[Afferent supply to the most ancient visual area of the neocortex, field 29 of the limbic cortex]

In white anesthetized rats electric stimulation of n. anterodorsalis and light stimulation evoked potentials in the retrosplenial cortex, field 29. The EPs were surface-negative, multicomponent, their latency at the n. anterodorsalis stimulation being 5.1 +/- 0.6 (with a range of 2-7) msec, at the light stimulation -- 21 +/- 1.7 (with range of 15-30) msec. The EPs in the field 29 at low-frequency rhythmic light stimulation and at n. anterodorsalis stimulation (1-5/sec) revealed the phenomenon of habituation and driving. The layer analysis of the light EPs showed reversal of polarity in the upper part of layer V of the cortex, while after n. anterodorsalis stimulation the reversal of polarity occurred beneath the layer VI. The possibility of existence of several thalamis visual inputs in the field 29, is discussed.