A Mirror-Symmetric Excitatory Link Coordinates Odor Maps across Olfactory Bulbs and Enables Odor Perceptual Unity

• DOI: 10.1016/j.neuron.2018.07.012
• Publication Date: 2018-08-02T14:42:58Z
• Authors: Mark Grobman; Tal Dalal; Hagar Lavian; Ronit Shmuel; Katya Belelovsky; Fuqiang Xu; Alon Korngreen; Rafi Haddad
• Keywords: Male; 0303 health sciences; Action Potentials; Mice, Transgenic; Olfactory Pathways; Olfactory Bulb; Smell; Mice; Random Allocation; 03 medical and health sciences; Odorants; Mice, Inbred CBA; Animals; Female; Mirror Neurons

Sensory input reaching the brain from bilateral and offset channels is nonetheless perceived as unified. This unity could be explained by simultaneous projections to both hemispheres, or inter-hemispheric information transfer between sensory cortical maps. Odor input, however, is not topographically organized, nor does it project bilaterally, making olfactory perceptual unity enigmatic. Here we report a circuit that interconnects mirror-symmetric isofunctional mitral/tufted cells between the mouse olfactory bulbs. Connected neurons respond to similar odors from ipsi- and contra-nostrils, whereas unconnected neurons do not respond to odors from the contralateral nostril. This connectivity is likely mediated through a one-to-one mapping from mitral/tufted neurons to the ipsilateral anterior olfactory nucleus pars externa, which activates the mirror-symmetric isofunctional mitral/tufted neurons glutamatergically. This circuit enables sharing of odor information across hemispheres in the absence of a cortical topographical organization, suggesting that olfactory glomerular maps are the equivalent of cortical sensory maps found in other senses.