The protocol provides a customizable, open-source toolbox for training and performing the 5-choice serial-reaction time task. This is a well-established behavioral test to study visuospatial attention and impulsiveness in rodents. The main advantage of the toolbox is its low cost and customizability.
It provides high flexibility regarding the specific stimulus parameters and reward configuration and encourages non-standard test designs. The 5-choice serial-reaction time task provides insights into the attentional processes, impulsivity and compulsivity in rodents. Our toolbox allows for easy adaptation to other non-rodent animal models.
It also allows semi-automated training of animals by an optional staircase procedure. In the video, we provide a step by step introduction to its usage. The procedure will be demonstrated By Eva Strippelmann, a biology student from our laboratory.
Begin by opening the freely available integrated development environment or IDE software. Go to the File and Open tabs and click on the script for hardware control. Next, plug the micro-controller USB into the computer.
In the top left half of the screen, navigate to the Tools to check whether the automatically chosen board and processor information correspond to the connected microcontroller board. After confirming the corresponding board and processor information, click on the Port tab to choose the available port. On the top left half of the screen, click on the Verify button to ensure no script mistakes.
When done, click on the Upload tab with an arrow to upload the script to the microcontroller board. After ensuring that all four scripts and functions for the experiment control are located in the same folder, open the programming platform and click on the Home toolbar and Set Path. Then go to the Add Folder button to select the folder containing all the experiment control scripts.
When done, click on the Save button and close the Set Path window. On the Home toolbar tab, press Open to open the scripts and functions. To prepare the toolbox for habituation, select the opened user script.
After confirming that the habituation variable on line seven is set to true, write a number in minutes on line eight to set a time limit for the habituation. On line nine, write a number between 0.01 and one to choose a brightness level for the stimulus light. To prepare the toolbox for the experiment session, select the opened user script and verify that the variable on line seven is defined as false.
On line 12, type in the directory path to automatically save the experiment data. Ensure that a directory with the exact name exists. Then type in the subject identification on line 13.
Next, ensure that the variables on lines 14 and 15 are defined as true. When done, type in a number on line 16 to set a trial, and on line 17, to set a time limit in minutes to stop the program automatically. For the configuration of the parameters for a standard 5-choice serial-reaction time task or 5CSRTT paradigm, enter a numerical value on line 45 that corresponds to the number of apertures that can be illuminated.
The variable on line 46 should be defined as pseudorandom or random. Set the stimulus duration length on line 47 in seconds. Check whether the variable on line 48 is denoted as single and the numerical value on line 49 is one.
On line 50, define the brightness of the target stimulus in a number. The variable on line 64 should be binary, whereas on line 65, be non-dependent. Then enter a numerical value on line 71 corresponding to the number of food pellets to be released following a correct nose poke.
Alternatively, different staircase procedures can be defined that allow for automated behavioral training. Check whether the variable on line 26 is defined as true. Then on line 29, type the name of the first or second group.
Later, select the opened staircase function. Type the name of the first group on line four and type the name of the second group on line 77. To change the criteria of the first group for the second training level, type one of the parameters calculated in the performance check and a chosen numerical value on line 17.
The criteria can be added or replaced. To change the parameters of the first group to be updated in the second training level, for example, the duration of a timeout, type the parameter and a chosen numerical value on line 19. Proceed accordingly if the second group of a subject is defined.
Before starting the behavioral training sessions, animals need to get habituated to the chamber. The toolbox provides a habituation protocol. To start the habituation session, prepare the operant chamber by placing two reward food pellets in each of the apertures.
Tape the magazine flap door to remain open for the first habituation stage. In the second habituation stage, remove the tape on the magazine flap door. Prepare the operant chamber by placing five food pellets in the magazine door.
Before starting the experimental training sessions, clean the walls and floor of the operant chamber. As the setup is ready, select the opened user script, ensure that the COM description on line 75 matches the chosen available port. If the description does not match, change the numerical value in the experimental control script.
Place the rat in the chamber. In the opened user script, click on the Editor toolbar tab before selecting the green play button Run. Check whether the program is running correctly by reading the command window information.
The toolbox will then start the task as previously defined by the user. The experiment session will be automatically stopped after the specified trial or time limit. If the animal reaches a pre-specified performance level before the session is terminated and the user has defined a staircase procedure, the toolbox will load the next training level and continue the training with the new settings.
The level will automatically load at the start of the next training session. To stop the experiment, press the Escape key on the computer's keyboard. When the message appears on the command window display, type in Y and press the Enter key on the computer's keyboard to stop the current session and save the acquired data.
Then a simple graph with the session's overview will be automatically displayed. 10 Lister hooded rats were trained using the 5-choice serial-reaction time task toolbox. The number of sessions spent per training level by each rat was analyzed and the average across all subjects was determined.
The variance between subjects was most significant in the initial levels and decreased in later levels. In level four, when the criteria changed to include a threshold for performance measures, the average number of sessions spent and variance between rats increased, with two rats taking five and six days to conclude the level. However, all rats reached the eighth level within 14 to 22 sessions.
The representative analysis shows the mean performance of subjects per training level and across all training days in the 5CSRTT apparatus. The accuracy percentage and the emission percentage were calculated and the average total number of correct responses across all the trials in each level was determined. All subjects achieved a final accuracy on the eighth and final training levels of more than 60%Many subjects achieved about 80%accuracy.
The 5-choice serial-reaction time task toolbox is fully customizable and open access. It provides many additional options for specifying the stimulus configuration and task design and a comprehensive set of recorded behavioral data. The toolbox allows to investigate nonstandard versions of the 5-choice serial-reaction time paradigm, for example, to get deeper insights into decision-making processes or reward related behavior.
