The purpose of this research study is to study how the brain learns to avoid certain stimuli or situations using an experimental paradigm. The big goal is to measure brain responses and subject's feelings and expectations when they are learning to actively avoid experimental stimuli, and how fear extinction learning and monetary cost can change how and when subjects are to avoid.
This study aims to study the neural correlates of avoidance learning using a recently validated conditioning and active avoidance paradigm (CAAP). The overarching objective is to measure the neural correlates of active avoidance, and how fear extinction learning and monetary cost modulate these avoidance responses. Participants will include healthy controls (HC), trauma-exposed healthy controls (TEHC), and participants with post-traumatic stress disorder (PTSD). Avoidance is common and often hinders the progression and success of extinction-based exposure therapy in PTSD. The data to be gathered in this study will enable us to probe neural mechanisms of avoidance, extinction, and decision-making to avoid or not, in addition to understanding the impact of cost on avoidance decision-making. These data will provide a more integrated platform for the understanding of the mechanisms of avoidance in both trauma-exposed healthy controls and PTSD psychopathology, which has important implications for treatment.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
300
Participants will be administered increasing intensities of mild electric shock via electrodes connected to the foot. New Biopac stimulators that can deliver higher shock intensity, provided participants agreement will be used to assure adequate conditioning levels. Stimulation is measures in milliamps (mA), and each delivered stimulation will be 0.5 seconds long (500 milliseconds). To colored (blue, red, \& yellow) light stimuli (CS). The light stimulus is followed by a shock or no shock depending on color.
Via button pressing. Only one stimulus-CS will enable control over experiencing the shock: the participant can press the button during the first 2 seconds of the light presentation to avoid the shock.
UTHealth Houston
Houston, Texas, United States
RECRUITINGSkin Conductance Response (SCR)
Skin Conductance Response (SCR) assesses the stress/seat level, or level of anxiety in a particular moment, or in response to a specific cue. SCR will be reported in microsiemens.
Time frame: Experimental Day 1, Experimental Day 2
Functional MRI (fMRI) responses
fMRI data, including blood-oxygen-level-dependent (BOLD) responses, is used in neuroimaging studies assess neural correlate activations and observe the increase/decrease in activation of a particular brain area in response to a specific cue.
Time frame: Experimental Day 1, Experimental Day 2
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After avoidance conditioning, the CS+ associated with avoidance responding appears with no button to press and no shock is administered.
On the next day, participants receive a monetary stipend to use to pay to guarantee that they are not to receive any shocks if they press a button from the CS+. This and all previously described experimental phases noted above will occur inside of the fMRI scanner.