Vivo Recording
Vivo Recording
Direction selectivity in hearing: monaural phase sensitivity in octopus neurons
The processing of temporal sound features is fundamental to hearing, and the auditory system displays a plethora of specializations, at many levels, to enable such processing. Octopus neurons are the most extreme temporally-specialized cells in the auditory (and perhaps entire) brain, which make them intriguing but also difficult to study. Notwithstanding the scant physiological data, these neurons have been a favorite cell type of modeling studies which have proposed that octopus cells have critical roles in pitch and speech perception. We used a range of in vivo recording and labeling methods to examine the hypothesis that tonotopic ordering of cochlear afferents combines with dendritic delays to compensate for cochlear delay - which would explain the highly entrained responses of octopus cells to sound transients. Unexpectedly, the experiments revealed that these neurons have marked selectivity to the direction of fast frequency glides, which is tied in a surprising way to intrinsic membrane properties and subthreshold events. The data suggest that octopus cells have a role in temporal comparisons across frequency and may play a role in auditory scene analysis.
Neuronal encoding of drug choices and preference in the orbitofrontal cortex
Human neuroimaging research has consistently shown that drug addiction is associated with structural and functional changes within the orbitofrontal cortex (OFC). In view of the important role of the OFC in value-based decision-making, these changes have been hypothesised to bias choice towards drug use despite and at the expense of other competing pursuits, thereby explaining drug addiction. Here I will present in vivo recording data in the OFC supporting this hypothesis in a choice-based model of addiction where rats could choose between two actions, one rewarded by a drug (cocaine or heroin), the other by a nondrug alternative (saccharin).