Frontal brain oscillatory coupling among men who vary in salivary testosterone levels.
ABSTRACT Recent studies suggest that cross-frequency coupling supports the integration of distinct neuronal oscillatory modes. In particular, spectral coupling between slow-wave delta and fast-wave beta oscillations may reflect subcortical-cortical interactions. Prior experiments have shown that delta-beta coupling appears to be sensitive to steroid hormone patterning. We attempted to extend this hypothesis by examining the relation between delta-beta EEG spectral coupling and endogenous testosterone measures in men. We collected resting regional brain electrical (EEG) activity and salivary testosterone from 34 healthy young adult males (M age=24 years). Males with high testosterone showed non-significant delta-beta coupling (delta-beta decoupling), while males with low testosterone exhibited significant delta-beta coupling. These relations were only found for the frontal brain region. There was also a significant group difference in the magnitude of coupling, but no differences in absolute delta and beta power. Findings are discussed in terms of emerging evidence relating steroid hormones to cross-frequency spectral coupling and directions for future work.
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ABSTRACT: In the last decade, the brain's oscillatory responses have invaded the literature. The studies on delta (0.5-3.5Hz) oscillatory responses in humans upon application of cognitive paradigms showed that delta oscillations are related to cognitive processes, mainly in decision making and attentional processes. The present manuscript comprehensively reviews the studies on delta oscillatory responses upon cognitive stimulation in healthy subjects and in different pathologies, namely Alzheimer's disease, Mild Cognitive Impairment (MCI), bipolar disorder, schizophrenia and alcoholism. Further delta oscillatory response upon presentation of faces, facial expressions, and affective pictures are reviewed. The relationship between pre-stimulus delta activity and post-stimulus evoked and event-related responses and/or oscillations are discussed. Cross-frequency couplings of delta oscillations with higher frequency windows are also included in the review. The conclusion of this review includes several important remarks, including that delta oscillatory responses are involved in cognitive and emotional processes. A decrease of delta oscillatory responses could be a general electrophysiological marker for cognitive dysfunction (Alzheimer's disease, MCI, bipolar disorder, schizophrenia and alcoholism). The pre-stimulus activity (phase or amplitude changes in delta activity) has an effect on post-stimulus EEG responses. Copyright © 2015. Published by Elsevier B.V.International journal of psychophysiology: official journal of the International Organization of Psychophysiology 02/2015; DOI:10.1016/j.ijpsycho.2015.02.001 · 2.65 Impact Factor
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ABSTRACT: Neuroimaging studies demonstrate considerable changes in white matter volume and microstructure during adolescence. Most studies have focused on age-related effects, whilst puberty-related changes are not well understood. Using diffusion tensor imaging and tract-based spatial statistics, we investigated the effects of pubertal status on white matter mean diffusivity (MD) and fractional anisotropy (FA) in 61 males aged 12.7-16.0 years. Participants were grouped into early-mid puberty (≤Tanner Stage 3 in pubic hair and gonadal development; n = 22) and late-post puberty (≥Tanner Stage 4 in pubic hair or gonadal development; n = 39). Salivary levels of pubertal hormones (testosterone, DHEA and oestradiol) were also measured. Pubertal stage was significantly related to MD in diverse white matter regions. No relationship was observed between pubertal status and FA. Regression modelling of MD in the significant regions demonstrated that an interaction model incorporating puberty, age and puberty × age best explained our findings. In addition, testosterone was correlated with MD in these pubertally significant regions. No relationship was observed between oestradiol or DHEA and MD. In conclusion, pubertal status was significantly related to MD, but not FA, and this relationship cannot be explained by changes in chronological age alone.Developmental Cognitive Neuroscience 10/2014; 11. DOI:10.1016/j.dcn.2014.10.002 · 3.71 Impact Factor
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ABSTRACT: In a manuscript entitled, “Bashful boys and coy girls: A review of gender differences in childhood shyness” Doey et al. (2013) suggest that shyness and its related constructs pose a greater developmental risk for boys compared to girls. They support this claim by citing empirical evidence suggesting that shy and anxiously withdrawn boys are responded to more negatively by important others (i.e., parents, peers, and teachers) and that the relationship between internalizing problems and anxious withdrawal is stronger for boys compared to girls. The principal aim of our commentary is to provide a critical examination of Doey et al.’s conclusions vis-à-vis gender differences in child and adolescent shyness. In this response, we begin by providing important theoretical background regarding shyness and its related constructs. Next, we critically examine the two main arguments the authors use in support of their conclusion through a review of existing empirical and theoretical work as well as the presentation of data from The Friendship Project. These data were analyzed with the specific purpose of providing an empirical test of the hypotheses implicit in Doey et al.’s primary arguments: 1) shy and anxiously withdrawn boys are responded to more negatively than girls and 2) the association between anxious withdrawal and internalizing problems is stronger for boys compared to girls. Our results indicate mixed support for these two claims. Finally, we conclude by suggesting new directions for future researchers interested in clarifying the relationship between gender and both the correlates and outcomes of childhood shyness.Sex Roles 04/2014; 70(7-8):274-284. DOI:10.1007/s11199-014-0357-9 · 1.47 Impact Factor