18 used a visual half field paradigm to investigate the influence of acute stress on FHAs. The effects of acute stress on FHAs however are not well understood. This raises the question whether not only long-term alterations in cortisol due to chronic or early life but also temporary changes in cortisol due to acute stress can induce similar effects. Contrary to this, patients with PTSD have been shown to display an increase in verbal hemispheric asymmetries 17. Moreover, many mental and neurodevelopmental disorders display changes in cortisol with higher cortisol levels being observed in individuals with for example schizophrenia and depression 15, 16. For example, low birth weight as a marker of less beneficial intrauterine development has been associated with decreased right-handedness 14.

Also in the non-clinical population, early life stress has been associated with changes in asymmetries. In a recent review, we proposed a model in which early life stress as well as chronic stress not only increases the risk for mental and neurodevelopmental disorders but also changes structural and functional hemispheric asymmetries leading to the aberrant lateralization patterns seen in these disorders 13. Acute stress has been shown to influence the entire information processing stream: it affects vigilance and attention 8, 9, memory processes 10, 11 and executive functioning 12. The slower acting Hypothalamus–Pituitary–Adrenal (HPA) axis releases corticotrophin-releasing hormone from the hypothalamus to stimulate secretion of adrenocorticotropic hormone from the anterior pituitary, which in turn leads to release of cortisol from the adrenal medulla 6, 7. The faster acting system is the sympathetic nervous system triggering release of adrenaline and noradrenaline from the adrenal medulla. The body is equipped with two systems that respond to acute stress. Many of these disorders are also associated with alterations in the patient’s physiological stress response. Functional hemispheric asymmetries (FHAs) emerge as both left- and right-hemispheric networks contribute to task processing with each hemisphere being specialized and dominant for different aspects of the task.Ĭlinical research has indicated that some neurodevelopmental and mental disorders are accompanied by changes in asymmetry patterns (e.g. These brain asymmetries are observable not only on the micro- and macrostructural level, but on the functional level as well 2. Future research using EEG, fMRI and pharmacological interventions is needed to further characterize the relation of hemispheric asymmetries and acute stress.Īlthough the brain seems to be symmetrical at first glance, it is organized in a fundamentally asymmetrical way 1. However, stress does seem to affect interhemispheric integration of information. This indicates that acute stress and the related increase in cortisol do not influence dichotic listening performance. In contrast, there was evidence for an influence of cortisol and sympathetic activation indicated by salivary alpha amylase changes on AFAs in the Banich–Belger task. There were no significant differences between the stress and control session in the dichotic listening tasks. We calculated across-field advantages (AFAs) in the Banich–Belger task and lateralization quotients for reaction times and responses per side in both dichotic listening tasks. One session included a stress induction via the Trier Social Stress Test, the other session included a control procedure. To investigate the influence of acute stress on FHAs, 60 participants performed a Banich–Belger task, as well as a verbal and an emotional dichotic listening task in two sessions. As the product of the stress-activated hypothalamus–pituitary–adrenal axis, cortisol influences information processing at every level from stimulus perception to decision making and action. Endocrinological processes have been demonstrated to alter FHAs.

However, past research has shown that FHAs are more plastic than initially thought. Functional hemispheric asymmetries (FHAs) have been thought to be relatively stable over time.

Isham 2000 dichotic listening