Sharp wave-associated synchronized inputs from the piriform cortex activate olfactory tubercle neurons during...

Area of Science:

• Neuroscience
• Sleep Research
• Olfactory System

Background:

• During slow-wave sleep, anterior piriform cortex (aPC) neurons exhibit synchronized discharges linked to olfactory cortex sharp waves (OC-SPWs).
• This synchronized activity is believed to influence olfactory bulb circuitry, but its impact on other central olfactory regions remains unclear.
• The olfactory tubercle (OT), part of the ventral striatum, is crucial for reward-based behaviors.

Purpose of the Study:

• To investigate whether OC-SPW-related activity influences the olfactory tubercle.
• To determine the temporal relationship and location of OC-SPW-associated inputs within the olfactory tubercle.

Main Methods:

• Local field potential (LFP) recordings in freely behaving rats to detect OC-SPW-like activity in the OT.
• Single-unit recordings to assess neuronal firing synchrony with OC-SPWs in the OT.
• Correlation analysis of neuronal activity between the aPC and OT.
• Current source density (CSD) analysis in urethane-anesthetized rats to pinpoint input locations.

Main Results:

• The olfactory tubercle receives synchronized inputs associated with OC-SPWs during slow-wave sleep.
• LFPs in the OT showed SPW-like activities synchronized with OC-SPWs, and a subset of OT neurons discharged in sync.
• aPC neuron discharges typically preceded OT neuron discharges.
• CSD analysis revealed that OC-SPW-associated inputs targeted layer III of the OT.

Conclusions:

• OC-SPW-associated synchronized discharges from the piriform cortex project to the deep layers of the olfactory tubercle, driving neuronal activity.
• The entrainment of OT neurons by OC-SPWs indicates that these events coordinate neuronal circuitry reorganization throughout the central olfactory system, including the OT, during sleep.