Interest in the medial prefrontal cortex (mPFC) as a source of behavioral inhibition
has increased with the mounting evidence for a functional role of the mPFC in extinction
of conditioned fear. In fear extinction, a tone-conditioned stimulus (CS) previously
paired with a footshock is presented repeatedly in the absence of footshock, causing
fear responses to diminish. Here, we review converging evidence from different laboratories
implicating the mPFC in memory circuits for fear extinction: (1) lesions of mPFC impair
recall of extinction under various conditions, (2) extinction potentiates mPFC physiological
responses to the CS, (3) mPFC potentiation is correlated with extinction behavior,
and (4) stimulation of mPFC strengthens extinction memory. These findings support
Pavlov’s original notion that extinction is new learning, rather than erasure of conditioning.
In people suffering from posttraumatic stress disorder (PTSD), homologous areas of
ventral mPFC show morphological and functional abnormalities, suggesting that extinction
circuits are compromised in PTSD. Strategies for augmenting prefrontal function for
clinical benefit are discussed.
Key Words
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Article info
Publication history
Published online: May 24, 2006
Accepted:
March 3,
2006
Received in revised form:
October 16,
2005
Received:
August 1,
2005
Identification
Copyright
© 2006 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
