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Journal of the Neurological Sciences Dec 2022Vestibular Agnosia - where peripheral vestibular activation triggers the usual reflex nystagmus response but with attenuated or no self-motion perception - is found in...
Vestibular Agnosia - where peripheral vestibular activation triggers the usual reflex nystagmus response but with attenuated or no self-motion perception - is found in brain disease with disrupted cortical network functioning, e.g. traumatic brain injury (TBI) or neurodegeneration (Parkinson's Disease). Patients with acute focal hemispheric lesions (e.g. stroke) do not manifest vestibular agnosia. Thus, brain network mapping techniques, e.g. resting state functional MRI (rsfMRI), are needed to interrogate functional brain networks mediating vestibular agnosia. Hence, we prospectively recruited 39 acute TBI patients with preserved peripheral vestibular function and obtained self-motion perceptual thresholds during passive yaw rotations in the dark and additionally acquired whole-brain rsfMRI in the acute phase. Following quality-control checks, 26 patient scans were analyzed. Using self-motion perceptual thresholds from a matched healthy control group, 11 acute TBI patients were classified as having vestibular agnosia versus 15 with normal self-motion perception thresholds. Using independent component analysis on the rsfMRI data, we found altered functional connectivity in bilateral lingual gyrus and temporo-occipital fusiform cortex in the vestibular agnosia patients. Moreover, regions of interest analyses showed both inter-hemispheric and intra-hemispheric network disruption in vestibular agnosia. In conclusion, our results show that vestibular agnosia is mediated by bilateral anterior and posterior network dysfunction and reveal the distributed brain mechanisms mediating vestibular self-motion perception.
Topics: Humans; Vestibule, Labyrinth; Brain; Brain Mapping; Magnetic Resonance Imaging; Brain Injuries; Sensation; Agnosia
PubMed: 36332321
DOI: 10.1016/j.jns.2022.120458 -
Annals of Physical and Rehabilitation... Feb 2016Neurobehavioral and self-awareness changes are frequently observed following traumatic brain injury (TBI). These disturbances have been related to negative consequences... (Review)
Review
Neurobehavioral and self-awareness changes are frequently observed following traumatic brain injury (TBI). These disturbances have been related to negative consequences on functional outcomes, caregiver distress and social reintegration, representing therefore a challenge for clinical research. Some studies have recently been conducted to specifically explore apathetic and impulsive manifestations, as well as self-awareness impairments in patients with TBI. These findings underlined the heterogeneity of clinical manifestations for each behavioral disturbance and the diversity of psychological processes involved. In this context, new multidimensional approaches taking into account the various processes at play have been proposed to better understand and apprehend the complexity and dynamic nature of these problematic behaviors. In addition, the involvement of social and environmental factors as well as premorbid personality traits have increasingly been addressed. These new multidimensional frameworks have the potential to ensure targeted and effective rehabilitation by allowing a better identification and therefore consideration of the various mechanisms involved in the onset of problematic behaviors. In this context, the main objective of this position paper was to demonstrate the interest of multidimensional approaches in the understanding and rehabilitation of problematic behaviors in patients with TBI.
Topics: Agnosia; Apathy; Brain Injuries; Disruptive, Impulse Control, and Conduct Disorders; Humans; Impulsive Behavior
PubMed: 26585583
DOI: 10.1016/j.rehab.2015.09.002 -
Philosophical Transactions of the Royal... Jun 2016Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local... (Review)
Review
Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy.This article is part of the themed issue 'Vision in our three-dimensional world'.
Topics: Agnosia; Alzheimer Disease; Animals; Depth Perception; Hemianopsia; Humans; Macaca; Perceptual Disorders; Vision, Binocular; Visual Cortex
PubMed: 27269597
DOI: 10.1098/rstb.2015.0254 -
Cerebrovascular Diseases (Basel,... 2009Anosognosia in stroke patients showed a relevant detrimental effect on the rehabilitation course and patients' quality of life, especially in those with brain injury.... (Review)
Review
BACKGROUND
Anosognosia in stroke patients showed a relevant detrimental effect on the rehabilitation course and patients' quality of life, especially in those with brain injury. Although a number of reliable scales for the assessment of anosognosia in stroke and traumatic brain injury have been developed, at present no single measure fully explores the multifaceted nature of the phenomenon.
METHOD
A PubMed search with appropriate terms was carried out in order to critically review the issue.
RESULTS
The main dimensions to consider in the investigation of anosognosia in brain-injured patients are (a) awareness of deficit and related functional implications, (b) modality specificity, (c) causal attribution, (d) expectations of recovery, (e) implicit knowledge and (f) differential diagnosis with psychological denial. Time elapsed from stroke, aetiology, laterality, aphasia and clinical complications may influence all these characteristics and must be taken into consideration. Finally, an adequate association of the anosognosia evaluation with other neuropsychological and behavioural aspects is relevant for a modern holistic approach to the patient.
CONCLUSIONS
This review is meant to stimulate the development of a new comprehensive assessment procedure for anosognosia in brain injury and particularly in stroke, in order to catch the multidimensionality of the phenomenon and to shape rehabilitation programmes suitable to the specific clinical features of every single patient.
Topics: Agnosia; Aphasia; Awareness; Denial, Psychological; Diagnosis, Differential; Disability Evaluation; Functional Laterality; Hemiplegia; Humans; Neuropsychological Tests; Predictive Value of Tests; Psychiatric Status Rating Scales; Recovery of Function; Self Concept; Severity of Illness Index; Stroke; Stroke Rehabilitation; Surveys and Questionnaires; Time Factors; Treatment Outcome
PubMed: 19202333
DOI: 10.1159/000199466 -
International Journal of Molecular... Apr 2021Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson's disease (PD) that start very early and frequently precede the PD... (Review)
Review
Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson's disease (PD) that start very early and frequently precede the PD motor symptoms. The limited data available suggest that the basis of the olfactory and gustatory dysfunction related to PD are likely multifactorial and may include the same determinants responsible for other non-motor symptoms of PD. This review describes the most relevant molecular and genetic factors involved in the PD-related smell and taste impairments, and their associations with the microbiota, which also may represent risk factors associated with the disease.
Topics: Agnosia; Biomarkers; Disease Susceptibility; Genetic Predisposition to Disease; Genetic Variation; Humans; Microbiota; Models, Biological; Olfactory Perception; Parkinson Disease; Taste Perception
PubMed: 33924222
DOI: 10.3390/ijms22084286 -
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 -
Current Opinion in Neurology Dec 2010Analysis of the auditory environment, source identification and vocal communication all require efficient brain mechanisms for disambiguating, representing and... (Review)
Review
PURPOSE OF REVIEW
Analysis of the auditory environment, source identification and vocal communication all require efficient brain mechanisms for disambiguating, representing and understanding complex natural sounds as 'auditory objects'. Failure of these mechanisms leads to a diverse spectrum of clinical deficits. Here we review current evidence concerning the phenomenology, mechanisms and brain substrates of auditory agnosias and related disorders of auditory object processing.
RECENT FINDINGS
Analysis of lesions causing auditory object deficits has revealed certain broad anatomical correlations: deficient parsing of the auditory scene is associated with lesions involving the parieto-temporal junction, while selective disorders of sound recognition occur with more anterior temporal lobe or extra-temporal damage. Distributed neural networks have been increasingly implicated in the pathogenesis of such disorders as developmental dyslexia, congenital amusia and tinnitus. Auditory category deficits may arise from defective interaction of spectrotemporal encoding and executive and mnestic processes. Dedicated brain mechanisms are likely to process specialized sound objects such as voices and melodies.
SUMMARY
Emerging empirical evidence suggests a clinically relevant, hierarchical and modular neuropsychological model of auditory object processing that provides a framework for understanding auditory agnosias and makes specific predictions to direct future work.
Topics: Agnosia; Auditory Cortex; Auditory Pathways; Auditory Perception; Cerebral Cortex; Humans; Language Development Disorders; Nerve Net; Neuropsychology
PubMed: 20975559
DOI: 10.1097/WCO.0b013e32834027f6 -
Philosophical Transactions of the Royal... Feb 2011We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms... (Review)
Review
We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans--and present additional original data--which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward. This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.
Topics: Agnosia; Animals; Apraxias; Haplorhini; Humans; Parietal Lobe; Saccades; Space Perception; Visual Perception
PubMed: 21242144
DOI: 10.1098/rstb.2010.0258 -
Neuron Mar 2014Optic ataxia is a high-order deficit in reaching to visual goals that occurs with posterior parietal cortex (PPC) lesions. It is a component of Balint's syndrome that... (Review)
Review
Optic ataxia is a high-order deficit in reaching to visual goals that occurs with posterior parietal cortex (PPC) lesions. It is a component of Balint's syndrome that also includes attentional and gaze disorders. Aspects of optic ataxia are misreaching in the contralesional visual field, difficulty preshaping the hand for grasping, and an inability to correct reaches online. Recent research in nonhuman primates (NHPs) suggests that many aspects of Balint's syndrome and optic ataxia are a result of damage to specific functional modules for reaching, saccades, grasp, attention, and state estimation. The deficits from large lesions in humans are probably composite effects from damage to combinations of these functional modules. Interactions between these modules, either within posterior parietal cortex or downstream within frontal cortex, may account for more complex behaviors such as hand-eye coordination and reach-to-grasp.
Topics: Agnosia; Animals; Ataxia; Attention; Humans; Parietal Lobe; Psychomotor Performance
PubMed: 24607223
DOI: 10.1016/j.neuron.2014.02.025 -
Cognitive Neuropsychiatry 2014Theories of delusions which rely on a combination of abnormal experience and defective belief evaluation and/ or cognitive bias are the subject of an emerging consensus....
INTRODUCTION
Theories of delusions which rely on a combination of abnormal experience and defective belief evaluation and/ or cognitive bias are the subject of an emerging consensus. This paper challenges the validity of these theories and constructs a two factor alternative.
METHODS
The paper starts by identifying the difficulty the current theories have explaining the complex delusions of schizophrenia and then, by considering, first, the aetiology of somatopsychotic symptoms, and second, the literature on the relationship between confabulation and allopsychotic symptoms, demonstrates that the natural solution is to retain the experiential factor whilst replacing the second factor with confabulation.
RESULTS
The paper is then able to demonstrate that the resultant two-factory theory can clarify recent work on the aetiological role of autonoetic agnosia and on the relationships between confabulation, delusion, and thought disorder.
CONCLUSIONS
The theory supersedes currently available theories in terms of its simplicity, fruitfulness, scope and conservatism and represents an advance in the search for unified theory of psychosis.
Topics: Agnosia; Culture; Delusions; Humans; Memory Disorders; Models, Psychological; Psychotic Disorders; Schizophrenic Psychology
PubMed: 24328860
DOI: 10.1080/13546805.2013.803959