The Effect of an Aversive State on Brainstem Auditory Evoked Potentials (BAEP) in Humans

Abstract

Background: The defence network is a network of brain structures that are activated when a person experiences fear or anxiety. Structures in this network, such as the amygdala, locus coeruleus (LC) and the inferior colliculus (IC), show heightened activation in aversive states. It is known that the IC generates Wave V of Brainstem Auditory Evoked Potentials (BAEP). BAEP are auditory reflexes which serve to localize oral stimuli. If a situation is experienced as potential threat, these reflexes might be heightened to initiate a faster response. The study of Baas, Milstein, Donlevy and Grillon (2006) investigated this hypothesis by testing how BAEP respond to an experimentally induced aversive state in healhy controls. They indeed found heightened amplitudes of Wave V. This study will serve as replication of the study of Baas et al. (2006). Method: BAEP was measured during a threat and safe condition in a sample of 13 healthy participants. Auditory stimuli activated Wave V. The aversive state was induced by an threat-of-shock paradigm. A paired samples t-test compared the peak-to-trough difference of Wave V in both conditions. A bivariate Pearson correlation investigated the possible relationship between trait anxiety, measured using the Spielberger State-Trait Anxiety Inventory (STAI), and the amplitude of Wave V. Results: The results showed no significant difference in the amplitude of Wave V under threat of shock. There was no correlation between trait anxiety and the amplitude of Wave V. Conclusion: The assumption that Wave V is modulated by an aversive state, could not be supported.