International journal of psychophysiology : official journal of the International Organization of Psychophysiology
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Int J Psychophysiol · Mar 2005
Comparative StudyHuman salivary alpha-amylase reactivity in a psychosocial stress paradigm.
Biological indicators for stress reactions are valuable markers in psychophysiological research and clinical practice. Since the release of salivary enzyme alpha-amylase was reported to react to physiological and psychological stressors, we set out to investigate human salivary alpha-amylase changes employing a reliable laboratory stress protocol to investigate the reactivity of salivary alpha-amylase to a brief period of psychosocial stress. In a within-subject repeated-measures design, 24 healthy adults were exposed to the TSST and a control condition on separate days with randomized sequence. ⋯ Significant differences between psychosocial stress and the rest condition in alpha-amylase activity [F(3.74,86.06)=4.52; P=0.003], cortisol levels [F(4.21,88.32)=12.48; P<0.001] and heart rate [F(1,22)=81.15; P<0.001] were observed, with marked increases before and after stress. The data corroborate findings from other studies that showed increased levels of alpha-amylase before and after psychological stress. We discuss the role of salivary alpha-amylase as a promising candidate for a reliable, noninvasive marker of psychosocial stress.
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Int J Psychophysiol · Apr 2004
Randomized Controlled Trial Clinical TrialFocused analgesia and generalized relaxation produce differential hypnotic analgesia in response to ascending stimulus intensity.
This study was designed in order to examine the effects of different types of hypnotic suggestion on hypnotic analgesia. Generalized relaxation and focused analgesia were induced in seven high-hypnotizable (HH) and eight low-hypnotizable (LH) subjects. Subjects were not aware to which group they belonged. ⋯ We conclude that by utilizing two modes of hypnotic suggestions in response to ascending stimuli, we were able to discover two components of hypnotic analgesia. One shows a parallel shift in the stimulus-response function, has features similar to placebo and bears no clear relationship to hypnotic susceptibility. The other shows a slope change in the stimulus-response curve and has a positive relationship to hypnotic susceptibility.
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Int J Psychophysiol · Mar 2004
Clinical TrialThe fear-inhibited light reflex: importance of the anticipation of an aversive event.
It has been shown previously that the amplitude of the pupillary light reflex response decreases when subjects anticipate an aversive stimulus (i.e. electric shock), compared to periods when subjects are resting ('fear-inhibited light reflex'). ⋯ The increase in initial pupil diameter is related to the anticipation of any stimulus, whereas the decrease in the amplitude of the light reflex response is associated with the aversiveness of the anticipated stimulus.
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Int J Psychophysiol · Aug 2003
Comparative StudyERPs to stimulus identification in persons with restrained eating behavior.
Restrained eating is an eating behavior in which hunger and satiety are not the only triggers for starting or ending a meal. Rather, cognitive factors control food consumption in these persons. The present study served to investigate cortical stimulus processing in restrained and unrestrained eaters by means of event-related potentials (ERPs). ⋯ Although, there were no differences between the ERPs of food-related and food-unrelated words, ERPs were more positive going in restrained eaters compared with unrestrained eaters. Food intake led to a decrease of the P2-amplitude in restrained eaters while increasing it in unrestrained eaters, regardless of stimulus-type. The results suggest that restrained eaters generally differ in their cortical stimulus processing from unrestrained eaters and that a preload has opponent effects in both groups of participants in the early states of stimulus processing.
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Int J Psychophysiol · Feb 2003
Clinical TrialTropicamide effects on pupil size and pupillary light reflexes in Alzheimer's and Parkinson's disease.
Diagnostic tests for Alzheimer's disease (AD) involving tropicamide blockade of cholinergic oculomotor functions were examined in AD patients (n=15), Parkinson's disease (PD) patients (n=15), and non-clinical control (NC) participants (n=15). Pupillographic methods were used to measure pupil diameter and pupillary light reflexes after double-blind ocular administration of dilute tropicamide (0.01%) in one eye and saline in the other eye. Changes in pupil size were measured in bright background light and near-darkness. ⋯ The pupillary light reflex test, therefore, was sensitive to AD, but lacked adequate specificity. Finally, peak constriction amplitude correlated significantly with dementia severity and donepezil treatment may have partially normalized pupillary light reflex abnormalities in AD patients. The pupillary light reflex test, therefore, may index central cholinergic dysfunction associated with disease progression and improvement in cholinergic function associated with pharmacologic treatment response in AD.