Long-range synchrony in the gamma band: role in music perception.
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Synchronization seems to be a central mechanism for neuronal information processing within and between multiple brain areas. Furthermore, synchronization in the gamma band has been shown to play an important role in higher cognitive functions, especially by binding the necessary spatial and temporal information in different cortical areas to build a coherent perception. Specific task-induced (evoked) gamma oscillations have often been taken as an indication of synchrony, but the presence of long-range synchrony cannot be inferred from spectral power in the gamma range. We studied the usefulness of a relatively new measure, called similarity index to detect asymmetric interdependency between two brain regions. Spontaneous EEG from two groups-musicians and non-musicians-were recorded during several states: listening to music, listening to text, and at rest (eyes closed and eyes open). While listening to music, degrees of the gamma band synchrony over distributed cortical areas were found to be significantly higher in musicians than non-musicians. Yet no differences between these two groups were found at resting conditions and while listening to a neutral text. In contrast to the degree of long-range synchrony, spectral power in the gamma band was higher in non-musicians. The degree of spatial synchrony, a measure of signal complexity based on eigen-decomposition method, was also significantly increased in musicians while listening to music. As compared with non-musicians, the finding of increased long-range synchrony in musicians independent of spectral power is interpreted as a manifestation of a more advanced musical memory of musicians in binding together several features of the intrinsic complexity of music in a dynamical way. (+info)
Social stress exacerbates stroke outcome by suppressing Bcl-2 expression.
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The relationship between stressful life events and the onset of disease is well documented. However, the role of psychological stress as a risk factor for life-threatening cerebrovascular insults such as stroke remains unspecified, but could explain individual variation in stroke outcome. To discover the mechanisms through which psychological stress may alter stroke outcome, we modeled the effects of chronic social intimidation and stress on ischemia-induced bcl-2 expression and early neuronal cell loss resulting from cerebral artery occlusion in mice (C57BL/6). The bcl-2 protooncogene promotes cell survival and protects against apoptosis and cellular necrosis in numerous neurodegenerative disorders, including stroke. In our study, male mice were chronically exposed to aggressive social stimuli before induction of a controlled, mild ischemic insult. Stressed mice expressed approximately 70% less bcl-2 mRNA than unstressed mice after ischemia. In addition, social stress greatly exacerbated infarct in wild-type mice but not in transgenic mice that constitutively express increased neuronal bcl-2. Despite similar postischemic concentrations of corticosterone, the major stress hormone in mice, high corticosterone concentrations were significantly correlated with larger infarcts in wild-type mice but not bcl-2 transgenic mice. Thus, enhanced bcl-2 expression offsets the potentially deleterious consequences of high postischemic plasma corticosterone concentrations. Taken together, these data demonstrate that stressful prestroke social milieu strongly compromises an endogenous molecular mechanism of neuroprotection in injured brain and offer a new behavioral target for stroke therapy. (+info)
Intensely pleasurable responses to music correlate with activity in brain regions implicated in reward and emotion.
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We used positron emission tomography to study neural mechanisms underlying intensely pleasant emotional responses to music. Cerebral blood flow changes were measured in response to subject-selected music that elicited the highly pleasurable experience of "shivers-down-the-spine" or "chills." Subjective reports of chills were accompanied by changes in heart rate, electromyogram, and respiration. As intensity of these chills increased, cerebral blood flow increases and decreases were observed in brain regions thought to be involved in reward/motivation, emotion, and arousal, including ventral striatum, midbrain, amygdala, orbitofrontal cortex, and ventral medial prefrontal cortex. These brain structures are known to be active in response to other euphoria-inducing stimuli, such as food, sex, and drugs of abuse. This finding links music with biologically relevant, survival-related stimuli via their common recruitment of brain circuitry involved in pleasure and reward. (+info)
Superior formation of cortical memory traces for melodic patterns in musicians.
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The human central auditory system has a remarkable ability to establish memory traces for invariant features in the acoustic environment despite continual acoustic variations in the sounds heard. By recording the memory-related mismatch negativity (MMN) component of the auditory electric and magnetic brain responses as well as behavioral performance, we investigated how subjects learn to discriminate changes in a melodic pattern presented at several frequency levels. In addition, we explored whether musical expertise facilitates this learning. Our data show that especially musicians who perform music primarily without a score learn easily to detect contour changes in a melodic pattern presented at variable frequency levels. After learning, their auditory cortex detects these changes even when their attention is directed away from the sounds. The present results thus show that, after perceptual learning during attentive listening has taken place, changes in a highly complex auditory pattern can be detected automatically by the human auditory cortex and, further, that this process is facilitated by musical expertise. (+info)
Using signs, artwork, and music to promote stair use in a public building.
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OBJECTIVES: This study assessed the impact on stair use of improving the attractiveness of a stairwell. METHODS: Observations of stair usage were made in a university building during baseline, 2 interventions, and follow-up. The first intervention involved signs; the second intervention added artwork and music in the stairwell. RESULTS: More participants used the stairs during the music and artwork intervention than at baseline or when signs alone were used. CONCLUSIONS: Improving the aesthetic qualities of a stairwell can increase rates of stair usage in a public building. Designs for buildings should take accessibility and aesthetic issues into consideration. (+info)
Consonance and dissonance of musical chords: neural correlates in auditory cortex of monkeys and humans.
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Some musical chords sound pleasant, or consonant, while others sound unpleasant, or dissonant. Helmholtz's psychoacoustic theory of consonance and dissonance attributes the perception of dissonance to the sensation of "beats" and "roughness" caused by interactions in the auditory periphery between adjacent partials of complex tones comprising a musical chord. Conversely, consonance is characterized by the relative absence of beats and roughness. Physiological studies in monkeys suggest that roughness may be represented in primary auditory cortex (A1) by oscillatory neuronal ensemble responses phase-locked to the amplitude-modulated temporal envelope of complex sounds. However, it remains unknown whether phase-locked responses also underlie the representation of dissonance in auditory cortex. In the present study, responses evoked by musical chords with varying degrees of consonance and dissonance were recorded in A1 of awake macaques and evaluated using auditory-evoked potential (AEP), multiunit activity (MUA), and current-source density (CSD) techniques. In parallel studies, intracranial AEPs evoked by the same musical chords were recorded directly from the auditory cortex of two human subjects undergoing surgical evaluation for medically intractable epilepsy. Chords were composed of two simultaneous harmonic complex tones. The magnitude of oscillatory phase-locked activity in A1 of the monkey correlates with the perceived dissonance of the musical chords. Responses evoked by dissonant chords, such as minor and major seconds, display oscillations phase-locked to the predicted difference frequencies, whereas responses evoked by consonant chords, such as octaves and perfect fifths, display little or no phase-locked activity. AEPs recorded in Heschl's gyrus display strikingly similar oscillatory patterns to those observed in monkey A1, with dissonant chords eliciting greater phase-locked activity than consonant chords. In contrast to recordings in Heschl's gyrus, AEPs recorded in the planum temporale do not display significant phase-locked activity, suggesting functional differentiation of auditory cortical regions in humans. These findings support the relevance of synchronous phase-locked neural ensemble activity in A1 for the physiological representation of sensory dissonance in humans and highlight the merits of complementary monkey/human studies in the investigation of neural substrates underlying auditory perception. (+info)
Universality in the brain while listening to music.
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The human brain, which is one of the most complex organic systems, involves billions of interacting physiological and chemical processes that give rise to experimentally observed neuroelectrical activity, which is called an electroencephalogram (EEG). The presence of non-stationarity and intermittency render standard available methods unsuitable for detecting hidden dynamical patterns in the EEG. In this paper, a method that is suitable for non-stationary signals and preserving the phase characteristics and that combines wavelet and Hilbert transforms was applied to multivariate EEG signals from human subjects at rest as well as in different cognitive states: listening to music, listening to text and performing spatial imagination. It was found that, if suitably rescaled, the gamma band EEG over distributed brain areas while listening to music can be described by a universal and homogeneous scaling, whereas this homogeneity in scale is reduced at resting conditions and also during listening to text and performing spatial imagination. The degree of universality is characterized by a Kullback-Leibler divergence measure. By statistical surrogate analysis, nonlinear phase interaction was found to play an important role in exhibiting universality among multiple cortical regions. (+info)
Asymmetry of brain functional activation: fMRI study under language and music stimulation.
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OBJECTIVE: To determine the asymmetry of the human brain functional activation. METHODS: With the help of GE Signa Horizon MRI system, 14 cases of right-handed volunteers were examined and the blood oxygenation level dependent method was used. The T1-weighted images were obtained with spin echo pulse sequence and the functional imaging (T2*-weighted) was performed using a single shot echo planar imaging pulse sequence. Data analysis was done with Sun Sparc Workstation and by the method of student t test or correlation analysis. RESULTS: Most of activation areas were in the left hemisphere under language stimulation, while they were in the right side under music stimulation. Besides, a few brain areas in the contralateral cerebral cortex were also activated under both stimulations. CONCLUSION: The present study supported the hypothesis of the asymmetry of brain functional activation and many brain areas of the cerebral cortex as well as both hemispheres worked in coordination. In addition, it also proved that fMRI is a feasible method in the study of human brain in vivo. (+info)