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Significance: High-density diffuse optical tomography (HD-DOT) has been shown to approach the resolution and localization accuracy of blood oxygen level dependent-functional magnetic resonance imaging in the adult brain by exploiting densely spaced, overlapping samples of the probed tissue volume, but the technique has to date required large and cumbersome optical fiber arrays. Aim: To evaluate a wearable HD-DOT system that provides a comparable sampling density to large, fiber-based HD-DOT systems, but with vastly improved ergonomics. Approach: We investigated the performance of this system by replicating a series of classic visual stimulation paradigms, carried out in one highly sampled participant during 15 sessions to assess imaging performance and repeatability. Results: Hemodynamic response functions and cortical activation maps replicate the results obtained with larger fiber-based systems. Our results demonstrate focal activations in both oxyhemoglobin and deoxyhemoglobin with a high degree of repeatability observed across all sessions. A comparison with a simulated low-density array explicitly demonstrates the improvements in spatial localization, resolution, repeatability, and image contrast that can be obtained with this high-density technology. Conclusions: The system offers the possibility for minimally constrained, spatially resolved functional imaging of the human brain in almost any environment and holds particular promise in enabling neuroscience applications outside of the laboratory setting. It also opens up new opportunities to investigate populations unsuited to traditional imaging technologies.

Dyslexia has been associated with a problem in visual–audio integration mechanisms. Here, we investigate for the first time the contribution of unisensory cues on multisensory audio and visual integration in 32 dyslexic children by modelling results using the Bayesian approach. Non‐linguistic stimuli were used. Children performed a temporal task: they had to report whether the middle of three stimuli was closer in time to the first one or to the last one presented. Children with dyslexia, compared with typical children, exhibited poorer unimodal thresholds, requiring greater temporal distance between items for correct judgements, while multisensory thresholds were well predicted by the Bayesian model. This result suggests that the multisensory deficit in dyslexia is due to impaired audio and visual inputs rather than impaired multisensory processing per se. We also observed that poorer temporal skills correlated with lower reading skills in dyslexic children, suggesting that this temporal capability can be linked to reading abilities., Multisensory audio visual processing in dyslexia is due to impaired audio and visual inputs rather than impaired multisensory processing per se.

Motor experiences and active exploration during early childhood may affect individual differences in a wide range of perceptual and cognitive abilities. In the current study, we suggest that active exploration of objects facilitates the ability to process object forms and magnitudes, which in turn impacts the development of numerosity perception. We tested our hypothesis by conducting a preregistered active exploration intervention with 59 8‐month‐old infants. The minimal intervention consisted of actively playing with and exploring blocks once a day for 8 weeks. In order to control for possible training effects on attention, we used book reading as a control condition. Pre‐ and post‐test assessments using eye‐tracking showed that block play improved visual form perception, where infants became better at detecting a deviant shape. Furthermore, using three control tasks, we showed that the intervention specifically improved infants' ability to process visual forms and the effect could not be explained by a domain general improvement in attention or visual perception. We found that the intervention did not improve numerosity perception and suggest that because of the sequential nature of our hypothesis, a longer time frame might be needed to see improvements in this ability. Our findings indicate that if infants are given more opportunities for play and exploration, it will have positive effects on their visual form perception, which in turn could help their understanding of geometrical concepts., Playing with blocks leads 8‐month‐old infants to develop better visual form perception, conceptualized here as detecting a deviant shape, compared to infants who were assigned to a reading control group.

Background: Patients with homonymous hemianopia often have some residual sensitivity for visual stimuli in their blind hemifield. Previous imaging studies suggest an important role for extrastriate cortical areas in such residual vision, but results of training to improve vision in patients with hemianopia are conflicting. Objective: To show that intensive training with flicker stimulation in the chronic stage of stroke can reorganise visual cortices of an adult patient. Methods: A 61-year-old patient with homonymous hemianopia was trained with flicker stimulation, starting 22 months after stroke. Changes in functioning during training were documented with magnetoencephalography, and the cortical organisation after training was examined with functional magnetic resonance imaging (fMRI). Results: Both imaging methods showed that, after training, visual information from both hemifields was processed mainly in the intact hemisphere. The fMRI mapping results showed the representations of both the blind and the normal hemifield in the same set of cortical areas in the intact hemisphere, more specifically in the visual motion-sensitive area V5, in a region around the superior temporal sulcus and in retinotopic visual areas V1 (primary visual cortex), V2, V3 and V3a. Conclusions: Intensive training of a blind hemifield can induce cortical reorganisation in an adult patient, and this case shows an ipsilateral representation of the trained visual hemifield in several cortical areas, including the primary visual cortex.

Background: Mild cognitive impairment (MCI) has been considered a transitional state between normal aging and dementia, characterised by memory impairment but normal general cognitive functioning. Recently other cognitive deficits have been reported. This has led to a modification of MCI criteria. Objective: To examine which neuropsychological tests most clearly distinguish MCI subjects from normal controls. Methods: 112 consecutive MCI subjects and 35 controls were included in the study. The diagnosis of MCI was based on an objective history of cognitive decline and a neuropsychiatric examination, comprising instruments STEP, I-Flex, MMSE, and CDR. Participants were examined with 21 neuropsychological tests in the cognitive domains speed/attention, memory and learning, visuospatial function, language, and executive function. Results: Controls were significantly older. No differences were found in education or general intellectual capacity. Controls performed significantly better than MCI on tests within all five cognitive domains. The clearest differences were seen on language tests, followed by executive function, and learning and memory. Only two subjects (1.8%) were purely amnestic; 17% showed no impairment compared with controls, with a cut off of 1.5 SD below age mean. These subjects were better educated and performed significantly better on measures of general cognitive capacity. Conclusions: The results illustrate the heterogeneity of MCI, with a significant degree of impairment in all five cognitive domains. When examined with a comprehensive neuropsychological battery, very few subjects had an isolated memory impairment.

Objective: To assess visual search and recognition of roadside targets and safety errors during a landmark and traffic sign identification task in drivers with Alzheimer's disease. Methods: 33 drivers with probable Alzheimer's disease of mild severity and 137 neurologically normal older adults underwent a battery of visual and cognitive tests and were asked to report detection of specific landmarks and traffic signs along a segment of an experimental drive. Results: The drivers with mild Alzheimer's disease identified significantly fewer landmarks and traffic signs and made more at-fault safety errors during the task than control subjects. Roadside target identification performance and safety errors were predicted by scores on standardised tests of visual and cognitive function. Conclusions: Drivers with Alzheimer's disease are impaired in a task of visual search and recognition of roadside targets; the demands of these targets on visual perception, attention, executive functions, and memory probably increase the cognitive load, worsening driving safety.

Objective: To investigate the role right foveal/parafoveal sparing plays in reading single words, word arrays, and eye movement patterns in a single case with an incongruous hemianopia. Methods: The patient, a 48 year old right handed male with a macular sparing hemianopia in his left eye and a macular splitting hemianopia in his right eye, performed various reading tasks. Single word reading speeds were monitored using a "voice-trigger" system. Eye movements were recorded while reading three passages of text, and PET data were gathered while the subject performed a variety of reading tasks in the camera. Results: The patient was faster at reading single words and text with his left eye compared with his right. A small word length effect was present in his right eye but not his left. His eye movement patterns were more orderly when reading text with his left eye, making fewer saccades. The PET data provided evidence of "top-down" processes involved in reading. Binocular single word reading produced activity in the representation of foveal V1 bilaterally; however, text reading with the left eye only was associated with activation in left but not right parafoveal V1, despite there being visual stimuli in both visual fields. Conclusions: The presence of a word length effect (typically associated with pure alexia) can be caused by a macular splitting hemianopia. Right parafoveal vision is not critically involved in single word identification, but is when planning left to right reading saccades. The influence of top-down attentional processes during text reading can be visualised in parafoveal V1 using PET.

Multisensory information has been shown to modulate attention in infants and facilitate learning in\ud adults, by enhancing the amodal properties of a stimulus. However, it remains unclear whether this\ud translates to learning in a multisensory environment across middle childhood, and particularly in the\ud case of incidental learning. One hundred and eighty-one children aged between 6 and 10 years\ud participated in this study using a novel Multisensory Attention Learning Task (MALT). Participants\ud were asked to respond to the presence of a target stimulus whilst ignoring distractors. Correct target\ud selection resulted in the movement of the target exemplar to either the upper left or right screen\ud quadrant, according to category membership. Category membership was defined either by visual-only,\ud auditory-only or multisensory information. As early as 6 years of age, children demonstrated greater\ud performance on the incidental categorization task following exposure to multisensory audiovisual\ud cues compared to unisensory information. These findings provide important insight into the use of\ud multisensory information in learning, and particularly on incidental category learning. Implications\ud for the deployment of multisensory learning tasks within education across development will be\ud discussed.

Objectives: Visuospatial deficits have been occasionally reported but never systematically studied in atypical parkinsonian syndromes. The interpretation of existing studies is complicated by the possible influence of motor and frontal executive deficits. Moreover, no attempt has been made to distinguish visuoperceptual from visuospatial tasks. The aim of the present study was to assess visuoperceptual and visuospatial abilities in three atypical parkinsonian syndromes while minimising the influence of confounding variables. Methods: Twenty patients with multiple system atrophy (MSA), 43 with progressive supranuclear palsy (PSP), and 25 with corticobasal degeneration (CBD) as well as 30 healthy age matched controls were examined with the Visual Object and Space Perception Battery (VOSP). Results: Visuospatial functions were intact in MSA patients. PSP patients showed mild deficits related to general cognitive decline and the severity of oculomotor symptoms. The CBD group showed the most pronounced deficits, with spatial tasks more impaired than object based tasks. Performance on object based, but not spatial, tasks was related to general cognitive status. The extent of the visuospatial impairment could not be predicted from disease duration or severity. Conclusion: Visuospatial functions are not consistently impaired in atypical parkinsonian syndromes. The degree and pattern of impairment varies across the diseases, suggesting that the observed deficits could have a different neural basis in each condition. The distinction between the object based (“ventral stream”) and the space oriented (“dorsal stream”) processing might be useful in the interpretation of visuospatial deficits in parkinsonian syndromes, especially in CBD.

Purpose This study investigated whether computers are a useful tool in the assessment of people with aphasia (PWA). Computerized and traditionally administered versions of tasks were compared to determine whether (a) the scores were equivalent, (b) the administration was comparable, (c) variables such as age affected performance, and (d) the participants' perceptions of the computerized and traditionally administered versions of the tasks were similar. Method Fifteen PWA were assessed on 2 language tasks—sentence-picture matching and grammaticality judgment—in 3 conditions: computer only, computer with the clinician present, and traditional. The participants also completed questionnaires rating aspects of each condition. Results Scores from the traditionally administered tasks were highly correlated with those from the computerized tasks, but scores from the computerized tasks were significantly lower. There was no significant difference in the time taken between the conditions. Whereas some individuals felt comfortable with the computer, overall, participants preferred the traditional assessment method or when another person was in the room. No factors were identified that predicted participants' relative performance in the computer condition. Conclusion The results suggest that PWA can be assessed using computerized versions of tasks, but that caution should be exercised when comparing scores to those collected using traditional methods, including norms. The variation in participants' opinions regarding computerized tasks suggests that this method might be more suitable for some participants than others.

Being able to see a talking face confers a considerable advantage for speech perception in adulthood. However, behavioural data currently suggest that children fail to make full use of these available visual speech cues until age 8 or 9. This is particularly surprising given the potential utility of multiple informational cues during language learning. We therefore explored this at the neural level. The event-related potential (ERP) technique has been used to assess the mechanisms of audio-visual speech perception in adults, with visual cues reliably modulating auditory ERP responses to speech. Previous work has shown congruence-dependent shortening of auditory N1/P2 latency and congruence-independent attenuation of amplitude in the presence of auditory and visual speech signals, compared to auditory alone. The aim of this study was to chart the development of these well-established modulatory effects over mid-to-late childhood. Experiment 1 employed an adult sample to validate a child-friendly stimulus set and paradigm by replicating previously observed effects of N1/P2 amplitude and latency modulation by visual speech cues; it also revealed greater attenuation of component amplitude given incongruent audio-visual stimuli, pointing to a new interpretation of the amplitude modulation effect. Experiment 2 used the same paradigm to map cross-sectional developmental change in these ERP responses between 6 and 11 years of age. The effect of amplitude modulation by visual cues emerged over development, while the effect of latency modulation was stable over the child sample. These data suggest that auditory ERP modulation by visual speech represents separable underlying cognitive processes, some of which show earlier maturation than others over the course of development.

Background: A fundamental feature underlying many movement disorders is increased variability in the motor response. Despite abnormalities of grip force control in people with dystonia, it is not clear whether dystonia is also associated with increased variability in force output and whether force variability in dystonia is affected by the presence or absence of visual feedback. Objective: To examine force variability in 16 patients with writer's cramp and 16 matched controls. Methods: The variability of force output at the wrist under conditions of both vision and no vision was examined. The underlying frequency structure of the force signal was also compared across groups. Participants produced isometric wrist flexion to targets at 25% and 50% of their maximum voluntary contraction strength under conditions of both vision and no vision. Results: Similar levels of force variability were observed in patients with dystonia and controls at the lower force levels, but patients with dystonia were less variable in their force output than controls at the higher force level. This reduction in variability in people with dystonia at 50% maximum voluntary contraction was not affected by vision. Although a similar dominant frequency in force output was observed in people with dystonia and controls, a reduced variability in the group with dystonia at the higher force level was due to reduced power in the 0-4-Hz frequency bin. Conclusions: The first evidence of a movement disorder with reduced variability is provided. The findings are compatible with a model of dystonia, which includes reduced cortical activation in response to sensory input from the periphery and reduced flexibility in motor output.

Objective: To assess cognitive function in variant Creutzfeldt-Jakob disease (vCJD). We describe the neuropsychological profiles of 10 cases and compare these data with cross sectional data obtained from patients with histologically confirmed sporadic CJD and cases with inherited prion disease with confirmed mutations in the prion protein gene. Methods: Patients referred to the Specialist Cognitive Disorders Clinic at the National Hospital for Neurology and Neurosurgery and the National Prion Clinic at St Mary's Hospital, London for further investigation of suspected CJD were recruited into the study. The neuropsychological test battery evaluated general intelligence, visual and verbal memory, nominal skills, literacy skills, visual perception and visuospatial functions, and visuospatial and executive function. Results: The results indicate that moderate to severe cognitive decline is a characteristic feature of vCJD. Specifically, verbal and visual memory impairments and executive dysfunction were pervasive in all disease groups. Nominal skills were impaired in variant and sporadic CJD, significantly so when compared with the inherited prion disease group. Perceptual impairment was less frequent in the vCJD group than in the sporadic and inherited groups. Conclusion: This study confirms the occurrence of generalised cognitive decline in patients with vCJD. Although decline in cognitive function ultimately affects all domains, there is a suggestion that some components of visual perception may be spared in vCJD. The results also suggest that nominal function may be preserved in some cases with inherited prion disease.

Background:The term "posterior cortical atrophy" (PCA) refers to a clinical syndrome in which higher order visual processing is disrupted owing to a neurodegenerative disorder, the most commonly associated pathology being Alzheimer's disease. Objective:To map the topography of hypometabolic brain regions in a group of subjects with PCA who had undergone detailed neuropsychological characterisation. Methods:Resting cerebral metabolism was measured with (18F)fluorodeoxyglucose-positron emission tomography (FDG-PET) in patients with PCA (n = 6), typical Alzheimer's disease (n = 10), and healthy controls (n = 10). The data were analysed using statistical parametric mapping (SPM99) and region of interest techniques. Results:Clinically, the PCA subjects showed predominant visuospatial deficits (including features of Balint's syndrome) consistent with damage to the dorsal stream of visual processing. Compared with the controls, the PCA group showed marked glucose hypometabolism primarily affecting the posterior cerebral hemispheres (right worse than left). In addition, the PCA group showed two symmetrical areas of hypometabolism in the region of the frontal eye fields. Compared with typical Alzheimer's disease, the PCA group had selective hypometabolism in the occipito-parietal region (right much worse than left). Conclusions:The neuropsychological and PET findings are consistent with damage predominantly to the dorsal stream of visual processing. Frontal eye field hypometabolism secondary to loss of input from the occipito-parietal region may be the mechanism for the ocular apraxia seen in Balint's syndrome.

This study explores three formats for the presentation of tangible line graphs to visually handicapped people, using the capsule-paper production process. The formats are L/no-grid (standard x and y axes/data curves on smooth background), box/no-grid (duplicated axes enclose graph space on all four sides/smooth background), and box/grid (duplicated axes/data curves superimposed on grid). Subjects answered questions concerning the coordinate value of points, the difference in coordinate value between two points, and configurational aspects of the data. Questions that involved determining coordinate values were answered most accurately from the box/grid format, followed by the box/no-grid, and, lastly, the L/no-grid. Response times did not differ. A different pattern emerged with questions concerning configurational aspects of the graph. With these there was no difference in accuracy between the formats, but the L/no-grid format led to faster responding than the box/no-grid, which in turn was faster than the box/grid. The practical implications of these data are considered.