-
Current Neurology and Neuroscience... Nov 2023To investigate the neurofunctional correlates of pure auditory agnosia and its varieties (global, verbal, and nonverbal), based on 116 anatomoclinical reports published... (Review)
Review
PURPOSE OF REVIEW
To investigate the neurofunctional correlates of pure auditory agnosia and its varieties (global, verbal, and nonverbal), based on 116 anatomoclinical reports published between 1893 and 2022, with emphasis on hemispheric lateralization, intrahemispheric lesion site, underlying cognitive impairments.
RECENT FINDINGS
Pure auditory agnosia is rare, and observations accumulate slowly. Recent patient reports and neuroimaging studies on neurotypical subjects offer insights into the putative mechanisms underlying auditory agnosia, while challenging traditional accounts. Global auditory agnosia frequently results from bilateral temporal damage. Verbal auditory agnosia strictly correlates with language-dominant hemisphere lesions. Damage involves the auditory pathways, but the critical lesion site is unclear. Both the auditory cortex and associative areas are reasonable candidates, but cases resulting from brainstem damage are on record. The hemispheric correlates of nonverbal auditory input disorders are less clear. They correlate with unilateral damage to either hemisphere, but evidence is scarce. Based on published cases, pure auditory agnosias are neurologically and functionally heterogeneous. Phenotypes are influenced by co-occurring cognitive impairments. Future studies should start from these facts and integrate patient data and studies in neurotypical individuals.
Topics: Humans; Agnosia; Auditory Perception
PubMed: 37747655
DOI: 10.1007/s11910-023-01302-1 -
Bosnian Journal of Basic Medical... Nov 2019Optogenetics is an emerging field, which uses light and molecular genetics to manipulate the activity of live cells by expressing light-sensitive proteins. With the... (Review)
Review
Optogenetics is an emerging field, which uses light and molecular genetics to manipulate the activity of live cells by expressing light-sensitive proteins. With the discovery of bacteriorhodopsin, a light-sensitive bacterial protein, in 1971 Oesterhelt and Stoeckenius laid the pavement of optogenetics. However, the cross-integration of different disciplines is a little more than a decade old. The toolbox contains fluorescent sensors and optogenetic actuators that enable visualization of signaling events and manipulation of cellular activities, respectively. Neuropathic pain is pain caused either by damage or disease that affects the somatosensory system. The exact mechanism for neuropathic pain is not known, however proposed mechanisms include immune reactions, ion channel expressions, and inflammation. Current regimen for the disease provides about 50% relief for only 40-60% of patients. Recent in vivo and in vitro studies demonstrate the potential therapeutic applications of optogenetics by manipulating the activity of neurons. This review summarizes the basic concept, therapeutic applications for neuropathy, and potential of optogenetics to reach from bench to bedside in the near future.
Topics: Agnosia; Animals; Bacteriorhodopsins; Blood-Brain Barrier; Chronic Pain; Epigenesis, Genetic; Humans; Inflammation; Interdisciplinary Research; Ion Channels; Light; Neuralgia; Neurons; Optogenetics; Pain Management; Retinitis Pigmentosa; Signal Transduction
PubMed: 30995901
DOI: 10.17305/bjbms.2019.4114 -
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 -
Cognitive and Behavioral Neurology :... Jun 2022Posterior cortical atrophy (PCA) is a progressive neurologic syndrome that presents with complex visual deficits. Although PCA is most commonly a form of Alzheimer...
BACKGROUND
Posterior cortical atrophy (PCA) is a progressive neurologic syndrome that presents with complex visual deficits. Although PCA is most commonly a form of Alzheimer disease (AD), its early diagnosis is usually delayed due to a lack of understanding for how best to clinically screen for the syndrome.
OBJECTIVE
To identify neurobehavioral screening tasks for PCA-beyond simple visual constructions-that can be administered in clinic or at bedside.
METHOD
We compared the performance of 12 individuals who met neuroimaging-supported consensus criteria for PCA with that of 12 matched individuals with typical AD (tAD) and 24 healthy controls (HC) on clinic/bedside tasks measuring (a) complex figure copying, (b) Balint syndrome, (c) visual object agnosia, (d) color identification, (e) figure-ground discrimination, (f) global-local processing, (g) dressing apraxia, (h) ideomotor apraxia, and (i) Gerstmann syndrome.
RESULTS
All of the individuals with PCA were impaired on the figure-ground discrimination task compared with half of the tAD group and no HC. Approximately half of the PCA group had Balint syndrome, dressing apraxia, and ideomotor apraxia compared with none in the tAD group. Difficulty copying a complex figure, global-local processing impairment, and Gerstmann syndrome did not distinguish between the two dementia groups.
CONCLUSION
The figure-ground discrimination task can be used successfully as an overall screening measure for PCA, followed by specific tasks for Balint syndrome and dressing and limb apraxia. Findings reinforce PCA as a predominant occipitoparietal disorder with dorsal visual stream involvement and parietal signs with spatiomotor impairments.
Topics: Alzheimer Disease; Apraxia, Ideomotor; Atrophy; Cerebral Cortex; Gerstmann Syndrome; Humans; Neuropsychological Tests
PubMed: 35639011
DOI: 10.1097/WNN.0000000000000297 -
Cortex; a Journal Devoted To the Study... Dec 2019
Topics: Agnosia; Ataxia; Humans; Vision Disorders; Visual Perception
PubMed: 31668647
DOI: 10.1016/j.cortex.2019.09.004 -
Cortex; a Journal Devoted To the Study... Mar 2024
PubMed: 38594164
DOI: 10.1016/j.cortex.2024.03.006 -
Restorative Neurology and Neuroscience 2022Agnosia for objects is often overlooked in neuropsychology, especially with respect to rehabilitation. Prosopagnosia has been studied more extensively, yet there have...
BACKGROUND
Agnosia for objects is often overlooked in neuropsychology, especially with respect to rehabilitation. Prosopagnosia has been studied more extensively, yet there have been few attempts at training it. The lack of training protocols may partially be accounted for by their relatively low incidence and specificity to sensory modality. However, finding effective rehabilitations for such deficits may help to reduce their impact on the social and psychological functioning of individuals.
OBJECTIVE
Our aim in this study was to provide clinicians and researchers with useful information with which to conduct new studies on the rehabilitation of object agnosia and prosopagnosia. To accomplish this, we performed a systematic and comprehensive review of the effect of neuropsychological rehabilitation on visual object and prosopagnosia.
METHODS
The Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed. In addition, the Single-Case Experimental Design (SCED) and the Critical Appraisal Skills Programme (CASP) scales were used to assess the quality of reporting.
RESULTS
Seven articles regarding object agnosia, eight articles describing treatments for prosopagnosia, and two articles describing treatments for both deficits were included.
CONCLUSIONS
In the light of the studies reviewed, treatments based on analysis of parts seem effective for object agnosia, while prosopagnosia appears to benefit most from treatments relying on holistic/configural processing. However, more attempts at rehabilitation of face and object agnosia are needed to clarify the mechanisms of these processes and possible rehabilitations. Moreover, a publication bias could mask a broader attempt to find effective treatments for visual agnosia and leaving out studies that are potentially more informative.
PubMed: 36155537
DOI: 10.3233/RNN-211234 -
La Revue Du Praticien Feb 2020Alzheimer's disease: a biological disorder? Alzheimer's disease often begins clinically with memory problems progressively followed by aphasia, apraxia, agnosia and... (Review)
Review
Alzheimer's disease: a biological disorder? Alzheimer's disease often begins clinically with memory problems progressively followed by aphasia, apraxia, agnosia and behavioral disturbances. Recent studies of biological markers of cerebrospinal fluid or amyloid and tau PET imaging have shown that abnormalities can begin one to two decades before the onset of symptoms. This clinically silent phase is a biological phase where neurons fight the toxic effects of amyloid and tau accumulations as well as neuroinflammation. An ATN biological classification has been proposed (A: amyloid, T tau, N: neurodegeneration). The discovery of blood or other biomarkers should allow detection of this silent phase leading to the setup of therapeutic trials when brain lesions are minimal and neurons less affected, to be able to prevent the late cognitive decline of this disease.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloidosis; Biomarkers; Cognitive Dysfunction; Humans; Positron-Emission Tomography; tau Proteins
PubMed: 32877125
DOI: No ID Found -
The Neuroscientist : a Review Journal... Jun 2020Color provides valuable information about the environment, yet the exact mechanisms explaining how colors appear to us remain poorly understood. Retinal signals are... (Review)
Review
Color provides valuable information about the environment, yet the exact mechanisms explaining how colors appear to us remain poorly understood. Retinal signals are processed in the visual cortex through high-level mechanisms that link color perception with top-down expectations and knowledge. Here, we review the neuroimaging evidence about color processing in the brain, and how it is affected by acquired brain lesions in humans. Evidence from patients with brain-damage suggests that high-level color processing may be divided into at least three modules: perceptual color experience, color naming, and color knowledge. These modules appear to be functionally independent but richly interconnected, and serve as cortical relays linking sensory and semantic information, with the final goal of directing object-related behavior. We argue that the relations between colors and their objects are key mechanisms to understand high-level color processing.
Topics: Agnosia; Anomia; Cerebral Cortex; Color Perception; Color Vision Defects; Humans; Visual Pathways
PubMed: 31691627
DOI: 10.1177/1073858419882621 -
Cortex; a Journal Devoted To the Study... Jun 2020
Topics: Agnosia; Humans
PubMed: 32284155
DOI: 10.1016/j.cortex.2020.03.003