Figure 10. Morphologic changes at thalamocortical synapses are transient during learning. A, Anticipatory licking frequency of mice to stimulus (green closed circles) and blank (red open circles) trials across 1 d of acclimation and multiple days of SAT. The average number of trials across time bins shown in gray. B, Performance (LStim – LBlank) across 5 d of SAT. C, Left, Schematic of L1 POm synapses from selected axonal segments. Middle, Cumulative distribution histogram of POm boutons in L1 from acclimation control (Acc; dashed black line; 960 boutons; 12 mice), SAT1 (blue line; 560 boutons; 7 mice), SAT2 (pink line; 400 boutons; 5 mice), and SAT5 (green line; 400 boutons; 5 mice) animals. K–S tests, Acc versus SAT1 (p = 0.012), Acc versus SAT2 (p = 0.26), and Acc versus SAT5 (p = 0.34). Right, Animal-averaged mean bouton volume + SEM by animal (solid dots); N = 12 Acc, 7 SAT1, 5 SAT2, 5 SAT5 mice; F(3,25) = 0.95; p = 0.43. D, Left, Schematic of L5a POm synapses from selected axonal segments. Middle, Cumulative distribution histogram of POm boutons in L5 from Acc (dashed black line; 960 boutons; 12 mice), SAT1 (blue line; 560 boutons; 7 mice), SAT2 (pink line; 400 boutons; 5 mice), and SAT5 (green line; 400 boutons; 5 mice) animals. K–S tests, Acc versus SAT1 (p = 3.87 × 10−9), Acc versus SAT2 (p = 4.53 × 10−5), and Acc versus SAT5 (p = 0.021). Right, Animal-averaged mean bouton volume + SEM by animal (solid dots); N = 12 Acc, 7 SAT1, 5 SAT2, 5 SAT5 mice; F(3,25) = 6.54; p = 0.0021. Tukey's p(Acc vs SAT1) = 0.013; Tukey's p(Acc vs SAT1) = 0.70; Tukey's p(Acc vs SAT5) = 0.79. E, Left, Cumulative distribution histogram of POm-assigned synapses in L1 showing an increase in synaptic size after training from Acc (dashed black line; 300 puncta; 12 mice) and SAT1 (blue line; 175 puncta; 7 mice), SAT2 (pink line; 125 puncta; 5 mice), and SAT5 (green line; 125 puncta; 5 mice) animals. K–S tests, Acc versus SAT1 (p = 0.042), Acc versus SAT2 (p = 0.021), and Acc versus SAT5 (p = 0.75). Right, Animal-averaged mean bouton volume + SEM by animal (solid dots); N = 12 Acc, 7 SAT1, 5 SAT2, 5 SAT5 mice; F(3,25) = 1.99; p = 0.14. F, Left, Cumulative distribution histogram of POm-assigned synapses in L5a showing renormalization of synaptic size after 5 d SAT. Acc (dashed black line; 720 puncta; 12 mice), SAT1 (blue line; 420 puncta; 7 mice) animals, SAT2 (pink line; 300 puncta; 5 mice), and SAT5 (green line; 300 puncta; 5 mice) animals. K–S tests, Acc versus SAT1 (p = 0.024), Acc versus SAT2 (p = 0.0031), and Acc versus SAT5 (p = 0.84). Right, Averaged mean puncta surface area + SEM by animal (solid dots); N = 12 Acc, 7 SAT1, 5 SAT2, 5 SAT5 mice; F(3,25) = 1.91; p = 0.15. Data from Acc and SAT1 animals replotted from earlier figures. Groups were compared using one-way ANOVA followed by post hoc Tukey tests for assessing significance for bar graphs in C–F.