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Ruhr-Universität Bochum
Fakultät für Psychologie
AE Biopsychologie
IB 6-121 - Postfach 18
D-44780 Bochum

Phone: +49 234 - 32 28213
Fax: +49 234 - 32 14377

Email: biopsychologie@rub.de
Homepage: http://www.bio.psy.rub.de

 

News

We would like to invite you to our Research Colloquium:

Monday, 06.12.2021, 1 - 3 pm, via Zoom

Gesa Berretz
How acute stress modulates hemispheric asymmetries: Investigating the role of endocrinological and affective parameters.

Please find more information here.

Guests are welcome to attend!

 

 

 

 

News & Views

Dichotic listening performance and interhemispheric integration after administration of hydrocortisone

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.

 

News & Views

Improved interhemispheric connectivity after stress during lexical decision making

One could think that, since we have two separate hemispheres, each hemisphere works independently of the other. To a certain extent, this is true: Functional hemispheric asymmetries emerge as the left and the right hemisphere are dominant for different aspects of task processing. However, the hemispheres constantly share information through the corpus callosum, the white matter connecting between them. The integration of information across the corpus callosum is dependent on its structural integrity and functionality. Several hormones, like estradiol and progesterone, can influence this function. Since earlier work has demonstrated that long-term changes in stress hormone levels are accompanied by changes in hemispheric asymmetries in several mental disorders, the aim of the current study was to investigate whether acute stress and the associated changes in stress hormone levels also affect information transfer across the corpus callosum. For this purpose, researchers from the biopsychology and the cognitive psychology of the Ruhr University Bochum collected EEG data from 51 participants while completing a lexical decision task and a Poffenberger paradigm twice, once after stress induction with the Trier Social Stress Test and once after a control-condition. While there were no differences in interhemispheric transfer between the stress and the non-stress condition in the Poffenberger paradigm, we observed shorter latencies to stimuli in the left visual field in the left hemisphere at the CP3-CP4 electrode pair after stress. These electrodes are positioned over the brain area that is involved in lexical processing. This suggest that the transfer of lexical material from the right to the left hemisphere was quicker under stress indicative of more efficient signal transfer across the corpus callosum between language related areas.


Berretz, G., Packheiser, J., Wolf, O. T., & Ocklenburg, S. (2021). Improved interhemispheric connectivity after stress during lexical decision making. Behavioural Brain Research, 113648.


News & Views

Unihemispheric Evidence Accumulation in Pigeons

Animals constantly have to make decisions: they often have to choose between foraging strategies, mates, territories, and social partners. Thus, proper decision-making is fundamental for survival. Studies in primates and rodents revealed a stochastic perceptual evidence accumulation process during decision-making. What about birds? The present study investigated whether perceptual decision-making in pigeons shows behavioral and computational dynamics comparable to those in mammals and rodents. Using a novel "pigeon helmet" with liquid shutter displays that control visual input to individual eyes/hemispheres with precise timing, we revealed highly similar perceptual decision-making dynamics. Thus, both mammals and birds seem to share this core cognitive process that possibly represents a fundamental constituent of decision-making throughout vertebrates. We additionally discovered that avian hemispheres start independent sensory accumulation processes without any major interhemispheric exchange under conditions of time pressure.

Wittek, N., Matsui, H., Behroozi, M., Otto, T., Wittek, K., Sarı, N., Stoecker, S., Letzner, S., Choudhary, V., Peterburs, J., & Güntürkün, O. (2021). Unihemispheric evidence accumulation in pigeons. Journal of experimental psychology. Animal learning and cognition, 47(3), 303–316. https://doi.org/10.1037/xan0000290

 

News & Views

Frontal and parietal alpha power asymmetry show good reliability
 

Frontal asymmetries during rest is one of the most widely investigated forms of hemispheric asymmetries. It is often assessed by measuring asymmetry in EEG resting-state alpha activation. Alpha asymmetries have been associated with important psychological outcomes like wellbeing, depression and motivation. However, studies on the reliability of alpha asymmetries are sparse and often consist of small sample sizes. In our study, we investigate short-term reliability of frontal and parietal alpha asymmetry in a large sample of 370 participants. We find that both frontal and parietal alpha asymmetry show a good reliability, especially when eyes are closed during the resting state recording. We also find, that reliability differs between recording sites, with frontomedial electrodes showing lower reliability than frontlateral and parietal sites.

Metzen, D.; Genc, E.; Getzmann, S.; Larra, M.; Wascher, E. & Ocklenburg, S. (2021). Frontal and parietal EEG alpha asymmetry: A large-scale investigation of short-term reliability on distinct EEG systems. Brain Struct Funct.

 

News & Views

Uncertainty resolution involves effort more than appetite for rewards
 

Motivated behavior has long been studied by psychologists, ethologists, and neuroscientists. To date, many scientists agree with the view that cue and reward attraction is the product of a dopamine-dependent unconscious process called incentive salience or “wanting”. This process allows the influence of multiple factors such as hunger and odors on motivational attraction. In some cases, however, the resulting motivated behavior differs from what the incentive salience hypothesis would predict. I argue that seeking behavior under reward uncertainty illustrates this situation: Organisms do not just “want” (appetite-based attraction) cues that are inconsistent or associated with reward occasionally, they “hope” that those cues will consistently predict reward procurement in the ongoing trial. Said otherwise, they become motivated to invest time and energy to find consistent cue-reward associations despite no guarantee of success (effort-based attraction). A multi-test comparison of performance between individuals trained under uncertainty and certainty reveals behavioral paradoxes suggesting that the concept of incentive salience cannot fully account for responding to inconsistent cues. A mathematical model explains how appetite-based and effort-based attractions might combine their effects.

Anselme, P. (2021). Effort-motivated behavior resolves paradoxes in appetitive conditioning. Behavioural Processes, 193, 104525.


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