Discharge dependencies of amygdala central nucleus neurons to the cardiac and respiratory cycle following local cocaine administration

We examined dependencies of amygdala central nucleus neuronal discharge to the cardiac and respiratory cycles in freely behaving cats following local microinjection of cocaine (100 micrograms/0.2 microliter). Cross-correlation histograms showed cycle-by-cycle dependencies between neuronal discharge and the cardiac and respiratory cycles in 10 of 30 cells and 7 of 30 cells, respectively, during baseline periods. After cocaine delivery, the discharge rate of half of the central nucleus of the amygdala cells (16/30, 53%) were partly or completely inhibited in a reversible manner. Excluding cardiac- and respiratory-dependent neurons which ceased firing after cocaine, more than half (5/8) of the remaining cardiac and two-thirds (4/6) of respiratory-dependent neurons altered discharge dependencies following cocaine administration. Of the cells that did not exhibit cardiac and respiratory dependencies pre-cocaine, 2 of 20 developed cardiac correlations and 3 of 23 developed respiratory correlations following cocaine administration. We speculate that a portion of the cardiac and respiratory responses induced by cocaine may be mediated through the central nucleus of the amygdala.