Auditory information processing is altered in novelty stress conditions: first session effects in auditory-evoked potentials

Novelty conditions may elicit stress responses. First session effects are systematic changes in physiological parameters, resulting from the interference of physiological processes with novelty stress. Along with endocrinological changes, these stress responses may be accompanied by alterations of sensory and attentional processes. The present study examines the impact of novelty conditions on event-related potential indicators of auditory information processing and on cortisol. Twenty-two healthy subjects participated in a series of experimental sessions. Auditory-evoked potentials were recorded, and the plasma cortisol levels were determined. The first session causes an activation of the hypothalamo-hypopituitary-adrenal axis. The auditory-evoked potentials show an additional slow negative potential component in the novelty condition. This potential component is maximal at fronto-central electrode sites and reaches its peak at about 240 ms after stimulus onset. Similarities with the processing negativity suggest alterations in attention-related auditory information-processing in the novelty condition encountered in the first session.