Date of Award
Doctor of Philosophy
High density electroencephalographic (EEG) measures were used to assess the effects of acute delta 9-tetrahyrdrocannabidol (THC) administration on extinction of conditioned fear responses. Fear conditioning was initiated using a differential classical conditioning paradigm that paired an aversive unconditioned stimulus (shock) with a signaling stimulus (CS+), whereas another stimulus served as a safety signal (CS-). Evoked potentials, induced event-related spectral perturbations (ERSP), and associated intertrial coherence (ITC) measures were used to quantify the acquisition and extinction of conditioned fear responses. Participants (N = 10 males) exhibited conditioning to the CS+ across fear acquisition training, as reflected by greater late positive (posterior sites) and late negative (anterior sites) potential amplitude to the CS+ relative to the CS-. Acute administration of THC facilitated extinction of the conditioned response to the CS+ relative to placebo, as reflected by greater LPP and LNP amplitude to the CS+ relative to the CS- in the placebo, but not THC condition. ERSP analyses suggest the lack of difference between CS+ and CS- ERP amplitude may be partially explained by a shifting of attention from external stimuli to internal processing in the THC condition. However, relative to placebo, THC administration also increased the amplitude of some measures of the conditioned response (LNP) to the CS-, suggesting a generalization of fear or lack of discrimination in this condition.
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