No abstract

No abstract

No abstract

The beneficial effects of placebo treatments on fear and anxiety (placebo anxiolysis) are well known from clinical practice, and there is strong evidence indicating a contribution of treatment expectations to the efficacy of anxiolytic drugs. Although clinically highly relevant, the neural mechanisms underlying placebo anxiolysis are poorly understood. In two studies in humans, we tested whether the administration of an inactive treatment along with verbal suggestions of anxiolysis can attenuate experimentally induced states of phasic fear and/or sustained anxiety. Phasic fear is the response to a well defined threat and includes attentional focusing on the source of threat and concomitant phasic increases of autonomic arousal, whereas in sustained states of anxiety potential and unclear danger requires vigilant scanning of the environment and elevated tonic arousal levels. Our placebo manipulation consistently reduced vigilance measured in terms of undifferentiated reactivity to salient cues (indexed by subjective ratings, skin conductance responses and EEG event-related potentials) and tonic arousal [indexed by cue-unrelated skin conductance levels and enhanced EEG alpha (8 -12 Hz) activity], indicating a downregulation of sustained anxiety rather than phasic fear. We also observed a placebo-dependent sustained increase of frontal midline EEG theta (4 -7 Hz) power and frontoposterior theta coupling, suggesting the recruitment of frontally based cognitive control functions. Our results thus support the crucial role of treatment expectations in placebo anxiolysis and provide insight into the underlying neural mechanisms.

No abstract

Linear motion perceptual thresholds (PTs) were compared between patients with Menière’s disease (MD) and vestibular migraine (VM). Twenty patients with VM, 27 patients with MD and 34 healthy controls (HC) were examined. PTs for linear motion along the inter-aural (IA), naso-occipital axes (NO), and head-vertical (HV) axis were measured using a multi-axis motion platform. Ocular and cervical vestibular evoked myogenic potentials (o/c VEMP) were performed and the dizziness handicap inventory (DHI) administered. In order to discriminate between VM and MD, we also evaluated the diagnostic accuracy of applied methods. PTs depended significantly on the group tested (VM, MD and HC), as revealed by ANCOVA with group as the factor and age as the covariate. This was true for all motion axes (IA, HV and NO). Thresholds were highest for MD patients, significantly higher than for all other groups for all motion axes, except for the IA axis when compared with HC group suggesting decreased otolith sensitivity in MD patients. VM patients had thresholds that were not different from those of HC, but were significantly lower than those of the MD group for all motion axes. The cVEMP p13 latencies differed significantly across groups being lowest in VM. There was a statistically significant association between HV and NO thresholds and cVEMP PP amplitudes. Diagnostic accuracy was highest for the IA axis, followed by cVEMP PP amplitudes, NO and HV axes. To conclude, patients with MD had significantly higher linear motion perception thresholds compared to patients with VM and controls. Except for reduced cVEMP latency, there were no differences in c/oVEMP between MD, VM and controls.

BackgroundThe processing of reward and punishment stimuli in humans appears to involve brain oscillatory activity of several frequencies, probably each with a distinct function. The exact nature of associations of these electrophysiological measures with impulsive or risk-seeking personality traits is not completely clear. Thus, the aim of the present study was to investigate event-related oscillatory activity during reward processing across a wide spectrum of frequencies, and its associations with impulsivity and sensation seeking in healthy subjects.MethodsDuring recording of a 32-channel EEG 22 healthy volunteers were characterized with the Barratt Impulsiveness and the Sensation Seeking Scale and performed a computerized two-choice gambling task comprising different feedback options with positive vs. negative valence (gain or loss) and high or low magnitude (5 vs. 25 points).ResultsWe observed greater increases of amplitudes of the feedback-related negativity and of activity in the theta, alpha and low-beta frequency range following loss feedback and, in contrast, greater increase of activity in the high-beta frequency range following gain feedback. Significant magnitude effects were observed for theta and delta oscillations, indicating greater amplitudes upon feedback concerning large stakes. The theta amplitude changes during loss were negatively correlated with motor impulsivity scores, whereas alpha and low-beta increase upon loss and high-beta increase upon gain were positively correlated with various dimensions of sensation seeking.ConclusionsThe findings suggest that the processing of feedback information involves several distinct processes, which are subserved by oscillations of different frequencies and are associated with different personality traits.

No abstract