MODULATION OF GAMMA BAND ACTIVITY IN THE PEDUNCULOPONTINE NUCLEUS

SMITH K; KEZUNOVIC N; URBANO FJ; GARCIA-RILL E

LLC Minneapolis, Minnesota, USA

Congreso; SLEEP 2011 25th Anniversary Meeting of the Associated Professional Sleep Societies; 2011

The Associated Professional Sleep Societies, USA

Introduction: We previously reported that gamma band activity is generated by intrinsic membrane properties of pedunculopontine (PPN) neurons, and other studies at this meeting suggest that high threshold voltage-gated calcium channels are responsible for this activity. Previous studies on the mechanisms behind gamma band activity in the cortex used slice recordings at 36-38oC instead of 30oC. These studies tested the a) temperature dependence of gamma band activity, and b) mechanism behind gamma band activity, in the PPN. Methods: Population responses were recorded using extracellular microelectrodes in an interface chamber in 9-16 days old rat brainstem slices. Recordings of activity were taken at 30, 32, 34, 36, and 38oC in each slice. In another experiment, carbachol (CAR), along with the GABAA receptor antagonist gabazine (10 microM), the glycine receptor antagonist strychnine (10 microM), and the glutamate receptor antagonists CNQX (10 microM) and APV (40 microM) were used to block fast synaptic transmission. These recordings manifested CAR-induced gamma oscillations. Either ω-agatoxin-IVA (100-200 nM), a P/Q-type calcium channel blocker, or ω-conotoxin-GVIA (1-3 microM), a N-type calcium channel blocker, was then applied. After 20 minutes, CAR was reapplied with synaptic blockers. Results: Population recordings showed a significant increase in response at theta, beta, and gamma frequencies as the temperature increased from 30-38oC (n=4, p