Acute Ethanol Administration and Reinforcer Magnitude Reduction Both Reduce Responding and Increase Response Latency in a Go/No-Go Task

Background: Ethanol (EtOH) administration decreases behavioral inhibition in human subjects, assessed using cued Go/No-Go tasks, in which an unreliable cue suggests whether participants will be required to respond or not when a signal occurs. Few studies have examined EtOH's effects on behavioral inhibition in animals, and those that have done so have used Go/No-Go tasks in which no warning cue was provided. Methods: Two cohorts of male Long-Evans rats were trained and tested on 2 different Go/No-Go procedures with differing ratios of Go to No-Go trials (25 to 75 and 50 to 50). Using a within-subjects design, each rat was administered 0.0, 0.63, 0.95, and 1.27 g/kg of EtOH (i.p.) on 3 separate occasions according to an incomplete Latin square. An additional experiment examined the effects of reducing the amount of sucrose given for correct responses to either the Go or the No-Go signal in the absence of EtOH administration. Results: Acute intraperitoneal EtOH administration dose-dependently decreased responding during the No-Go signal (false alarms), the Go signal (hits), and responding prior to the occurrence of either signal (precue response rate). These effects were more pronounced in rats with the 50 to 50 ratio. Reducing the amount of sucrose presented generally led to a decrease in responding, although this effect was also moderated by the Go to No-Go ratio employed and the contingency relationship (reduced sucrose for correct Go trial responding or for correct No-Go trial response withholding). Conclusions: Acute EtOH administration does not decrease behavioral inhibition in rats in this task. Rather EtOH appears to dose-dependently decrease behavior in general, possibly by reducing the efficacy of the sucrose reinforcer, as both EtOH administration and sucrose reduction for Go trials yielded similar patterns of behavioral responding in this task in rats.