MECHANISM BEHIND GAMMA BAND ACTIVITY IN PEDUNCULOPONTINE NUCLEUS

KEZUNOVIC N; SIMON C; HYDE J; SMITH K; 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: The pedunculopontine nucleus (PPN) modulates waking and paradoxical sleep, during which the EEG shows activity at gamma frequencies (~20-80 Hz). Gamma oscillations appear to participate in sensory perception, problem solving, and memory, and this coherence may occur at cortical or subcortical levels. We previously reported that PPN neurons fired maximally in the gamma range (20-60 Hz). The present studies tested the hypothesis that P/Q- and N-type calcium channels are responsible for generating the rising phase of gamma band oscillations in PPN neurons. Methods: Whole-cell patch-clamp responses were recorded using 9-14 days old rat brainstem slices at 370C while perfused with oxygenated aCSF in an immersion chamber containing 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) to block fast synaptic transmission. Tetrodotoxin (TTX)was used to block sodium channels, while the specific calcium channel blockers ω-agatoxin-IVA (100-200 nM), and ω-conotoxin-GVIA (1-3 microM) were used to block P/Q- and N-type calcium channels, respectively. Results: Gamma band oscillations were induced in all 3 types of PPN cells (n=103) at higher amplitudes using ramps compared to steps(p