Differential distribution of barrel or visual cortex - Evoked responses along the rostro-caudal axis of the peri- and postrhinal cortices

The functional connections between the barrel cortex and visual cortex on t he one hand and the perirhinal (PER) and postrhinal (POR) cortices on the o ther hand were investigated in the rat. Stimulation of the barrel cortex ev oked field potentials throughout the longitudinal extent of both PER and FO R. In contrast, visual cortex stimulation evoked responses only in the caud al portion of PER as well as in FOR. Therefore, the information from the vi sual cortex on the way to the hippocampus is transferred preferentially by a relay in FOR, whereas somatosensory information is transferred via both P ER and FOR. Moreover, stimulation of both cortical regions elicited tiring of multiple units; however, unit activity was more commonly found in FOR th an in PER. We conclude that the transfer of somatosensory and visual inform ation to the hippocampal formation is preferentially mediated by parallel c hannels through PER and FOR respectively. Although the information transfer through these channels does overlap to some extent, each channel appears t o have specific properties. (C) 2000 Elsevier Science B.V. All rights reser ved.