Behavioral Flexibility in Alcohol-Drinking Monkeys: The Morning After

Alcohol Clin Exp Res. 2020 Mar;44(3):729-737. doi: 10.1111/acer.14289. Epub 2020 Feb 18.


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.

Keywords: Alcohol Abuse; Late Adolescence; Rhesus Macaques; Set Shifting.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Behavior, Animal / drug effects*
  • Behavior, Animal / physiology*
  • Binge Drinking / physiopathology*
  • Binge Drinking / psychology
  • Blood Alcohol Content
  • Cognition / drug effects*
  • Cognition / physiology
  • Ethanol / administration & dosage*
  • Macaca mulatta / physiology*
  • Macaca mulatta / psychology
  • Male
  • Photic Stimulation
  • Sensorimotor Cortex / drug effects
  • Sensorimotor Cortex / physiopathology


  • Blood Alcohol Content
  • Ethanol