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Cortex; a Journal Devoted To the Study... Jan 2018An influential model of vision suggests the presence of two visual streams within the brain: a dorsal occipito-parietal stream which mediates action and a ventral...
An influential model of vision suggests the presence of two visual streams within the brain: a dorsal occipito-parietal stream which mediates action and a ventral occipito-temporal stream which mediates perception. One of the cornerstones of this model is DF, a patient with visual form agnosia following bilateral ventral stream lesions. Despite her inability to identify and distinguish visual stimuli, DF can still use visual information to control her hand actions towards these stimuli. These observations have been widely interpreted as demonstrating a double dissociation from optic ataxia, a condition observed after bilateral dorsal stream damage in which patients are unable to act towards objects that they can recognize. In Experiment 1, we investigated how patient DF performed on the classical diagnostic task for optic ataxia, reaching in central and peripheral vision. We replicated recent findings that DF is remarkably inaccurate when reaching to peripheral targets, but not when reaching in free vision. In addition we present new evidence that her peripheral reaching errors follow the optic ataxia pattern increasing with target eccentricity and being biased towards fixation. In Experiments 2 and 3, for the first time we examined DF's on-line control of reaching using a double-step paradigm in fixation-controlled and free-vision versions of the task. DF was impaired when performing fast on-line corrections on all conditions tested, similarly to optic ataxia patients. Our findings question the long-standing assumption that DF's dorsal visual stream is functionally intact and that her on-line visuomotor control is spared. In contrast, in addition to visual form agnosia, DF also has visuomotor symptoms of optic ataxia which are most likely explained by bilateral damage to the superior parietal-occipital cortex (SPOC). We thus conclude that patient DF can no longer be considered as an appropriate single-case model for testing the neural basis of perception and action dissociations.
Topics: Agnosia; Ataxia; Female; Humans; Middle Aged; Psychomotor Performance; Reaction Time; Visual Perception
PubMed: 28532578
DOI: 10.1016/j.cortex.2017.04.004 -
Vision Research May 2015Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when...
Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width of objects when reaching out to pick them up (grip scaling). While this spared ability to grasp objects is presumed to be mediated by visuomotor modules in her relatively intact dorsal stream, it is possible that it may rely abnormally on online visual or haptic feedback. We report here that DF's grip scaling remained intact when her vision was completely suppressed during grasp movements, and it still dissociated sharply from her poor perceptual estimates of target size. We then tested whether providing trial-by-trial haptic feedback after making such perceptual estimates might improve DF's performance, but found that they remained significantly impaired. In a final experiment, we re-examined whether DF's grip scaling depends on receiving veridical haptic feedback during grasping. In one condition, the haptic feedback was identical to the visual targets. In a second condition, the haptic feedback was of a constant intermediate width while the visual target varied trial by trial. Despite this incongruent feedback, DF still scaled her grip aperture to the visual widths of the target blocks, showing only normal adaptation to the false haptically-experienced width. Taken together, these results strengthen the view that DF's spared grasping relies on a normal mode of dorsal-stream functioning, based chiefly on visual feedforward processing.
Topics: Aged; Agnosia; Analysis of Variance; Carbon Monoxide Poisoning; Feedback, Sensory; Female; Hand; Humans; Male; Middle Aged; Movement; Psychomotor Performance; Vision Disorders; Visual Perception
PubMed: 25199609
DOI: 10.1016/j.visres.2014.08.016 -
Cortex; a Journal Devoted To the Study... Feb 2022An 84-year-old man manifested false recognition/misidentification of unfamiliar person after cardiogenic cerebral infarction. He had good visual and hearing acuity, no...
An 84-year-old man manifested false recognition/misidentification of unfamiliar person after cardiogenic cerebral infarction. He had good visual and hearing acuity, no hemianopsia, unilateral spatial neglect and visual object agnosia. However, he was unable to remember faces of his rehabilitation therapists, and repeatedly misidentified other patients' visitors and therapists as his family members and friends, without recognizing his mistakes. General cognitive function was preserved with Hasegawa dementia score-revised (HDS-R) 25/30 (cut-off score 20). In terms of recognition of faces, tasks not requiring recognition of facial identity, such as interpreting facial emotions, and gender and age assessment, were relatively preserved, but recognition of family members and celebrities was severely impaired, and matching unfamiliar faces was slightly impaired. Semantic information of family and friends was retained. Although his symptoms resembled associative prosopagnosia, they differed from general associative prosopagnosia in having phonagnosia. MRI lesions were localized in the frontal and temporal lobes including the right anterior temporal lobe, and not in the right occipital and temporal lobes considered to the lesion site of multimodal people recognition disorders manifesting inability of utilization of visual (face) and auditory (voice) cues for person identification. In addition to the facial cognitive impairment, impaired exploratory (monitoring) function of the frontal lobe on the temporal lobe may also contribute to the false recognition/misidentification of this case.
Topics: Aged, 80 and over; Agnosia; Cerebral Infarction; Cognition; Humans; Male; Prosopagnosia; Temporal Lobe
PubMed: 35051711
DOI: 10.1016/j.cortex.2021.12.005 -
Consciousness and Cognition May 2015Despite the coherence and seeming directness of our bodily experience, our perception of the world, including that of our own body, may constitute an inference based on... (Review)
Review
Despite the coherence and seeming directness of our bodily experience, our perception of the world, including that of our own body, may constitute an inference based on ambiguous sensory data and prior expectations. In this article, I apply a 'psychologised' version of the recently proposed free energy framework to the understanding of certain disorders of neurological unawareness in order to examine how inferential processes may determine our body perception. I specifically consider three facets of body perception in such disorders: namely, the 'external body' as inferred on the basis of exteroceptive signals and related predictions; the 'internal body' as inferred on the basis of proprioceptive and interoceptive signals and related predictions; and lastly the 'impersonalised body' as inferred on the basis of signals from social and third-person perspectives on the body and related predictions. Several conclusions will be drawn from these considerations: (a) there is a deep interdependency of prior beliefs and sensory data; as the brain uses sensory data to update its virtual model of the world, lack or imprecision of sensory prediction errors may lead to aberrant inferences influenced disproportionally by outdated, premorbid predictions; (b) interoception and interoceptive salience have a unique role in our inferences about body awareness and (c) social, 'objectified' prior beliefs about the body may have a silent but potent role in our bodily self-awareness. Finally, the article emphasizes that our learned, virtual model of the body is depended on the nature and thus integrity of the very body that allowed the model to be formed in the first place.
Topics: Agnosia; Hemiplegia; Humans; Theory of Mind
PubMed: 25459651
DOI: 10.1016/j.concog.2014.09.018 -
Cortex; a Journal Devoted To the Study... Jun 2018Periventricular leukomalacia (PVL) is characterized by focal necrosis at the level of the periventricular white matter, often observed in preterm infants. PVL is...
Periventricular leukomalacia (PVL) is characterized by focal necrosis at the level of the periventricular white matter, often observed in preterm infants. PVL is frequently associated with motor impairment and with visual deficits affecting primary stages of visual processes as well as higher visual cognitive abilities. Here we describe six PVL subjects, with normal verbal IQ, showing orientation perception deficits in both the haptic and visual domains. Subjects were asked to compare the orientation of two stimuli presented simultaneously or sequentially, using both a two alternative forced choice (2AFC) orientation-discrimination and a matching procedure. Visual stimuli were oriented gratings or bars or collinear short lines embedded within a random pattern. Haptic stimuli comprised two rotatable wooden sticks. PVL patients performed at chance in discriminating the oblique orientation, both for visual and haptic stimuli. Moreover when asked to reproduce the oblique orientation, they often oriented the stimulus along the symmetric mirror orientation. The deficit generalized to stimuli varying in many low level features, was invariant for spatiotopic object orientation, and also occurred for sequential presentations. The deficit was specific to oblique orientations, and not for horizontal or vertical stimuli. These findings show that PVL can affect a specific network involved with the supramodal perception of mirror symmetry orientation.
Topics: Adolescent; Agnosia; Child; Female; Humans; Leukomalacia, Periventricular; Male; Orientation; Space Perception; Young Adult
PubMed: 29655042
DOI: 10.1016/j.cortex.2018.03.010 -
Neuroscience and Biobehavioral Reviews Mar 2024Face-selective regions in the human ventral occipito-temporal cortex (VOTC) have been defined for decades mainly with functional magnetic resonance imaging. This... (Review)
Review
Face-selective regions in the human ventral occipito-temporal cortex (VOTC) have been defined for decades mainly with functional magnetic resonance imaging. This face-selective VOTC network is traditionally divided in a posterior 'core' system thought to subtend face perception, and regions of the anterior temporal lobe as a semantic memory component of an extended general system. In between these two putative systems lies the anterior fusiform gyrus and surrounding sulci, affected by magnetic susceptibility artifacts. Here we suggest that this methodological gap overlaps with and contributes to a conceptual gap between (visual) perception and semantic memory for faces. Filling this gap with intracerebral recordings and direct electrical stimulation reveals robust face-selectivity in the anterior fusiform gyrus and a crucial role of this region, especially in the right hemisphere, in identity recognition for both familiar and unfamiliar faces. Based on these observations, we propose an integrated theoretical framework for human face (identity) recognition according to which face-selective regions in the anterior fusiform gyrus join the dots between posterior and anterior cortical face memories.
Topics: Humans; Prosopagnosia; Temporal Lobe; Facial Recognition; Recognition, Psychology; Magnetic Resonance Imaging; Pattern Recognition, Visual; Brain Mapping; Photic Stimulation
PubMed: 38191080
DOI: 10.1016/j.neubiorev.2024.105535 -
Scientific Reports May 2017A wealth of evidence from behavioural, neuropsychological and neuroimaging research supports the view that face recognition is reliant upon a domain-specific network...
A wealth of evidence from behavioural, neuropsychological and neuroimaging research supports the view that face recognition is reliant upon a domain-specific network that does not process words. In contrast, the recent many-to-many model of visual recognition posits that brain areas involved in word and face recognition are functionally integrated. Developmental prosopagnosia (DP) is characterised by severe deficits in the recognition of faces, which the many-to-many model predicts should negatively affect word recognition. Alternatively, domain-specific accounts suggest that impairments in face and word processing need not go hand in hand. To test these possibilities, we ran a battery of 7 tasks examining word processing in a group of DP cases and controls. One of our prosopagnosia cases exhibited a severe reading impairment with delayed response times during reading aloud tasks, but not lexical decision tasks. Overall, however, we found no evidence of global word processing deficits in DP, consistent with a dissociation account for face and word processing.
Topics: Adult; Aged; Behavior; Female; Humans; Linguistics; Male; Middle Aged; Neuropsychological Tests; Prosopagnosia; Reading; Task Performance and Analysis; Visual Perception; Young Adult
PubMed: 28490791
DOI: 10.1038/s41598-017-01917-8 -
Lin Chuang Er Bi Yan Hou Tou Jing Wai... Jun 2021This study aimed to provide better understanding of the otolaryngologic features, combined with ophthalmologic and neurologic characteristics in mitochondrial...
This study aimed to provide better understanding of the otolaryngologic features, combined with ophthalmologic and neurologic characteristics in mitochondrial encephalomyopathy(MEM), and to help ENT and auditory practitioner making correct diagnosis as well. Twenty-eight patients with MEM were enrolled between September 2001 and January 2020. Information about family histories and clinical symptoms was retrospectively analyzed. All patients underwent otorhinolaryngological, ophthalmological and neurological examinations, including: pure-tone audiometry, acoustic immittance(AI), distortion-product otoacoustic emissions(DPOAE), auditory brainstem response(ABR), cochlear micropotential(CM), speech discrimination score(SDS), electroneurography(ENoG), computed tomography(CT) of the temporal bone and cranial magnetic resonance weighted imaging scan(MRI), muscle biopsy and mtDNA gene testing. ENT subjective manifestations were present in 15 cases (53.6%) with sensorineural hearing loss(SNHL), 4(14.3%) with tinnitus, 4(14.3%) with facial weakness, 3(10.7%) with dysphagia, 1(3.6%) with auditory agnosia. Ophthalmological and neurological symptoms included ptosis in 16 cases (57.1%), exercise intolerance in 16(57.1%), optic atrophy in 15(53.6%), muscular atrophy in 6(21.4%), and stroke-like episodes in 5(17.9%). The results of objective examinations were as follows: DPOAE were not elicited in 18(64.3%) cases, ABR abnormalities in 18(64.3%) cases, hearing threshold shift in 15(53.6%) cases, AI normal and CM was not detected in all cases, SDS decreased in 6(21.4%) cases, facial ENoG abnormalities in 4(14.3%) cases, laryngeal ENoG abnormalities in 3(10.7%) cases, EMG abnormalities in 6(21.4%) cases, and ECG abnormalities in 8(28.6%) cases. Temporal CT were normal, but cranial MRI abnormalities were found in 19 cases(67.9%), including central nerve demyelination, white matter hyperintensities, generalized cerebellar and cerebral atrophy, multiple cortical/subcortical infarct-like lesions, basal ganglia calcification. Multisystemic syndromes in MEM can present as a variety of otolaryngological, ophthalmological and neurological abnormalities, such as ptosis, audio-visual disturbance, exercise intolerance and stroke-like episodes etc. SNHL, tinnitus, auditory agnosia, facial weakness and dysphagia were ENT specific manifestations. SNHL in MEM is bilateral symmetrical progressive or of sudden onset since teenage. mtDNA testing may be helpful for adolescent patient whose SNHL was associated with neuromuscular symptoms. Muscle biopsy should be considered when middle-aged patients developed facial weakness and dysphagia. DPOAE and ABR are the optimal objective audiometric tests to monitor the progression of MEM associated with SNHL.
Topics: Adolescent; Audiometry, Pure-Tone; Evoked Potentials, Auditory, Brain Stem; Hearing Loss, Sensorineural; Humans; Middle Aged; Mitochondrial Encephalomyopathies; Neurology; Ophthalmology; Otoacoustic Emissions, Spontaneous; Otolaryngology; Retrospective Studies
PubMed: 34304513
DOI: 10.13201/j.issn.2096-7993.2021.06.010 -
Brain Imaging and Behavior Jun 2022Simultanagnosia is a common symptom of posterior cortical atrophy, and its association with brain structural and functional changes remains unclear. In our study, 18...
Simultanagnosia is a common symptom of posterior cortical atrophy, and its association with brain structural and functional changes remains unclear. In our study, 18 posterior cortical atrophy patients with simultanagnosia, 29 patients with Alzheimer's disease and 20 cognitively normal controls were recruited and subjected to full neuropsychological evaluation, including simultanagnosia tests, and structural and resting-state functional MRI. The gray matter volume was assessed by voxel-based morphometry, while the intrinsic functional connectivity was evaluated using the reduced gray matter volume regions of interest as the seed. In contrast to the patients with Alzheimer's disease, those with posterior cortical atrophy showed the following: (1) markedly lower simultanagnosia test scores, (2) an altered regional gray matter volume of the left middle occipital gyrus and ventral occipital areas, and (3) lowered intrinsic functional connectivity with the left middle occipital gyrus, left lingual gyrus and right middle occipital gyrus separately. Additionally, the gray matter volume of the left middle occipital gyrus and left inferior occipital gyrus were each correlated with simultanagnosia in posterior cortical atrophy patients. The intrinsic functional connectivity of the left middle occipital gyrus with the right superior occipital gyrus and that of the right middle occipital gyrus with the left superior parietal gyrus were also correlated with simultanagnosia in posterior cortical atrophy patients. In summary, this study indicated that simultanagnosia is associated with gray matter reductions and decreased functional connectivity in the left middle occipital gyrus and the left inferior occipital gyrus in patients with posterior cortical atrophy.
Topics: Alzheimer Disease; Atrophy; Brain; Brain Mapping; Gray Matter; Humans; Magnetic Resonance Imaging
PubMed: 34787788
DOI: 10.1007/s11682-021-00568-8 -
Cortex; a Journal Devoted To the Study... May 2021The organisational principles of the visual ventral stream are still highly debated, particularly the relative association/dissociation between word and face recognition...
The organisational principles of the visual ventral stream are still highly debated, particularly the relative association/dissociation between word and face recognition and the degree of lateralisation of the underlying processes. Reports of dissociations between word and face recognition stem from single case-studies of category selective impairments, and neuroimaging investigations of healthy participants. Despite the historical reliance on single case-studies, more recent group studies have highlighted a greater commonality between word and face recognition. Studying individual patients with rare selective deficits misses (a) important variability between patients, (b) systematic associations between task performance, and (c) patients with mild, severe and/or non-selective impairments; meaning that the full spectrum of deficits is unknown. The Back of the Brain project assessed the range and specificity of visual perceptual impairment in 64 patients with posterior cerebral artery stroke recruited based on lesion localization and not behavioural performance. Word, object, and face processing were measured with comparable tests across different levels of processing to investigate associations and dissociations across domains. We present two complementary analyses of the extensive behavioural battery: (1) a data-driven analysis of the whole patient group, and (2) a single-subject case-series analysis testing for deficits and dissociations in each individual patient. In both analyses, the general organisational principle was of associations between words, objects, and faces even following unilateral lesions. The majority of patients either showed deficits across all domains or in no domain, suggesting a spectrum of visuo-perceptual deficits post stroke. Dissociations were observed, but they were the exception and not the rule: Category-selective impairments were found in only a minority of patients, all of whom showed disproportionate deficits for words. Interestingly, such selective word impairments were found following both left and right hemisphere lesions. This large-scale investigation of posterior cerebral artery stroke patients highlights the bilateral representation of visual perceptual function.
Topics: Brain; Humans; Temporal Lobe
PubMed: 33770511
DOI: 10.1016/j.cortex.2021.01.021