Effect of brain lesions on conditioned cortical electropotentials.
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Biomedical subjects
Publications and source records attributed to F Morrell.
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In this paper, we review the evidence indicating that the common disturbance in recent memory associated with aging is a consequence of functional and structural impairment in the hippocampal formation. In the Fischer 344 rat, an experimental model of the human age-related memory disorder was developed. The majority of aged rats of this strain show impaired performance in the 8-arm radial maze in a manner typical of young rats with bilateral hippocampal lesions. Aged animals also exhibit rapid decay of LTP and slower kindling of the perforant path-dentate synapse. Furthermore, quantitative morphometric analysis of the hippocampal synaptic architecture revealed that aged, memory-impaired rats had a specific loss of perforated axospinous synapses in the middle third of the dentate gyrus molecular layer; the extent of loss was directly related to the degree of memory dysfunction. Most important was the fact that the electrophysiological and morphological abnormalities did not appear in equally old animals with good memory.
The success of surgery for seizure focus resection depends on postoperative reduction or disappearance in number of seizures, improvement in psychosocial functioning, and low morbidity and mortality. Permanent neurologic sequelae are most often not discussed in this context. Deficits more than a superior quadrantanopsia are not expected after temporal lobectomy. Four cases of ischemic stroke after seizure focus resection, each distant from the site of tissue removal, are reported. These are the first such radiologically documented reports of "manipulation hemiplegia." The permanent neurologic deficits are not attributed to resected tissue or edema.
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