It might be presumed that due to the presence of two distinct hemispheres, each hemisphere operates autonomously without any interaction with the other. However, it is important to note that the hemispheres continually exchange information through the corpus callosum, a bundle of white matter that connects them.
The integration of information across the corpus callosum can be influenced by hormones like estradiol and progesterone. The objective of the present study was to examine whether acute stress and its accompanying fluctuations in stress hormone levels impact the transfer of information across the corpus callosum.
For this purpose, we collected EEG data from 50 participants while completing a lexical decision task and a Poffenberger paradigm twice, once after the administration of 20mg of hydrocortisone and once after a control condition. There were no differences in interhemispheric transfer between the experimental and the control in any of the tasks used to measure information exchange between the hemispheres. This suggests that increases in cortisol levels alone are not sufficient to affect interhemispheric interaction through the corpus callosum.

Berretz G, Packheiser J, Wolf OT and Ocklenburg S (2023) A single dose of hydrocortisone does not alter interhemispheric transfer of information or transcallosal integration. Front. Psychiatry 14:1054168. doi: 10.3389/fpsyt.2023.1054168