Acute stress alters auditory selective attention in humans independent of HPA: a study of evoked potentials

Background

Acute stress is a stereotypical, but multimodal response to a present orimminent challenge overcharging an organism. Among the different branches ofthis multimodal response, the consequences of glucocorticoid secretion havebeen extensively investigated, mostly in connection with long-term memory(LTM). However, stress responses comprise other endocrine signaling andaltered neuronal activity wholly independent of pituitary regulation. Todate, knowledge of the impact of such “paracorticoidal” stressresponses on higher cognitive functions is scarce.We investigated the impact of an ecological stressor on the ability to directselective attention using event-related potentials in humans. Based onresearch in rodents, we assumed that a stress-induced imbalance ofcatecholaminergic transmission would impair this ability.

Methodology/Principal Findings

The stressor consisted of a single cold pressor test. Auditory negativedifference (Nd) and mismatch negativity (MMN) were recorded in a tonaldichotic listening task. A time series of such tasks confirmed an increaseddistractibility occuring 4–7 minutes after onset of the stressor asreflected by an attenuated Nd. Salivary cortisol began to rise 8–11minutes after onset when no further modulations in the event-relatedpotentials (ERP) occurred, thus precluding a causal relationship.This effect may be attributed to a stress-induced activation of mesofrontaldopaminergic projections. It may also be attributed to an activation ofnoradrenergic projections. Known characteristics of the modulation of ERP bydifferent stress-related ligands were used for further disambiguation ofcausality. The conjuncture of an attenuated Nd and an increased MMN might beinterpreted as indicating a dopaminergic influence. The selective effect onthe late portion of the Nd provides another tentative clue for this.

Conclusions/Significance

Prior studies have deliberately tracked the adrenocortical influence oncognition, as it has proven most influential with respect to LTM. However,current cortisol-optimized study designs would have failed to detect thepresent findings regarding attention.