State-dependent respiratory and cardiac relationships with neuronal discharge in the bed nucleus of the stria terminalis.

Discharge patterns of 63 neurons in the bed nucleus of the stria terminalis (BNST) were cross-correlated with inspiratory onsets of the respiratory cycle and the R wave of the cardiac cycle in seven unrestrained, drug-free cats during waking (AW), quiet sleep (QS) and rapid eye movement (REM) sleep. BNST neurons fired slowly, with half having rates of less than 1/second; rates were higher in AW and REM states than in QS. Approximately one-quarter of cells showed a phasic discharge timing relationship with the respiratory cycle, and one-fifth with the cardiac cycle, in at least one sleep-waking state. Respiratory-cell correlations occurred more frequently during AW (18 cells) and QS (15) than REM (6), while cardiac-neuronal correlations preferentially developed during QS (13 cells) or REM sleep (11), with a smaller proportion during waking (7). Cardiac-cell discharge correlations were weaker than respiratory-cell correlations and much weaker during REM than during either AW or QS. The data suggest that sleep states modulate a respiratory-dependent neuronal discharge in this rostral site classically associated with affective functions, with the relationship being reduced during REM.