Figure 3: Effects of chronic alcohol drinking on current-injected firing in male rhesus BNST neurons.

A) Illustration of various basal states of activity observed in male rhesus BNST neurons measured in current clamp configuration. B) The proportions of neurons in each basal state did not differ between control males (CON M) and alcohol males (EtOH M; Fisher’s exact test: p > 0.99). C) The resting membrane potential (RMP) of neurons basally at rest did not differ between CON M and EtOH M (unpaired t-test: t₁₇ = 1.01, p = 0.327). D-E) I_h magnitude was higher in resting neurons compared to those basally firing or in depolarization block (D; unpaired t-test: t₂₄ = 3.10, **p = 0.005) and negatively correlated with RMP in resting neurons (E; Pearson’s correlation: R = −0.650, **p = 0.005). F-G) Membrane resistance was lower in resting neurons compared to those basally firing or in depolarization block (G; unpaired t-test: t₂₃ = 4.69, ***p = 0.0001) and negatively correlated with RMP in resting neurons (E; Pearson’s correlation: R = −0.650, **p = 0.005). H-K) Action potential firing in response to a ramp current injection stimulus in current clamp at RMP. H) Example trace for (above) and stimulus waveform of (below) a ramp current-injected firing during current-clamp recordings in BNST neurons at RMP. I) The threshold to fire an action potential did not differ between CON M and EtOH M (unpaired t-test: t₁₆ = 0.38, p = 0.708). J) The rheobase (minimum amount of injected current required to elicit an action potential) measured from RMP in resting neurons was lower in EtOH M than CON M (unpaired t-test with Welch’s correction: t_9.6 = 2.34, *p = 0.042). K) Rheobase was negatively correlated with RMP in male BNST neurons (R = −0.732, ***p = 0.0005). L) When neurons were held at a common membrane potential of −70 mV, there was no difference in rheobase between CON M and EtOH M (unpaired t-test: t₂₆ = 0.64, p = 0.527).