Assessment of attention threshold in rats by titration of visual cue duration during the five choice serial reaction time task.

ABSTRACT

BACKGROUND: The 5 choice serial reaction time task (5CSRTT) is commonly used to assess attention in rodents. We sought to develop a variant of the 5CSRTT that would speed training to objective success criteria, and to test whether this variant could determine attention capability in each subject. NEW METHOD: Fisher 344 rats were trained to perform a variant of the 5CSRTT in which the duration of visual cue presentation (cue duration) was titrated between trials based upon performance. The cue duration was decreased when the subject made a correct response, or increased with incorrect responses or omissions. Additionally, test day challenges were provided consisting of lengthening the intertrial interval and inclusion of a visual distracting stimulus. RESULTS: Rats readily titrated the cue duration to less than 1s in 25 training sessions or less (mean±SEM, 22.9±0.7), and the median cue duration (MCD) was calculated as a measure of attention threshold. Increasing the intertrial interval increased premature responses, decreased the number of trials completed, and increased the MCD. Decreasing the intertrial interval and time allotted for consuming the food reward demonstrated that a minimum of 3.5s is required for rats to consume two food pellets and successfully attend to the next trial. Visual distraction in the form of a 3Hz flashing light increased the MCD and both premature and time out responses. COMPARISON WITH EXISTING METHOD: The titration variant of the 5CSRTT is a useful method that dynamically measures attention threshold across a wide range of subject performance, and significantly decreases the time required for training. Task challenges produce similar effects in the titration method as reported for the classical procedure. CONCLUSIONS: The titration 5CSRTT method is an efficient training procedure for assessing attention and can be utilized to assess the limit in performance ability across subjects and various schedule manipulations.