1/169. Cerebral polyopia with extrastriate quadrantanopia: report of a case with magnetic resonance documentation of V2/V3 cortical infarction.This is a case report of the occurrence of cerebral diplopia with right-side superior homonymous quadrantanopia in a young woman after chiropractic neck manipulation. magnetic resonance imaging confirmed an infarct in the left inferior V2/V3 (extrastriate) cortex. The characteristics of the diplopia are illustrated with the patient's drawings, and persisting abnormalities in perception are described in the area of the initial field defect after static (computed) visual field testing yielded normal results.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
2/169. Spatial characteristics of cerebral polyopia: a case study.A 41-year-old woman showed bilateral monocular polyopia and an incomplete, right-sided homonymous hemianopia following bilateral cerebral strokes confirmed by neuroimaging. She was tested with briefly-presented visual stimuli to determine whether her polyopic images varied with visual field position of stimuli which evoked them. Stimuli close to her scotoma elicited polyopic images at shorter latency and higher probability than did stimuli more distant from it. RS could maintain stable fixation on small stimuli, suggesting that eye movements were not responsible for her polyopia. We discuss the possibility that cerebral polyopia is due to recoding of visual receptive fields in primary visual cortex and that bilateral occipital lesions are a causative factor in the genesis of the disorder.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
3/169. Bilateral ptosis and changes in state of alertness in thalamic infarction.Uni- or bilateral supranuclear ptosis is known to be caused by cerebral lesion. The exact anatomical cortical and subcortical basis is still undefined. We report a case of a patient developing bilateral ptosis with a left thalamic lesion. The bilateral ptosis was associated with transient changes in the state of alertness. We postulate that the thalamus, especially the anterior region, may have an influential role on the pathway from the cortex via the posterior branch of the internal capsule to the levator palpebrae superioris nuclei.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
4/169. Contributions of prefrontal cortex to recognition memory: electrophysiological and behavioral evidence.To clarify the involvement of prefrontal cortex in episodic memory, behavioral and event-related potential (ERP) measures of recognition were examined in patients with dorsolateral prefrontal lesions. In controls, recognition accuracy and the ERP old-new effect declined with increasing retention intervals. Although frontal patients showed a higher false-alarm rate to new words, their hit rate to old words and ERP old-new effect were intact, suggesting that recognition processes were not fundamentally altered by prefrontal damage. The opposite behavioral pattern was observed in patients with hippocampal lesions: a normal false-alarm rate and a precipitous decline in hit rate at long lags. The intact ERP effect and the change in response bias during recognition suggest that frontal patients exhibited a deficit in strategic processing or postretrieval monitoring, in contrast to the more purely mnemonic deficit shown by hippocampal patients.- - - - - - - - - - ranking = 5keywords = cortex (Clic here for more details about this article) |
5/169. migraine with aura-like headache associated with moyamoya disease.A 49-year-old woman was admitted to our hospital because of severe headache. She had a 10-month history of migraine with aura-like headache that occurred every 7 to 10 days and was preceded by photopsia. brain CT showed cerebral infarction of the left occipital lobe. Bilateral carotid angiograms showed vascular occlusions in the supraclinoid portion of the bilateral internal carotid arteries with telangiectatic vessels acting as collateral channels to the occluded distal carotid arteries, which were consistent with the diagnosis of moyamoya disease. headache resolved gradually and has never developed again after the infarct of the left occipital lobe. Pathophysiological mechanisms of migraine-like headache were discussed. We conclude that borderline perfusion of occipital lobe cortex could be a trigger for the development of migraine with aura-like headache in susceptible patients. In the case of atypical attack of migraine detailed investigation should be done to detect underlying vascular diseases such as moyamoya disease.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
6/169. Aicardi-Goutieres syndrome: a genetic microangiopathy?Aicardi-Goutieres syndrome (AGS) (McKusick 225750) is an autosomal recessive disease with onset in the 1st year of life, resulting in progressive microcephaly, calcification of cerebral white matter, thalamus and basal ganglia, generalized cerebral demyelination and a chronic low-grade CSF lymphocytosis, without evidence of infection. We report the autopsy of a patient who died with this disorder at the age of 17 years. Findings were severe microencephaly, diffuse but inhomogeneous cerebral white matter loss with associated astrocytosis, calcific deposits in the white matter, thalami and basal ganglia. neocortex and cerebellar cortex were affected by wedge-shaped microinfarctions. Small vessels showed calcification in the media, adventitia and perivascular spaces. These findings are similar to some previous publications that in retrospect may have been AGS, but this is the first reported cerebral microangiopathy in which the diagnosis AGS was made during lifetime. This report provides evidence that microangiopathy plays a significant role in the pathogenesis of AGS.- - - - - - - - - - ranking = 2keywords = cortex (Clic here for more details about this article) |
7/169. Tactile morphagnosia secondary to spatial deficits.A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patient's inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
8/169. Delineating necessary and sufficient neural systems with functional imaging studies of neuropsychological patients.This paper demonstrates how functional imaging studies of neuropsychological patients can provide a way of determining which areas in a cognitive network are jointly necessary and sufficient. The approach is illustrated with an investigation of the neural system underlying semantic similarity judgments. functional neuroimaging demonstrates that normal subjects activate left temporal, parietal, and inferior frontal cortices during this task relative to physical size judgments. neuropsychology demonstrates that damage to the temporal and parietal regions results in semantic deficits, indicating that these areas are necessary for task performance. In contrast, damage to the inferior frontal cortex does not impair task performance, indicating that the inferior frontal cortex might not be necessary. However, there are two other possible accounts of intact performance following frontal lobe damage: (1) there is functional reorganization involving the right frontal cortex and (2) there is peri-infarct activity around the damaged left-hemisphere tissue. Functional imaging of the patient is required to discount these possibilities. We investigated a patient (SW), who was able to associate words and pictures on the basis of semantic relationships despite extensive damage to the left frontal, inferior parietal, and superior temporal cortices. Although SW showed peri-infarct activation in left extrasylvian temporal cortices, no activity was observed in either left or right inferior frontal cortices. These findings demonstrate that activity in extrasylvian temporo-parietal and medial superior frontal regions is sufficient to perform semantic similarity judgments. In contrast, the left inferior frontal activations detected in each control subject appear not to be necessary for task performance. In conclusion, necessary and sufficient brain systems can be delineated by functional imaging or brain-damaged patients who are not functionally impaired.- - - - - - - - - - ranking = 3keywords = cortex (Clic here for more details about this article) |
9/169. Somatotopic gradients in the distributed organization of the human primary motor cortex hand area: evidence from small infarcts.Nine cases of relatively selective hand weakness produced by stroke were analyzed to examine the degree to which representations of different fingers are segregated in the human primary motor cortex (M1). In five cases, all the digits were involved uniformly; in four cases the radial versus ulnar digits of the hand were involved differentially. No patient showed discrete involvement of a single digit, nor did any patient have greatest weakness in the index, middle or ring finger. These findings provide little evidence that each digit is represented in a separate cortical territory, but rather suggest that broadly overlapping gradients - with the radial digits somewhat more heavily represented laterally and the ulnar digits somewhat more heavily represented medially - are superimposed on an underlying organization in which control of each finger is distributed widely throughout the human M1 hand area.- - - - - - - - - - ranking = 5keywords = cortex (Clic here for more details about this article) |
10/169. Pure motor monoparesis of a lower limb due to a small infarction in the contralateral motor cortex.Pure motor monoparesis (PMM) is a rare condition characterized by weakness limited to one limb without sensory disturbance. We report a 42-year-old woman with PMM of the right lower limb caused by a small infarction in the contralateral motor cortex that could be detected by the magnetic resonance imaging of the brain. This case suggests that small lesions, missed by carelessly performed scans, could be a potential cause of PMM. This is especially true in the case of lower limb PMM, because the lesion may be located in the top of the frontal lobe cortex, an area that can be easily missed by routine scans. Therefore, we should pay careful attention to the opposite side of the motor cortex in examining neuroimages of PMM cases.- - - - - - - - - - ranking = 7keywords = cortex (Clic here for more details about this article) |
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