抄録
Extra- and intracellular recordings were performed from neurons in in vitro slices of the lateral geniculate nucleus (LGN) prepared from cats anesthetized with Nembutal. Based on responses to stimulation of the optic tract (OT), neurons were classified into three types, i. e., P-cells (principal relay cells), I-cells (intrinsic cells) and unclassified cells. P-cells were characterized by an IPSP following an EPSP or an action spike which appeared at a short latency in response to OT stimulation, while I-cells were characterized by a long lasting EPSP on which a burst of spikes were superimposed. These observations were com-parable with those reported in situ. The incidence of P- and I-cells was in-vestigated for a total of 118 neurons recorded intracellularly from in vitro slices of LGN of cats at various ages; 73.0% and 5.4% for P- and I-cells respectively in 1-day-old kittens, 71.4 and 9.5% in 3-day-old, 81.8 and 9.1% in 1-week-old, 80.8 and 7.7% in 6-week-old kittens, and 82.6 and 13.0% in adult cats. From these findings it was concluded that there exist physiologically differentiated P-and I-cells in the LGN even at birth and that I-cells are responsible for intrageni-culate inhibition.
