Fig. 6: S1-Tr cortical neurons in stress-induced fear memory and anxiety mice encode the somatic pain stimulus and the battle sound.

A illustrates a scheme of electrophysiological recording in vivo. The electrical signals from S1-Tr cortical neurons were recorded as spontaneous spikes and evoked spikes in response to the sound signal of the battle sound and the touch stimulus to the body-injury area. B representative traces show these spontaneous and evoked spikes from S1-Tr neurons in control and intruder mice. The touch stimulus (20 s in the duration) was given at one minute of recording traces. The battle sound (20 s in the duration) was given at two minutes and twenty seconds. C depicts the activity patterns of S1-Tr cortical neurons by plotting the ratio of spike frequencies in response to the sound signal to spontaneous spike frequencies on the Y-axis as well as the ratio of spike frequencies in response to pain stimulus to the spontaneous spike frequencies on the X-axis. These plots illustrate the data for both control mice (left panel) and intruder mice (right panel). The gray lines in these scatter plots indicate that those ratios were set at 1.5. Gray dots present that S1-Tr cortical neurons exhibit a diminished response to both the sound signal and tactile stimulus, or response-null cells. Red dots signify that S1-Tr cortical neurons respond to both sound signal and tactile stimulus, presumably associative memory neurons. Green dots present S1-Tr cortical neurons that respond only to the sound signal, or auditory-encoding cells. Blue dots denote those that respond only to the tactile stimulus, or tactile-encoding cells. Insets show percentages of S1-Tr cortical neurons in response to the sound signal, the pain stimulus or both signals in control and intruder mice. D represents the proportions of associative memory neurons in control and intruder mice, along with their chi-square test results. E left panel shows activity levels (normalized spike frequencies) of S1-Tr cortical neurons in response to the tactile stimulus from control mice (blue bar) and intruder mice (red bar; mean ± SEM, students’ t test, *p < 0.05). Right panel shows the activity levels of S1-Tr cortical neurons in response to the sound signal from control mice (blue bar) and intruder mice (red bar; mean ± SEM, students’ t test, *p < 0.05).