Sound tuning of amygdala plasticity in auditory fear conditioning.

Sungmo Park,Sukwon Lee,Jieun Kim,Ingie Hong,Kyungjoon Park,Junuk Lee,Jeongyeon Kim,Beomjong Song,Sukwoo Choi

doi:10.1038/srep31069

Abstract

Various auditory tones have been used as conditioned stimuli (CS) for fear conditioning, but researchers have largely neglected the effect that different types of auditory tones may have on fear memory processing. Here, we report that at lateral amygdala (LA) synapses (a storage site for fear memory), conditioning with different types of auditory CSs (2.8 kHz tone, white noise, FM tone) recruits distinct forms of long-term potentiation (LTP) and inserts calcium permeable AMPA receptor (CP-AMPAR) for variable periods. White noise or FM tone conditioning produced brief insertion (<6 hr after conditioning) of CP-AMPARs, whereas 2.8 kHz tone conditioning induced more persistent insertion (≥6 hr). Consistently, conditioned fear to 2.8 kHz tone but not to white noise or FM tones was erased by reconsolidation-update (which depends on the insertion of CP-AMPARs at LA synapses) when it was performed 6 hr after conditioning. Our data suggest that conditioning with different auditory CSs recruits distinct forms of LA synaptic plasticity, resulting in more malleable fear memory to some tones than to others.

Highlights

Be highly important to dissect out the precise roles of these synaptic plasticities in the formation, maintenance or modulation of conditioned fear memory
We chose to use three different auditory conditioned stimuli (CS) because these CSs were widely used in previous studies[3,7,8,10,11,38] and because they are representatives of a wide span of auditory stimuli, including a pure tone (2.8 kHz), a broad-band mixture of pure tones, and a complex tone, respectively
We found that six pairings of CS and US produced robust freezing responses but showed no significant differences in freezing among the three groups (2.8 kHz, 74.98 ± 7.12%, n = 6; white noise, 82.69 ± 2.20%, n = 8; FM tone, 86.75 ± 4.34%, n = 8; F(2,21) = 1.601, p = 0.2277, one-way ANOVA; p > 0.05 for all pairs, Newman-Keuls post-hoc test) (Fig. 1B)

Summary

Introduction

Be highly important to dissect out the precise roles of these synaptic plasticities in the formation, maintenance or modulation of conditioned fear memory. Previous studies have suggested that reconsolidation-update depends on the insertion of CP-AMPARs at LA synapses[27,34]. We found that different auditory CSs (2.8 kHz, white noise or FM tones) recruit distinct forms of LTP, respectively. These different auditory CSs produced synaptic insertion of CP-AMPARs for a variable period, respectively. CP-AMPARs, which were inserted after pure tone conditioning, were maintained stably (≥6 hr after conditioning), whereas complex tone conditioning produced a transient insertion (

Methods

Results

Conclusion