Chronic stress has been shown to have long-term effects on natural differences in function between the left and right hemisphere – so called functional hemispheric asymmetries (FHAs). The short-term effects of acute stress exposure on functional hemispheric asymmetries are less well investigated.

Chronic stress has been shown to have long-term effects on natural differences in function between the left and right hemisphere – so called functional hemispheric asymmetries (FHAs). The short-term effects of acute stress exposure on functional hemispheric asymmetries are less well investigated. It has been suggested that acute stress can affect FHAs by affecting the corpus callosum, the white matter pathway that connects the two hemispheres. On the molecular level, this modulation may be caused by a stress-related increase in cortisol, a major stress hormone. Therefore, a team from the biopsychology, the cognitive psychology and the department of neurology from the RUB set out to investigate the acute effects of cortisol on FHAs. Overall, 60 participants were tested after administration of 20 mg hydrocortisone or a placebo tablet in a cross-over design: participants performed a verbal and an emotional dichotic listening task to assess language and emotional lateralization respectively, as well as a Banich–Belger task to assess interhemispheric integration both times. Lateralization quotients were determined for both reaction times and correctly identified syllables in both dichotic listening tasks. In the Banich–Belger task, across-field advantages were determined to quantify interhemispheric integration. While we could replicate previously reported findings for these tasks in the placebo session, we could not detect any differences in asymmetry between hydrocortisone and placebo treatment. This partially corroborates the results of a previous study we performed using social stress to induce cortisol increases. This suggests that an increase in cortisol does not influence dichotic listening performance on a behavioral level.

Berretz, G., Packheiser, J., Höffken, O., Wolf, O. T., & Ocklenburg, S. (2021). Dichotic listening performance and interhemispheric integration after administration of hydrocortisone. Scientific Reports, 11(1), 1-11. https://doi.org/10.1038/s41598-021-00896-1