[Organization of impulse flows and selective neuronal death in the hyperstriatum of chick embryos and chicks]

Studies have been made on changes in the number of neurones per volume unit of the tissue of hyperstriatum tissue in chick embryos from the 18th day of incubation to the 3rd day after hatching. Significant interhemispheric asymmetry in migration rate and cell death was revealed in the dorsal hyperstriatum from the 19th day of embryogenesis, which may be due to asymmetry in the intensity of visual afferentation which depends on the stationary position of the embryo in the egg. In the activity of neuronal populations within the dorsal hyperstriatum at a stage which immediately precedes mass death of cells (up to 40%), a structure of impulse volley was found which is characterised by the onset of impulse discharges following each other in a form of short series. Sometimes it is possible to reveal correlation between the duration of dominating interdischarge intervals and the extremes in the recovery of excitability of neuronal pools, which indirectly indicates putative reverberative origin of impulse cyclic phenomenon.