All ETDs from UAB

Advisory Committee Chair

David C Knight

Advisory Committee Members

Edwin W Cook, Iii

Kristina Visscher

Document Type

Thesis

Date of Award

2013

Degree Name by School

Master of Arts (MA) College of Arts and Sciences

Abstract

Recognizing cues that predict a threat allows one to react more effectively under threatening conditions, attenuating or potentiating the response to the threat depending on the circumstances. This is demonstrated during Pavlovian fear conditioning when the unconditioned response (UCR) to a predictable unconditioned stimulus (UCS) is diminished compared to the UCR of an unpredictable UCS (Dunsmoor, Bandettini, & Knight, 2008; Wood, Ver Hoef, & Knight, 2012). In the current study skin conductance, electromyography (orbicularis oculi), UCS expectancy, and blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) were assessed during a Pavlovian temporal fear conditioning paradigm. Right-handed volunteers were exposed to two different temporal sequences of fixed (fixed ITI: 20 s) and random (random ITI: 6-34 s) UCS presentations. Thirty UCSs were presented during each of four 620 s fMRI scans (120 total UCS presentations). Diminution of the UCR was observed in the dlPFC, but no other behavioral measures. UCS expectancy showed evidence of learning with higher ratings for fixed compared to random trials. Counter to expectations, the unconditioned SCR was potentiated in the fixed compared to random condition. This is the first temporal conditioning paradigm completed in the fMRI environment. Findings implicate that learning-related changes in the neural activity within the dlPFC may mediate conditioned changes in UCS expectancy and unconditioned SCR.

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