Fig. (1) Conditioned and unconditioned stimuli. Each acquisition scan consisted of CS+ (8 trials), CS− (8 trials), and test trials (1 CS+UCS, 1 CS−UCS, and 1 UCS alone trial). The acquisition phase consisted of four acquisition scans, followed by the test phase. The test phase consisted of 10 CS+UCS trials, 10 CS−UCS trials, and 10 UCS alone trials. Stimuli were counterbalanced and presented in a pseudorandom order such that no more than two trials of the same stimulus were consecutively presented.