DOI: 10.5061/dryad.z612jm6c0
title: Sex differences in learning from exploration

description: Sex-based modulation of cognitive processes could set the stage for
 individual differences in vulnerability to neuropsychiatric disorders.
 While value-based decision making processes in particular have been
 proposed to be influenced by sex differences, the overall correct
 performance in decision making tasks often show variable or minimal
 differences across sexes. Computational tools allow us to uncover latent
 variables that define different decision making approaches, even in
 animals with similar correct performance. Here, we quantify sex
 differences in mice in the latent variables underlying behavior in a
 classic value-based decision making task: a restless 2-armed bandit. While
 male and female mice had similar accuracy, they achieved this performance
 via different patterns of exploration. Male mice tended to make more
 exploratory choices overall, largely because they appeared to get “stuck”
 in exploration once they had started. Female mice tended to explore less,
 but learned more quickly during exploration. Together, these results
 suggest that sex exerts stronger influences on decision making during
 periods of learning and exploration than during stable choices.
 Exploration during decision making is altered in people diagnosed
 addictions, depression, and neurodevelopmental disabilities, pinpointing
 the neural mechanisms of exploration as a highly translational avenue for
 conferring sex-modulated vulnerability to neuropsychiatric diagnoses.
description: Thirty-two BL6129SF1/J mice (16 males and 16 females) were
 obtained from Jackson Laboratories (stock #101043). Mice arrived at the
 lab at 7 weeks of age, and they were housed in groups of four with ad
 libitum access to water while being mildly food restricted (85-95% of free
 feeding weight) for the experiment. Animals engaging in operant testing
 were housed in a 0900–2100 hours reversed light cycle to permit testing
 during the dark period. Before operant chamber training, animals were food
 restricted to 85%-90% of free feeding body weight. Operant testing
 occurred five days per week (Monday-Friday). All animals were cared for
 according to the guidelines of the National Institution of Health and the
 University of Minnesota. Behavioral task. Two-armed
 spatial restless bandit task. Animals were trained to perform a two-armed
 spatial restless bandit task in the touchscreen operant chamber. Each
 trial, animals were presented with two identical squares on the left and
 right side of the screen. Nose poke to one of the target locations on the
 touchscreen was required to register a response. Each location is
 associated with some probability of reward, which changes independently
 over time. For every trial, there is a 10% chance that the reward
 probability of a given arm will increase or decrease by 10%. All the walks
 were generated randomly with a few criteria: 1) the overall reward
 probabilities of two arms are within 2% of each other, preventing one arm
 being overly better than the other, 2) the reward probability cannot go
 down to 0% or go up to 100%, 3) there are no 30 consecutive trials where
 the reward probabilities of both arms are lower than 20% to ensure
 motivation. Animals ran a simple deterministic schedule on Monday to
 re-adapt to operant chamber after weekends off and ran a different
 restless bandit task each day from Tuesday to Friday. Animals ran for 2
 rounds of 4 consecutive days and within each day, animals completed either
 300 trials or spent a maximum of two hours in the operant chamber. Data
 was recorded by the ABET II system and was exported for further analysis.
 All computational modeling was conducted using python.
 Detailed data analyses can be found:
 https://www.biorxiv.org/content/10.1101/2020.12.29.424773v2