The loudness dependence auditory evoked potential is insensitive to acute changes in serotonergic and noradrenergic neurotransmission

Abstract

The loudness dependence of the auditory evoked potential (LDAEP) has been proposed as an electrophysiological marker for assessing serotonergic function in vivo in humans, although accumulating evidence suggests that it is insensitive to acute changes in serotonergic neurotransmission. Very little is known about the sensitivity of the LDAEP to other neurotransmitter systems including the noradrenergic system. The current study examined the effects of noradrenergic modulation as well as serotonergic modulation on the LDAEP. The study utilised a double-blind placebo-controlled design in which the LDAEP in 17 healthy males and females was tested following acute administration of each of citalopram (20 mg), reboxetine (4 mg) and placebo. Neither citalopram nor reboxetine modulated the LDAEP relative to placebo treatment (p > 0.05). These findings suggest that the LDAEP is insensitive to acute changes in serotonergic or noradrenergic neurotransmission and thus is a poor pharmacodynamic marker of these systems.