X- and Y-cells identified in the cat lateral geniculate nucleus in vitro.

Using an in vitro preparation of the cat dorsal lateral geniculate nucleus, we have studied the passive membrane properties and the electrotonic structure of single cells each identified as X or Y on the basis of their morphological features following intrasomatic injection of horseradish peroxidase. The input resistance of X-cells is higher and the membrane time constant longer than of Y-cells. The electrotonic length and the dendritic to somatic conductance ratio are similar for both classes of neurones.