Maximizing exposure therapy: An inhibitory learning approach
An article by: Craske, M. G., Treanor, M., Conway, C. C., Zbozinek, T., & Vervliet, B. (2014).
Behaviour Research and Therapy, 58, 10-23

Inhibitory learning model of extinction

In a Pavlovian conditioning model, a neutral stimulus (conditional stimulus, CS) is followed by an aversive stimulus (unconditional stimulus, US). After a number of parings, the CS will come to elicit anticipatory fear reactions (conditional response, CR). The CR is presumed to depend upon the CS becoming a reliable predictor of the US. An association is posited between the memory representations of the CS and the US such that presentations of the CS will indirectly activate the memory of the US.

One powerful way to reduce conditional fear reactions is through extinction, in which the CS is repeatedly presented in the absence of the US.

Inhibitory learning is regarded as being central to extinction, although additional mechanisms, such as habituation, are likely to be involved. Inhibitory learning models mean that the original CS-US association learned during fear conditioning is not erased during extinction, but rather is left intact as new, secondary inhibitory learning about the CS-US develops, specifically that the CS no longer predicts the US.

The amygdala, which is particularly active during fear conditioning, appears to be inhibited by cortical influences identified as occurring from the medial prefrontal cortex as a result of extinction learning. After extinction, the CS possesses two meanings: 1) Its original excitatory meaning (CS-US). 2) an additional inhibitory meaning (CS-no US)

Even though fear subsides with enough trials of the CS in the absence of the US, retention of at least part of the original association can be uncovered by various procedures, which each one showing a continuing effect of the original excitatory association after extinction. 1) Conditional fear shows spontaneous recovering. 2) The strength of the CR increases in proportion to the amount of time since the end of extinction. 3) Renewal of conditional fear occurs if the surrounding context is changes between extinction and retest 4) Fear extinction appears to be specific to the context in which extinction occurs 5) Reinstatement of conditional fear occurs if unsignaled (or unpaired) US presentations occur between extinction and retest. 6) Rapid reacquisition of the CR is seen if the CS-US pairings are repeated following extinction

Deficits in inhibition and