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Neuroimage. 2008 Apr 1;40(2):811-817. doi: 10.1016/j.neuroimage.2007.11.042. Epub 2007 Dec 8.

Neural correlates of unconditioned response diminution during Pavlovian conditioning.

Author information

1
Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, MD 20892, USA.
2
Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, MD 20892, USA. Electronic address: knightdc@uab.edu.

Abstract

Pavlovian conditioning research has shown that unconditioned responses (UCR) to aversive unconditioned stimuli (UCS) are reduced when a UCS is predictable. This effect is known as UCR diminution. In the present study, we examined UCR diminution in the functional magnetic resonance imaging (fMRI) signal by varying the rate at which a neutral conditioned stimulus (CS) was paired with an aversive UCS. UCR diminution was observed within several brain regions associated with fear learning, including the amygdala, anterior cingulate, auditory cortex, and dorsolateral prefrontal cortex when a CS continuously relative to intermittently predicted the UCS. In addition, an inverse relationship between UCS expectancy and UCR magnitude was observed within the amygdala, anterior cingulate, and dorsolateral prefrontal cortex, such that as UCS expectancy increased the UCR decreased. These findings demonstrate UCR diminution within the fMRI signal, and suggest that UCS expectancies modulate UCR magnitude.

PMID:
18203622
PMCID:
PMC2712889
DOI:
10.1016/j.neuroimage.2007.11.042
[Indexed for MEDLINE]
Free PMC Article

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