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The Canadian Journal of Neurological... Sep 2023
Topics: Humans; Encephalitis; Hashimoto Disease; Agnosia; Autoimmune Diseases of the Nervous System; Auditory Perception
PubMed: 35929447
DOI: 10.1017/cjn.2022.284 -
Cognitive Neuropsychology 2023Visual imagery has a close overlapping relationship with visual perception. Posterior cortical atrophy (PCA) is a neurodegenerative syndrome marked by early impairments...
Visual imagery has a close overlapping relationship with visual perception. Posterior cortical atrophy (PCA) is a neurodegenerative syndrome marked by early impairments in visuospatial processing and visual object recognition. We asked whether PCA would therefore also be marked by deficits in visual imagery, tested using objective forced-choice questionnaires, and whether imagery deficits would be selective for certain properties. We recruited four patients with PCA and a patient with integrative visual agnosia due to bilateral occipitotemporal strokes for comparison. We administered a test battery probing imagery for object shape, size, colour lightness, hue, upper-case letters, lower-case letters, word shape, letter construction, and faces. All subjects showed significant impairments in visual imagery, with imagery for lower-case letters most likely to be spared. We conclude that PCA subjects can show severe deficits in visual imagery. Further work is needed to establish how frequently this occurs and how early it can be found.
Topics: Humans; Male; Female; Atrophy; Aged; Imagination; Middle Aged; Cerebral Cortex; Neuropsychological Tests; Agnosia; Pattern Recognition, Visual; Visual Perception; Magnetic Resonance Imaging; Perceptual Disorders
PubMed: 38698499
DOI: 10.1080/02643294.2024.2346362 -
Psychonomic Bulletin & Review Feb 2024Is object orientation an inherent aspect of the shape of the object or is it represented separately and bound to the object shape in a similar way to other features,... (Review)
Review
Is object orientation an inherent aspect of the shape of the object or is it represented separately and bound to the object shape in a similar way to other features, such as colour? This review brings together findings from neuropsychological studies of patients with agnosia for object orientation and experimental studies of object perception in healthy individuals that provide converging evidence of separate processing of object identity and orientation. Individuals with agnosia for object orientation, which typically results from damage to the right parietal lobe, can recognize objects presented in a range of orientations yet are unable to interpret or discriminate the objects' orientation. Healthy individuals tested with briefly presented objects demonstrate a similar dissociation: object identity is extracted rapidly in an orientation-invariant way, whereas processing the object's orientation is slower, requires attention and is influenced by the degree of departure from the canonical orientation. This asymmetry in processing can sometimes lead to incorrect bindings between the identity and orientation of objects presented in close temporal proximity. Overall, the available evidence indicates that object recognition is achieved in a largely orientation-invariant manner and that interpreting the object's orientation requires an additional step of mapping this orientation-invariant representation to a spatial reference frame.
PubMed: 38302790
DOI: 10.3758/s13423-024-02458-8 -
PloS One 2023Colour agnosia is a disorder that impairs colour knowledge (naming, recognition) despite intact colour perception. Previously, we have identified the first and...
Colour agnosia is a disorder that impairs colour knowledge (naming, recognition) despite intact colour perception. Previously, we have identified the first and only-known family with hereditary developmental colour agnosia. The aim of the current study was to explore genomic regions and candidate genes that potentially cause this trait in this family. For three family members with developmental colour agnosia and three unaffected family members CGH-array analysis and exome sequencing was performed, and linkage analysis was carried out using DominantMapper, resulting in the identification of 19 cosegregating chromosomal regions. Whole exome sequencing resulted in 11 rare coding variants present in all affected family members with developmental colour agnosia and absent in unaffected members. These variants affected genes that have been implicated in neural processes and functions (CACNA2D4, DDX25, GRINA, MYO15A) or that have an indirect link to brain function, development or disease (MAML2, STAU1, TMED3, RABEPK), and a remaining group lacking brain expression or involved in non-neural traits (DEPDC7, OR1J1, OR8D4). Although this is an explorative study, the small set of candidate genes that could serve as a starting point for unravelling mechanisms of higher level cognitive functions and cortical specialization, and disorders therein such as developmental colour agnosia.
Topics: Humans; Agnosia; Brain; Color; Cytoskeletal Proteins; RNA-Binding Proteins; Vesicular Transport Proteins
PubMed: 37672513
DOI: 10.1371/journal.pone.0290013 -
Beyoglu Eye Journal 2024Optic aphasia is a rare neurological disorder that affects the visual-semantic ability of patients with normal vision and is caused by a lesion in the left occipital...
Optic aphasia is a rare neurological disorder that affects the visual-semantic ability of patients with normal vision and is caused by a lesion in the left occipital lobe. The signs and symptoms of optic aphasia are similar to those of associative visual agnosia, where patients have difficulty recognizing objects both in shape and function, resulting in challenges performing daily tasks. The transformation to optic aphasia or associative visual agnosia is closely related to the degree of damage to the corpus callosum, with some studies hypothetically suggesting that complete damage to the corpus callosum leads to optic aphasia, whereas incomplete damage causes associative visual agnosia. We present a case of a 60-year-old man with a history of intracerebral hemorrhage in the left occipitotemporoparietal lobe. The patient complained of intermittent episodes of painless, blurry vision. Upon examination, we observed that the patient was unable to read the Snellen chart, although he could draw the letter. Furthermore, we discovered that the patient had difficulty naming objects and instruments, even though he was able to express their shape and function through gestures and mimicry. The signs and symptoms of the patient, along with the result of the multi-slice non-contrast CT scan, suggest that he had optic aphasia rather than associative visual agnosia. A comprehensive neuropsychological and aphasia examination needs to be performed to further assess the condition of our patient and establish the diagnosis.
PubMed: 38854903
DOI: 10.14744/bej.2024.43765 -
Cerebral Cortex (New York, N.Y. : 1991) May 2024We report an investigation of the neural processes involved in the processing of faces and objects of brain-lesioned patient PS, a well-documented case of pure acquired...
We report an investigation of the neural processes involved in the processing of faces and objects of brain-lesioned patient PS, a well-documented case of pure acquired prosopagnosia. We gathered a substantial dataset of high-density electrophysiological recordings from both PS and neurotypicals. Using representational similarity analysis, we produced time-resolved brain representations in a format that facilitates direct comparisons across time points, different individuals, and computational models. To understand how the lesions in PS's ventral stream affect the temporal evolution of her brain representations, we computed the temporal generalization of her brain representations. We uncovered that PS's early brain representations exhibit an unusual similarity to later representations, implying an excessive generalization of early visual patterns. To reveal the underlying computational deficits, we correlated PS' brain representations with those of deep neural networks (DNN). We found that the computations underlying PS' brain activity bore a closer resemblance to early layers of a visual DNN than those of controls. However, the brain representations in neurotypicals became more akin to those of the later layers of the model compared to PS. We confirmed PS's deficits in high-level brain representations by demonstrating that her brain representations exhibited less similarity with those of a DNN of semantics.
Topics: Humans; Prosopagnosia; Female; Adult; Brain; Neural Networks, Computer; Middle Aged; Pattern Recognition, Visual; Male; Models, Neurological
PubMed: 38795358
DOI: 10.1093/cercor/bhae211 -
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 -
Cognition Sep 2023Individuals with developmental prosopagnosia (DPs) experience severe and lifelong deficits recognising faces, but whether their deficits are selective to the processing...
Individuals with developmental prosopagnosia (DPs) experience severe and lifelong deficits recognising faces, but whether their deficits are selective to the processing of face identity or extend to the processing of face expression remains unclear. Clarifying this issue is important for understanding DP impairments and advancing theories of face processing. We compared identity and expression processing in a large sample of DPs (N = 124) using three different matching tasks that each assessed identity and expression processing with identical experimental formats. We ran each task in upright and inverted orientations and we measured inversion effects to assess the integrity of upright-specific face processes. We report three main results. First, DPs showed large deficits at discriminating identity but only subtle deficits at discriminating expression. Second, DPs showed a reduced inversion effect for identity but a normal inversion effect for expression. Third, DPs' performance on the expression tasks were linked to autism traits, but their performance on the identity tasks were not. These results constitute several dissociations between identity and expression processing in DP, and they are consistent with the view that the core impairment in DP is highly selective to identity.
Topics: Humans; Facial Recognition; Prosopagnosia; Facial Expression; Photic Stimulation; Orientation; Pattern Recognition, Visual
PubMed: 37216847
DOI: 10.1016/j.cognition.2023.105469 -
Neurocritical Care Jun 2024Gerstmann syndrome, characterized by a tetrad of symptoms, which are agraphia, acalculia, left-right disorientation, and finger agnosia, presents challenges in both...
Gerstmann syndrome, characterized by a tetrad of symptoms, which are agraphia, acalculia, left-right disorientation, and finger agnosia, presents challenges in both understanding its pathophysiology and establishing effective treatment modalities. Neuroanatomical studies have highlighted the involvement of the dominant parietal lobe, particularly the inferior parietal lobule, in the development of Gerstmann syndrome. Although current treatment options are largely supportive, recent research suggests a potential role for deep brain stimulation (DBS) in managing this condition. DBS, known for its efficacy in various neurological disorders, has been hypothesized to modulate neuronal pathways associated with Gerstmann syndrome. However, clinical evidence supporting DBS in Gerstmann syndrome remains scarce, posing challenges in patient selection and ethical considerations. Future research should prioritize investigating the efficacy and safety of DBS in Gerstmann syndrome to improve patient outcomes and quality of life.
PubMed: 38914905
DOI: 10.1007/s12028-024-02013-2 -
Neurological Sciences : Official... Apr 2024In recent years, the stroke incidence has been increasing year by year, and the related sequelae after stroke, such as cognitive impairment, motor dysfunction, and... (Review)
Review
Clinical application of repetitive transcranial magnetic stimulation in improving functional impairments post-stroke: review of the current evidence and potential challenges.
In recent years, the stroke incidence has been increasing year by year, and the related sequelae after stroke, such as cognitive impairment, motor dysfunction, and post-stroke depression, seriously affect the patient's rehabilitation and daily activities. Repetitive transcranial magnetic stimulation (rTMS), as a safe, non-invasive, and effective new rehabilitation method, has been widely recognized in clinical practice. This article reviews the application and research progress of rTMS in treating different functional impairments (cognitive impairment, motor dysfunction, unilateral spatial neglect, depression) after stroke in recent years, and preliminary summarized the possible mechanisms. It has been found that the key parameters that determine the effectiveness of rTMS in improving post-stroke functional impairments include pulse number, stimulated brain areas, stimulation intensity and frequency, as well as duration. Generally, high-frequency stimulation is used to excite the ipsilateral cerebral cortex, while low-frequency stimulation is used to inhibit the contralateral cerebral cortex, thus achieving a balance of excitability between the two hemispheres. However, the specific mechanisms and the optimal stimulation mode for different functional impairments have not yet reached a consistent conclusion, and more research is needed to explore and clarify the best way to use rTMS. Furthermore, we will identify the issues and challenges in the current research, explore possible mechanisms to deepen understanding of rTMS, propose future research directions, and offer insightful insights for better clinical applications.
Topics: Humans; Transcranial Magnetic Stimulation; Stroke Rehabilitation; Stroke; Brain; Cerebral Cortex; Agnosia
PubMed: 38102519
DOI: 10.1007/s10072-023-07217-6