FIG. 4.

Odorant stimulation induces various activity patterns in individual OSNs. Two types of responses were frequently observed following stimulation with isoamyl acetate (ISO, 100 μM, duration is indicated on each picture). A: in some neurons, brief puffs of ISO elicited a nondecrementing burst, observed either in cell-attached (top) or perforated patch-clamp (current-clamp mode) configuration (bottom). B: in other neurons, brief puffs of ISO elicited an initial burst (b) followed by a silence (s) and a firing rebound (r) in cell-attached configuration (top). A similar pattern was observed in perforated patch-clamp configuration (bottom): the initial burst (b) was grafted on a large receptor potential, which kept the membrane potential in a depolarized state (s). During repolarization, the rebound (r) firing appeared before a complete return to the spontaneous activity. C: 2 neurons were stimulated for 250 ms by ISO puffs that elicited a small (top) or a large (bottom) inward transduction current recorded under voltage-clamp mode. Despite the presence of 1 μM TTX in the bath perfusion, some action potentials (→) occurred in response to ISO. The holding potential for both cells was −80 mV.