Norepinephrine enables the induction of associative long-term potentiation at thalamo-amygdala synapses.
Emotional arousal, linked to a surge of norepinephrine (NE) in the amygdala, leads to creation of stronger and longer-lasting memories. However, little is known about the synaptic mechanisms of such modulatory NE influences. Long-term potentiation (LTP) in auditory inputs to the lateral nucleus of the amygdala was recently linked to the acquisition of fear memory. Therefore we explored whether LTP induction at thalamo-amygdala projections, conveying the acoustic conditioned stimulus information to the amygdala during fear conditioning, is under adrenergic control. Using whole-cell recordings from amygdala slices, we show that NE suppresses GABAergic inhibition of projection neurons in the lateral amygdala and enables the induction of LTP at thalamo-amygdala synapses under conditions of intact GABA(A) receptor-mediated inhibition. Our data indicate that the NE effects on the efficacy of inhibition could result from a decrease in excitability of local circuit interneurons, without direct effects of NE on release machinery of the GABA-containing vesicles or the size of single-quanta postsynaptic GABA(A) receptor-mediated responses. Thus, adrenergic modulation of local interneurons may contribute to the formation of fear memory by gating LTP in the conditioned stimulus pathways.
Tully
Keith
K
Department of Psychiatry, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA.
Li
Yan
Y
Tsvetkov
Evgeny
E
Bolshakov
Vadim Y
VY
D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001245:Association Learning; D017774:Long-Term Potentiation / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology; D013569:Synapses / Q000502:physiology*; D013788:Thalamus / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D009638:Norepinephrine
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