Multisite optical recording of the rat piriform cortex activity

OPTICAL signals were recorded in the in vivorat piriform cortex (PC) in response to olfactory bulb (OB) electrical stimulations delivered at 4 different sites. Afferent activity had a relatively wide (26.6 of the recorded area) but non-homogeneous distribution on the PC surface. The different patterns of afferent activity observed in response to the 4 OB stimulations were intermixed with an overlap of only 38.5. This activity was redistributed to the whole PC by intrinsic association fibres. The increase in the delay (from 4 ms to 12 ms) between afferent and redistributed activities along the antero-posterior axis indicated that the rostral to caudal association fibre system originating in the anterior PC was mainly responsible for the redistribution.