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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 -
Brain Structure & Function Jun 2024Optic Aphasia (OA) and Associative Visual Agnosia (AVA) are neuropsychological disorders characterized by impaired naming on visual presentation. From a cognitive point...
Optic Aphasia (OA) and Associative Visual Agnosia (AVA) are neuropsychological disorders characterized by impaired naming on visual presentation. From a cognitive point of view, while stimulus identification is largely unimpaired in OA (where access to semantic knowledge is still possible), in AVA it is not. OA has been linked with right hemianopia and disconnection of the occipital right-hemisphere (RH) visual processing from the left hemisphere (LH) language areas.In this paper, we describe the case of AA, an 81-year-old housewife suffering from a deficit in naming visually presented stimuli after left occipital lesion and damage to the interhemispheric splenial pathway. AA has been tested through a set of tasks assessing different levels of visual object processing. We discuss behavioral performance as well as the pattern of lesion and disconnection in relation to a neurocognitive model adapted from Luzzatti and colleagues (1998). Despite the complexity of the neuropsychological picture, behavioral data suggest that semantic access from visual input is possible, while a lesion-based structural disconnectome investigation demonstrated the splenial involvement.Altogether, neuropsychological and neuroanatomical findings support the assumption of visuo-verbal callosal disconnection compatible with a diagnosis of OA.
PubMed: 38914895
DOI: 10.1007/s00429-024-02818-z -
Current Neurology and Neuroscience... Jun 2024To review the literature on visual dysfunction in dementia with Lewy bodies (DLB), including its mechanisms and clinical implications. (Review)
Review
PURPOSE OF REVIEW
To review the literature on visual dysfunction in dementia with Lewy bodies (DLB), including its mechanisms and clinical implications.
RECENT FINDINGS
Recent studies have explored novel aspects of visual dysfunction in DLB, including visual texture agnosia, mental rotation of 3-dimensional drawn objects, and reading fragmented letters. Recent studies have shown parietal and occipital hypoperfusion correlating with impaired visuoconstruction performance. While visual dysfunction in clinically manifest DLB is well recognized, recent work has focused on prodromal or mild cognitive impairment (MCI) due to Lewy body pathology with mixed results. Advances in retinal imaging have recently led to the identification of abnormalities such as parafoveal thinning in DLB. Patients with DLB experience impairment in color perception, form and object identification, space and motion perception, visuoconstruction tasks, and illusions in association with visual cortex and network dysfunction. These symptoms are associated with visual hallucinations, driving impairment, falls, and other negative outcomes.
PubMed: 38907811
DOI: 10.1007/s11910-024-01349-8 -
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 -
Brain Research Jun 2024Peripheral vestibular activation results in multi-level responses, from brainstem-mediated reflexes (e.g. vestibular ocular reflex - VOR) to perception of self-motion....
Peripheral vestibular activation results in multi-level responses, from brainstem-mediated reflexes (e.g. vestibular ocular reflex - VOR) to perception of self-motion. While VOR responses indicate preserved vestibular peripheral and brainstem functioning, there are no automated measures of vestibular perception of self-motion - important since some patients with brain disconnection syndromes manifest a vestibular agnosia (intact VOR but impaired self-motion perception). Electroencephalography ('EEG') - may provide a surrogate marker of vestibular perception of self-motion. A related objective is obtaining an EEG marker of vestibular sensory signal processing, distinct from vestibular-motion perception. We performed a pilot study comparing EEG responses in the dark when healthy participants sat in a vibrationless computer-controlled motorised rotating chair moving at near threshold of self-motion perception, versus a second situation in which subjects sat in the chair at rest in the dark who could be induced (or not) into falsely perceiving self-motion. In both conditions subjects could perceive self-motion perception, but in the second there was no bottom-up reflex-brainstem activation. Time-frequency analyses showed: (i) alpha frequency band activity is linked to vestibular sensory-signal activation; and (ii) theta band activity is a marker of vestibular-mediated self-motion perception. Consistent with emerging animal data, our findings support the role of theta activity in the processing of self-motion perception.
PubMed: 38844198
DOI: 10.1016/j.brainres.2024.149048 -
Cortex; a Journal Devoted To the Study... Jul 2024The goal of this preregistered scoping review is to create an overview of the research on developmental prosopagnosia (DP). Through analysis of all empirical studies of... (Review)
Review
The goal of this preregistered scoping review is to create an overview of the research on developmental prosopagnosia (DP). Through analysis of all empirical studies of DP in adults, we investigate 1) how DP is conceptualized and defined, 2) how individuals are classified with DP and 3) which aspects of DP are investigated in the literature. We reviewed 224 peer-reviewed studies of DP. Our analysis of the literature reveals that while DP is predominantly defined as a lifelong face recognition impairment in the absence of acquired brain injury and intellectual/cognitive problems, there is far from consensus on the specifics of the definition with some studies emphasizing e.g., deficits in face perception, discrimination and/or matching as core characteristics of DP. These differences in DP definitions is further reflected in the vast heterogeneity in classification procedures. Only about half of the included studies explicitly state how they classify individuals with DP, and these studies adopt 40 different assessment tools. The two most frequently studied aspects of DP are the role of holistic processing and the specificity of face processing, and alongside a substantial body of neuroimaging studies of DP, this paints a picture of a research field whose scientific interests and aims are rooted in cognitive neuropsychology and neuroscience. We argue that these roots - alongside the heterogeneity in DP definition and classification - may have limited the scope and interest of DP research unnecessarily, and we point to new avenues of research for the field.
Topics: Prosopagnosia; Humans; Facial Recognition; Recognition, Psychology
PubMed: 38795651
DOI: 10.1016/j.cortex.2024.04.011 -
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 -
Cortex; a Journal Devoted To the Study... Jul 2024Developmental prosopagnosia (DP) is associated with considerable perceptual heterogeneity, though the nature of this heterogeneity and whether there are discrete...
Developmental prosopagnosia (DP) is associated with considerable perceptual heterogeneity, though the nature of this heterogeneity and whether there are discrete subgroups versus continuous deficits remains unclear. Bennetts et al. (2022) recently found that holistic versus featural processing deficits distinguished discrete DP subgroups, but their sample was relatively small (N = 37), and subgroups were defined using a single task. To characterize perceptual heterogeneity in DPs more comprehensively, we administered a broad face perception battery to a large sample of 109 DPs and 134 controls, including validated measures of face matching (Cambridge Face Perception Test - CFPT, Computerized Benton Facial Recognition Test, Same/Different Face Matching Task), holistic processing (Part-Whole Task), and feature processing (Georges Task and Part-Whole part trials). When examining face matching measures, DPs exhibited a similar distribution of performance as controls, though shifted towards impairment by an average of 1.4 SD. We next applied Bennetts (2022) hierarchical clustering approach and k-means clustering to the CFPT upright, inverted, and inversion index measures, similarly finding one group of DPs with poorer inverted face performance and another with a decreased face inversion effect (holistic processing). However, these subgroup differences failed to generalize to other measures of feature and holistic processing beyond the CFPT. We finally ran hierarchical and k-means cluster analyses on our larger battery of face matching, feature, and holistic processing measures. Results clearly showed subgroups with generally better versus worse performance across all measures, with the distinction between groups being somewhat arbitrary. Together, these findings support a continuous account of DP perceptual heterogeneity, with performance differing primarily across all aspects of face perception.
Topics: Humans; Prosopagnosia; Female; Male; Adult; Facial Recognition; Middle Aged; Young Adult; Neuropsychological Tests; Recognition, Psychology; Pattern Recognition, Visual; Visual Perception; Adolescent
PubMed: 38744075
DOI: 10.1016/j.cortex.2024.03.011 -
Neurological Sciences : Official... May 2024To explore efficacy of the "Rey-Osterrieth complex figure (ROCF) tracing task" as a new test to detect unilateral spatial neglect (USN).
PURPOSE
To explore efficacy of the "Rey-Osterrieth complex figure (ROCF) tracing task" as a new test to detect unilateral spatial neglect (USN).
METHODS
Subjects were 40 healthy control (HC) and 20 right brain-damaged patients with (USN + , n = 10) or without USN (USN - , n = 10). After the ROCF copying task, the tracing task was performed under conditions that did not leave any tracing lines on the sample figure. Evaluation used the conventional 36-point scoring system, laterality index (LI) as the ratio of the left and right structure scores, and the number of overlaps for each of the left and right structures scored.
RESULTS
In the tracing task, USN + showed a lower LI than HC. Furthermore, left-sided neglect was sometimes more evident than in the copying task. Regarding the total overlapping score, USN + showed a greater score than HC. The right-sided overlapping scores in USN + and USN - were also greater than that in HC. In the right brain-damaged subjects, clinically meaningful correlations were not found between evaluations in the ROCF tracing task and in conventional USN screening tests. Receiver-operating-characteristic analysis to test the power of detection showed moderate performance for the tracing LI (AUC = 0.76, 95% CI = 0.54-0.97), which was greater than that of other tests. Further, the total overlapping score in the tracing task showed sensitivity 0.9 (highest among the tests performed), specificity 0.5, and AUC 0.68 (95% CI = 0.43-0.92).
CONCLUSION
The ROCF tracing task might be a convenient method to detect USN and to reveal the extent of spatial working memory impairment.
PubMed: 38717579
DOI: 10.1007/s10072-024-07540-6 -
Neuropathology : Official Journal of... May 2024A 68-year-old woman presented with difficulty finding words and writing characters. Neurological examination led to clinical diagnosis at onset of the logopenic variant...
An autopsy case of type A FTLD-TDP with a GRN mutation presenting with the logopenic variant of primary progressive aphasia at onset and with corticobasal syndrome subsequently.
A 68-year-old woman presented with difficulty finding words and writing characters. Neurological examination led to clinical diagnosis at onset of the logopenic variant of primary progressive aphasia accompanied with ideomotor apraxia, visuospatial agnosia on the right, and Gerstmann syndrome. Bradykinesia and rigidity on the right with shuffling gait developed after one year. Treatment with L-dopa had no effect. The patient was diagnosed with corticobasal syndrome (CBS). Brain magnetic resonance imaging revealed diffuse cortical atrophy dominantly on the left, especially in the temporal, parietal, and occipital lobes. Positron emission tomography did not reveal any significant accumulation of amyloid β or tau protein. She died five years later. Neuropathological examination revealed diffuse cortical atrophy with severe neuronal loss and fibrous gliosis in the cortex. Neuronal cytoplasmic inclusions, short dystrophic neurites, and, most notably, neuronal intranuclear inclusions, all immunoreactive for phosphorylated TDP-43, were observed. Western blotting revealed a full length and fragments of phosphorylated TDP-43 at 45 and 23 kDa, respectively, confirming the pathological diagnosis of type A FTLD-TDP. Whole exome sequencing revealed a pathogenic mutation in GRN (c.87dupC). FTLD-TDP should be included in the differential diagnosis of CBS.
PubMed: 38715398
DOI: 10.1111/neup.12980