Fig. 67

Sparse incomplete representations (SIR). In our previously formulated model of the main olfactory bulb network [1], MCs receive inputs from receptor neurons in the glomeruli (black circles) and interact with GCs through dendrodendritic synapses. GCs build representations of MC glomerular inputs (red arrows). The representations are contained in the inhibitory inputs returned by the GCs to the MCs (blue arrows). Because GCs inhibit each other through second-order inhibitory interactions, only a few GCs respond to an odorant (full blue circles with a dendrite shown). The vast majority of GCs do not change their firing rate in response to an odorant (empty circles). Thus, the responses of GCs are sparse. Because some MCs manage to retain the responses to odorants, the representation by GCs is called incomplete. According to this model, MCs transmit to higher areas the errors in the GC representation