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See detailCardiac cycle phases affect auditory-evoked potentials, startle eye blink and pre-motor reaction times in response to acoustic startle stimuli
Schulz, André UL; Vögele, Claus UL; Bertsch, Katja et al

in International Journal of Psychophysiology (2020), 157(1), 70-81

Startle stimuli evoke lower responses when presented during the early as compared to the late cardiac cycle phase, an effect that has been called ‘cardiac modulation of startle’ (CMS). The CMS effect may ... [more ▼]

Startle stimuli evoke lower responses when presented during the early as compared to the late cardiac cycle phase, an effect that has been called ‘cardiac modulation of startle’ (CMS). The CMS effect may be associated with visceral-afferent neural traffic, as it is reduced in individuals with degeneration of afferent autonomic nerves. The aim of this study was to investigate whether the CMS effect is due a modulation of only early, automatic stages of stimulus processing by baro-afferent neural traffic, or if late stages are also affected. We, therefore, investigated early and late components of auditory-evoked potentials (AEPs) to acoustic startle stimuli (105, 100, 95 dB), which were presented during the early (R-wave +230 ms) or the late cardiac cycle phase (R +530 ms) in two studies. In Study 1, participants were requested to ignore (n=25) or to respond to the stimuli with button-presses (n=24). In Study 2 (n=23), participants were asked to rate the intensity of the stimuli. We found lower EMG startle response magnitudes (both studies) and slower pre-motor reaction times in the early as compared to the late cardiac cycle phase (Study 1). We also observed lower N1 negativity (both studies), but higher P2 (Study 1) and P3 positivity (both studies) in response to stimuli presented in the early cardiac cycle phase. This AEP modulation pattern appears to be specific to the CMS effect, suggesting that early stages of startle stimulus processing are attenuated, whereas late stages are enhanced by baro-afferent neural traffic [less ▲]

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See detailInfluence of acute stress on response inhibition in healthy men: An ERP study
Dierolf, Angelika UL; Fechtner, Julia; Böhnke, Robina et al

in Psychophysiology (2017), 54(5), 684-695

The current study investigated the influence of acute stress and the resulting cortisol increase on response inhibition and its underlying cortical processes, using EEG. Before and after an acute stressor ... [more ▼]

The current study investigated the influence of acute stress and the resulting cortisol increase on response inhibition and its underlying cortical processes, using EEG. Before and after an acute stressor or a control condition, 39 healthy men performed a go/no-go task while ERPs (N2, P3), reaction times, errors, and salivary cortisol were measured. Acute stress impaired neither accuracy nor reaction times, but differentially affected the neural correlates of response inhibition; namely, stress led to enhanced amplitudes of the N2 difference waves (N2d, no-go minus go), indicating enhanced response inhibition and conflict monitoring. Moreover, participants responding to the stressor with an acute substantial rise in cortisol (high cortisol responders) showed reduced amplitudes of the P3 of the difference waves (P3d, no-go minus go) after the stressor, indicating an impaired evaluation and finalization of the inhibitory process. Our findings indicate that stress leads to a reallocation of cognitive resources to the neural subprocesses of inhibitory control, strengthening premotor response inhibition and the detection of response conflict, while concurrently diminishing the subsequent finalization process within the stream of processing. [less ▲]

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See detailEffects of basal and acute cortisol on cognitive flexibility in an emotional task switching paradigm in men
Dierolf, Angelika UL; Arlt, Lea Esther; Roelofs et al

in Hormones and Behavior (2016), 81

The stress hormone cortisol is assumed to influence cognitive functions. While cortisol-induced alterations of declarative memory in particular are well-investigated, considerably less is known about its ... [more ▼]

The stress hormone cortisol is assumed to influence cognitive functions. While cortisol-induced alterations of declarative memory in particular are well-investigated, considerably less is known about its influence on executive functions. Moreover, most research has been focused on slow effects, and rapid non-genomic effects have not been studied. The present study sought to investigate the impact of acute cortisol administration as well as basal cortisol levels on cognitive flexibility, a core executive function, within the non-genomic time frame. Thirty-eight healthy male participants were randomly assigned to intravenously receive either cortisol or a placebo before performing a task switching paradigm with happy and angry faces as stimuli. Cortisol levels were measured at six points during the experiment. Additionally, before the experiment, basal cortisol measures for the cortisol awakening response were collected on three consecutive weekdays immediately following awakening and 30, 45, and 60 min after. First and foremost, results showed a pronounced impact of acute and basal cortisol on reaction time switch costs, particularly for angry faces. In the placebo group, low basal cortisol was associated with minimal switch costs, whereas high basal cortisol was related to maximal switch costs. In contrast, after cortisol injection, basal cortisol levels showed no impact. These results show that cognitive flexibility-enhancing effects of acute cortisol administration are only seen in men with high basal cortisol levels. This result supports the context dependency of cortisol administration and shows the relevance of taking basal cortisol levels into account. [less ▲]

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See detailDistractor inhibition: Evidence from lateralized readiness potentials
Pramme, Lisa; Dierolf, Angelika UL; Naumann, Ewald et al

in Brain and Cognition (2015), 98

The present study investigated distractor inhibition on the level of stimulus representation. In a sequential distractor-to-distractor priming task participants had to respond to target letters flanked by ... [more ▼]

The present study investigated distractor inhibition on the level of stimulus representation. In a sequential distractor-to-distractor priming task participants had to respond to target letters flanked by distractor digits. Reaction time and stimulus-locked lateralized readiness potentials (S-LRPs) of probe responses were measured. Distractor-target onset asynchrony was varied. For RTs responses to probe targets were faster in the case of prime-distractor repetition compared to distractor changes indicating distractor inhibition. Benefits in RTs and the latency of S-LRP onsets for distractor repetition were also modulated by distractor-target onset asynchrony. For S-LRPs distractor inhibition was only present with a simultaneous onset of distractors and target. The results confirm previous results indicating inhibitory mechanisms of object-based selective attention on the level of distractor representations. [less ▲]

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