The touchscreen operant platform for testing working memory and pattern separation in rats and mice

Abstract

The automated touchscreen operant chamber for rats and mice allows for the assessment of multiple cognitive domains within the same testing environment. This protocol presents the Location Discrimination task (LD) and the Trial-Unique delayed Nonmatching-to-Location task (TUNL), which both assess memory for location. On these tasks, animals are trained to a predefined criterion during ~20-40 daily sessions. In LD-sessions, touching the same location on the screen is rewarded on consecutive trials, followed by a reversal of location-reward contingencies. TUNL, a working memory task, requires animals to "non-match" to a sample location after a delay. In both LD and TUNL spatial similarity can be varied, allowing assessment of "pattern separation" ability, a function thought to be performed by the dentate gyrus. These tasks are therefore particularly useful in animal models of hippocampal, and specifically dentate gyrus function, but additionally permit discernment of changes in pattern separation from those in working memory.

MK-801-induced impairments on the trial-unique, delayed nonmatching-to-location task in rats: effects of acute sodium nitroprusside

“…By manipulating the length of delay and distance between the sample and choice square, the demand on working memory and pattern separation can be respectively altered. For example, longer delays require a greater demand on working memory and closer together squares are more difficult to maintain as separate patterns (Oomen et al 2013). As mentioned, one way to improve the predictive validity is to focus on the preclinical-clinical translation of cognitive tasks.…”

“…The TUNL task is conducted in touchscreen-equipped operant conditioning chambers (Oomen et al 2013). By using an automated touchscreen system, variability amongst trials is reduced and researcher bias during data collection is eliminated (Talpos et al 2010;Oomen et al 2013). Further, this system makes the administration of tasks simple, time-efficient, and consistent.…”

“…Once the last criterion was met, rats were left undisturbed in the vivarium while the remaining rats were trained to criterion. Rats were given reminder training sessions once a week to maintain performance until testing began (Oomen et al 2013). Once all rats were trained to the second criterion, they were reintroduced to daily testing for at least three days to collect baseline measurements prior to drug treatment.…”

“…The Trial-Unique, Delayed Nonmatching-to-Location (TUNL) task was developed to address the weaknesses of the delayed nonmatching-to-position task. The TUNL task is conducted in touchscreen-equipped operant conditioning chambers (Oomen et al 2013). By using an automated touchscreen system, variability amongst trials is reduced and researcher bias during data collection is eliminated (Talpos et al 2010;Oomen et al 2013).…”

MAM (E17) rodent developmental model of neuropsychiatric disease: disruptions in learning and dysregulation of nucleus accumbens dopamine release, but spared executive function

“…The continuous trial unique non-match to location task (cTUNL) is an adaptation of the trial unique non-match to location task (TUNL), which was designed to assess pattern separation and working memory (Oomen et al 2013) in rodents. The initial training stages of the cTUNL are the same as the TUNL and have been described in depth elsewhere and are summarized in brief here (McAllister et al 2013;Oomen et al 2013;Talpos et al 2010). All training and testing for cTUNL was carried out in touchscreen operant boxes (Campden Instruments Ltd., Lafayette, IN, USA) located inside a sound attenuating chamber.…”