Papers by Belinda Pletzer
Frontiers in Endocrinology
Frontiers Research Topics
Communications Biology
Sex differences in navigation have often been attributed to the use of different navigation strat... more Sex differences in navigation have often been attributed to the use of different navigation strategies in men and women. However, no study so far has investigated sex differences in the brain networks supporting different navigation strategies. To address this issue, we employed a 3D-navigation task during functional MRI in 36 men and 36 women, all scanned thrice, and modeled navigation strategies by instructions requiring an allocentric vs. egocentric reference frame on the one hand, as well as landmark-based vs. Euclidian strategies on the other hand. We found distinct brain networks supporting different perspectives/strategies. Men showed stronger activation of frontal areas, whereas women showed stronger activation of posterior brain regions. The left inferior frontal gyrus was more strongly recruited during landmark-based navigation in men. The hippocampus showed stronger connectivity with left-lateralized frontal areas in women and stronger connectivity with superior parietal ...
Frontiers in Neuroscience
Prospective randomized controlled trials on hormonal contraceptive (HC) effects on the brain are ... more Prospective randomized controlled trials on hormonal contraceptive (HC) effects on the brain are rare due to a number of methodological challenges. Thus, much of the evidence on HC effects on the brain comes from cross-sectional studies comparing HC-users to non-users. In interpreting these findings, it is of importance to be aware of potential confounds associated with women’s contraceptive choices. Previous studies have discussed age, education, social status, sexual orientation, relationship status, and tolerability of HC. Given the current trend toward a reduction in HC use and increased skepticism toward HC it seems relevant to also identify variables associated with women’s attitudes toward HC and whether they may represent confounds for neuroscientific studies. In the present study, we investigated whether women’s personality characteristics were associated with their choice to use or not use HC in the present, past and future and the type of HC chosen. 1,391 females aged 18–...
Frontiers in Neuroscience
Sex differences in spatial navigation have been related to different navigation strategies. For e... more Sex differences in spatial navigation have been related to different navigation strategies. For example, women are more likely to utilize local landmark-information in the environment compared to men. Furthermore, sex differences appear to be more pronounced when distances need to be judged in Euclidian terms and an allocentric representation of the environment is necessary. This suggests differential attentional processes during spatial navigation in men and women. However, eye-tracking studies on spatial navigation exploring these attentional processes are rare. The present study (39 men and 36 women) set out to investigate sex differences in eye-movements during spatial navigation in a 3D environment using virtual reality goggles. While we observed the expected sex differences in overall navigation performance, women did not benefit from the landmark-based instructions. Gaze fixations were in accordance with the preferred Euclidian strategy in men, but did not confirm the expecte...
Combined oral contraceptives (COC) are among the most commonly used contraceptive methods worldwi... more Combined oral contraceptives (COC) are among the most commonly used contraceptive methods worldwide, and mood side effects are the major reason for discontinuation of treatment. We here investigate the directed connectivity patterns associated with the mood side effects of an androgenic COC in a double-blind randomized, placebo-controlled trial in women with a history of affective COC side effects (n=34). We used spectral dynamic causal modeling on a triple network model consisting of the default mode network (DMN), salience network (SN) and executive central network (ECN). Within this framework, we assessed the treatment-related changes in directed connectivity associated with adverse mood side effects. Overall, during COC use, we found a pattern of enhanced connectivity within the DMN and decreased connectivity within the ECN. The dorsal anterior cingulate cortex mediates an increased recruitment of the DMN by the ECN during treatment. Mood lability was the most prominent COC-indu...
Frontiers in Behavioral Neuroscience, 2022
Recent research into the effects of hormonal contraceptives on emotion processing and brain funct... more Recent research into the effects of hormonal contraceptives on emotion processing and brain function suggests that hormonal contraceptive users show (a) reduced accuracy in recognizing emotions compared to naturally cycling women, and (b) alterations in amygdala volume and connectivity at rest. To date, these observations have not been linked, although the amygdala has certainly been identified as core region activated during emotion recognition. To assess, whether volume, oscillatory activity and connectivity of emotion-related brain areas at rest are predictive of participant’s ability to recognize facial emotional expressions, 72 participants (20 men, 20 naturally cycling women, 16 users of androgenic contraceptives, 16 users of anti-androgenic contraceptives) completed a brain structural and resting state fMRI scan, as well as an emotion recognition task. Our results showed that resting brain characteristics did not mediate oral contraceptive effects on emotion recognition perfo...
Communications Biology, 2021
Longitudinal menstrual cycle studies allow to investigate the effects of ovarian hormones on brai... more Longitudinal menstrual cycle studies allow to investigate the effects of ovarian hormones on brain organization. Here, we use spectral dynamic causal modelling (spDCM) in a triple network model to assess effective connectivity changes along the menstrual cycle within and between the default mode, salience and executive control networks (DMN, SN, and ECN). Sixty healthy young women were scanned three times along their menstrual cycle, during early follicular, pre-ovulatory and mid-luteal phase. Related to estradiol, right before ovulation the left insula recruits the ECN, while the right middle frontal gyrus decreases its connectivity to the precuneus and the DMN decouples into anterior/posterior parts. Related to progesterone during the mid-luteal phase, the insulae (SN) engage to each other, while decreasing their connectivity to parietal ECN, which in turn engages the posterior DMN. When including the most confident connections in a leave-one out cross-validation, we find an above...
Neuroscience, 2020
Hubs emerge in structural and resting state network analysis as areas highly connected to other p... more Hubs emerge in structural and resting state network analysis as areas highly connected to other parts of the brain and have been shown to respond to several task domains in functional imaging studies. A cognitive explanation for this multi-functionality is still wanting. We propose, that hubs subserve domain-general meta-cognitive functions, relevant to a variety of domain-specific networks and test this hypothesis for the example of processing explicit identity information. To isolate this meta-cognitive function from the processing of domain-specific context, we investigate the overlapping activations to linguistic identity processes (e.g. Mr. Dietrich is the dentist) on the one hand and numerical identity processes (e.g. do "3 × 8" and "36-12" give the same number) on the other hand. The main question was, whether these overlapping activations would fall within areas, consistently identified as hubs by network-based analyses. Indeed, the two contrasts showed significant conjunctions in the left inferior parietal lobe (IPL), precuneus (PC), and posterior cingulate. Accordingly, identity processing may well be one domain-general meta-cognitive function that hub-areas provide to domain-specific networks. For the parietal lobe we back up our hypothesis further with existing reports of activation peaks for other tasks that depend on identity processing, e.g., episodic recollection, theory of mind, and visual perspective taking.
Biological Psychology, 2021
Coupling between delta (1‒4 Hz) and beta (14‒30 Hz) oscillations is posited to reflect subcortico... more Coupling between delta (1‒4 Hz) and beta (14‒30 Hz) oscillations is posited to reflect subcortico-cortical communication and stress regulation. To validate delta-beta coupling (DBC) as an index of neural stress regulation, we investigated whether DBC changes during stress and whether these changes are associated with established stress responses. We induced stress using a social-evaluative threat (impromptu speech) task and measured frontal and parietal delta-beta amplitude-amplitude correlation (AAC) and phase-amplitude coupling (PAC), as well as cardiovascular, affective, and endocrine stress responses. Results showed no significant changes in either AAC or PAC in response to stress and no correlations with stress responses. However, baseline AAC tended to be related to more adaptive endocrine stress responses. Our results suggest that delta-beta AAC or PAC are not valid neural indices of stress regulation itself, but rather traits that relate to differences in neuroendocrine stress responses.
Open data and R analysis scripts for the paper as published: "Poppelaars, E. S., Klackl, J.,... more Open data and R analysis scripts for the paper as published: "Poppelaars, E. S., Klackl, J., Pletzer, B., Wilhelm, F.H. & Jonas, E. (2019). Social-evaluative threat: Stress response stages and influences of biological sex and neuroticism. Psychoneuroendocrinology, 109, 104378. https://doi.org/10.1016/j.psyneuen.2019.104378. Description of the dataset: A dataset of 37 men and 30 women (tested in the luteal phase of their menstrual cycle) participated in a public speaking task to induce social-evaluative threat. Responses of multiple stress systems were measured (trait appraisal, sympathetic and parasympathetic nervous system activity, self-reported motivation and affect, and hypothalamic–pituitary–adrenal axis activity), as well as personality traits (e.g. neuroticism and extraversion). Description of files: - File 'README.txt' contains the description of the files (metadata). - File 'SETData.sav' contains the raw data. - File 'Codebook.xlsx' contains a description of all variables in the 'SET.outl.del.imp.RData' file (metadata). - File 'SET.outl.del.imp.RData' contains multiple imputed datasets (without missing values) that can be used to reproduce results from the paper. - File '01_CalculationOfData.R' is an R analysis script that imports the raw data, calculates new variables, and imputes missing data via multiple imputation using the 'predictorMatrixAdj.xlsx' file. - File '02_AnalysisOfImputedData.R' is an R analysis script that calculates descriptive statistics, creates plots, and tests hypotheses using t-tests, Bayesian statistics, and multiple lineair regressions.
Journal of Experimental Psychology: General, 2021
Number processing and visual hierarchical processing (global-local processing) have much in commo... more Number processing and visual hierarchical processing (global-local processing) have much in common. However, the shared aspects of number processing and global-local processing have not been investigated so far. Most visual stimuli are hierarchical with global structures made up of local parts. Processing of global and local aspects occurs in parallel and the global advantage effect indicates faster reactions to global than local aspects. Likewise, multidigit numbers can be represented holistically (whole number magnitudes) or in a decomposed fashion (single digit magnitudes). During comparison of 2-digit numbers, the unit-decade compatibility effect indicates slower responses when the larger number contains the smaller unit digit and has been suggested as a measure of how strongly participants rely on decomposed number representations. However, this interpretation of the compatibility effect is still controversial and a link between global-local processing and the individual tendency to rely on decomposed representations of multidigit numbers remains to be established. To that end we assessed whether the compatibility effect during number comparison was related to various measures of global advantage. To answer this question we drew upon existing data from participants who had completed both, the number comparison task and 2 global-local tasks. Results show that the compatibility effect is indeed negatively related to several measures of global advantage in women, with no evidence for such a relationship in men. These results demonstrate that global-local processing transcends into the numerical domain but also suggest that the compatibility effect reflects different mechanisms in men and women. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Clocks & Sleep, 2021
Previously, we presented our preliminary results (N = 14) investigating the effects of short-wave... more Previously, we presented our preliminary results (N = 14) investigating the effects of short-wavelength light from a smartphone during the evening on sleep and circadian rhythms (Höhn et al., 2021). Here, we now demonstrate our full sample (N = 33 men), where polysomnography and body temperature were recorded during three experimental nights and subjects read for 90 min on a smartphone with or without a filter or from a book. Cortisol, melatonin and affectivity were assessed before and after sleep. These results confirm our earlier findings, indicating reduced slow-wave-sleep and -activity in the first night quarter after reading on the smartphone without a filter. The same was true for the cortisol-awakening-response. Although subjective sleepiness was not affected, the evening melatonin increase was attenuated in both smartphone conditions. Accordingly, the distal-proximal skin temperature gradient increased less after short-wavelength light exposure than after reading a book. Int...
Clocks & Sleep, 2021
Smartphone usage strongly increased in the last decade, especially before bedtime. There is growi... more Smartphone usage strongly increased in the last decade, especially before bedtime. There is growing evidence that short-wavelength light affects hormonal secretion, thermoregulation, sleep and alertness. Whether blue light filters can attenuate these negative effects is still not clear. Therefore, here, we present preliminary data of 14 male participants (21.93 ± 2.17 years), who spent three nights in the sleep laboratory, reading 90 min either on a smartphone (1) with or (2) without a blue light filter, or (3) on printed material before bedtime. Subjective sleepiness was decreased during reading on a smartphone, but no effects were present on evening objective alertness in a GO/NOGO task. Cortisol was elevated in the morning after reading on the smartphone without a filter, which resulted in a reduced cortisol awakening response. Evening melatonin and nightly vasodilation (i.e., distal-proximal skin temperature gradient) were increased after reading on printed material. Early slow ...
Physiology & Behavior, 2020
Multi-digit numbers are of a hierarchical nature with whole number magnitudes depending on digit ... more Multi-digit numbers are of a hierarchical nature with whole number magnitudes depending on digit magnitudes. Processing of multi-digit numbers can occur in a holistic or decomposed fashion. The unit-decade compatibility effect during number comparison is often used as a measure of decomposed processing. It refers to the fact that performance is reduced when the larger number contains the smaller unit digit (e.g. 73 vs. 26). It has been demonstrated that women show a larger compatibility effect than men, which is in accordance with their general tendency towards focusing on stimulus details during processing of visual hierarchical stimuli (local processing style). Such a local processing style has been related to higher progesterone and lower testosterone levels. One method to study individual processing styles is eye-tracking. The aim of the present study was to examine whether sex and sex hormones (estradiol, progesterone, testosterone) relate to eye movement behavior in the number comparison task. Unlike previous studies we found no evidence for sex differences in the behavioral compatibility effect. Nevertheless, women look more often and longer at individual digits and show a stronger compatibility effect in fixation durations compared to men, while men show more saccades between numbers than women. Estradiol and progesterone were related to fewer fixations and shorter fixation durations and more saccades between numbers in men, but not in women. Furthermore, the compatibility effect in the number of fixations and fixation durations was negatively related to testosterone in women. In summary, this is the first study to demonstrate sex differences and sex hormone influences on eye gaze behavior during number comparison.
Behavioural Brain Research, 2021
Sex differences in functional hemispheric asymmetries (FHA) have been hypothesized as a fundament... more Sex differences in functional hemispheric asymmetries (FHA) have been hypothesized as a fundamental mechanism behind sex differences in global-local processing. So far, it has not been assessed how interactive effects of sex and hemifield presentation influence common indicators of global precedence. The current study is the first to investigate the involvement of FHAs by using a divided visual field Navon paradigm and controlling for sex hormone status. Moreover, various factors that have previously shown a reliable influence on global-local processing performance are verified within the context of unilateral presentation. 39 men and 39 naturally cycling women in their luteal cycle phase completed a divided visual field Navon task with the instruction to detect targets either at any level (divided attention) or only at the global or local level (selective attention) in three different spacing conditions. The obtained evidence reveals significant sex differences in the global advantage effect (faster reaction to global vs. local level targets) for densely spaced letter stimuli, as well as significant sex differences in global-local level interference, with findings on both measures being mediated by testosterone. Also, estradiol showed different relationships to the global advantage effect in men and women together with a positive relationship to global advantage for the selective attention condition. Behavioural reaction time results were mirrored by accuracy measures but presented significantly higher global- over local-level accuracy in women compared to men for the divided attention condition. Our results did not show significant sex differences in FHAs but indicate differential relationships between progesterone and FHAs in men and women. In conclusion, sex hormones emerged as central mediators of sex differences in global precedence and possible moderators of hemispheric asymmetries.
Longitudinal menstrual cycle research allows the assessment of sex hormones effects on brain orga... more Longitudinal menstrual cycle research allows the assessment of sex hormones effects on brain organization in a natural framework. Here, we used spectral dynamic causal modelling (spDCM) in a triple network model consisting of the default mode, salience and executive central networks (DMN, SN, and ECN), in order to address the changes in effective connectivity across the menstrual cycle. Sixty healthy young women were scanned three times (menses, pre-ovulatory and luteal phase) and spDCM was estimated for a total of 174 scans. Group level analysis using Parametric empirical Bayes showed lateralized and anterior-posterior changes in connectivity patterns depending on the cycle phase and related to the endogenous hormonal milieu. Right before ovulation the left insula recruited the frontoparietal network, while the right middle frontal gyrus decreased its connectivity to the precuneus. In exchange, the precuneus engaged bilateral angular gyrus, decoupling the DMN into anterior/posterio...
Brain and Language, 2020
Sex differences in cognitive functions are heavily debated. Recent work suggests that sex differe... more Sex differences in cognitive functions are heavily debated. Recent work suggests that sex differences do stem from different processing strategies utilized by men and women. While these processing strategies are likely reflected in different brain networks, so far the link between brain networks and processing strategies remains speculative. In the present study we seek for the first time to link sex differences in brain activation patterns to sex differences in processing strategies utilizing a semantic verbal fluency task in a large sample of 35 men and 35 women, all scanned thrice. For verbal fluency, strategies of clustering and switching have been described. Our results show that men show higher activation in the brain network supporting clustering, while women show higher activation in the brain network supporting switching. Furthermore, converging evidence from activation results, lateralization indices and connectivity analyses suggests that men recruit the right hemisphere more strongly during clustering, but women during switching. These results may explain findings of differential performance and strategy-use in previous behavioral studies.
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Papers by Belinda Pletzer