Measuring Active and Passive Tameness Separately in Mice

This method can evaluate the level of tameness in each mouse, and the data will be highly useful for further studies of tameness such as genetic mapping of genes related to tameness. The main advantage of this technique is that it can evaluate two major components of tameness:active and passive tameness, separately, by using this method. Demonstrating the procedure will be Mr.Hiromichi Nagayama, a graduate student, and Ms.Motoko Nihei, a technician from my laboratory.

To begin, turn on the digital camera and start the recording. Then, use a pair of large tweezers to gently pick the mouse up by the tail. Transfer the mouse from its home cage to the center of the open field apparatus.

After starting the stopwatch, place a hand in the lower, left corner of the apparatus. With the palm facing up, wiggle the fingers, slowly and steadily. Slowly, move the hand toward the mouse and stop 10 centimeters away from the side of the mouse's body.

Maintain this distance if the mouse attempts to move away. If the mouse approaches the hand, keep the hand in the same position, and continue to move the fingers slowly and steadily. Remove the mouse with the free hand if it attempts to climb up the arm.

After one minute, conclude the test. After positioning the mouse in the apparatus, place the left hand in the apparatus. Then, slowly and steadily move the hand toward the mouse and gently touch the mouse with the fingertips.

Continue to touch the mouse with the fingertips until it moves away. When the mouse attempts to break contact, follow it with the hand and re-initiate the contact. Conclude the test after one minute.

Immediately after the previous test concludes, use a pair of large tweezers to lift the mouse by the tail and place it gently on the left palm. Stroke the mouse gently with the left thumb, until it leaves the hand. Then, place the mouse back onto the palm with the tweezers.

After the third trial, stop the video recording and weigh the mouse. After returning the mouse to its home cage, record the amount of feces and urine left in the open field of the apparatus. Next, wipe the apparatus and gloves with a paper towel soaked in 0.2%iodophor sanitizer, and wipe the apparatus with the dry paper towel.

After assigning keys for each behavior index, launch the tanaMove software. Next, drag and drop the video file to be analyzed into the window. Confirm that the file is loaded and that the information in the datafile.

csv box is correct. Click the Ready button and enter the assigned keys for each behavior index in the subsequent window. Then, click the Play button to start the video file and Stop to pause it.

Press A when the mouse is observed heading toward or approaching the hand. Press R when the mouse is observed locomoting without heading toward the hand during the Active Tameness Test. Press and hold W when the timer sound is heard at 60 seconds to mark the end of the Active Tameness Test.

When the left hand enters the frame, start the analysis for the Passive Tameness Test. Press A when the mouse is observed heading toward the hand and R when the mouse is observed traveling without heading toward the hand. Then, press and hold W when the timer sound is heard at 60 seconds.

Initiate the Passive Tameness analysis when the left hand is observed entering the frame. While the video plays, press A when the mouse is observed approaching the hand and R when the mouse is observed moving without heading toward the hand. Once more, press W when the timer is heard at 60 seconds.

After this, press T every time the mouse stays on the hand during the test. After the test is over, click Stop. Then, click the Back button to activate a new window, and enter a new file name for the CSV data input.

Next, click the Ready button, and enter the appropriate keys into the new window. Then, click the Play button to restart the video and initiate analysis of the Active Tameness Test. While the video plays, press T whenever the mouse contacts the handler voluntarily.

When the timer sounds at 60 seconds, press and hold W.During the Passive Tameness Test, press T when the mouse allows the handler to touch its body. Then, press and hold W when the timer sounds after 60 seconds. After this, click the Stop button and then the Back button before entering a file name for the CSV data output.

Next, click the Ready button to activate a new window to enter the assigned keys. Then, click Play to begin the Active Tameness Test. When the mouse is observed jumping, press J.Then, press W when the timer sounds after 60 seconds.

Click the Stop button, to stop the video observation and the timer sounds again at 60 seconds. Then, click the Back button and enter a file name for the CSV data output. Next, save all of the raw data files in the folder containing the supplementary two file.

Open the supplementary two file and click the Summarize button. Finally, save the results as a separate file for further analyses. Using selective breeding, mice with high-level Active Tameness were produced.

Mice from the selective breeding groups scored higher on the Active Tameness Test, exhibiting longer durations of contact with the human hand than control mice. Mice from the two groups did not differ significantly in heading, locomotion or jumping duration. However, the selected mice did score higher on the Passive Tameness Test.

Additionally, the selected mice stayed on a human hand for significantly longer than the control mice did in the Stay-On-Hand Test. While attempting this procedure, it's important to remember to avoid handling the mice until performing the Tameness test, since handling experience may affect tameness of each mouse significantly.