Bilateral Alignment of Receptive Fields in the Olfactory Cortex Points to Non-Random Connectivity

Abstract

While olfactory sensory neurons expressing the same receptor in the nose converge to the same location in olfactory bulb, projections from the olfactory bulb to the cortex exhibit no recognizable spatial topography. This lack of topography is thought to carry over for interhemispheric connectivity, which originates cortically. If connections to and within the cortex are random, information reaching a cortical neuron from both nostrils will be uncorrelated. Instead, we found that the odor responses of individual neurons to stimulation of both nostrils are highly matched. More surprisingly, odor identity decoding optimized with information arriving from one nostril transfers very well to the other side. Computational analysis shows that such matched odor tuning is incompatible with random connections, but is explained readily by local Hebbian plasticity. Our data reveal that despite the distributed nature of the sensory representation in the olfactory cortex, odor information across the two hemispheres is highly coordinated.