Differential spatial memory impairment after right temporal lobectomy demonstrated using temporal titration.
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In this study a temporal titration method to explore the extent to which spatial memory is differentially impaired following right temporal lobectomy was employed. The spatial and non-spatial memory of 19 left and 19 right temporal lobectomy (TL) patients was compared with that of 16 normal controls. The subjects studied an array of 16 toy objects and were subsequently tested for object recall, object recognition and memory for the location of the objects. By systematically varying the retention intervals for each group, it was possible to match all three groups on object recall at sub-ceiling levels. When memory for the position of the objects was assessed at equivalent delays, the right TL group revealed disrupted spatial memory, compared with both left TL and control groups (P < 0.05). MRI was used to quantify the extent of temporal lobe resection in the two groups and a significant correlation between hippocampal removal and both recall of spatial location and object name recall in the right TL group only was shown. These data support the notion of a selective (but not exclusive) spatial memory impairment associated with right temporal lobe damage that is related to the integrity of the hippocampal functioning. (+info)
Improvement by nefiracetam of beta-amyloid-(1-42)-induced learning and memory impairments in rats.
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1. We have previously demonstrated that continuous i.c.v. infusion of amyloid beta-peptide (A beta), the major constituent of senile plaques in the brains of patients with Alzheimer's disease, results in learning and memory deficits in rats. 2. In the present study, we investigated the effects of nefiracetam [N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, DM-9384] on A beta-(1-42)-induced learning and memory deficits in rats. 3. In the A beta-(1-42)-infused rats, spontaneous alternation behaviour in a Y-maze task, spatial reference and working memory in a water maze task, and retention of passive avoidance learning were significantly impaired as compared with A beta-(40-1)-infused control rats. 4. Nefiracetam, at a dose range of 1-10 mg kg(-1), improved learning and memory deficits in the A beta-(1-42)-infused rats when it was administered p.o. 1 h before the behavioural tests. 5. Nefiracetam at a dose of 3 mg kg(-1) p.o. increased the activity of choline acetyltransferase in the hippocampus of A beta-(1-42)-infused rats. 6. Nefiracetam increased dopamine turnover in the cerebral cortex and striatum of A beta-(1-42)-infused rats, but failed to affect the noradrenaline, serotonin and 5-hydroxyindoleacetic acid content. 7. These results suggest that nefiracetam may be useful for the treatment of patients with Alzheimer's disease. (+info)
Progressive multifocal leukoencephalopathy after autologous bone marrow transplantation and alpha-interferon immunotherapy.
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A patient with a stage IV mantle cell lymphoma (according to the REAL classification) was treated with high-dose chemotherapy and autologous bone marrow transplantation. One year later while on alpha-interferon immunotherapy she suffered from progressive loss of short-term memory and reported difficulties in recognizing objects. Magnetic resonance imaging (MRI) showed a vast ring-enhancing lesion of the left postcentral parietal area. Serial stereotactic biopsies disclosed progressive multifocal leukoencephalopathy without JC-virus in the cerebrospinal fluid. Therapy with subcutaneous interleukin-2 (IL-2) every other day and intrathecal cytarabine once a week was started. After 4 weeks the patient refused further treatment. Nevertheless her condition improved over the next 8 months and MRI scans showed a marked improvement in the lesions. (+info)
Neuromyotonia: an unusual presentation of intrathoracic malignancy.
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A 48 year old woman is described who presented with increasing muscular rigidity and who was found to have a mediastinal tumour. Electrophysiological studies revealed that the muscular stiffness resulted from very high frequency motor unit activity which outlasted voluntary effort, and which was abolished by nerve block. The abnormal activity may have arisen at the anterior horn cell level. Marked improvement followed the administration of diphenylhydantoin. (+info)
Relation between neuropsychological and neuroimaging findings in patients with late whiplash syndrome.
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OBJECTIVES: The interpretation of long term cognitive impairment after whiplash injury is still a problem for many physicians. On the grounds of nuclear medicine findings previous research speculated that brain damage is responsible for cognitive problems of patients with whiplash. To test this hypothesis the relation between neuroimaging and neuropsychological findings was analysed. METHODS: Twenty one patients (11 women, 10 men, mean age 42.2 (SD 8.6) years) with the late whiplash syndrome (average interval of trauma 26.1 (SD 20.7) months) referred for diagnostic action to the Department of Neurology were investigated. Assessment included computer assisted assessment of working memory and divided attention, neuroimaging (by the means of [99mTc]-HMPAO-SPECT, [15O]-H2O-PET and [18F]-FDG-PET), testing of emotional functioning (depression and anxiety ratings), and pain intensity at the time of testing. RESULTS: On average, scoring on tests of cognitive functioning was very low. However, no significant correlations were found between regional perfusion or metabolism in any brain area and the scores of divided attention or working memory. By contrast, significant relations were found between indices of impaired emotional functioning (state anxiety) and divided attention. In addition, low scoring in divided attention was significantly correlated with pain intensity at the time of testing. CONCLUSIONS: The present data do not provide evidence of a significant relation between detectable morphological or functional brain damage and impaired cognitive performance in the late whiplash syndrome. Results indicate triggering of emotional and cognitive symptoms on the basis of initial injury of the cervical spine. (+info)
Cognitive deficits in spinocerebellar ataxia 2.
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This is one of the first studies assessing the pattern of cognitive impairment in spinocerebellar ataxia 2 (SCA2). Cognitive function was studied in 17 patients with genetically confirmed SCA2 and 15 age- and IQ- matched controls using a neuropsychological test battery comprising tests for IQ, attention, verbal and visuospatial memory, as well as executive functions. Twenty-five percent of the SCA2 subjects showed evidence of dementia. Even in non-demented SCA2 subjects, there was evidence of verbal memory and executive dysfunction. Tests of visuospatial memory and attention were not significantly impaired in the non-demented group compared with controls. There was no relationship between test performance and motor disability, repeat length or age of onset, while disease duration was shown to be inversely correlated with two tests reflecting the progression of cognitive deficits during the course of the disease. Intellectual impairment should therefore not be interpreted as a secondary effect of progressive motor disability, but represents an important and independent part of the SCA2 phenotype. (+info)
Path integration absent in scent-tracking fimbria-fornix rats: evidence for hippocampal involvement in "sense of direction" and "sense of distance" using self-movement cues.
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Allothetic and idiothetic navigation strategies use very different cue constellations and computational processes. Allothetic navigation requires the use of the relationships between relatively stable external (visual, olfactory, auditory) cues, whereas idiothetic navigation requires the integration of cues generated by self-movement and/or efferent copy of movement commands. The flexibility with which animals can switch between these strategies and the neural structures that support these strategies are not well understood. By capitalizing on the proclivity of foraging rats to carry large food pellets back to a refuge for eating, the present study examined the contribution of the hippocampus to the use of allothetic versus idiothetic navigation strategies. Control rats and fimbria-fornix-ablated rats were trained to follow linear, polygonal, and octagonal scent trails that led to a piece of food. The ability of the rats to return to the refuge with the food via the shortest route using allothetic cues (visual cues and/or the odor trail available) or using ideothetic cues (the odor trail removed and the rats blindfolded or tested in infrared light) was examined. Control rats "closed the polygon" by returning directly home in all cue conditions. Fimbria-fornix rats successfully used allothetic cues (closed the polygon using visual cues or tracked back on the string) but were insensitive to the direction and distance of the refuge and were lost when restricted to idiothetic cues. The results support the hypothesis that the hippocampal formation is necessary for navigation requiring the integration of idiothetic cues. (+info)
Early visual impairment is independent of the visuocognitive and memory disturbances in Alzheimer's disease.
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Static and dynamic contrast sensitivity (SCS and DCS), semantic object identification, and verbal recall functions were evaluated in 20 Alzheimer's disease (AD) patients and in 20 control subjects. We found general SCS and DCS loss in the 0.48-14.34 c deg-1 spatial frequency range. In relation to the cognitive functions, semantic object identification was intact, whereas explicit memory was markedly impaired in the AD group. There was no significant correlation between the CS and the memory disturbances. The results suggest that early visual impairment and higher-level cognitive disturbances are independent in AD. (+info)