The role of somatosensory information in a constrained locomotor task.

The purpose of this project was to study the role of somatosensory information in the performance of a constrained locomotor task by rats and to further examine the influence of structural recovery in the somatosensory thalamus, specifically the ventral posterolateral nucleus (VPL). Groups of rats were trained to traverse an elevated, one inch bar for a reward. The time taken to run across the bar (run time) was used as a measure of the success of the goal-directed behavior.

Dendritic outgrowth from neural cells transplanted to the hippocampal fissure.

Transplants of cell suspensions that were either selective for granule cells or contained all hippocampal cell types were placed in the hippocampal fissure or in the infragranular cleavage plane (IGCP) of the dentate gyrus. Several transplants were found in both areas in the same dentate gyrus. After a variety of post-transplant survival times, neurons of both the donor and the host were filled with lucifer yellow in fixed sections.

Traumatic lesions and transplants of granule cells in the dentate gyrus alter the distribution of afferent fibers in the molecular layer.

The present experiments determined whether traumatic lesions of the dentate gyrus granule cells had a different effect on the afferents in the molecular layer (ML) than nontraumatic lesions. Nontraumatic lesions of the granule cells induced by colchicine, ibotenic acid, x-radiation, and adrenalectomy have been reported to reduce both the acetylcholinesterase (AChE)-positive fibers and entorhinal afferents in the ML. After the nontraumatic granule cell lesions, the laminar distribution of the entorhinal afferents was maintained in the ML, whereas the AChE laminar pattern was lost.

The differentiation of dentate granule cells following transplantation.

Immature cells transplanted into an adult host must adapt to their new environment. In the present study we have shown the dendritic development of dentate granule cells following transplantation. The adult host granule cells were lesioned by a fluid injection into the infragranular cleavage plane of the dentate gyrus.

Isomorphic activation of astrocytes in the somatosensory thalamus.

Structural recovery in the rat somatosensory thalamus after the loss of one of its major inputs provided a model for studying the changes in astrocytes associated with reactive synaptogenesis. The temporal separation of the initiation of Wallerian degeneration and reactive synaptogenesis permitted astrocytic changes to be correlated either with the removal of degeneration, early in the recovery sequence, or with synaptogenesis, later in recovery. Over a period of post-lesion times ranging from 3 days to 13.