-
Perception Sep 2023Aphantasia and prosopagnosia are both rare conditions with impairments in visual cognition. While prosopagnosia refers to a face recognition deficit, aphantasics exhibit...
Aphantasia and prosopagnosia are both rare conditions with impairments in visual cognition. While prosopagnosia refers to a face recognition deficit, aphantasics exhibit a lack of mental imagery. Current object recognition theories propose an interplay of perception and mental representations, making an association between recognition performance and visual imagery plausible. While the literature assumes a link between aphantasia and prosopagnosia, other impairments in aphantasia have been shown to be rather global. Therefore, we assumed that aphantasics do not solely exhibit impairments in face recognition but rather in general visual recognition performance, probably moderated by stimulus complexity. To test this hypothesis, 65 aphantasics were compared to 55 controls in a face recognition task, the Cambridge Face Memory Test, and a corresponding object recognition task, the Cambridge Car Memory Test. In both tasks, aphantasics performed worse than controls, indicating mild recognition deficits without face-specificity. Additional correlations between imagery vividness and performance in both tasks were found, suggesting that visual imagery influences visual recognition not only in imagery extremes. Stimulus complexity produced the expected moderation effect but only for the whole imagery-spectrum and only with face stimuli. Overall, the results imply that aphantasia is linked to a general but mild deficit in visual recognition.
Topics: Humans; Prosopagnosia; Prevalence; Recognition, Psychology; Cognition; Visual Perception; Pattern Recognition, Visual
PubMed: 37321679
DOI: 10.1177/03010066231180712 -
Tidsskrift For Den Norske Laegeforening... Nov 2023Neurological disorders can present with a vast array of visual disturbances. The constellation of symptoms and findings in this patient prompted workup for unusual...
BACKGROUND
Neurological disorders can present with a vast array of visual disturbances. The constellation of symptoms and findings in this patient prompted workup for unusual causes of both stroke and neurodegenerative disorder.
CASE PRESENTATION
A woman in her sixties presented with visual disturbances, followed by weakness in her right arm and aphasia three days later. Her close acquaintances had suspected progressive cognitive decline during the previous year. CT and MRI showed an occluded left posterior cerebral artery with a subacute occipito-temporal infarction. The finding of extensive white matter lesions and segmental arterial vasoconstriction necessitated further workup of vasculitis and hereditary small vessel disease, which were ruled out. The stroke aetiology was considered to be atherosclerotic intracranial large vessel disease. FDG-PET scan revealed decreased metabolism in the left hemisphere, and cerebrospinal biomarkers had slightly decreased beta-amyloid. The findings were suggestive of early Alzheimer's disease or primary progressive aphasia, but currently inconclusive.
INTERPRETATION
Based on clinical-anatomical correlation, the patient's visual disturbances, in this case right hemianopsia and object agnosia, were solely related to the stroke and not to a neurodegenerative disorder. Knowledge and interpretation of visual agnosias can in many cases be clinically valuable.
Topics: Female; Humans; Agnosia; Magnetic Resonance Imaging; Neurodegenerative Diseases; Positron-Emission Tomography; Stroke; Vision Disorders; Aged
PubMed: 37938009
DOI: 10.4045/tidsskr.23.0198 -
Acta Neurologica Belgica Oct 2023A precise understanding of the neural substrates underlying tactually-related cognitive impairments such as bilateral tactile agnosia, bilateral agraphesthesia,...
INTRODUCTION
A precise understanding of the neural substrates underlying tactually-related cognitive impairments such as bilateral tactile agnosia, bilateral agraphesthesia, kinesthetic alexia and kinesthetic reading difficulty is currently incomplete. In particular, recent data have implicated a role for the lateral occipital tactile visual region, or LOtv, in tactile object naming (Amedi et al. Cerebral Cortex 2002). Thus, this study set out to examine the degree to which the LOtv may be involved in tactually-related cognitive impairments by examining two unique cases.
METHODS
To assess whether LOtv or the visual word form area (VWFA) is involved in tactually-related cognitive impairments, the average activation point of LOtv and that of VWFA were placed on the single-photon emission computed tomography (SPECT) cerebral blood flow images of two patients: one with bilateral associative tactile agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading, and the other with kinesthetic reading difficulty.
RESULTS
The average LOtv coordinate was involved in the area of hypoperfusion in both patients, whereas that of VWFA was not included in any of the hypoperfused areas.
CONCLUSIONS
The results support the view that interruption of LOtv or disconnection to LOtv and to VWFA may cause these tactually-related cognitive impairments. Further, bilateral associative tactile agnosia and bilateral agraphesthesia are attributable toward the damage of the occipital lobe, whereas unilateral or predominantly one-sided associative tactile agnosia and agraphesthesia are attributable toward the damage of the parietal lobe.
Topics: Humans; Reading; Agnosia; Touch; Cerebral Cortex; Cognitive Dysfunction
PubMed: 36336779
DOI: 10.1007/s13760-022-02130-9 -
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 -
Medicine Apr 2024Colonoscopy is a commonly performed gastroenterological procedure in patients associated with anxiety and pain. Various approaches have been used to provide sedation and... (Randomized Controlled Trial)
Randomized Controlled Trial
Comparison of patient-controlled analgesia and sedation (PCAS) with remifentanil and propofol versus total intravenous anesthesia (TIVA) with midazolam, fentanyl, and propofol for colonoscopy.
BACKGROUND
Colonoscopy is a commonly performed gastroenterological procedure in patients associated with anxiety and pain. Various approaches have been used to provide sedation and analgesia during colonoscopy, including patient-controlled analgesia and sedation (PCAS). This study aims to evaluate the feasibility and efficiency of PCAS administered with propofol and remifentanil for colonoscopy.
METHODS
This randomized controlled trial was performed in an authorized and approved endoscopy center. A total of 80 outpatients were recruited for the colonoscopy studies. Patients were randomly allocated into PCAS and total intravenous anesthesia (TIVA) groups. In the PCAS group, the dose of 0.1 ml/kg/min of the mixture was injected after an initial bolus of 3 ml mixture (1 ml containing 3 mg of propofol and 10 μg of remifentanil). Each 1 ml of bolus was delivered with a lockout time of 1 min. In the TIVA group, patients were administered fentanyl 1 μg/kg, midazolam 0.02 mg/kg, and propofol (dosage titrated). Cardiorespiratory parameters and auditory evoked response index were continuously monitored during the procedure. The recovery from anesthesia was assessed using the Aldrete scale and the Observer's Assessment of Alertness/Sedation Scale. The Visual Analogue Scale was used to assess the satisfaction of patients and endoscopists.
RESULTS
No statistical differences were observed in the Visual Analogue Scale scores of the patients (9.58 vs 9.50) and the endoscopist (9.43 vs 9.30). A significant decline in the mean arterial blood pressure, heart rate, and auditory evoked response index parameters was recorded in the TIVA group (P < 0.05). The recovery time was significantly shorter in the PCAS group than in the TIVA group (P = 0.00).
CONCLUSION
The combination of remifentanil and propofol could provide sufficient analgesia, better hemodynamic stability, lighter sedation, and faster recovery in the PCAS group of patients compared with the TIVA group.
Topics: Humans; Propofol; Remifentanil; Midazolam; Analgesia, Patient-Controlled; Fentanyl; Anesthesia, Intravenous; Anesthesia, General; Colonoscopy; Pain; Agnosia
PubMed: 38608087
DOI: 10.1097/MD.0000000000037411 -
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 -
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 -
Cortex; a Journal Devoted To the Study... Feb 2024Self-unawareness concerning current symptoms remains a clinical challenge in Alzheimer's disease. Reduced self-awareness likely depends on complex biopsychosocial... (Review)
Review
Self-unawareness concerning current symptoms remains a clinical challenge in Alzheimer's disease. Reduced self-awareness likely depends on complex biopsychosocial mechanisms that comprise multiple cognitive processes, regulated by personal goals and values. We specifically reviewed the cognitive processes impaired in unaware participants with AD by emphasizing the related impaired brain activity observed during task-based fMRI. Unawareness can be explained by a failure in functioning of or in connection between brain regions that intervene in access, retrieval and updating of (present or extended) self-information (posterior midline, medial temporal, inferior parietal cortices), or in its monitoring, evaluation, or control (medial and lateral prefrontal cortices). Although one must be cautious when relating function to brain regions, impaired processes were tentatively related to the Cognitive Awareness Model. Although brain function depends on neural networks, impaired brain activity during cognitive processes was discussed according to previous studies reporting correlations between brain regions and scores of anosognosia. The review provides a framework to help clinicians considering processes that can explain unawareness in dementia. In patients at early stages of AD, different levels of awareness of cognitive or social clinical changes might be described as impairment in the interaction between specific cognitive processes and contents.
Topics: Humans; Alzheimer Disease; Awareness; Neuropsychological Tests; Brain; Prefrontal Cortex; Agnosia; Cognitive Dysfunction
PubMed: 37977109
DOI: 10.1016/j.cortex.2023.10.009 -
Neuropsychological Rehabilitation Mar 2024In some patients with unilateral spatial neglect, symptoms reflect impaired lateralized spatial attention and representation (perceptual bias) whereas in others the...
In some patients with unilateral spatial neglect, symptoms reflect impaired lateralized spatial attention and representation (perceptual bias) whereas in others the inability to respond to stimuli located in contralesional space (response bias). Here, we investigated whether prismatic adaptation (PA) and visual scanning training (VST) differentially affect perceptual and response bias and whether rehabilitation outcome depends on the type of bias underlying symptoms. Two groups of neglect patients in the subacute phase were evaluated before, immediately after, and two weeks following 10 days of PA ( = 9) or VST ( = 9). Standard neuropsychological tests (i.e., Behavioural Inattentional Test, Diller cancellation test, and Line Bisection test) were administered to assess neglect symptoms, while the Landmark task was used to disentangle perceptual and response biases. Performance on the Landmark task revealed that PA was more effective in improving the perceptual bias, while VST mainly modulated the response bias. Neuropsychological tests performance suggested that VST is better suited to modulate neglect in patients with response bias, while PA may be effective in patients with both types of bias. These findings may offer novel insights into the efficacy of PA and VST in the rehabilitation of perceptual and response biases in patients with neglect.
Topics: Humans; Perceptual Disorders; Agnosia; Treatment Outcome; Neuropsychological Tests; Adaptation, Physiological; Functional Laterality; Space Perception
PubMed: 36652376
DOI: 10.1080/09602011.2022.2158876 -
Cognition Aug 2023An on-going debate in psychology and neuroscience concerns the way faces and objects are represented. Domain-specific theories suggest that faces are processed via a...
An on-going debate in psychology and neuroscience concerns the way faces and objects are represented. Domain-specific theories suggest that faces are processed via a specialised mechanism, separate from objects. Developmental prosopagnosia (DP) is a neurodevelopmental disorder in which there is a deficit in the ability to recognize conspecific (human) faces. It is unclear, however, whether prosopagnosia also affects recognition of heterospecific (animal) faces. To address this question, we compared recognition performance with human and animal faces in neurotypical controls and participants with DP. We found that DPs showed deficits in the recognition of both human and animal faces compared to neurotypical controls. In contrast to, we found no group-level deficit in the recognition of animate or inanimate non-face objects in DPs. Using an individual-level approach, we demonstrate that in 60% of cases in which face recognition is impaired, there is a concurrent deficit with animal faces. Together, these results show that DPs have a general deficit in the recognition of faces that encompass a range of configural and morphological structures.
Topics: Humans; Animals; Prosopagnosia; Recognition, Psychology; Pattern Recognition, Visual; Facial Recognition
PubMed: 37156079
DOI: 10.1016/j.cognition.2023.105477