The estrous cycle and the olivo-cerebellar circuit. II. Enhanced selective sensory gating of responses from the rostral dorsal accessory olive.

This study demonstrates that gating of responses of the rostral dorsal accessory olive (rDAO) to somatosensory stimulation varies across the estrous hormone cycle of the rat. The rDAO has been suggested as an "error" or event signal generator for the cerebellar cortex. Selective sensory gating of input to this structure may underlie this error signalling function. In the present study, as many as 23 single neurons were recorded simultaneously from either the forepaw or the snout areas of the rDAO. Responses of these neurons to electrical stimulation of peripheral afferents were determined during active movement or non-movement conditions. These results were then compared across the estrous cycle or after administration of the estrous hormones 17 beta-estradiol (E2) and/or progesterone (P) to rats on diestrus or following E2 priming. Elevations in circulating estrous hormones produced greater excitatory responses of rDAO neurons to stimulation during non-movement, and, conversely, enhanced inhibition of rDAO activity during active movement of the stimulated peripheral area compared with control diestrous conditions, suggesting that selective gating processes to the rDAO are enhanced by estrous hormones. The results of this study suggest that the night of behavioral estrus is associated with enhanced selective sensory gating processes associated with improved detection and processing of error signals.