Ihre Suche

Suche zurücksetzen
In authors or contributors
Thema

Ergebnisse 4 Einträge

RelevanzNeueste zuerstÄlteste zuerstAutor A-ZAutor Z-ATitel A-ZTitel Z-A
Abstracts
  • Stark, R., Schienle, A., Klöpper, R., & Vaitl, D. (1998). Effects of magnetic stimulation through VLF-sferics on reaction time. Perceptual and Motor Skills, 86(3 Pt 1), 808–810. https://doi.org/10.2466/pms.1998.86.3.808
  • Vaitl, D., Gruppe, H., Stark, R., & Pössel, P. (1996). Simulated micro-gravity and cortical inhibition: a study of the hemodynamic-brain interaction. Biological Psychology, 42(1–2), 87–103. https://doi.org/10.1016/0301-0511(95)05148-1

    The present study was carried out to determine the inhibitory cortical processes induced by changes in hemodynamics. Previous experiments in humans conducted in our laboratory have shown that there is a close relationship between posture and delta and theta EEG activity. The most pronounced effects were obtained during the 6 degrees head-down tilt (HDT) position. In space medicine the HDT procedure is very frequently employed to simulate micro-gravity and to determine the neurohormonal counter-regulations evoked by the expansion of central volume. Twenty male subjects spent 23 h in bed in 6 degrees HDT and 23 h in 6 degrees HUT (head-up tilt) positions during which EEG (frontal, central, parietal, occipital), startle responses, and reaction-times were measured every 2 h (from 10:00 h till 20:00 h). The effects of cardiovascular deconditioning (CD) regularly occurring after HDT were assessed by examining orthostatic tolerance and the physical work capacity (bicycle ergometry). As expected, 23 h HDT led to more pronounced CD than HUT. Spectral power analyses of EEG revealed increases in delta and theta frequency hands similar to those found during HDT in previous EEG studies. In addition, subjects responded more slowly (S1-S2 reaction-time task) during HDT as compared with HUT bedrest. The influence of HDT on startle response, however, was not in keeping with the initial hypothesis (i.e. dampening of reflex activity). The EEG data and the sensorimotor performance indicated that the body fluid shift towards the thoracic cavity induced by HDT resulted in signs of cortical inhibition. In addition to neural mechanisms, other processes must be postulated which are closely related to the counter-regulation evoked by the varying body positions.

  • Vaitl, D., Lipp, O., Bauer, U., Schüler, G., Stark, R., Zimmermann, M., & Kirsch, P. (2002). Latent inhibition and schizophrenia: Pavlovian conditioning of autonomic responses. Schizophrenia Research, 55(1–2), 147–158. https://doi.org/10.1016/s0920-9964(01)00250-x

    Latent inhibition (LI) is an important model for understanding cognitive deficits in schizophrenia. Disruption of LI is thought to result from an inability to ignore irrelevant stimuli. The study investigated LI in schizophrenic patients by using Pavlovian conditioning of electrodermal responses in a complete within-subject design. Thirty-two schizophrenic patients (16 acute, unmedicated and 16 medicated patients) and 16 healthy control subjects (matched with respect to age and gender) participated in the study. The experiment consisted of two stages: preexposure and conditioning. During preexposure two visual stimuli were presented. one of which served as the to-be-conditioned stimulus (CSp + ) and the other one was the not-to-be-conditioned stimulus (CSp - ) during the following conditioning ( = acquisition). During acquisition, two novel visual stimuli(CSn + and CSn - ) were introduced. A reaction time task was used as the unconditioned stimulus (US). LI was defined as the difference in response differentiation observed between preexposed and non-preexposed sets of CS + and CS - . During preexposure, the schizophrenic patients did not differ in electrodermal responding from the control subjects, neither concerning the extent of orienting nor the course of habituation. The exposure to novel stimuli at the beginning of the acquisition elicited reduced orienting responses in unmedicated patients compared to medicated patients and control subjects. LI was observed in medicated schizophrenic patients and healthy controls, but not in acute unmedicated patients. Furthermore LI was found to be correlated with the duration of illness: it was attenuated in patients who had suffered their first psychotic episode.

  • Stark, R., Bauer, E., Merz, C. J., Zimmermann, M., Reuter, M., Plichta, M. M., Kirsch, P., Lesch, K. P., Fallgatter, A. J., Vaitl, D., & Herrmann, M. J. (2011). ADHD related behaviors are associated with brain activation in the reward system. Neuropsychologia, 49(3), 426–434. https://doi.org/10.1016/j.neuropsychologia.2010.12.012

    Neuroimaging studies on attention-deficit/hyperactivity disorder (ADHD) suggest dysfunctional reward processing, with hypo-responsiveness during reward anticipation in the reward system including the nucleus accumbens (NAcc). In this study, we investigated the association between ADHD related behaviors and the reward system using functional magnetic resonance imaging in a non-clinical sample. Participants were 31 healthy, female undergraduate students with varying levels of self-reported ADHD related behaviors measured by the adult ADHD self-report scale. The anticipation of different types of reward was investigated: monetary reward, punishment avoidance, and verbal feedback. All three reward anticipation conditions were found to be associated with increased brain activation in the reward system, with the highest activation in the monetary reward anticipation condition, followed by the punishment avoidance anticipation condition, and the lowest activation in the verbal feedback anticipation condition. Most interestingly, in all three conditions, NAcc activation was negatively correlated with ADHD related behaviors. In conclusion, our results from a non-clinical sample are in accordance with reported deficits in the reward system in ADHD patients: the higher the number and severity of ADHD related behaviors, the lower the neural responses in the dopaminergic driven reward anticipation task. Thus, our data support current aetiological models of ADHD which assume that deficits in the reward system might be responsible for many of the ADHD related behaviors.

RIS

Empfohlenes Format für die meisten Literaturverwaltungsprogramme

BibTeX

Empfohlenes Format für BibTeX-fähige software

Custom feed
Last update from database: 11.08.25, 05:41 (UTC)