A cost-benefit analysis is a weighing-scale approach that the brain performs during the course of decision making. Here, we propose a protocol to train rats on an operant-based decision-making paradigm where rats choose higher rewards at the expense of waiting for 15 s to receive them.
This technique can answer key questions in cognitive neurosciences such as how comparing consequences and causes can affect making a decision. The main advantage of this technique is that the special elements such as the location of the board do not affect the animal's decision. Begin by restricting food access to adult male rats in a room with a 12-hour light/dark cycle.
On days one to three, handle the animals for five minutes twice a day. Then, weigh the animals after each handling session to determine the free-feeding amount. Next, obtain a T maze equipped with three partitions or arms, two stimulus speakers, five retractable doors, and five infrared motion sensors or Infrared Beam or IRB sensors.
Copy the experimental software code into the computer. Then, download the experimental software and install it on a computer. Connect the microcontroller to the computer using a USB port.
Next, on the computer, click the software icon, go to Tools and then select Port. From the dropdown menu, choose the COM port which connects the software to the computer. Go to Tools and select Boards.
From the dropdown menu, select the type of software that controls the T maze. Then, click Upload on the top left of the interface window. Select the experimental software code, wait until the process finishes.
After the process has finished, click Serial Monitor at the top right of the interface window. Then, in a new popup window, change the baud rate to 115, 200. For five days prior to the experimental day, bring the animals to the experiment room for at least one hour.
Leave 10 sugar pellets at each goal arm and leave all doors open. During days one through three, place the animals individually in the maze for periods of 10 minutes once per day to explore the maze with no restrictions. During days four through five, place the animals individually in the maze.
Leave two pellets in each arm and allow them to sample the food from both sides. Remove the animal from the maze immediately after eating the pellets from both sides or after five minutes of being in the maze. Finally, after each habituation session, clean the maze's floors with 70%ethanol and make sure the ethanol has evaporated before placing the next animal in the maze.
On day six, bring the animals to the experiment room at least one hour prior to the experiment. Run the software program and set the trial number to 14 of which the first four trials will be forced choice and the rest will be choice trials. Before each trial begins, place four pellets in the goal arm which is to be cued as the High Reward Arm, HRA, and two pellets in the other arm which is the Low Reward Arm, LRA.
For the forced choice trial training, pseudo randomly block one arm before each trial so that the animal is forced to select the other arm. Place an animal in the start box. After five to seven seconds, simultaneously open the start gate and click Start in the software's interface window.
Collect the animal immediately after eating pellets or after five minutes of being in the maze and leave the animal in the home cage for two minutes. Prior to each trial, close door B in the arm which is selected by the software to be the HRA. Leave door A open in the opposite arm, the LRA.
Then, place an animal in the start box. After five to seven seconds, simultaneously open the start gate and click Start. Let the animal freely choose either arm.
If the animal chooses the HRA, open door A, let the animal enter the chamber, shut door A and open door B immediately to give the animal access to the selected food well. If the animal chooses the LRA, open door B in order to give the animal access to the food well. Next, remove the animal after it has eaten all the food in the selected food well and leave it in the home cage for two minutes.
Complete the 10 choice trials for each animal and record the animal's choice, either HRA or LRA in each trial. Calculate the percentage of High Reward Choice, HRC, for all choice trials after each training session. Finally, after each animal has reached 80%of HRC in the discrimination training, complete the delay training by opening door B after a five-second delay once the animal chooses the HRA.
Run 10 trials per day for each animal. Results indicated that there was a decrease in both the low and the high frequency powers in the ACC from the onset to the end of the stimulus. Comparing the time spent outside the chamber with the time in the chamber, the spectral analysis showed no changes in the oscillatory activities in the ACC.
Further, mid to high frequency band activities in the OFC increased following the stimulus onset. No significant changes were observed in the pre-chamber and chamber time windows when they were compared together. While attempting this procedure, it is important to remove any source of anxiety as it can affect the animal's decision and impair the reliability of the result.
