Inhibition of pyramidal cells could serve a similar function
of generating distinguishable,sparse odor representations.
Layer 1 GABAergic interneurons in piriform cortex
receive inputs from many glomeruli and are excited by a
broad range of odors (Figure 3c) [33
]. Inhibition from
these interneurons makes pyramidal cells less responsive
to odors [33
]. This broadly tuned inhibition could be
enhanced when animals are presented with odor mixtures,
suppressing a number of pyramidal cells, leading to
the sparse piriform neural activity pattern. Not surprisingly,
around 50% of the piriform pyramidal cells that are
activated in response to the individual odorants comprising
an odor mixture do not respond to the mixed stimulus
[34]. A graded GABAergic inhibition plays a similar role
in restricting the odor tuning of Kenyon cells in insect