Parabucki, A. | bioRxiv Science

bioRxiv2017

Coupling Of Tactile LFP Signals Between Mouse Cortex And Olfactory Bulb

Local field potentials are an important measure of brain activity and have been used to address various mechanistic and behavioral questions. We revealed a prominent whisker evoked local field potential signal in the olfactory bulb and investigated its physiology. This signal, dependent on barrel cortex activation and highly correlated with its local activity, represented a pure volume conductance signal that was sourced back to the activity in the ventro-lateral orbitofrontal cortex, located a few millimeters away. Thus, we suggest that special care should be taken when acquiring and interpreting LFP data.

neuroscience↗

bioRxiv2017

Odor concentration change detectors in the Olfactory Bulb

Dynamical changes in the environment strongly impact our perception 1,2. Consistent with this, sensory systems preferentially represent stimulus changes, enhancing temporal contrast 3,4. In olfaction, odor concentration changes across consecutive inhalations ({Delta}Ct) can guide odor source localization. Yet the neural representation of {Delta}Ct has not been studied in vertebrates. We have found that a subset of mitral/tufted (M/T) cells in the olfactory bulb explicitly represent {Delta}Ct. These concentration change detectors are direction selective: some respond to positive {Delta}Ct, while others represent negative {Delta}Ct. This change detection enhances the contrast between different concentrations and the magnitude of contrast enhancement scales with the size of the concentration step. Further, {Delta}Ct can be read out from the total spike count per sniff, unlike odor identity and intensity, which are represented by fast temporal spike patterns. Our results demonstrate that a subset of M/T cells explicitly represents {Delta}Ct, providing a signal that may instruct navigational decisions in downstream olfactory circuits.

neuroscience↗