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Biomedical subjects

F Morrell

Publications and source records attributed to F Morrell.

72 records · Page 4Linked to original sources
PubMed1965

Clinical neurology. Some applications of scanning by computer.

The use of averaging techniques permits a great increase in the resolution of time-locked waveforms in the electroencephologram. Averaged evoked potentials may be used to study sensory-sensory interactions and the effect of irritative and destructive lesions on the average evoked potential. More complex computations are possible once averages are derived, as was shown in the application of potential contour mapping, where considerable differences were noted between premature and newborn infants on the one hand and adults on the other. The flat, low voltage surface potential contour of the neonate was interpreted as reflecting a volume-conducted event having a distant, deep and midline source. Potential contour patterns in the adult were interpreted as showing predominantly neuronally propagated activity arising at the cortical surface.

Adult↗
PubMedDate not supplied

Age-dependent alterations in hippocampal synaptic plasticity: relation to memory disorders.

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.

Aging↗
PubMedDate not supplied

Alzheimer's disease: in vivo detection of differential vulnerability of brain regions.

The severe cognitive impairment during the later stages of Alzheimer's disease is usually preceded by a selective disturbance in the ability to remember new experiences. With quantitative, high-resolution magnetic resonance imaging techniques, it is now possible to determine, in vivo, differences in the pattern of anatomical changes that might reflect behavioral symptomatology during different stages of the disease. In the present investigation, magnetic resonance imaging examinations were carried out in aged controls and in clinically diagnosed Alzheimer's disease patients who were divided into three groups based upon dementia severity. Atrophy of the hippocampal formation, a region important for memory function, was observed even in Alzheimer's disease patients with the mildest dementia. With more prominent dementia, atrophy extended to the parahippocampal gyrus and the temporal neocortex.

Adult↗
PubMedDate not supplied

Infarction after surgery for focal epilepsy: manipulation hemiplegia revisited.

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.

Adolescent↗