International journal of psychophysiology : official journal of the International Organization of Psychophysiology
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Int J Psychophysiol · Aug 2013
Randomized Controlled TrialModulation of γ and spindle-range power by slow oscillations in scalp sleep EEG of children.
Deep sleep is characterized by slow waves of electrical activity in the cerebral cortex. They represent alternating down states and up states of, respectively, hyperpolarization with accompanying neuronal silence and depolarization during which neuronal firing resumes. The up states give rise to faster oscillations, notably spindles and gamma activity which appear to be of major importance to the role of sleep in brain function and cognition. ⋯ There were no differences between the groups who received and did not receive acoustic stimulation in the sleep parameters and slow wave-locked time-frequency analysis. Our findings show, for the first time in scalp EEG in humans, that gamma activity is associated with the up-going slope and peak of the slow wave. We propose that studies in children provide a uniquely feasible opportunity to conduct investigations into the role of gamma during sleep.
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Int J Psychophysiol · Aug 2013
ReviewThe microstructure of sleep in primary insomnia: an overview and extension.
The present review was undertaken to summarize studies elucidating sleep microstructural differences in chronic insomnia. The etiology of insomnia is still unknown, whereas the hyperarousal concept has gained much attention with respect to pathophysiology. According to this model, insomnia is characterized by significant hyperarousal on an autonomous and central nervous level. ⋯ These methods include the spectral analysis of the sleep EEG, micro-arousal and CAP (cyclic alternating pattern) analysis as well as the assessment of event-related potentials (ERPs) during night-sleep. The application of these methods shows stronger correlations with the subjective experience of disturbed sleep than standard sleep EEG scoring. An overview of the relevant empirical evidence is presented, previous investigations are extended and a theoretical synthesis within the framework of the hyperarousal concept of insomnia is attempted.
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Int J Psychophysiol · Jul 2013
Response competition and response inhibition during different choice-discrimination tasks: evidence from ERP measured inside MRI scanner.
We investigated the neural correlates underlying response inhibition and conflict detection processes using ERPs and source localization analyses simultaneously acquired during fMRI scanning. ERPs were elicited by a simple reaction time task (SRT), a Go/NoGo task, and a Stroop-like task (CST). The cognitive conflict was thus manipulated in order to probe the degree to which information processing is shared across cognitive systems. ⋯ Congruent and incongruent conditions of the CST task also elicited similar N2, P3 and late negativity (LN) ERPs, though CST-incongruent trials revealed a larger LN and enhanced prefrontal and ACC activations. Considering the stimulus probability and experimental manipulation of our study, current findings suggest that NoGo N2 and frontal NoGo P3 appear to be more associated to response inhibition rather than a specific conflict monitoring, whereas occipito-parietal P3 of Go and CST conditions may be more linked to a planned response competition between the prepared and required response. LN, however, appears to be related to higher level conflict monitoring associated with response choice-discrimination but not when the presence of cognitive conflict is associated with response inhibition.
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Int J Psychophysiol · Jul 2013
Visual information constrains early and late stages of spoken-word recognition in sentence context.
Audiovisual speech perception has been frequently studied considering phoneme, syllable and word processing levels. Here, we examined the constraints that visual speech information might exert during the recognition of words embedded in a natural sentence context. We recorded event-related potentials (ERPs) to words that could be either strongly or weakly predictable on the basis of the prior semantic sentential context and, whose initial phoneme varied in the degree of visual saliency from lip movements. ⋯ When comparing audio-visual versus auditory alone presentation (Experiment 2), the typical amplitude-reduction effect over the auditory-evoked N100 response was observed in the audiovisual modality. Interestingly, a specific benefit of high- versus low-visual saliency constraints occurred over the early N100 response and at the late N400 time window, confirming the result of Experiment 1. Taken together, our results indicate that the saliency of visual speech can exert an influence over both auditory processing and word recognition at relatively late stages, and thus suggest strong interactivity between audio-visual integration and other (arguably higher) stages of information processing during natural speech comprehension.
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Int J Psychophysiol · Apr 2013
Blunted salivary and plasma cortisol response in patients with panic disorder under psychosocial stress.
Panic disorder (PD) has been associated with an altered activity of the hypothalamic-pituitary-adrenal-cortical (HPA) axis. Recent findings from a patient sample with PD with secondary depression on psychotropic medication using salivary cortisol as outcome measure suggest a non-responsiveness of the HPA-axis under acute psychosocial stress. Salivary cortisol does not necessarily reflect the total plasma cortisol due to interfering variables. Whether the present findings can be replicated on a patient sample with pure PD using both salivary cortisol and total plasma cortisol as outcome variables remains to be elucidated. ⋯ These findings provide strong evidence for a hypo-responsiveness of the HPA-axis as measured in both blood and saliva. Salivary and total plasma cortisol showed a strong concordance of results. Thus, future investigations could consider salivary cortisol as reliable marker of the HPA-axis under psychosocial stress.