['Chronic ethanol use is known to disrupt normal sleep rhythms, but the cellular basis for this disruption is unknown. An important contributor to normal sleep patterns is a low-threshold calcium current mediated by T-type calcium channels. The T-type calcium current underlies burst responses in thalamic nuclei that are important to spindle propagation, and we recently observed that this current is sensitive to acute low doses of ethanol.', 'We used a combination of current clamp and voltage clamp recordings in an in vitro brain slice preparation of the dorsal lateral geniculate nucleus (LGN) of macaque monkeys that have chronically self-administered ethanol to determine whether chronic ethanol exposure may affect T-type currents.', 'Current clamp recordings from the LGN of ethanol naive macaques showed characteristic burst responses. However, recordings from the LGN in macaques that self-administered ethanol revealed a significant attenuation of bursts across a range of voltages (n=5). Voltage clamp recordings from control LGN neurons (n=16) and neurons (n=29) from brain slices from chronically drinking macaques showed no significant differences (P>0.05) in T-type current kinetics or in the membrane resistance of the thalamic cells between the two cohorts. However, mean T-type current amplitude measured in the chronically drinking animals was reduced by 31% (P<0.01).'] Does chronic ethanol drinking reduce native T-type calcium current in the thalamus of nonhuman primates?