The central amygdala controls learning in the lateral amygdala

Abstract

Experience-driven synaptic plasticity in the lateral amygdala is thought to underlie the formation of associations between sensory stimuli and an ensuing threat. However, how the central amygdala participates in such a learning process remains unclear. Here we show that PKC-δ-expressing central amygdala neurons are essential for the synaptic plasticity underlying learning in the lateral amygdala, as they convey information about the unconditioned stimulus to lateral amygdala neurons during fear conditioning.

Fig. 1. PKC-δ⁺ CeL neurons are required for plasticity underlying learning in the LA

(a) A schematic of the experimental configuration. Pyramidal neurons in the dorsal LA were chosen for recording. (b) Example traces of the excitatory postsynaptic currents (EPSCs). (c) Quantification of A/N (from left to right: n = 20 cells/3 mice, 22 cells/3 mice, 9 cells/2 mice, 29 cells/4 mice, 30 cells/4 mice; F(4,105) = 15.28, P < 0.0001; ****P < 0.0001, n.s., not significant (P > 0.05), compared with the control naïve group; one-way ANOVA followed by Bonferroni’s test). (d) Quantification of freezing behaviour (GFP, n = 11, TeLC, n = 11, F(1,20) = 57.88, P < 0.0001; ****P < 0.0001, ***P < 0.001, two-way RM-ANOVA followed by Bonferroni’s test). (e) A schematic of the experimental configuration. (f) Quantification of freezing behaviour (GFP, n = 3, Arch, n = 4, F(1,5) = 52.41, P < 0.001; *P < 0.05, **P < 0.01, ****P < 0.0001, n.s., not significant (P > 0.05); two-way RM-ANOVA followed by Bonferroni’s test). Note that the light illumination period coincided with the duration of CS and US presentations in each trial. Data are presented as mean ± s.e.m. in c, d, and f.

Fig. 2. The CS and US responses in PKC-δ⁺ CeL neurons during fear conditioning

(a) A schematic of the experimental configuration. (b) Heat-maps of the average temporal calcium activities of all CS-responsive PKC-δ⁺ CeL neurons (data from 3 mice) for each trial during habituation, conditioning, and recall. Dashed lines indicate the timing of CS or US. (c) Average CS-induced responses in the same neurons as those in (b) for each trial. Shaded areas represent s.e.m. (d) CS responses of the same neurons as those in (c), averaged for all trials during habituation, conditioning, or recall (F(2,100) = 17.97, P < 0.0001; ***P < 0.001, ****P < 0.0001, n.s., not significant (P > 0.05); one-way ANOVA followed by Bonferroni’s test). (e) A heat-map of the average temporal calcium activities of all US-responsive PKC-δ⁺ CeL neurons for each trial during conditioning. Dashed lines indicate the timing of CS or US. (f) The time course (left) and peak amplitude (right) of US-evoked responses in the same neurons as those in (e), averaged for the trials in different stages of conditioning (n = 93 cells, 3 mice; F(1.5,140.2) = 26.41, P < 0.0001; **P < 0.01, ****P < 0.0001; one-way RM-ANOVA followed by Bonferroni’s test; shaded areas in (f) represent s.e.m.). Data are presented as mean ± s.e.m. in c, d, and f.

Fig. 3. PKC-δ⁺ CeL neurons are required for the US responses of LA neurons

(a). A schematic of the experimental configuration. (b) Heat-maps of the temporal calcium activities of a representative LA neuron, before (top panel) and after (bottom panel) DMSO application. The dashed line indicates the onset of US. (c) Left: average temporal activities of all shock-responsive LA neurons aligned to shock onset (dashed line), before and after DMSO treatment. Shaded areas represent s.e.m. Right: scatter plot of the peak shock responses of each of the neurons before and after DMSO treatment (T(17) = 0.93, n.s., P > 0.05; paired t test; n = 18 neurons/4 mice; 18/123 (15%) of LA neurons showed shock responses). (d & e) Same as in (b & c), except that SALB was applied instead of DMSO to the same mice in different imaging sessions (T(23) = 3.5, **P < 0.01; paired t test; n = 24 neurons/4 mice; 24/143 (17%) of LA neurons showed shock responses). Data are presented as mean ± s.e.m. in c and e.