeting myelination in the central nervous system. ANN NEUROL 2012

Age-related macular degeneration (AMD) is characterized by a central vision loss. We explored the relationship between the retinal lesions in AMD patients and the processing of spatial frequencies in natural scene categorization. Since the lesion on the retina is central, we expected preservation of low spatial frequency (LSF) processing and the impairment of high spatial frequency (HSF) processing. We conducted two experiments that differed in the set of scene stimuli used and their exposure duration. Twelve AMD patients and 12 healthy age-matched participants in Experiment 1 and 10 different AMD patients and 10 healthy age-matched participants in Experiment 2 performed categorization tasks of natural scenes (Indoors vs. Outdoors) filtered in LSF and HSF. Experiment 1 revealed that AMD patients made more no-responses to categorize HSF than LSF scenes, irrespective of the scene category. In addition, AMD patients had longer reaction times to categorize HSF than LSF scenes only for indoors. Healthy participants’ performance was not differentially affected by spatial frequency content of the scenes. In Experiment 2, AMD patients demonstrated the same pattern of errors as in Experiment 1. Furthermore, AMD patients had longer reaction times to categorize HSF than LSF scenes, irrespective of the scene category. Again, spatial frequency processing was equivalent for healthy participants. The present findings point to a specific deficit in the processing of HSF information contained in photographs of natural scenes in AMD patients. The processing of LSF information is relatively preserved. Moreover, the fact that the deficit is more important when categorizing HSF indoors, may lead to new perspectives for rehabilitation procedures in AMD.

In young children, visual attention, analysis or memory is only rarely evaluated. Moreover, tools to test for such higher-order visual capacities in children are limited. In an attempt to develop and refine such tools, we selected nine tests to assess visuo-attentional abilities before formal reading education (grade 1). The battery consisted of gaze fixation, visual field, visual extinction, binocular visual pursuit, visual memory, "A" cancellation, Teddy bears cancellation, embedded figures, and matching tasks. This battery was used in the general population (n=110) to calculate cut-off scores identifying the lower 5% of the general population to obtain a screening measure for neurovisual disabilities in children. To evaluate our battery's sensitivity and specificity to neurovisual disorders over ophthalmological diseases, a neurovisual group (n=9) and an ophthalmologic group (n=13) also completed the tests. Overall, all but three tests of the battery could be used to discriminate between neurovisual and ophthalmologic children. The ophthalmologic children failed the visual field extent examination and the cancellation tasks, consistent with deleterious effects of ophthalmologic disease on visual perception as well as higher-order vision. Using the cut-off scores, the battery identified only 2 out of 13 ophthalmologic patients, but 5 out of 9 neurovisual patients. In the general population, these cut-off scores identified seven children. These children were previously undiagnosed with any disability (i.e., no diagnosis of ophthalmological, neurological, or psychiatric disease) and thus did not receive any rehabilitation. This preliminary study highlights the necessity for a neurovisual disorder screening tool for young children.

International audience; The present study aimed to show that bidirectional reading and language exposure influence the position of egocentric reference (ER), the perceived direction of the body's sagittal axis proposed to act as an anchor for movements in extracorporeal space. Directional factors (e.g., visual scanning bias and reading habits) have been proposed to influence visuospatial performance, such as in line bisection and figure drawing. In past studies, bidirectional readers have been less consistent in demonstrating a bias compared to unidirectional readers. Using a straight-ahead pointing task to assess egocentric reference, we compared 14 unidirectional left-to-right readers (Uni-LR) to three bidirectional reading groups that differed in the reading direction of their native language and/or the level of their second language literacy: 16 low-English literate, native right-to-left, bidirectional readers (Lo-Bi-RL), 13 high-English literate, native right-to-left, bidirectional readers (Hi-Bi-RL), and 15 native left-to-right, bidirectional readers (Bi-LR). Participants were asked to point straight-ahead while blindfolded using either a left-to-right or a right-to-left scanning direction to approach the subjective sagittal midline. Uni-LRs showed left-side spatial bias when scanning left-to-right and right-side bias during right-to-left scanning, Bi-LRs and Lo-Bi-RLs (i.e., intermediate level or less in their second language) demonstrated the opposite pattern, and Hi-Bi-RLs showed left-side spatial bias regardless of scanning direction. Results are discussed in terms of accuracy and spatial bias regarding the interaction between reading direction and spatial cognition based on the level of bidirectional literacy and language exposure.

International audience; Left unilateral neglect, a dramatic condition which impairs awareness of left-sided events, has been classically reported after right hemisphere cortical lesions involving the inferior parietal region. More recently, the involvement of long range white matter tracts has been highlighted, consistent with the idea that awareness of events occurring in space depends on the coordinated activity of anatomically distributed brain regions. Damage to the superior longitudinal fasciculus (SLF), linking parietal to frontal cortical regions, or to the inferior longitudinal fasciculus (ILF), connecting occipital and temporal lobes, has been described in neglect patients. In this study, four right-handed patients with right hemisphere strokes underwent a high definition anatomical MRI with diffusion tensor imaging (DTI) sequences and a pencil and paper neglect battery of tests. We used DTI tractography to visualise the SLF, ILF and the inferior fronto-occipital fasciculus (IFOF), a pathway running the depth of the temporal lobe, not hitherto associated with neglect. Two patients with cortical involvement of the inferior parietal and superior temporal regions, but intact and symmetrical fasciculi, showed no signs of neglect. The other two patients with signs of left neglect had superficial damage to the inferior parietal cortex and white matter damage involving the IFOF. These findings suggest that superficial damage to the inferior parietal cortex per se may not be sufficient to produce visual neglect. In some cases, a lesion to the direct connections between ventral occipital and frontal regions (ie, IFOF) may contribute to the manifestation of neglect by impairing the top down modulation of visual areas from the frontal cortex.

International audience; Over the past several decades a growing amount of research has focused on the possibility of transiently reducing left neglect signs in right brain-damaged patients by using vestibular and/or visuo-proprioceptive stimulations. Here we review seminal papers dealing with these visuo-vestibulo-proprioceptive stimulations in normal controls, right brain-damaged (RBD) patients, and animals. We discuss these data in terms of clinical implications but also with regards to theoretical frameworks commonly used to explain the unilateral neglect syndrome. We undermine the effect of these stimulations on the position of the egocentric reference and extend the notion that the positive effects of these stimulation techniques may stem from a reorientation of attention towards the neglected side of space or from a recalibration of sensori-motor correlations. We conclude this review with discussing the possible interaction between experimental rehabilitation, models of neglect and basic spatial cognition research.

International audience; In addition to exhibiting a severe contralesional deficit, hemianopic patients may also show a subtle ipsilesional visual deficit, called sightblindness (the reverse case of 'blindsight). We have tested for the presence, nature and extent of such an ipsilesional visual field (IVF) deficit in hemianopic patients that we assigned to perform two visual tasks. Namely, we aimed to ascertain any links between this ipsilesional deficit, the lesion side, and the tasks performed or the stimuli used. We tested left and right homonymous hemianopic (right brain-damaged RBD and left brain-damaged LBD, respectively) patients and healthy controls. Natural-scene images, either non-filtered or filtered in low or high spatial frequency (LSF or HSF, respectively) were presented in the IVF of each subject. For the two tasks, detection ("Is an image present?") and categorization ("Is the image of a forest or a city?"), accuracy and response time were recorded. In the IVF the RBD (left hemianopes) patients made more errors on the categorization task than did their matched controls, regardless of image type. In contrast, the only task in which the LBD (right hemianopes) patients made more errors than did the controls was the HSF-images task. Furthermore, in both tasks (detection and categorization), the RBD patients performed worse than did the LBD patients. Homonymous hemianopic patients do indeed exhibit a specific visual deficit in their IVF, which was previously thought to be unaffected. We have demonstrated that the nature and severity of this ipsilesional deficit is determined by the side of the occipital lesion as well as by the tasks and the stimuli. Our findings corroborate the idea of hemispheric specialization at the occipital level, which might determine the nature and severity of ipsilesional deficits in hemianopic patients.

The extent of and reasons for visuo-manual coordination deficits in moderate and late preterm born infants without neurological impairments are not well known. This paper presents a longitudinal study on the visuo-manual development of twelve preterm infants, born after 33-36 weeks of gestation without neurological complications, between the ages of 6 and 12 months. Visuo-manual integration and grasping were assessed using the Peabody Developmental Motor Scales, along with bimanual coordination and handedness tests. Visual function was examined once prior to the beginning of the study. Gross motor development was also evaluated every month. Preterm infants were compared to a control group of ten full-term infants according to corrected age. Compared to full-terms, the visual perception of preterm infants was close to normal, with only a measure of visual fixation lower than in full-terms. In contrast, preterm infants had delayed development of visuo-manual integration, grasping, bimanual coordination, and handedness even when compared using corrected age. Tonicity and gestational age at birth were the main variables associated to the delays. These results are discussed in terms of the possible factors underlying such delays. They need to be confirmed on a larger sample of preterm born children, and to be correlated with later development. This would allow developing markers of future neuropsychological impairments during childhood.

This fMRI study investigates the activation of the thalamic nuclei in a spatial focusing-of-attention task previously shown to activate the pulvinar with FDG-PET and assesses the connectivity of the thalamic nuclei with cortical areas. Normal right-handed subjects (eight men, eight women, average age=32 years) viewed four types of stimuli positioned to the right or left of the central fixation point (left hemifield-large letter, left hemifield-small letter display with flanking letters; right hemifield-large letter, right hemifield-small letter display with flankers). BOLD responses to small letters surrounded by flankers were compared with responses to large isolated letters. To examine maximum functional regional connectivity, we modeled "subject" as a random effect and attained fixed effect parameter estimates and t-statistics for functional connectivity between each of the thalamic nuclei (pulvinar, medial dorsal, and anterior) as the seed region and each non-seed voxel. Greater BOLD activation for letters surrounded by flankers than for large letters was observed in the pulvinar as anticipated and was also marked in the medial dorsal nucleus (MDN), anterior and superior cingulate (BA24 and BA24'), dorsolateral prefrontal cortex, and frontal operculum and insula. For the MDN, maximal functional connectivity was with the dorsolateral prefrontal cortex; correlations with left superior temporal, parietal, posterior frontal, and occipital regions were also observed. For the pulvinar, maximal functional connectivity was with parietal BA39; for anterior thalamus, with anterior cingulate.

A prospective study on childhood craniopharyngiomas (CPs) was conducted from 1994 to 1998 to appreciate the pre- and postoperative clinical, endocrine, mental, and intellectual status of the patients and to determine the incidence and severity of the postoperative hypothalamic syndrome. The series included 14 consecutive CPs. Twelve were retrochiasmatic and intraventricular, and two were partly prechiasmatic and extraventricular. All were treated with the aim of “total” removal. The removal was “total” in nine cases but incomplete in the other five. Immediate postoperative follow-up was uncomplicated in all cases. At 2-year follow-up, the two children with an extraventricular CP and a “total” tumor removal were intellectually normal, had no hypothalamic syndrome, and attended normal school with good results. The 12 others, although still intellectually normal, were more or less severely affected by a hypothalamic syndrome which altered their social insertion and caused academic failure. The authors conclude from this study that radical surgery should be reserved to extraventricular CPs only.

Objectives: The lack of agreement regarding assessment methods is responsible for the variability in the reported rate of occurrence of spatial neglect after stroke. The aim of this study was to assess the sensitivity of different tests of neglect after right hemisphere stroke. Methods: Two hundred and six subacute right hemisphere stroke patients were given a test battery including a preliminary assessment of anosognosia and of visual extinction, a clinical assessment of gaze orientation and of personal neglect, and paper and pencil tests of spatial neglect in the peripersonal space. Patients were compared with a previously reported control group. A subgroup of patients (n=69) received a behavioural assessment of neglect in daily life situations. Results: The most sensitive paper and pencil measure was the starting point in the cancellation task. The whole battery was more sensitive than any single test alone. About 85% of patients Presented some degree of neglect on at least one measure. An important finding was that behavioural assessment of neglect in daily life was more sensitive than any other single measure of neglect. Behavioural neglect was considered as moderate to severe in 36% of cases. A factorial analysis revealed that paper and pencil tests were related to two underlying factors. Dissociations were found between extrapersonal neglect, personal neglect, anosognosia, and extinction. Anatomical analyses showed that neglect was more common and severe when the posterior association cortex was damaged. Conclusions: The automatic rightward orientation bias is the most sensitive clinical measure of neglect. Behavioural assessment is more sensitive than any single paper and pencil test. The results also support the assumption that neglect is a heterogeneous disorder.

International audience; In order to further our understanding of actionblindsight, four hemianopic patients suffering from visual field loss contralateral to a unilateral occipital lesion were compared to six healthy controls during a double task of verbally reported target detection and saccadic responsestoward the target. Three oculomotor tasks were used: a fixation task (i.e., without saccade) and two saccade tasks (eliciting reflexive and voluntary saccades, using step and overlap 600 ms paradigms, respectively), in separate sessions. The visual target was briefly presented at two different eccentricities (5° and 8°), in the right or left visual hemifield. Blank trials were interleaved with target trials, and signal detection theory was applied. Despite their hemifield defect, hemianopic patients retained the ability to direct a saccade toward their contralesional hemifield, whereas verbal detection reports were at chance level. however, saccade parameters (latency and amplitude) were altered by the defect. saccades to the contralesional hemifield exhibited longer latencies and shorter amplitudes compared to those of the healthy group, whereas only the latencies of reflexive saccades to the ipsilesional hemifield were altered. Furthermore, healthy participants showed the expected latency difference between reflexive and voluntary saccades, with the latter longer than the former. this difference was not found in three out of four patients in either hemifield. Our results show action-blindsight for saccades, but also show that unilateral occipital lesions have effects on saccade generation in both visual hemifields.

Normal subjects and patients with right hemisphere lesions with or without signs of left unilateral neglect judged the length of a horizontal line presented on the left or on the right side of space. In half of the trials, the line was presented with a centrally located square or diamond, and subjects had to identify the central stimulus before performing the judgment of length. The presence of the central stimulus improved accuracy of performance in controls and in patients without neglect; neglect patients, however, produced more overestimations of left-sided lines when these was presented with a central stimulus than when the lines occurred in isolation. This finding underlines the importance of attentional factors in length estimates performed by neglect patients in their neglected space.

Left unilateral neglect is a neurological condition characterized by an impairment in orienting and responding to events occurring on the left side. To gain insight into the brain mechanisms of space processing and to provide theoretical foundations for patient rehabilitation, it is important to explore the attentional bias shown by neglect patients in the light of existing models of normal attentional orienting. Three experiments tested the hypothesis that attentional bias in neglect involves primarily exogenous, or stimulus-based, orienting of attention, with relatively preserved endogenous, or voluntary, orienting. Six patients with right hemisphere damage and left unilateral neglect and 18 age-matched participants without brain damage performed a cued reaction time (RT) task to targets which could appear in one of two lateral boxes. Cues consisted of a brief brightening of the contour of one of the boxes. The target followed the cue at 150, 550, or 1000 ms stimulus-onset asynchrony (SOA). In experiment 1, the cues were not informative about the future location of the target, and thus elicited a purely exogenous orienting of attention. Controls showed slowed RTs to the cued locations at SOAs > 150 ms, consistent with the notion of inhibition of return (IOR). Neglect patients had no evidence of IOR for right targets; they showed a disproportionate cost for left targets preceded by right (invalid) cues; this cost was maximal at the shortest SOA, consistent with the idea of a biased exogenous orienting in neglect. In experiment 2, 80% of the cues were valid (i.e., they correctly predicted the location of the impending target), thus inducing an initially exogenous, and later endogenous, attentional shift toward the cued box. Neglect patients showed again a cost for left invalidly cued targets, which this time persisted at SOAs > 150 ms, as if patients' attention had been cued to the right side not only exogenously, but also endogenously, thus rendering more difficult an endogenous reorienting toward the left. In experiment 3, only 20% of the cues were valid, so that the best response strategy was to endogenously orient attention toward the box opposite to the cued one. Controls were able to take advantage of invalid cues to rapidly respond to targets. In this condition, neglect patients were able to nullify their spatial bias; they achieved their fastest RTs to left targets, which were in the range of their RTs to right targets. However, for neglect patients fast responses to left targets occurred only at 1000 ms SOA, while controls were able to redirect their attention to the uncued box already at 550 ms SOA. Altogether, these results suggest that endogenous orienting is relatively spared, if slowed, in unilateral neglect.

A letter-identification task, previously demonstrated to show activation of the pulvinar nucleus of the thalamus with fluodeoxyglucose position emission tomography, was administered to 20 normal volunteers. The letter to be detected could appear alone as a big stimulus or as a small one stimulus surrounded by flanking letters. To test for a hemispheric specialization for filtering processes, the stimuli were displayed horizontally, either in the left or in the right hemifield, or vertically, either above or below the fixation point. In addition, to study the effect of cognitive processes on selective attention resources, we varied the feedback conditions, by delivering or not delivering a blue flash in cases of misses or mistakes. The results show a significant interaction between the type of stimulus (alone or surrounded by flankers) and the hemifield of presentation (left or right) only in the condition where the subjects were presented stimuli horizontally without any feedback. In this condition, reaction times (RTs) were shorter in the left hemifield than in the right hemifield for single stimuli, whereas for stimuli surrounded by flankers, the opposite pattern was observed, that is, shorter RT in the right hemifield than in the left one. The present findings suggest a hemispheric specialization for selective attention, in particular at the subcortical level.

Whole blood coagulation analysers are widely used during percutaneous coronary interventions. The precise degree of anticoagulation in patients is important in this setting. The aim of this investigation was to compare the results obtained with ACT (Hemochron) and HMT, the Heparin Management Test (TAS) in patients undergoing percutaneous coronary interventions. Patients ( n =100) were enrolled prospectively. Each patient received 10,000 units of heparin. At the end of the procedure, the mean ACT was 284±31 seconds and the mean HMT was 292±33 seconds. The correlation between the two methods was highly significant ( r =0.64, p

Objective: To identify the source of delayed visual evoked potential (VEP) latencies in the fellow eyes of patients with optic neuritis (ON) and determine whether these latencies stem from clinically silent demyelination or reflect an adaptive process for synchronization with the affected eyes. Methods: The study sample comprised 17 patients whom we followed for 12 to 26 months after unilateral first-ever ON diagnosis and 17 age-matched controls. To avoid confounding effects of axonal loss, only intact fellow eyes (except for VEPs) were included. Subjects underwent standard visual evaluation, motion perception, as well as static and time-constrained stereo tasks. Assessments included VEP, optical coherence tomography, high-resolution MRI, and diffusion tensor imaging. Results: We observed delayed VEP peaks (P100) in both affected and fellow eyes. However, while these were derived from prolonged time-to-start in the affected eyes, supporting the existence of demyelination, time-to-start in the fellow eyes was intact. VEP latencies in the fellow eyes could not be explained by demyelinative lesions along postchiasmal pathways (assessed by diffusion tensor imaging). Delayed peaks in fellow eyes resulted from a wider waveform, which evolved over time and occurred with a concomitant decrease in the gap in time between VEP peaks of both eyes. These changes offered a functional advantage; synchronization of inputs highly correlated with improved time-constrained binocular perception. Conclusion: Delayed latencies in the fellow eyes may reflect adaptive mechanisms at the cortical level that improve binocular integration over time to adjust for the damage incurred. These data provide a unique demonstration of temporal reorganization that compensates for delayed transmittal of visual information to the cortex.

Many studies have examined effects of prenatal stress on pregnancy and fetal development, especially on prematurity and birthweight, and more recently long-term effects on child behavioral and emotional development. These studies are reviewed and their limitations are discussed with regard to definitions (including the concepts of stress and anxiety), stress measurements, samples, and control for confounds such as depression. It appears necessary to assess individual stress reactivity prospectively and separately at each trimester of pregnancy, to discriminate chronic from acute stress, and to take into consideration moderator variables such as past life events, sociocultural factors, predictability, social support and coping strategies. Furthermore, it might be useful to examine simultaneously, during but also after pregnancy, stress, anxiety and depression in order to understand better their relationships and to evaluate their specific effects on pregnancy and child development. Finally, further research could benefit from an integrated psychological and biological approach studying together subjective perceived stress and objective physiological stress responses in pregnant women, and their effects on fetal and child development as well as on mother-infant interactions.

In order to study the effect of normal aging and cardiovascular disease on selective attention, a letter-identification task was proposed to younger and older healthy adults as well as patients with a recent myocardial infarction or a recent coronary artery bypass grafting. Participants had to detect either a big stimulus or a small one surrounded by flanking letters. The stimuli were displayed horizontally, either in the left (LVF) or in the right visual field (RVF). The interaction between the type of stimulus and the hemifield of presentation reached significance in all groups except in patients who underwent a coronary artery bypass. Only young normal adults showed the expected significant RVF advantage when detecting big stimuli and an LVF advantage when detecting small stimuli surrounded by flankers. In older control adults and in patients with myocardial infarction, the RVF advantage for the condition with selective attention vanished. In patients who underwent a coronary artery bypass, reaction times were increased and no hemispheric specialization for selective attention emerged. The results are discussed with regard to the hypothesis of a Hemispheric Asymmetry Reduction in Older Adults (HAROLD model) and to the presence of cognitive dysfunction consecutive to cardiovascular disease.

Thirty normal subjects and a patient with a left unilateral neglect were submitted to a straight-ahead pointing task in the three following trunk orientations: head and trunk aligned at 0 degree, and trunk rotated 15 degrees to the left or to the right relative to the head. The position of the egocentric reference was found to be dependent upon the trunk orientation, lateralization of the motor response and starting position, and thus on motor direction. The results are discussed with regard to egocentric hypotheses of neglect, spatio-motor cueing and scanning direction.

The aim of this study was to explore the visuo-attentional skills of children with an ophthalmic disorder. Twenty-four patients and 60 healthy controls between the ages 4 and 7 years, all right-handed with normal or corrected-to-normal close visual acuity, were divided into four age groups. Patients' diagnoses included refractive disorders (e.g., myopia, hypermetropia), strabismus, amblyopia, cataract, and nystagmus. All participants performed nine paper-and-pencil visuospatial tasks aiming to assess selective attention (cancellation tasks), spatial working memory (symbol orientation task), fine visual analysis (embedded figures test), and simple perceptual analysis (shape-matching task). In healthy children, the results showed that performance on all visuo-attentional tasks improved with age. While perception, orientation of attention, and visual working memory develop by the time children begin school (age 5), more sophisticated abilities such as attention disengagement and motor control continue to develop during late childhood. Moreover, a spatial bias in attention orienting appeared with reading acquisition (6-7 years). In ophthalmic children, at 4 years of age defects were observed in all assessed functions, but at 7 years an attentional deficit was virtually the only one remaining. Overall, the results demonstrate that children with an ophthalmologic disorder may experience difficulties with visuospatial tasks despite corrected-to-normal visual acuity.

International audience; Theories on visual perception agree that visual recognition begins with global analysis and ends with detailed analysis. Different results from neurophysiological, computational, and behavioral studies all indicate that the totality of visual information is not immediately conveyed, but that information analysis follows a predominantly coarse-to-fine processing sequence (low spatial frequencies are extracted first, followed by high spatial frequencies). We tested whether such processing continues to occur in normally aging subjects. Young and aged participants performed a categorization task (indoor vs. outdoor scenes), using dynamic natural scene stimuli, in which they resorted to either a coarse-to-fine (CtF) sequence or a reverse fine-to-coarse sequence (FtC). The results show that young participants categorized CtF sequences more quickly than FtC sequences. However, sequence processing interacts with semantic category only for aged participants. The present data support the notion that CtF categorization is effective even in aged participants, but is constrained by the spatial features of the scenes, thus highlighting new perspectives in visual models.

International audience; Cerebrovascular disease is recognized as a common cause of cognitive impairment and dementia, alone or coexisting with other neurodegenerative diseases, mostly Alzheimer's disease. Vascular cognitive impairment (VCI) is a part of the heterogenous disorders group related to cerebral vessel disease. Although age is one of the most important risk factors for VCI, other common cardiovascular risk factors are also involved. By investigating these risk factors, a high proportion of these cognitive disorders can be prevented and/or delayed. Until now, only treatment of rnidlife arterial hypertension has been recognized as a preventing factor of vascular dementia. Brain MRI is becoming the method of choice to investigate cerebral vascular pathologies. However, this form of morphological imaging remains inadequate and does not provide useful functional information during VCI exploration, despite which functional imaging such as brain perfusion single-photon computed tomography, performed in baseline conditions and/or after an acetazolamide challenge, is underutilized in VCI exploration. The common strategies for VCI screening have not been standardized until now, and therefore further long-term imaging studies are needed to establish early diagnostic protocols. The present review summarizes the potential benefits of brain perfusion single-photon computed tomography imaging and possible scintigraphic quantification of cerebral hemodynamic reserves in investigation of VCI. Nucl Med Commun 33:571-580 (c) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.