PT  - JOURNAL ARTICLE
AU  - He Li
AU  - Susan R. B. Weiss
AU  - De-Maw Chuang
AU  - Robert M. Post
AU  - Michael A. Rogawski
TI  - Bidirectional Synaptic Plasticity in the Rat Basolateral Amygdala: Characterization of an Activity-Dependent Switch Sensitive to the Presynaptic Metabotropic Glutamate Receptor Antagonist 2S-α-Ethylglutamic Acid
AID  - 10.1523/JNEUROSCI.18-05-01662.1998
DP  - 1998 Mar 01
TA  - The Journal of Neuroscience
PG  - 1662--1670
VI  - 18
IP  - 5
4099  - http://www.jneurosci.org/content/18/5/1662.short
4100  - http://www.jneurosci.org/content/18/5/1662.full
SO  - J. Neurosci.1998 Mar 01; 18
AB  - This study examines forms of activity-dependent synaptic plasticity in the basolateral amygdala in vitro and demonstrates that a brief high frequency stimulus (HFS) train can induce a switch in the direction of the enduring change in synaptic strength induced by subsequent low-frequency stimulation (LFS). LFS (1 Hz, 15 min) of the external capsule (EC) induced a persistent 1.7-fold enhancement in the amplitude of synaptic potentials recorded intracellularly in basolateral amygdala neurons. The enhancement occurred gradually during the stimulation and was maintained for >30 min after termination of the stimulus train. LFS-induced enduring synaptic facilitation was not affected by the NMDA receptor antagonistd(−)-2-amino-5-phosphonopentanoate (APV; 100 μm). Brief high-frequency EC stimulation (HFS; 100 Hz, 1 sec) induced APV-sensitive short-term potentiation (2.5-fold) that generally decayed within 10 min. When LFS was applied after recovery from the short-term potentiating effect of HFS (HFS/LFS), there was an initial transient (<10 min) enhancement of the synaptic response followed by persistent synaptic depression (synaptic potential amplitude reduced by 22% at 30 min). This represents the first demonstration of stimulus-dependent long-lasting synaptic depression in the amygdala. Application of the presynaptic (group II) metabotropic glutamate receptor antagonist 2S-α-ethylglutamic acid (EGLU; 50 μm) prevented the HFS-dependent switch from synaptic facilitation to depression. Thus, LFS in the in vitroamygdala slice can induce either enduring synaptic potentiation or depression, depending on whether a priming HFS train has been applied. This experience-dependent switch, a novel form of metaplasticity, is not dependent on NMDA receptors but may require group II metabotropic glutamate receptors. In the amygdala, experiential modification of activity-dependent long-term synaptic plasticity adds flexibility to the ways in which synaptic strength can be modified and could play a role in diverse amygdala-dependent processes, including the formation, storage, and extinction of emotional memory and the regulation of epileptogenesis.