Rat olfactory bulb mitral cells receive sparse glomerular inputs.
Center-surround receptive fields are a fundamental unit of brain organization. It has been proposed that olfactory bulb mitral cells exhibit this functional circuitry, with excitation from one glomerulus and inhibition from a broad field of glomeruli within reach of the lateral dendrites. We investigated this hypothesis using a combination of in vivo intrinsic imaging, single-unit recording, and a large panel of odors. Assuming a broad inhibitory field, a mitral cell would be influenced by >100 contiguous glomeruli and should respond to many odors. Instead, the observed response rate was an order of magnitude lower. A quantitative model indicates that mitral cell responses can be explained by just a handful of glomeruli. These glomeruli are spatially dispersed on the bulb and represent a broad range of odor sensitivities. We conclude that mitral cells do not have center-surround receptive fields. Instead, each mitral cell performs a specific computation combining a small and diverse set of glomerular inputs.
Fantana
Antoniu L
AL
Molecular and Cellular Biology Department and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
Soucy
Edward R
ER
Meister
Markus
M
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D017711:Nonlinear Dynamics; D009812:Odorants; D009830:Olfactory Bulb / Q000166:cytology*; D009833:Olfactory Pathways / Q000502:physiology; D025341:Principal Component Analysis; D051381:Rats; D017208:Rats, Wistar; D012903:Smell / Q000502:physiology*; D013268:Stimulation, Chemical