Figure 2.

Optogenetic LC-NA stimulation paired with lever pressing induces frequency-dependent plasticity in M1. A, Cortical motor maps from representative subjects in each treatment group that exhibited the median total map area and PFL representation for that group. DFL, distal forelimb; Ant., anterior body (vibrissa + jaw + neck); Post., posterior body (trunk + hindlimb + tail); NR, nonresponsive. Scale for all maps shown below the 3 Hz map. Maps for all animals in the study are shown in Figure 3. B,C, Optogenetic LC stimulation does not significantly alter the total motor map area (B) or posterior (Post.) body representations (C). For all bar plots, cyan bars represent ChR2-expressing rats that received 3, 10, or 30 Hz (as labeled) laser stimulation of the LC, the gray bar represents the eYFP-expressing control group that received 10 Hz laser stimulation, and the white bar on the right represents training- and stimulation-naive (N) group. Error bars denote SEM. Dots represent individual data of male (filled/black dots) and female (open/white dots) rats; averages for all male and female rats are plotted to the right of each bar plot. Male rats were found to have larger posterior body representations (C). ^#p < 0.05, sex effect, two-way ANOVA. D,E, No significant effects of LC stimulation or sex were seen for anterior (Ant.) body representations in M1 (D) or for distal forelimb (FL) representations (E). F, Skilled lever pressing paired with phasic 10 Hz optogenetic LC-NA stimulation resulted in a significant enlargement of the task-relevant proximal FL representation in M1 compared to all other treatment groups. **p < 0.01, ***p < 0.001, Bonferroni-corrected t tests. F,G, Age at ICMS mapping was not significantly correlated with total map size (G) or total forelimb (FL) map area (F).