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Biomedical subjects

J J Sloper

Publications and source records attributed to J J Sloper.

48 records · Page 3Linked to original sources
PubMed1978

The intrinsic connections of the cortex of area 4 of the monkey.

The intrinsic connections of area 4 of the monkey have been investigated with axonal degeneration methods after the placement of microelectrode lesions within the cortex. The fibre degeneration is restricted to within a few millimetres of the damage and is asymmetrically distributed in the form of an ellipse with its long axis anteroposteriorly. The same pattern is found in all topographic subdivisions of the motor cortex. There are two distinct zones of degeneration, dense fine terminal degeneration for 200 to 300 micrometer all around the lesion, and a moderate degree of fibre terminal degeneration for a further 2 to 3 mm. The intrinsic connections are disposed predominantly in a horizontal or oblique direction and within the laminae of origin, but there are fibres passing between adjoining laminae and between layers III and V and VI. Two horizontal plexuses of degenerating fibres are present, at the boundary layers II and III and at the level of the Betz cells, and these fibres arise within the cortex. The afferent and efferent fibres of the cortex are arranged strictly perpendicular to the surface. The extent and pattern of the intrinsic connections of area 4 are very similar to those of area 17 of the visual cortex.

Animals↗
PubMed1978

An electron microscopic study of the termination of intracortical axons upon Betz cells in area 4 of the monkey.

After small lesions within the cortex of area 4 of the monkey degenerating axon terminals have been seen with the electron microscopy to contact the cell bodies, proximal parts of the apical dendrites and initial segments of Betz cells 0.5 to 2.5 mm from the damage. The degenerating axon terminals make symmetrical synapses which are presumed to be inhibitory in function. The degenerating terminals are probably from the axons of the basket cells described in Golgi-impregnated material, and which correspond to the large stellate cell recognized in electron microscopic studies.

Animals↗
PubMedDate not supplied

Abnormal tubular structures associated with the granular endoplasmic reticulum of neocortical neurons in a biopsy from a patient with Alzheimer's disease.

The electron microscope has been used to examine a diagnostic biopsy of frontal neocortex which showed the light microscopic features of Alzheimer's disease. In addition to plaques and tangles, the biopsy showed some neurons which contained abnormal tubular profiles specifically associated with their granular endoplasmic reticulum. In transverse section the profiles consisted of two concentric layers of trilaminar unit membrane with an overall diameter of approximately 75 nm and they appeared to lie within the cisternae of granular endoplasmic reticulum. When cut longitudinally, the structures appeared as elongated tubes lying within the endoplasmic reticulum, but a number of ends were found where the inner membrane formed a closed tube and the outer membrane folded back and was continuous with the membrane forming the outer layer of the sac of endoplasmic reticulum. These profiles do not appear to have been described previously although similarities between their ultrastructure and that of the coat of certain unusual forms of Rhabdovirus are noted.

Alzheimer Disease↗
PubMedDate not supplied

Reduction in binocular enhancement of the visual-evoked potential during development accompanies increasing stereoacuity.

PURPOSE: To study the maturation of normal binocular vision. METHODS: Binocular visual function has been studied and monocular and binocular pattern reversal visual-evoked potentials (VEP) recorded in 20 normal subjects aged 5 to 43 years. RESULTS: Stereoacuity improved significantly between the age of 5 and adulthood. Mean stereoacuity for eight children measured by the Titmus test was 61 seconds of arc and 56 seconds of arc by the TNO test. For the 12 adults in the study, corresponding mean stereoacuities were 45 and 31 seconds of arc. Over the same timespan, binocular enhancement of the VEP P100 amplitude decreased. For the children aged 5 to 10 years, the mean binocular VEP enhancement to 20' checks was 1.60, whereas for young adults it was 1.19. There was no comparable change in the binocular enhancement to 40' checks, with mean binocular enhancement of 1.31 in the children and 1.26 in the young adults. Over the same age range, VEP latency also decreased. CONCLUSION: During visual maturation, improvement in stereoacuity is accompanied by a fall in binocular enhancement of the P100 amplitude of the VEP to small checks and a reduction in the P100 latency.

Adolescent↗