38 results
Search Results
2. Evaluating a new generation of wearable high-density diffuse optical tomography technology via retinotopic mapping of the adult visual cortex
- Author
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Samuel Powell, Reuben Nixon-Hill, Luke Dunne, Gregory G. Smith, Nick Everdell, Ernesto E. Vidal-Rosas, Robert J. Cooper, and Hubin Zhao
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Paper ,Optical fiber ,Visual perception ,Computer science ,Neuroscience (miscellaneous) ,wearable ,law.invention ,law ,medicine ,functional near-infrared spectroscopy ,Radiology, Nuclear Medicine and imaging ,Computer vision ,Radiological and Ultrasound Technology ,business.industry ,3D modeling ,Research Papers ,Diffuse optical imaging ,Visualization ,Functional imaging ,Visual cortex ,medicine.anatomical_structure ,high-density diffuse optical tomography ,Radiology Nuclear Medicine and imaging ,short-separation regression ,Functional near-infrared spectroscopy ,visual stimuli ,Artificial intelligence ,business - Abstract
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.
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- 2021
3. Bridging sensory and language theories of dyslexia: Toward a multifactorial model
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Jason D. Yeatman and Gabrielle O'Brien
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Paper ,Cognitive Neuroscience ,media_common.quotation_subject ,deficit ,Sensory system ,Biological theories of dyslexia ,050105 experimental psychology ,Visual processing ,Dyslexia ,Cognition ,psychophysics ,Phonetics ,Reading (process) ,Perception ,Developmental and Educational Psychology ,medicine ,Psychophysics ,Humans ,0501 psychology and cognitive sciences ,10. No inequality ,Child ,media_common ,Language ,learning ,05 social sciences ,phonological ,Statistical model ,medicine.disease ,Reading ,Papers ,Visual Perception ,visual ,Psychology ,050104 developmental & child psychology ,Cognitive psychology - Abstract
Competing theories of dyslexia posit that reading difficulties arise from impaired visual, auditory, phonological, or statistical learning mechanisms. Importantly, many theories posit that dyslexia reflects a cascade of impairments emanating from a single “core deficit”. Here we report two studies evaluating core deficit and multifactorial models. In Study 1, we use publicly available data from the Healthy Brain Network to test the accuracy of phonological processing measures for predicting dyslexia diagnosis and find that over 30% of cases are misclassified (sensitivity = 66.7%; specificity = 68.2%). In Study 2, we collect a battery of psychophysical measures of visual motion processing and standardized measures of phonological processing in 106 school‐aged children to investigate whether dyslexia is best conceptualized under a core‐deficit model, or as a disorder with heterogenous origins. Specifically, by capitalizing on the drift diffusion model to analyze performance on a visual motion discrimination experiment, we show that deficits in visual motion processing, perceptual decision‐making, and phonological processing manifest largely independently. Based on statistical models of how variance in reading skill is parceled across measures of visual processing, phonological processing, and decision‐making, our results challenge the notion that a unifying deficit characterizes dyslexia. Instead, these findings indicate a model where reading skill is explained by several distinct, additive predictors, or risk factors, of reading (dis)ability., Using predictors from a visual motion processing experiment and linguistic measures, we show that a single‐mechanism model of reading disability cannot account for the range of linguistic and sensory processing outcomes observed in children. We propose an additive risk factor model where different aspects of sensory, cognitive and language function each contribute independently to reading development.
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- 2020
4. Temporal representation impairment in developmental dyslexia for unisensory and multisensory stimuli
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Monica Gori, Kinga M. Ober, Olivier A. Coubard, and Francesca Tinelli
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Male ,Paper ,Auditory perception ,medicine.medical_specialty ,Visual perception ,Cognitive Neuroscience ,media_common.quotation_subject ,integration ,Development ,Audiology ,Bayesian ,behavioral disciplines and activities ,050105 experimental psychology ,Dyslexia ,Judgment ,Bayes' theorem ,Reading (process) ,Developmental and Educational Psychology ,medicine ,Humans ,0501 psychology and cognitive sciences ,Child ,Association (psychology) ,media_common ,Multisensory ,05 social sciences ,Representation (systemics) ,Bayes Theorem ,medicine.disease ,Reading ,Audio ,Papers ,Auditory Perception ,Visual Perception ,Female ,Cues ,Visual ,Psychology ,Reading skills ,050104 developmental & child psychology - Abstract
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.
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- 2020
5. The right hemispheric dominance for face perception in preschool children depends on the visual discrimination level
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Bruno Rossion, Christine Schiltz, Aliette Lochy, University of Luxembourg [Luxembourg], Université du Luxembourg (Uni.lu), Université Catholique de Louvain = Catholic University of Louvain (UCL), Centre de Recherche en Automatique de Nancy (CRAN), and Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
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Paper ,Adult ,Male ,medicine.medical_specialty ,preschool children ,Cognitive Neuroscience ,Population ,Audiology ,Electroencephalography ,050105 experimental psychology ,Lateralization of brain function ,Functional Laterality ,[SCCO]Cognitive science ,Discrimination, Psychological ,Face perception ,Developmental and Educational Psychology ,medicine ,Humans ,0501 psychology and cognitive sciences ,FPVS–EEG ,10. No inequality ,education ,Child ,Cerebrum ,ComputingMilieux_MISCELLANEOUS ,Cerebral Cortex ,education.field_of_study ,right hemisphere ,medicine.diagnostic_test ,05 social sciences ,Brain ,Human brain ,discrimination level ,medicine.anatomical_structure ,faces ,Scalp ,Visual discrimination ,Child, Preschool ,Papers ,FPVS-EEG ,Visual Perception ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Written language ,Female ,Psychology ,Facial Recognition ,Photic Stimulation ,050104 developmental & child psychology - Abstract
The developmental origin of human adults’ right hemispheric dominance in response to face stimuli remains unclear, in particular because young infants’ right hemispheric advantage in face‐selective response is no longer present in preschool children, before written language acquisition. Here we used fast periodic visual stimulation (FPVS) with scalp electroencephalography (EEG) to test 52 preschool children (5.5 years old) at two different levels of face discrimination: discrimination of faces against objects, measuring face‐selectivity, or discrimination between individual faces. While the contrast between faces and nonface objects elicits strictly bilateral occipital responses in children, strengthening previous observations, discrimination of individual faces in the same children reveals a strong right hemispheric lateralization over the occipitotemporal cortex. Picture‐plane inversion of the face stimuli significantly decreases the individual discrimination response, although to a much smaller extent than in older children and adults tested with the same paradigm. However, there is only a nonsignificant trend for a decrease in right hemispheric lateralization with inversion. There is no relationship between the right hemispheric lateralization in individual face discrimination and preschool levels of readings abilities. The observed difference in the right hemispheric lateralization obtained in the same population of children with two different paradigms measuring neural responses to faces indicates that the level of visual discrimination is a key factor to consider when making inferences about the development of hemispheric lateralization of face perception in the human brain., Using a fast periodic visual presentation paradigm combined with EEG we show that the right hemisphere involvement in face processing depends on discrimination level in preschool children. While face individuation (identity) relies on the right hemisphere, bilateral occipital networks were activated by generic face categorization (faces vs objects). Since right lateralization is present in pre‐readers these results challenge the hypothesis that learning to reading entails the right‐lateralization for faces observed in adulthood.
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- 2020
6. Influence of paper whiteness and luminescent background on visibility of security features on papers and documents.
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Azharonok, V., Korochkin, L., and Knyukshto, V.
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LUMINESCENCE , *FLUORESCENCE spectroscopy , *BRIGHTNESS perception , *VISUAL perception , *SPECTRUM analysis - Abstract
ISO brightness, fluorescence spectra, and the fluorescence integrated intensity of papers from domestic and foreign manufacturers were studied. The contrast index of the tested paper samples, which is defined as the ratio of the ISO brightness to the paper integrated fluorescence intensity in the spectral range from 380 to 700 nm, was estimated. An alternative method for controlling the paper background fluorescence level was proposed. [ABSTRACT FROM AUTHOR]
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- 2012
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7. Visualisation of the distribution of ink components in printed coated paper using focused ion beam techniques
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Heard, P.J., Preston, J.S., Parsons, D.J., Cox, J., and Allen, G.C.
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MENTAL imagery , *VISUAL perception , *MAIL-order business , *ECONOMICS - Abstract
Rotogravure printing is the preferred method when large print runs are required, such as for catalogues. Penetration of ink into the paper is not desirable as this increases the amount of ink needed to obtain a certain print density. Thus the differences in ink demand between different papers have a significant impact on the economics of the process. In order to control the ink penetration, paper is often coated with a thin layer of kaolin clay. The extent of penetration depends on the structure of this coating and the characteristics of the ink used.High spatial resolution gallium ion SIMS has been used to study ink penetration by embedding the paper in resin and imaging in cross-section, as well as depth profiling the ink film on the paper. For inks that react with the embedding resin however, the former technique fails. More recently, focused ion beam (FIB) cross-sections were used to visualise the penetration of ink into the paper. The more conductive nature of the ink used here compared with the coating gave high contrast between them, allowing easy assessment of the penetration. Results obtained from this method on paper with two different coatings were consistent with print gloss, print density and size of the printed dots. Ink is seen to have penetrated further into a paper coating with a ‘blocky’ morphology than one with a ‘platey’ morphology. This is consistent with the smaller dot area, lower print gloss and lower print density achieved on the blocky paper coating. TEM sections were obtained using the FIB with ex situ lift-out, providing a more direct view of the ink-paper interface. [Copyright &y& Elsevier]
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- 2004
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8. Paper characterisation by texture using visualisation-based training.
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Turtinen, M., Pietikäinen, M., Silvén, O., Maenpää, T., and Niskanen, M.
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PAPER , *MATERIALS texture , *VISUAL perception , *PROPERTIES of matter , *LIGHT , *IMAGE processing - Abstract
In this paper, a non-supervised technique for on-line paper characterisation is presented. The method uses self-organising maps (SOM) and texture analysis for clustering different kinds of paper according to their properties. A light-through technique is used to get pictures of paper. Then, effective texture features are extracted from greyscale images and the dimensionality of the feature data is reduced with SOM allowing visual analysis of measurements. The method makes it possible to implicitly extract important information about paper formation. The approach provides excellent results. A classification error below 1% was achieved for four quality classes when local binary pattern (LBP) texture features were used. The improvement to the previously used texture features in paper inspection is huge: the classification error was reduced by over 40 times. In addition to the excellent classification accuracy, the method also offers a self-intuitive user interface and a synthetic view of the inspected data. [ABSTRACT FROM AUTHOR]
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- 2003
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9. Play enhances visual form perception in infancy-an active training study
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Elin, Schröder, Gustaf, Gredebäck, Jessica, Gunnarsson, and Marcus, Lindskog
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Male ,Paper ,approximate number system ,visual form perception ,genetic structures ,Infant ,Play and Playthings ,Form Perception ,Papers ,Visual Perception ,Humans ,Attention ,Female ,Child ,Comprehension ,embodiment - Abstract
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.
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- 2018
10. Language experience influences audiovisual speech integration in unimodal and bimodal bilingual infants
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Elena Kushnerenko, Harriet Bowden-Howl, Mairéad MacSweeney, Laura Goldberg, Evelyne Mercure, Kimberley Coulson, and Mark H. Johnson
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Paper ,Adult ,Male ,medicine.medical_specialty ,Visual perception ,Eye Movements ,Cognitive Neuroscience ,Multilingualism ,Audiology ,Sign language ,050105 experimental psychology ,psyc ,Developmental and Educational Psychology ,medicine ,Humans ,0501 psychology and cognitive sciences ,Attention ,10. No inequality ,Sensory cue ,Neuroscience of multilingualism ,Mouth ,05 social sciences ,Novelty ,Infant ,Manner of articulation ,Face ,Papers ,Speech Perception ,Visual Perception ,Female ,Cues ,Psychology ,Language Experience Approach ,050104 developmental & child psychology - Abstract
Infants as young as 2 months can integrate audio and visual aspects of speech articulation. A shift of attention from the eyes towards the mouth of talking faces occurs around 6 months of age in monolingual infants. However, it is unknown whether this pattern of attention during audiovisual speech processing is influenced by speech and language experience in infancy. The present study investigated this question by analysing audiovisual speech processing in three groups of 4‐ to 8‐month‐old infants who differed in their language experience: monolinguals, unimodal bilinguals (infants exposed to two or more spoken languages) and bimodal bilinguals (hearing infants with Deaf mothers). Eye‐tracking was used to study patterns of face scanning while infants were viewing faces articulating syllables with congruent, incongruent and silent auditory tracks. Monolinguals and unimodal bilinguals increased their attention to the mouth of talking faces between 4 and 8 months, while bimodal bilinguals did not show any age difference in their scanning patterns. Moreover, older (6.6 to 8 months), but not younger, monolinguals (4 to 6.5 months) showed increased visual attention to the mouth of faces articulating audiovisually incongruent rather than congruent faces, indicating surprise or novelty. In contrast, no audiovisual congruency effect was found in unimodal or bimodal bilinguals. Results suggest that speech and language experience influences audiovisual integration in infancy. Specifically, reduced or more variable experience of audiovisual speech from the primary caregiver may lead to less sensitivity to the integration of audio and visual cues of speech articulation.
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- 2018
11. Risky visuomotor choices during rapid reaching in childhood
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Dekker, Tessa M. and Nardini, Marko
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Paper ,Adult ,Male ,Analysis of Variance ,Adolescent ,Movement ,Decision Making ,Age Factors ,Choice Behavior ,Young Adult ,Risk-Taking ,Papers ,Visual Perception ,Humans ,Learning ,Female ,Child ,Psychomotor Performance ,Probability - Abstract
Many everyday actions are implicit gambles because imprecisions in our visuomotor systems place probabilities on our success or failure. Choosing optimal action strategies involves weighting the costs and gains of potential outcomes by their corresponding probabilities, and requires stable representations of one's own imprecisions. How this ability is acquired during development in childhood when visuomotor skills change drastically is unknown. In a rewarded rapid reaching task, 6‐ to 11‐year‐old children followed ‘risk‐seeking’ strategies leading to overly high point‐loss. Adults' performance, in contrast, was close to optimal. Children's errors were not explained by distorted estimates of value or probability, but may reflect different action selection criteria or immature integration of value and probability information while planning movements. These findings provide a starting point for understanding children's risk‐taking in everyday visuomotor situations when suboptimal choices can be dangerous. Moreover, children's risky visuomotor decisions mirror those reported for non‐motor gambles, raising the possibility that common processes underlie development across decision‐making domains.
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- 2015
12. Training-induced cortical representation of a hemianopic hemifield
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Lea Hyvärinen, Risto Näsänen, Linda Henriksson, Antti Raninen, and Simo Vanni
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Male ,Paper ,medicine.medical_specialty ,Visual perception ,genetic structures ,Flicker fusion threshold ,Audiology ,Flicker Fusion ,Neuroimaging ,medicine ,Humans ,Hemianopsia ,Visual Cortex ,medicine.diagnostic_test ,Magnetoencephalography ,Superior temporal sulcus ,Middle Aged ,medicine.disease ,Magnetic Resonance Imaging ,eye diseases ,Stroke ,Psychiatry and Mental health ,Visual cortex ,medicine.anatomical_structure ,Visual Perception ,Surgery ,Neurology (clinical) ,Psychology ,Functional magnetic resonance imaging ,Neuroscience - Abstract
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.
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- 2007
13. The Goteborg MCI study: mild cognitive impairment is a heterogeneous condition
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Magnus Sjögren, Per M. Hellström, Anders Wallin, Arto Nordlund, Sindre Rolstad, and Stefan Hansen
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Male ,Paper ,medicine.medical_specialty ,Population ,Neuropsychological Tests ,Audiology ,behavioral disciplines and activities ,Severity of Illness Index ,Perceptual Disorders ,mental disorders ,Reaction Time ,medicine ,Humans ,Learning ,Memory impairment ,Dementia ,Cognitive skill ,Cognitive decline ,Vascular dementia ,education ,Psychiatry ,Aged ,Demography ,Language Disorders ,Memory Disorders ,education.field_of_study ,Neuropsychology ,Cognition ,Middle Aged ,medicine.disease ,nervous system diseases ,Psychiatry and Mental health ,Space Perception ,Mental Recall ,Visual Perception ,Female ,Surgery ,Neurology (clinical) ,Cognition Disorders ,Psychology ,human activities - Abstract
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.
- Published
- 2005
14. Driver landmark and traffic sign identification in early Alzheimer's disease
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Qichang Shi, Ergun Y. Uc, Jeffrey D. Dawson, Matthew Rizzo, and Steven W. Anderson
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Male ,Symbolism ,Paper ,endocrine system ,Automobile Driving ,medicine.medical_specialty ,Signal Detection, Psychological ,Time Factors ,Visual perception ,genetic structures ,Poison control ,Neuropsychological Tests ,Severity of Illness Index ,Perceptual Disorders ,Physical medicine and rehabilitation ,Alzheimer Disease ,medicine ,Humans ,Dementia ,Attention ,Psychiatry ,Aged ,Visual search ,Brain ,Recognition, Psychology ,Cognition ,Executive functions ,medicine.disease ,Cognitive test ,Psychiatry and Mental health ,Visual Perception ,Female ,Surgery ,Neurology (clinical) ,Cognition Disorders ,Psychology ,Traffic sign ,psychological phenomena and processes - Abstract
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.
- Published
- 2005
15. 'Bottom-up' and 'top-down' effects on reading saccades: a case study
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R. J. S. Wise, Alexander P. Leff, Timothy L. Hodgson, N J Upton, and Gordon T. Plant
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Male ,Paper ,medicine.medical_specialty ,Visual perception ,genetic structures ,media_common.quotation_subject ,Eye disease ,Audiology ,Gaze-contingency paradigm ,Foveal ,Reading (process) ,Saccades ,medicine ,Humans ,Hemianopsia ,media_common ,Communication ,business.industry ,Eye movement ,Linguistics ,Middle Aged ,medicine.disease ,Pure alexia ,eye diseases ,Psychiatry and Mental health ,Reading ,Surgery ,sense organs ,Neurology (clinical) ,business ,Psychology ,Tomography, Emission-Computed - Abstract
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.
- Published
- 2003
16. Incidental learning in a multisensory environment across childhood
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Natasha Z. Kirkham, Denis Mareschal, Hayley White, and Hannah Broadbent
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Paper ,Adult ,Male ,Visual perception ,Movement ,Cognitive Neuroscience ,Stimulus (physiology) ,050105 experimental psychology ,psyc ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Concept learning ,Developmental and Educational Psychology ,Humans ,Learning ,Attention ,0501 psychology and cognitive sciences ,Child ,10. No inequality ,4. Education ,05 social sciences ,Amodal perception ,Age Factors ,Attentional control ,Incidental learning ,Categorization ,Papers ,Auditory Perception ,Visual Perception ,Task analysis ,Female ,Cues ,Psychology ,Photic Stimulation ,030217 neurology & neurosurgery ,Cognitive psychology - Abstract
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.
- Published
- 2017
17. Visuospatial functions in atypical parkinsonian syndromes
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John R. Hodges, Thomas H. Bak, Diana Caine, and V C Hearn
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Male ,Paper ,medicine.medical_specialty ,Visual perception ,Parkinson's disease ,Eye Movements ,Neuropsychological Tests ,Audiology ,Spatial memory ,Progressive supranuclear palsy ,Perceptual Disorders ,Disability Evaluation ,Degenerative disease ,medicine ,Humans ,Corticobasal degeneration ,Cognitive decline ,Aged ,Spinocerebellar Degenerations ,Parkinson Disease ,Middle Aged ,Multiple System Atrophy ,medicine.disease ,Psychiatry and Mental health ,Space Perception ,Visual Perception ,Female ,Surgery ,Supranuclear Palsy, Progressive ,Neurology (clinical) ,Cognition Disorders ,Psychology ,Neuroscience - Abstract
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.
- Published
- 2006
18. A comparison of computerized and paper-based language tests with adults with aphasia
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Caroline Newton, Kadia Acres, and Carolyn Bruce
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Adult ,Male ,Paper ,Linguistics and Language ,Visual perception ,Speech-Language Pathology ,medicine.medical_treatment ,Developmental psychology ,Speech and Hearing ,Judgment ,Raven's Progressive Matrices ,Aphasia ,Surveys and Questionnaires ,Developmental and Educational Psychology ,medicine ,Humans ,Diagnosis, Computer-Assisted ,Equivalence (measure theory) ,Stroke ,Aged ,Rehabilitation ,Language Tests ,Patient Preference ,Paper based ,Middle Aged ,medicine.disease ,Otorhinolaryngology ,Auditory stimuli ,Female ,medicine.symptom ,Psychology ,Cognitive psychology - Abstract
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.
- Published
- 2013
19. Audio-visual speech perception: a developmental ERP investigation
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Annette Karmiloff-Smith, Victoria C. P. Knowland, Evelyne Mercure, Michael S.C. Thomas, and Fred Dick
- Subjects
Auditory perception ,Adult ,Male ,Paper ,Visual perception ,Speech perception ,genetic structures ,Cognitive Neuroscience ,Stimulus (physiology) ,psyc ,Young Adult ,Developmental and Educational Psychology ,Humans ,Child ,Sensory cue ,Evoked Potentials ,Analysis of Variance ,Cognition ,Child development ,P1 ,Acoustic Stimulation ,Auditory Perception ,Speech Perception ,Visual Perception ,Voice ,Female ,Neurocomputational speech processing ,Cues ,Psychology ,Cognitive psychology - Abstract
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.
- Published
- 2012
20. Visual neglect after right posterior cerebral artery infarction
- Author
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Elizabeth Coulthard, Paresh Malhotra, Chris M. Bird, Andrew Parton, Matthew F. S. Rushworth, and Masud Husain
- Subjects
Paper ,Male ,medicine.medical_specialty ,genetic structures ,media_common.quotation_subject ,Splenium ,Posterior cerebral artery ,Audiology ,Corpus callosum ,Severity of Illness Index ,Neglect ,Perceptual Disorders ,Angular gyrus ,medicine.artery ,medicine ,Humans ,Aged ,media_common ,Posterior Cerebral Artery ,Parietal lobe ,Cerebral Infarction ,Middle Aged ,Psychiatry and Mental health ,medicine.anatomical_structure ,nervous system ,Visual Perception ,Parahippocampal Gyrus ,Female ,Surgery ,Occipital Lobe ,Neurology (clinical) ,Occipital lobe ,Psychology ,Neuroscience ,Parahippocampal gyrus - Abstract
This article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright © 2006 BMJ Publishing Group. Objectives: To investigate the characteristics and neuroanatomical correlates of visual neglect after right-sided posterior cerebral artery (PCA) infarction.Methods: 15 patients with acute PCA strokes were screened for the presence of neglect on a comprehensive battery of cognitive tests. Extra tests of visual perception were also carried out on six patients. To establish which areas were critically associated with neglect, the lesions of patients with and without neglect were compared.Results: Neglect of varying severity was documented in 8 patients. In addition, higher-order visual perception was impaired in 5 of the 6 patients. Neglect was critically associated with damage to an area of white matter in the occipital lobe corresponding to a white matter tract connecting the parahippocampal gyrus with the angular gyrus of the parietal lobe. Lesions of the thalamus or splenium of the corpus callosum did not appear necessary or sufficient to cause neglect, but may mediate its severity in these patients.Conclusions: PCA stroke can result in visual neglect. Interruption of the white matter fibres connecting the parahippocampal gyrus to the angular gyrus may be important in determining whether a patient will manifest neglect.
- Published
- 2006
21. Effects of focal hand dystonia on visually guided and internally guided force control
- Author
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David E. Vaillancourt, Daniel M. Corcos, and Janey Prodoehl
- Subjects
Adult ,Male ,Paper ,medicine.medical_specialty ,Visual perception ,Movement disorders ,Neurological disorder ,Isometric exercise ,Wrist ,Feedback ,Physical medicine and rehabilitation ,Hand strength ,otorhinolaryngologic diseases ,medicine ,Humans ,Dystonia ,Cerebral Cortex ,Hand Strength ,Middle Aged ,medicine.disease ,Hand ,nervous system diseases ,Psychiatry and Mental health ,medicine.anatomical_structure ,Dystonic Disorders ,Case-Control Studies ,Physical therapy ,Visual Perception ,Surgery ,Female ,Neurology (clinical) ,medicine.symptom ,Psychology ,Dystonic disorder - Abstract
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.
- Published
- 2006
22. Do children with developmental dyslexia have an implicit learning deficit?
- Author
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Deny Menghini, A. Finzi, Luigi Marotta, Stefano Vicari, Laura Petrosini, and S Baldi
- Subjects
Serial reaction time ,Paper ,Male ,genetic structures ,education ,behavioral disciplines and activities ,Severity of Illness Index ,Procedural memory ,Dyslexia ,Communication disorder ,mental disorders ,medicine ,Reaction Time ,Humans ,Language disorder ,Child ,Learning Disabilities ,Wechsler Scales ,medicine.disease ,Implicit learning ,Psychiatry and Mental health ,Socioeconomic Factors ,Space Perception ,Learning disability ,Visual Perception ,Surgery ,Female ,Neurology (clinical) ,Sequence learning ,medicine.symptom ,Psychology ,psychological phenomena and processes ,Cognitive psychology - Abstract
Objective: The purpose of this study was to investigate the effects of specific types of tasks on the efficiency of implicit procedural learning in the presence of developmental dyslexia (DD). Methods: Sixteen children with DD (mean (SD) age 11.6 (1.4) years) and 16 matched normal reader controls (mean age 11.4 (1.9) years) were administered two tests (the Serial Reaction Time test and the Mirror Drawing test) in which implicit knowledge was gradually acquired across multiple trials. Although both tests analyse implicit learning abilities, they tap different competencies. The Serial Reaction Time test requires the development of sequential learning and little (if any) procedural learning, whereas the Mirror Drawing test involves fast and repetitive processing of visuospatial stimuli but no acquisition of sequences. Results: The children with DD were impaired on both implicit learning tasks, suggesting that the learning deficit observed in dyslexia does not depend on the material to be learned (with or without motor sequence of response action) but on the implicit nature of the learning that characterises the tasks. Conclusion: Individuals with DD have impaired implicit procedural learning.
- Published
- 2005
23. White matter hyperintensities as a predictor of neuropsychological deficits post-stroke
- Author
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Raija Ylikoski, Timo Erkinjuntti, Markku Kaste, Hanna Jokinen, Riitta Mäntylä, Tarja Pohjasvaara, Marja Hietanen, and Hely Kalska
- Subjects
Male ,Paper ,medicine.medical_specialty ,Short-term memory ,Audiology ,Neuropsychological Tests ,Developmental psychology ,medicine ,Humans ,Cognitive decline ,Stroke ,Aged ,Aged, 80 and over ,Memory Disorders ,medicine.diagnostic_test ,Neuropsychology ,Brain ,Cognition ,Neuropsychological test ,Middle Aged ,medicine.disease ,Executive functions ,Prognosis ,Hyperintensity ,Psychiatry and Mental health ,Editorial Commentary ,Diffusion Magnetic Resonance Imaging ,Space Perception ,Visual Perception ,Regression Analysis ,Surgery ,Female ,Neurology (clinical) ,Psychology ,Cognition Disorders - Abstract
Objectives: Cerebral white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) are a recognised risk factor for post-stroke dementia. Their specific relations to cognitive impairment are still not well known. The purpose of this study was to explore how the severity and location of WMHs predict neuropsychological test performance in the context of other brain lesions in elderly stroke patients. Methods: In the Helsinki Stroke Aging Memory Study, 323 patients, aged from 55 to 85 years, completed a detailed neuropsychological test battery and MRI 3 months after an ischaemic stroke. The demographic and MRI predictors of cognition were studied with sequential linear regression analyses. Results: After age, education and total infarct volume were controlled for, the overall degree of WMHs predicted poor performance in tests of mental speed, executive functions, memory, and visuospatial functions, but not in those of short term memory storage or verbal conceptualisation. However, the contribution of separate white matter regions was relatively low. Only the lesions along the bodies of lateral ventricles were independently associated with speed and executive measures. Additionally, general cortical atrophy clearly predicted a wide range of cognitive deficits while infarct volume had less relevance. Further analyses revealed that executive functions act as a strong mediator between the relationship of WMHs to memory and visuospatial functions. Conclusions: The degree of WMHs is independently related to post-stroke cognitive decline. The most affected cognitive domains seem to be executive functions and speed of mental processing, which may lead to secondary deficits of memory and visuospatial functions.
- Published
- 2005
24. The neuropsychology of variant CJD: a comparative study with inherited and sporadic forms of prion disease
- Author
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Lisa Cipolotti, John Collinge, R. J. Cordery, K Alner, Martin N. Rossor, A Kennedy, MA Ron, CORDERY RJ, ALNER K, CIPOLOTTI L, RON M, KENNEDY A, COLLINGE J, and ROSSOR MN
- Subjects
Adult ,Male ,Paper ,Pediatrics ,medicine.medical_specialty ,Prions ,animal diseases ,DNA Mutational Analysis ,Neuropsychological Tests ,Creutzfeldt-Jakob Syndrome ,Prion Diseases ,National Prion Clinic ,mental disorders ,medicine ,Dementia ,Humans ,Cognitive decline ,Psychiatry ,medicine.diagnostic_test ,Settore M-PSI/02 - Psicobiologia E Psicologia Fisiologica ,business.industry ,Neuropsychology ,Neuropsychological test ,Middle Aged ,medicine.disease ,nervous system diseases ,Psychiatry and Mental health ,Cross-Sectional Studies ,Adult, Cognition Disorders/etiology, Creutzfeldt-Jakob Syndrome/complications, Creutzfeldt-Jakob Syndrome/genetics, Creutzfeldt-Jakob Syndrome/psychology, Cross-Sectional Studies, DNA Mutational Analysis, Disease Progression, Female, Humans, Male, Middle Aged, Neuropsychological Tests, Prion Diseases/genetics, Prion Diseases/psychology, Prions/genetics, Visual Perception ,Disease Progression ,Visual Perception ,Surgery ,Female ,Neurology (clinical) ,Verbal memory ,business ,Cognition Disorders ,Executive dysfunction - Abstract
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.
- Published
- 2005
25. Subthalamic nucleus stimulation induces deficits in decoding emotional facial expressions in Parkinson's disease
- Author
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Dujardin, K, Blairy, S, Defebvre, L, Krystkowiak, P, Hess, U, Blond, S, and Destee, A
- Subjects
Paper ,Male ,Electric Stimulation Therapy ,Parkinson Disease ,Middle Aged ,Neuropsychological Tests ,Severity of Illness Index ,Basal Ganglia ,Functional Laterality ,nervous system diseases ,Electrodes, Implanted ,Facial Expression ,Perceptual Disorders ,Affect ,nervous system ,Subthalamic Nucleus ,Aphasia ,Visual Perception ,Humans ,Female ,Cognition Disorders - Abstract
Bilateral subthalamic nucleus (STN) stimulation is recognised as a treatment for parkinsonian patients with severe levodopa related motor complications. Although adverse effects are infrequent, some behavioural disturbances have been reported.To investigate the consequences of STN stimulation on emotional information processing in Parkinson's disease by assessing the performance of an emotional facial expression (EFE) decoding task in a group of patients before and after surgery.12 non-demented patients with Parkinson's disease were studied. They were assessed one month before surgery and three months after. Their ability to decode EFEs was assessed using a standardised quantitative task. Overall cognitive function, executive function, visuospatial perception, depression, and anxiety were also measured. Twelve healthy controls were matched for age, sex, and duration of education.Before surgery, the patients showed no impairment in EFE decoding compared with the controls. Their overall cognitive status was preserved but they had a moderate dysexecutive syndrome. Three months after surgery, they had significant impairment of EFE decoding. This was not related to their overall cognitive status or to depression/anxiety scores. Visuospatial perception was not impaired. There was no change in the extent of the dysexecutive syndrome except for a reduction in phonemic word fluency.Bilateral STN stimulation disturbs negative emotional information processing in Parkinson's disease. The impairment appears specific and unrelated to certain secondary variables. This behavioural complication of STN may have implications for the patient's social life.
- Published
- 2004
26. Visuospatial abilities in cerebellar disorders
- Author
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Marco Molinari, Petrosini, L., Misciagna, S., and Leggio, M. G.
- Subjects
Adult ,Aged, 80 and over ,Male ,Paper ,Rotation ,Middle Aged ,Neuropsychological Tests ,Magnetic Resonance Imaging ,Severity of Illness Index ,benton line orientation test ,cerebellum ,differential aptitude test ,mental rotation ,minnesota paper form board test ,Perceptual Disorders ,nervous system ,Cerebellar Diseases ,Space Perception ,Visual Perception ,Humans ,Female ,Cognition Disorders ,Aged - Abstract
Cerebellar involvement in spatial data management has been suggested on experimental and clinical grounds.To attempt a specific analysis of visuospatial abilities in a group of subjects with focal or atrophic cerebellar damage.Visuospatial performance was tested using the spatial subtests of the WAIS, the Benton line orientation test, and two tests of mental rotation of objects-the Minnesota paper form board test (MIN) and the differential aptitude test (DAT).In the Benton line orientation test, a test of sensory analysis and elementary perception, no deficits were present in subjects with cerebellar damage. In MIN, which analyses the capacity to process bidimensional complex figures mentally, and in the DAT, which is based on mental folding and manipulation of tridimensional stimuli, subjects with cerebellar damage were impaired.The results indicate that lesions of the cerebellar circuits affect visuospatial ability. The ability to rotate objects mentally is a possible functional substrate of the observed deficits. A comparison between visuospatial performance of subjects with focal right and left cerebellar lesions shows side differences in the characteristics of the visuospatial syndrome. Thus cerebellar influences on spatial cognition appear to act on multiple cognitive modules.
- Published
- 2004
27. The topography of metabolic deficits in posterior cortical atrophy (the visual variant of Alzheimer's disease) with FDG-PET
- Author
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J Clarke, Diana Caine, John R. Hodges, Tim D. Fryer, and Peter J. Nestor
- Subjects
Male ,Paper ,Pathology ,medicine.medical_specialty ,Vision Disorders ,Neuropsychological Tests ,Statistical parametric mapping ,Apraxia ,Central nervous system disease ,Atrophy ,Alzheimer Disease ,Fluorodeoxyglucose F18 ,medicine ,Humans ,Aged ,Cerebral atrophy ,Cerebral Cortex ,Brain Mapping ,Posterior cortical atrophy ,Frontal eye fields ,Middle Aged ,medicine.disease ,Psychiatry and Mental health ,Case-Control Studies ,Visual Perception ,Surgery ,Female ,Neurology (clinical) ,Alzheimer's disease ,Radiopharmaceuticals ,Psychology ,Tomography, Emission-Computed - Abstract
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.
- Published
- 2003
28. Tangible line graphs: an experimental investigation of three formats using capsule paper
- Author
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Alan J. Parkin and Frances Aldrich
- Subjects
Space (punctuation) ,Paper ,Engineering ,Injury control ,Vision Disorders ,Poison control ,Value (computer science) ,Human Factors and Ergonomics ,law.invention ,Behavioral Neuroscience ,law ,Line graph ,Task Performance and Analysis ,Humans ,0501 psychology and cognitive sciences ,Arithmetic ,Practical implications ,Computer Science::Distributed, Parallel, and Cluster Computing ,050107 human factors ,Applied Psychology ,Simulation ,business.industry ,05 social sciences ,050301 education ,Grid ,Reading ,Visual Perception ,Graph (abstract data type) ,business ,0503 education - Abstract
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.
- Published
- 1987
29. Stories of O
- Author
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Wood, Catherine
- Published
- 2004
30. Primary and Secondary Qualities
- Author
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Slomann, Aage
- Published
- 1964
31. On Having the Same Visual Experiences
- Author
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Hanson, Norwood Russell
- Published
- 1960
32. The Effect of Typography upon the Perceptual Span in Reading
- Author
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Paterson, Donald G. and Tinker, Miles A.
- Published
- 1947
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33. Human Knowledge: Its Scope and Limits
- Author
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Russell, L. J.
- Published
- 1949
34. William Charles Wells and the Races of Man
- Published
- 1973
35. Seeing and Naming
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Hall, Richard J.
- Published
- 1977
36. The Effect of Typographical Variations upon Eye Movement in Reading
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Tinker, Miles A. and Paterson, Donald G.
- Published
- 1955
37. Perceptual Skills: A Concern of the Classroom Teacher?
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Rosner, Jerome
- Published
- 1971
38. Visual Fatigue and Reading
- Author
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DEMILIA, LORRAINE A.
- Published
- 1968
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