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Synaptic encoding of fear extinction in mPFC-amygdala circuits
Jun-Hyeong Cho1, Karl Deisseroth2, Vadim Y Bolshakov1
1Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, MA 02478, USA.
Neuron
|December 3, 2013
Summary
Fear extinction learning reduces the strength of connections between the medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA). This synaptic change helps diminish fear responses by altering neural communication pathways.
Area of Science:
- Neuroscience
- Synaptic Plasticity
- Fear Memory
Background:
- Fear extinction memory retrieval involves increased medial prefrontal cortex (mPFC) neuronal activity.
- Mechanisms by which mPFC changes influence amygdala targets after extinction are not fully understood.
Purpose of the Study:
- To investigate how extinction learning alters synaptic transmission from the mPFC to amygdala nuclei.
- To elucidate the neural pathways involved in fear memory extinction.
Main Methods:
- Electrophysiological recordings in rodent models.
- Examined synaptic transmission in mPFC projections to the basolateral nucleus of the amygdala (BLA) and intercalated neurons.
- Assessed heterosynaptic inhibition in auditory cortical inputs to the BLA.
Main Results:
- Fear extinction decreased excitatory synaptic transmission efficacy from mPFC to BLA.
- Inhibitory responses and synaptic strength at mPFC inputs to intercalated neurons remained unchanged.
- mPFC stimulation induced heterosynaptic inhibition in auditory cortical inputs to the BLA.
Conclusions:
- Reduced mPFC-BLA excitatory transmission is a key synaptic mechanism in fear extinction.
- These changes diminish the capacity of mPFC projections to drive BLA activity.
- Preserved inhibition by intercalated neurons contributes to regulating amygdala output during extinction memory.
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