Amygdala involvement in human avoidance, escape and approach behavior Page: 3
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Schlund and Cataldo Page 3
et al., 1976; Herdade et al., 2006; Mobbs et al., 2009) and to approach involving reward/
reinforcement (Baxter and Murray, 2002; Hirai et al., 2009; Hommer et al., 2003; Machado
and Bachevalier, 2007). The inclusion of these conditions provided a novel opportunity to
Z compare amygdala responses to other aversive and appetitive conditions to determine if it
serves a broader role as a 'behavioral relevance' detector (Ousdal et al., 2008; Paton et al.,
2006; Sander et al., 2003; Schoenbaum et al., 2003).
Methods and Materials
SEighteen, healthy right-handed adults (9 male) participated. Subjects reported being between
c 18 and 50 years of age, free of medications affecting the central nervous system or the
autonomic system for at least 2 weeks, and without a personal history of psychiatric disorder
-r or substance abuse. Informed, written consent was obtained from all subjects according to the
institutional guidelines established by the Johns Hopkins Human Subjects Protection
Task and Training
Prior to functional neuroimaging, subjects completed extensive training that involved learning,
through trial and error, to respond appropriately to several cue-response-outcome
Z contingencies. Training ensured stable performances during neuroimaging and eliminated
I possible confounds associated with regional activation reflecting acquisition of Pavlovian cue-
T3 outcome relations and operant response-outcome relations. In any task requiring decision-
making, performance anxiety can also play a critical role in modulating behavior, cognition
and emotion. Accordingly, pretraining also minimized the contributions of performance related
anxiety to anxiety/fear that presumably would emerge during our avoidance and escape
Figure 1 highlights the structure of trials and timing parameters employed during both training
and neuroimaging. A trial consisted of the presentation of a visual cue for 8 s during which
O subjects were free to press or not press three available response buttons. Next, a 2 s outcome
prompt revealed the magnitude of money gain or loss in accordance with the current
contingency. A variable 4-6 s intertrial interval signaled by a fixation stimulus separated cue
onsets. Three different cue-response-outcome contingencies were employed during training to
establish approach, avoidance, and escape behavior. In addition, instructions highlighted that
a fixation "+" stimulus (6 s in duration) would appear randomly during the task. Fixation served
as the neutral baseline cue from which to identify voxels showing significant BOLD response
increases in experimental conditions.
" As seen in Figure 1, the approach cue was associated with a positive reinforcement contingency
T" such that emitting greater than six presses on a target button (e.g., button #1) produced money
gain ($2.00), but less than six presses or pressing other response buttons produced no monetary
Gain ($0.00). The avoidance cue was associated with a negative reinforcement contingency
. such that emitting greater than six presses on a target button (#2) cancelled a future monetary
1 loss ($0.00), but less than six presses or pressing other response buttons resulted in loss (-
$0.50). The escape cue was also associated with a negative reinforcement contingency such
that presses on a target button (#3) paused escalating money loss for 1 s which began with cue
m onset and continued to the outcome period. Under escape, pressing other response buttons or
O non-responding resulted in total loss (-$0.48) and emitting less than six target responses
a resulted in loss proportional to the total number of responses emitted. Emitting more than 6
responses resulted in no loss ($0.00). Also included was a punishment cue where any button
press produced a $0.05 loss. This cue condition was included to ensure that response-dependent
Neuroimage. Author manuscript; available in PMC 2011 November 1.
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Schlund, Michael W. & Cataldo, Michael F. Amygdala involvement in human avoidance, escape and approach behavior, article, November 1, 2010; [Amsterdam, Netherlands]. (digital.library.unt.edu/ark:/67531/metadc77178/m1/3/: accessed May 27, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Public Affairs and Community Service.