Three Choice Serial Reaction Time Task (3CSRTT)

Introduction

Hauser  et al explored how a lack of nutritional essential fatty acids has been suggested to be associated with neurodevelopmental and neuropsychiatric disorders to cause changes in neurotransmission and behavior, affecting habituation, locomotion, and cognition. Supplementation of these fatty acids is neuroprotective. The experiment used the 3CSRTT task to measure these behavioral domains in omega-3 depleted rats, as well as in those on an omega-3 adequate diet.

The 3CSRTT consists of an operant test chamber containing a curved wall with three nose poke apertures. A stimulus LED light is present in each aperture to signal food retrieval. Food can be retrieved from a food cachet connected to a food dispenser on the opposite wall of the chamber. During the task, the subject must pay attention to the apertures to detect the signal and respond correctly to obtain the food reward within a limited time window. If the subject responds incorrectly by an error of commission (responding in a hole where the signal is not presented), error of omission (failing to respond to the signal within the prescribed time limit), or premature responses (responding before the signal presentation), it is punished by a time-out period, which is a brief period of darkness. In addition, the 3CSRTT Apparatus also contains a shocker floor grid to provide punishment.

5CSRTT

Apparatus and Equipment

The 3CSRTT Apparatus consists of a chamber measuring 25 × 25 in length and width and 30 cm in height. It contains two plexiglass sidewalls, an aluminum front wall, and a stainless steel back wall. The aluminum front wall is curved and contains five nose poke apertures measuring 2.5 × 2.2 × 2.2 cm each, 2 cm above the floor. The apparatus contains an infrared nose poke sensor to detect the subject’s nose pokes into each aperture. A stimulus LED light is present in each nose poke opening as a signal for food retrieval.  The food is dispensed in the back wall through a food cachet installed to provide food pellets from the pellet dispenser. The floor of the apparatus consists of a shocker floor grid to provide punishment during trials. A removable tray is present below the grid for easy removal and cleaning of urine and feces.

Rodent location can be tracked using a video tracking software package such as ConductVision, Noldus EthoVision, ANY-Maze.

Training Protocol

Animals

Seven generations of Wistar rats that were fed an experimental ω-3 PUFA deficient diet. The male offspring of the seventh generation of ω-3 PUFA deficient dams were used in the behavioral experiment. These dams were randomly assigned to two diet groups: a diet sufficient in ω-3 PUFAs or one deficient in ω-3 PUFAs. The male offspring were tested using the three-choice serial-reaction-time-task (3CSRTT) and were housed in standard cages under standard animal laboratory conditions. The rats were monitored daily for health concerns and body weight.

Habituation Phase

Rats were habituated to the 3CSRTT boxes for 30 minutes per day.

Over two consecutive days, 10 pellets were baited in the food tray with one pellet placed in each illuminated hole. The habituation phase was finished when all pellets were found and collected.

Training phase

The rats were divided into three groups and fed either an omega-3 sufficient diet or an omega-3 deficient diet during prenatal, perinatal, and lactation periods.

The rats were trained using the three-choice serial reaction time task (3CSRTT) to test their attention and impulsive behavior. The rats were required to respond correctly to a stimulus to obtain a food pellet (i.e. random illumination of a hole, once per trial). The stimulus duration was gradually reduced when a rat responded correctly in order to obtain a food pellet until the rats responded correctly in at least 80% of the trials with an omission rate of less than 20%. The stimulus lasted from 60 s (training level 1) to 1.5 s (final training).

Testing phase

The final (testing) phase involved a stimulus duration of 1.5 seconds and random inter-trial intervals ranging from 1.5 to 8.5 seconds. The testing sessions were similar to the training sessions and each inter-trial interval occurred 9 times in a session. The order in which the groups and rats were tested was randomized in all phases.

Data Analysis

The following parameters can be observed using the Octopus three-chambered social apparatus:

• Number of correct responses
• Number of incorrect responses
• Number of premature responses (nose-pokes made during inter-trial intervals)
• Number of perseverative responses (total number of additional responses emitted after the initial nose-poke within a single trial)
• Number of omission errors
• Time taken to make the correct choice
• Times taken to collect the reward pellet following the correct choice

Literature Review

Alterations of attention and impulsivity in the rat following a transgenerational decrease in dietary omega-3 fatty acids

Using the 3CSRTT, Huaser et al found that rats in the ω-3 PUFA deficient diet group, which had lower levels of omega-3 fatty acids, performed worse than the ω-3 PUFA sufficient diet group in attentional processes and had more impulsive behavior. The group which had some omega-3 fatty acid supplementation ((re)introduction of an ω-3 PUFA sufficient diet), performed better in attentional processes compared to the ω-3-/ω-3- group, but there were no significant differences in impulsive behavior. The reintroduced group also performed worse in impulsive behavior compared to the ω-3 PUFA sufficient diet group.

Strengths and Limitations

Strengths

The 3CRSTT Apparatus can be used to study attention and impulsivity in rodents. Different aspects of attention, such as sustained attention and selective attention, can be assessed using this apparatus. The 3CRSTT Apparatus contains five nose poke apertures, so the visual cue signal can vary between these five apertures across trials to challenge the subject’s attention. Furthermore, variations can also be presented in the visual cue duration and pre-cue delay between trial onset and visual cue presentation across trials. The apparatus contains a shocker grid floor to punish the subjects if they respond incorrectly during trials. Additionally, the house light can also be turned off for a brief moment of darkness as a less aversive form of punishment.

Limitations

The 3CRSTT requires a time-intensive training period. The subject’s motivation to complete long training sessions and trials are essential for task performance. Task performance can be affected by the subject’s ability to learn and perform the task, which can also be affected by the subject’s age, gender, and strain. Improper handling of the subjects can induce stress and alter behavioral outcomes such as learning and memory. A sound-attenuating chamber may be required to keep the apparatus during testing sessions to prevent external distracting stimuli from affecting the task performance.

Summary

• The 3CSRTT (5-Choice Serial Reaction Time Test) Apparatus assesses attention, psychomotor activity, and impulsivity in rodents.
• It consists of a testing chamber containing a curved wall with five nose poke apertures in which a visual cue signal can be displayed. A food cachet is present opposite the curved wall, connected to a food dispenser that dispenses food pellets if the subject responds correctly during trials.
• The 3CSRTT Apparatus can be used as a model to investigate neurological deficit disorders which are characterized by impaired attention and increased impulsivity. It can also be used to investigate the effect of dietary and pharmacological manipulations on attention and impulse control.

References

Hauser, J., Stollberg, E., Reissmann, A., Kaunzinger, I., & Lange, K. W. (2018). Alterations of attention and impulsivity in the rat following a transgenerational decrease in dietary omega-3 fatty acids. Food Science and Human Wellness, 7(1), 49–56. doi:10.1016/j.fshw.2017.12.004