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Synaptic events that generate fast oscillations in piriform cortex
1Department of Anatomy, University of Wisconsin, Madison 53706.
Summary
Fast oscillations in the olfactory bulb and piriform cortex, similar to odor responses, are generated by intrinsic neuronal circuits. Olfactory bulb activity drives piriform cortex oscillations via afferent fibers.
Area of Science:
- Neuroscience
- Olfactory System Research
Background:
- Fast (40-60 Hz) oscillations are prominent in the olfactory bulb and piriform cortex during odor perception.
- These oscillations occur in both awake and anesthetized animals.
Purpose of the Study:
- To investigate the origin of fast oscillations evoked by weak afferent fiber shocks.
- To compare shock-evoked oscillations with odor-evoked oscillations.
Main Methods:
- Current source-density analysis was used to examine membrane currents.
- Analysis focused on the timing and location of synaptic events.
Main Results:
- Shock-evoked oscillations involve a series of membrane currents similar to non-oscillatory responses.
- Each oscillation cycle starts with afferent fiber EPSCs in layer Ia, followed by intrinsic fiber EPSCs in layer Ib.
- A subsequent inward current in deeper layers may represent a Cl(-)-mediated IPSC.
Conclusions:
- The study concludes that weak shock-evoked oscillations originate in the olfactory bulb.
- Periodic activity in olfactory bulb afferent fibers drives piriform cortex oscillations.