Oscillations in the olfactory bulb carry information about odorant history.

While odorant-evoked oscillations in the vertebrate olfactory bulb have been studied extensively, information about their possible cognitive role has been missing. Using voltage-sensitive dye imaging, we show that repeated odorant presentations with interstimulus intervals of 2-12 s had dramatic and diverse effects on the three oscillations that occur in the turtle olfactory bulb. Two of the oscillations are strikingly depressed in response to the second stimulation even of a new odorant was presented. The third oscillation is enhanced if the odorant is the same but suppressed if the odorant is new. The effects suggest that the oscillations carry information about odorant novelty and consistency.