Investigating Temporal Memory Strength and Time-Based Impulse Control Using the DRL Task

Abstract

Differential reinforcement of low rate (DRL) responding is a schedule-controlled behavior sometimes used in timing research, but also received critics of not providing a pure measure of timing due to the influence of the subject’s motivation or inhibitory control. Nevertheless, we argue that the DRL task provides a unique approach to study how timing and emotion interact with each other. Here, we review evidence showing that male rats prenatally treated with choline supplementation had difficulty in acquiring longer criterion times in the DRL task. This was possibly due to the stronger memory strength of their previously learned shorter criterion times. Female rats, in contrast, performed better than male rats in the same task, but those receiving prenatal choline supplementation were the best performers in this task with longer criterion times because they required less training. Like all female rats, male rats treated with prenatal choline supplementation made very few burst responses, suggesting that the treatment improved male rats’ emotional regulation when facing ‘frustrating’ outcomes. The differential impulse control plus different memory strength of the rats trained in the DRL task revealed the potential interaction of sex hormones and prenatal choline supplementation, a rare combination in a single animal study on timing and time perception. In summary, although the DRL task is certainly not the best timing task, it may be useful in assisting us in better understanding how time perception participates in emotional regulation, especially relevant when the emotion is triggered by a failure in timing.

Interval timing relative to response inhibition in the differential reinforcement of low-rate responding in normally developing young adults

“…The operant behaviour of withholding a response might involve restraining the motor action, but 'for how long' each response should be withheld would be much critical to the subjects in any of the DRL schedules. Given that the criterion time interval is typically set within the range of seconds (e.g., 5, 10, 20, or 36 s) in most DRL, the behaviour of interval timing, which refers to how individuals perceive and estimate the time durations accurately, has been an alternative suggestion in DRL behaviour 26,29,[33][34][35][36][37] . This type of response is usually observed as the second peak on the bimodal IRT distributions, and mostly located at the expected time interval for the requirements of a DRL, defined as the peak time [38][39][40][41] .…”