MECHANISM BEHIND GAMMA BAND SINGLE CELL ACTIVITY IN THE PARAFASCICULAR NUCLEUS

HYDE J; KEZUNOVIC N; SIMON C; 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 parafascicular nucleus (Pf) is part of the “non-specific” intralaminar thalamus involved in waking and REM sleep, during which the EEG shows activity at gamma frequencies (~20-80Hz). 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 Pf neurons fired maximally in the gamma range (20-60Hz). 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 Pf neurons. Methods: Single cell responses were recorded using whole-cell patch clamp electrodes in an immersion chamber using 9-18 day old rat brainstem slices. Recordings were made at 37°C while perfusing aCSF 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 Pf cells (n=31) at higher amplitudes using ramps than steps (p