Behavioral Flexibility in Alcohol‐Drinking Monkeys: The Morning After

• Published in: Alcoholism, clinical and experimental research clinical and experimental research, 2020-03, Vol.44 (3), p.729-737
• Main Authors: Shnitko, Tatiana A., Gonzales, Steven W., Newman, Natali, Grant, Kathleen A.
• Format: Article
• Language: English
• Subjects: Alcohol Abuse; Alcohol use; Behavior; Blood levels; Cognitive ability; Discriminative stimuli; Drinking behavior; Ethanol; Flexibility; Late Adolescence; Primates; Rhesus Macaques; Set Shifting; Teenagers; Visual discrimination
• ISSN: 0145-6008; 1530-0277
• DOI: 10.1111/acer.14289

Background Heavy alcohol drinking has aspects of inflexible behavior. This study addressed the consequences of chronic alcohol drinking on cognitive and sensory‐motor domains of behavioral flexibility in rhesus monkeys. Methods Behavioral flexibility was assessed in 12 monkeys (n = 9, ethanol [EtOH] drinkers) with a set‐shifting visual discrimination procedure before alcohol self‐administration and while maintaining consumption of 1.5 g/kg/d EtOH. Task performance was assessed in the morning after ~18 hours of drinking 1.5 g/kg, and 1 hour before the next day's drinking session began. The first 10 set‐shifting sessions had the original (preethanol) test parameters and were used to determine retention of preethanol performance. Then, an effect of sensory‐motor challenge (60% reduction in the size of the discriminative stimuli) on performance was assessed during 10 additional sessions. Results There were no average group‐dependent differences in the performance between control and EtOH groups at the preethanol time‐point. The daily consumption of 1.5 g/kg/d produced binge alcohol intakes in 7 of 9 monkeys (blood EtOH concentration [BEC ≥ 80 mg/dl]). Chronic daily intakes of 1.5 g/kg had no effect on retention of the task in the sober state. However, when challenged with a reduction in the size of the stimuli, daily 1.5 g/kg EtOH resulted in a decrement in performance due to an increase in the number of errors. Conclusions Rhesus monkeys consuming 1.5 g/kg alcohol daily perform equally as could as control monkeys in retention of a well‐learned cognitive task. However, this pattern of daily alcohol intake robustly decreased the ability to flexibly adjust behavior when confronted with novel changes to perceptual stimuli. Heavy alcohol drinking has aspects of inflexible behavior. This study addressed the consequences of chronic alcohol drinking on cognitive and sensory‐motor domains of behavioral flexibility in rhesus monkeys. Rhesus monkeys consuming approximately 6 alcohol drinks daily perform equally well as control monkeys in retention of a well‐learned cognitive task. However, this pattern of daily alcohol intake robustly decreased the ability to flexibly adjust behavior when confronted with novel changes to perceptual stimuli.