We used neural ensemble recording to examine odor-evoked ensemble patterns
in the moth antennal (olfactory) lobe. Different odors are thought to evoke
unique spatiotemporal patterns of glomerular activity, but little is known
about the population dynamics underlying formation of these patterns. Using
a silicon multielectrode array, we observed dynamic network interactions within
and between glomeruli. Whereas brief odor pulses repeatedly triggered activity
in the same coding ensemble, the temporal pattern of synchronous activity
superimposed on the ensemble was neither oscillatory nor odor specific. Rather,
synchrony strongly depended on contextual variables such as odor intensity
and intermittency. Also, because of emergent inhibitory circuit interactions,
odor blends evoked temporal ensemble patterns that could not be predicted
from the responses to the individual odorants. Thus even at this early stage
of information processing, the timing of odor-evoked neural representations
is modulated by key stimulus factors unrelated to the molecular identity of
the odor.
