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Frontiers in Aging Neuroscience 2018Alzheimer's disease (AD) is marked by memory disturbances followed by aphasia, apraxia and agnosia. Brain lesions include the accumulation of the amyloid peptide in... (Review)
Review
Alzheimer's disease (AD) is marked by memory disturbances followed by aphasia, apraxia and agnosia. Brain lesions include the accumulation of the amyloid peptide in extracellular plaques, neurofibrillary tangles with abnormally phosphorylated tau protein and synaptic and neuronal loss. New findings have suggested that brain lesions could occur one or two decades before the first clinical signs. This asymptomatic preclinical phase could be an opportunity to put in place a secondary prevention but the detection of these brain lesions can only be achieved so far by cerebrospinal fluid (CSF) evaluation or molecular amyloid and tau PET imaging. There is an urgent need to find out simple and easily accessible new biomarkers to set up an efficient screening in adult and aging population. Neuropathological and biochemical studies have revealed that abnormal accumulations of potentially toxic kinases are present in the brains of AD patients. Kinase activation leads to abnormal tau phosphorylation, amyloid production, apoptosis and neuroinflammation. Increased levels of these kinases are present in the CSF of mild cognitive impairment (MCI) and AD patients. Over the last years the search for abnormal kinase levels was performed in the blood of patients. Glycogen synthase kinase 3 (GSK 3), protein kinase R (PKR), mamalian target of rapamycin (mTOR), dual specificity tyrosine-phosphorylation-regulated kinase 1A (DIRK1A), c-Jun N-terminal kinase (JNK), protein 70 kD ribosomal protein S6 kinase (P70S6K), ERK2 and other kinase concentrations were evaluated and abnormal levels were found in many studies. For example, GSK3 levels are increased in MCI and AD patients. PKR levels are also augmented in peripheral blood mononuclear cells (PBMC) of AD patients. In the future, the assessment of several blood kinase levels in large cohorts of patients will be needed to confirm the usefulness of this test at an early phase of the disease.
PubMed: 30487744
DOI: 10.3389/fnagi.2018.00338 -
Journal of Alzheimer's Disease : JAD 2021D. Frank Benson and colleagues first described the clinical and neuropathological features of posterior cortical atrophy (PCA) from patients in the UCLA Neurobehavior... (Review)
Review
BACKGROUND
D. Frank Benson and colleagues first described the clinical and neuropathological features of posterior cortical atrophy (PCA) from patients in the UCLA Neurobehavior Program.
OBJECTIVE
We reviewed the Program's subsequent clinical experience with PCA, and its potential for clarifying this relatively rare syndrome in comparison to the accumulated literature on PCA.
METHODS
Using the original criteria derived from this clinic, 65 patients with neuroimaging-supported PCA were diagnosed between 1995 and 2020.
RESULTS
On presentation, most had visual localization complaints and related visuospatial symptoms, but nearly half had memory complaints followed by symptoms of depression. Neurobehavioral testing showed predominant difficulty with visuospatial constructions, Gerstmann's syndrome, and Balint's syndrome, but also impaired memory and naming. On retrospective application of the current Consensus Criteria for PCA, 59 (91%) met PCA criteria with a modification allowing for "significantly greater visuospatial over memory and naming deficits." There were 37 deaths (56.9%) with the median overall survival of 10.3 years (95% CI: 9.6-13.6 years), consistent with a slow neurodegenerative disorder in most patients.
CONCLUSION
Together, these findings recommend modifying the PCA criteria for "relatively spared" memory, language, and behavior to include secondary memory and naming difficulty and depression, with increased emphasis on the presence of Gerstmann's and Balint's syndromes.
Topics: Agnosia; Alzheimer Disease; Atrophy; Biomarkers; Diagnosis, Differential; Female; Gerstmann Syndrome; Humans; Male; Middle Aged; Neuroimaging; Neuropsychological Tests; Occipital Lobe; Parietal Lobe
PubMed: 34057092
DOI: 10.3233/JAD-210368 -
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 -
Annals of Physical and Rehabilitation... Jun 2017Among the many dissociations describing the visual system, the dual theory of two visual systems, respectively dedicated to perception and action, has yielded a lot of... (Review)
Review
Among the many dissociations describing the visual system, the dual theory of two visual systems, respectively dedicated to perception and action, has yielded a lot of support. There are psychophysical, anatomical and neuropsychological arguments in favor of this theory. Several behavioral studies that used sensory and motor psychophysical parameters observed differences between perceptive and motor responses. The anatomical network of the visual system in the non-human primate was very readily organized according to two major pathways, dorsal and ventral. Neuropsychological studies, exploring optic ataxia and visual agnosia as characteristic deficits of these two pathways, led to the proposal of a functional double dissociation between visuomotor and visual perceptual functions. After a major wave of popularity that promoted great advances, particularly in knowledge of visuomotor functions, the guiding theory is now being reconsidered. Firstly, the idea of a double dissociation between optic ataxia and visual form agnosia, as cleanly separating visuomotor from visual perceptual functions, is no longer tenable; optic ataxia does not support a dissociation between perception and action and might be more accurately viewed as a negative image of action blindsight. Secondly, dissociations between perceptive and motor responses highlighted in the framework of this theory concern a very elementary level of action, even automatically guided action routines. Thirdly, the very rich interconnected network of the visual brain yields few arguments in favor of a strict perception/action dissociation. Overall, the dissociation between motor function and perceptive function explored by these behavioral and neuropsychological studies can help define an automatic level of action organization deficient in optic ataxia and preserved in action blindsight, and underlines the renewed need to consider the perception-action circle as a functional ensemble.
Topics: Ataxia; Humans; Perceptual Disorders; Psychophysics; Systems Theory; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 28545844
DOI: 10.1016/j.rehab.2017.02.002 -
Neurologia (Barcelona, Spain) Oct 2014Patients who have difficulties recognising visual form stimuli are usually labelled as having visual agnosia. However, recent studies let us identify different clinical... (Review)
Review
INTRODUCTION
Patients who have difficulties recognising visual form stimuli are usually labelled as having visual agnosia. However, recent studies let us identify different clinical manifestations corresponding to discrete diagnostic entities which reflect a variety of deficits along the continuum of cortical visual processing.
DEVELOPMENT
We reviewed different clinical cases published in medical literature as well as proposals for classifying deficits in order to provide a global perspective of the subject. Here, we present the main findings on the neuroanatomical basis of visual form processing and discuss the criteria for evaluating processing which may be abnormal. We also include an inclusive diagram of visual form processing deficits which represents the different clinical cases described in the literature. Lastly, we propose a boosted decision tree to serve as a guide in the process of diagnosing such cases.
CONCLUSIONS
Although the medical community largely agrees on which cortical areas and neuronal circuits are involved in visual processing, future studies making use of new functional neuroimaging techniques will provide more in-depth information. A well-structured and exhaustive assessment of the different stages of visual processing, designed with a global view of the deficit in mind, will give a better idea of the prognosis and serve as a basis for planning personalised psychostimulation and rehabilitation strategies.
Topics: Agnosia; Decision Support Techniques; Female; Humans; Neuropsychological Tests; Vision Disorders; Visual Perception
PubMed: 22652145
DOI: 10.1016/j.nrl.2012.03.006 -
Quarterly Journal of Experimental... Feb 2017Over the last 20 years much attention in the field of face recognition has been directed towards the study of developmental prosopagnosia (DP), with some authors...
Over the last 20 years much attention in the field of face recognition has been directed towards the study of developmental prosopagnosia (DP), with some authors investigating the behavioural characteristics of the condition, and many others using these individuals to further our theoretical understanding of the typical face-processing system. It is broadly agreed that the term "DP" refers to people who have failed to develop the ability to recognize faces in the absence of neurological illness or injury, yet more precise terminology in relation to potential subtypes of the population are yet to be confirmed. Furthermore, specific diagnostic techniques and inclusion and exclusion criteria have yet to be uniformly accepted across the field, making cross-paper comparisons and meta-analyses very difficult. This paper presents an overview of the current challenges that face research into DP and introduces a series of papers that attempt to further our understanding of the condition's characteristics. It is hoped that this special issue will provide a springboard for further research addressing these issues, improving the current state of the art by ensuring the quality of theoretical investigations into DP, and by posing advances that will assist those who have the condition.
Topics: Humans; Prosopagnosia
PubMed: 27251859
DOI: 10.1080/17470218.2016.1195414 -
OTJR : Occupation, Participation and... Apr 2018Unilateral neglect (neglect) and anosognosia often co-occur post stroke. It is unknown whether anosognosia of neglect varies for different types of daily activities. The...
Unilateral neglect (neglect) and anosognosia often co-occur post stroke. It is unknown whether anosognosia of neglect varies for different types of daily activities. The objective is to examine the frequency of anosognosia of neglect for items on the Catherine Bergego Scale (CBS) and to determine the level of agreement between participant/assessor item ratings and total scores. Secondary analysis of data was carried out. We conducted descriptive analyses and interrater reliability analyses (Cohen's kappa) to determine the level of agreement between assessor and participant item ratings. A paired t test was conducted to compare assessor and participant total scores. The frequency of anosognosia among items varied (29.2%-83.3%) and Kappa statistics ranged from -0.07 (no agreement) to 0.23 (fair agreement) for item ratings. There was a significant difference- t(36) = 3.02, p ≤ .01)-between assessor ( M = 8.0, SD = 5.2) and participant-rated ( M = 5.3, SD = 4.5) total CBS scores. Anosognosia is prevalent among those with neglect. Findings highlight the importance of assessing for anosognosia.
Topics: Aged; Agnosia; Cross-Sectional Studies; Female; Humans; Male; Middle Aged; Neuropsychological Tests; Observer Variation; Perceptual Disorders; Prevalence; Psychometrics; Reproducibility of Results; Stroke
PubMed: 29251546
DOI: 10.1177/1539449217747586 -
Neuropsychologia Feb 2023Healthy observers recognize more accurately same-than other-race faces (i.e., the Same-Race Recognition Advantage - SRRA) but categorize them by race more slowly than...
Healthy observers recognize more accurately same-than other-race faces (i.e., the Same-Race Recognition Advantage - SRRA) but categorize them by race more slowly than other-race faces (i.e., the Other-Race Categorization Advantage - ORCA). Several fMRI studies reported discrepant bilateral activations in the Fusiform Face Area (FFA) and Occipital Face Area (OFA) correlating with both effects. However, due to the very nature and limits of fMRI results, whether these face-sensitive regions play an unequivocal causal role in those other-race effects remains to be clarified. To this aim, we tested PS, a well-studied pure case of acquired prosopagnosia with lesions encompassing the left FFA and the right OFA. PS, healthy age-matched and young adults performed two recognition and three categorization by race tasks, respectively using Western Caucasian and East Asian faces normalized for their low-level properties with and without-external features, as well as in naturalistic settings. As expected, PS was slower and less accurate than the controls. Crucially, however, the magnitudes of her SRRA and ORCA were comparable to the controls in all the tasks. Our data show that prosopagnosia does not abolish other-race effects, as an intact face system, the left FFA and/or right OFA are not critical for eliciting the SRRA and ORCA. Race is a strong visual and social signal that is encoded in a large neural face-sensitive network, robustly tuned for processing same-race faces.
Topics: Female; Humans; Young Adult; Cerebral Cortex; Magnetic Resonance Imaging; Pattern Recognition, Visual; Prosopagnosia; Recognition, Psychology; White People; East Asian People
PubMed: 36623806
DOI: 10.1016/j.neuropsychologia.2023.108479 -
Frontiers in Neurology 2014Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the... (Review)
Review
Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the geometry of a goal object. This striking dissociation between perception and action in DF provided a key piece of evidence for the formulation of Goodale and Milner's Two Visual Systems Hypothesis (TVSH). According to the TVSH, the ventral stream plays a critical role in constructing our visual percepts, whereas the dorsal stream mediates the visual control of action, such as visually guided grasping. In this review, we discuss recent studies of DF that provide new insights into the functional organization of the dorsal and ventral streams. We confirm recent evidence that DF has dorsal as well as ventral brain damage - and that her dorsal-stream lesions and surrounding atrophy have increased in size since her first published brain scan. We argue that the damage to DF's dorsal stream explains her deficits in directing actions at targets in the periphery. We then focus on DF's ability to accurately adjust her in-flight hand aperture to changes in the width of goal objects (grip scaling) whose dimensions she cannot explicitly report. An examination of several studies of DF's grip scaling under natural conditions reveals a modest though significant deficit. Importantly, however, she continues to show a robust dissociation between form vision for perception and form vision-for-action. We also review recent studies that explore the role of online visual feedback and terminal haptic feedback in the programming and control of her grasping. These studies make it clear that DF is no more reliant on visual or haptic feedback than are neurologically intact individuals. In short, we argue that her ability to grasp objects depends on visual feedforward processing carried out by visuomotor networks in her dorsal stream that function in the much the same way as they do in neurologically intact individuals.
PubMed: 25538675
DOI: 10.3389/fneur.2014.00255