Role of the supplementary motor area in auditory sensory attenuation.

Self-generated tones elicit smaller brain responses as compared to externally generated tones. This phenomenon known as sensory attenuation has been explained in terms of an internal forward model in which the brain predicts the upcoming events and thereby attenuates the sensory processing. Such prediction processes have been suggested to occur via an efference copy of the motor command that is sent from the motor system to the lower order sensory cortex. However, little is known about how the prediction is implemented in the brain's network organization. Because the supplementary motor area (SMA) is a primary brain structure of the motor system, we attributed the implementation of the prediction to the SMA. To address this question, we examined generative network models for auditory ERPs. ERPs were evoked by either a self-generated or externally generated tone, while subjects were paying attention to their motor action or to the tone. The tone itself was the same throughout all conditions. The network models consisted of three subsets embedding alternative hypotheses of the hierarchical structures: (1) auditory fields of the temporal lobe, (2) adding connections to the SMA, and (3) adding prediction signal to the SMA. The model comparison revealed that all ERP responses were mediated by the network connections across the auditory cortex and the SMA. Importantly, the prediction signal to the SMA was required when the tone was self-generated irrespective of the attention factor, whereas the externally generated tone did not require the prediction. We discussed these results in the context of the predictive coding framework.

Phase synchrony in slow cortical potentials is decreased in both expert and trained novice meditators.

Neuronal interactions coupled by phase synchronization have been studied in a wide range of frequency bands, but fluctuations below the delta frequency have often been neglected. In the present study, phase synchrony in slow cortical potentials (SCPs, 0.01-0.1 Hz) was examined during two different mental states; a resting state and a breath-focused mindfulness meditation. SCP phase synchrony in 9 long-term expert meditators (on average 22 years of experience) were compared with the data obtained from 11 novices. Additionally, after the novices attended an 8-week mindfulness-based stress reduction (MBSR) program, SCP phase synchrony was measured again. While expert meditators and novices exhibited the same amount of SCP phase synchrony in the resting state, decreased synchronization was found during meditation among expert meditators as well as novices who had participated in the MBSR program (but not prior to the program). These findings suggest that phase synchrony in slow cortical activity is context-dependent and could provide crucial information in the study of the human mind.

Remote meditation support - a multimodal distant intention experiment.

BACKGROUND: Distant intention research refers to experiments in which a distant interaction between two persons is assessed that precludes conventional communication. In these experiments the intention of one person is varied systematically while the effect of this variation is assessed in the remote other person. AIMS: Our study aimed at improving effect sizes by participant selection based on a screening test and by including experienced meditators. METHOD: 66 participants with meditation experience participated in a forced-choice psi-test as a screening test. Participants with similar performance were invited as pairs for a distant intention experiment. The task of the helpee was to focus attention on a candle and to indicate lapses in attention by pressing a button. In a within-subject design the task of the remote helper was either to assist the helpee in this effort or to engage in a distraction task. Electrodermal activity (EDA) and button presses from the helpee served as dependent variables. RESULTS AND CONCLUSION: Participants' performance in the psi-screening test did not exceed chance expectations. In the distant intention experiment with 30 sessions no distant intention effect could be found in the prespecified analyses. The results in the psi-screening test were not correlated with performance in the main experiment. However, we found a large negative correlation between self-reported exceptional experiences of the helper and two EDA variables, namely skin conductance level and number of non-specific skin conductance responses. This correlation, if replicated, can hardly be explained without the assumption of a distant interaction.

Frontal Theta Dynamics during Response Conflict in Long-Term Mindfulness Meditators.

Mindfulness meditators often show greater efficiency in resolving response conflicts than non-meditators. However, the neural mechanisms underlying the improved behavioral efficiency are unclear. Here, we investigated frontal theta dynamics-a neural mechanism involved in cognitive control processes-in long-term mindfulness meditators. The dynamics of EEG theta oscillations (4-8 Hz) recorded over the medial frontal cortex (MFC) were examined in terms of their power (MFC theta power) and their functional connectivity with other brain areas (the MFC-centered theta network). Using a flanker-type paradigm, EEG data were obtained from 22 long-term mindfulness meditators and compared to those from 23 matched controls without meditation experience. Meditators showed more efficient cognitive control after conflicts, evidenced by fewer error responses irrespective of response timing. Furthermore, meditators exhibited enhanced conflict modulations of the MFC-centered theta network shortly before the response, in particular for the functional connection between the MFC and the motor cortex. In contrast, MFC theta power was comparable between groups. These results suggest that the higher behavioral efficiency after conflicts in mindfulness meditators could be a function of increased engagement to control the motor system in association with the MFC-centered theta network.

Rolandic beta-band activity correlates with decision time to move.

Research findings link rolandic beta-band activity to voluntary movements, but a linkage with the decision time to move remains unknown. We found that beta-band (16-28Hz) activity shortly before the movement onset is relevant for the decision time to move: the more pronounced the decrease in beta-band synchronization, the earlier the subjective experience of the decision to move. The linkage was relevant regarding 'decision', but not regarding 'intention' timing that has been often applied in the study of free will. Our findings suggest that oscillatory neural activity in the beta-band is an important neural signature pertaining to the subjective experience of making a decision to move.

Meditation and attention: A controlled study on long-term meditators in behavioral performance and event-related potentials of attentional control.

Meditation practice involves attention regulation, and thus is thought to facilitate attention control mechanisms. Studies on meditation techniques using a behavioral measurement of the Attention Network Test (ANT) have shown enhanced attention control, but neural features remain unknown. In the present study, event-related potentials (ERPs) and behavioral data from twenty long-term meditators were examined, compared to data obtained from twenty matched controls. Results showed that meditators made fewer error responses than controls, especially during the incongruent target condition, suggesting higher accuracy in executive attention control among meditators. The P3 amplitude in the parietal area remained constant in the congruent and incongruent target conditions among meditators, indicating a higher parietal P3 amplitude during the incongruent target condition relative to matched controls. The findings that meditators exhibited fewer error responses on the ANT and a lack of parietal P3 modulation irrespective of reaction time are discussed in the context of attentional resource allocation.

Do meditators have higher awareness of their intentions to act?

Intuitively, being aware of one's inner processes to move should be crucial for the control of voluntary movements. However, research findings suggest that we are not always aware of the processes leading to movement execution. The present study investigated induced first-person access to inner processes of movement initiation and the underlying brain activities which contribute to the emergence of voluntary movement. Moreover, we investigated differences in task performance between mindfulness meditators and non-meditators while assuming that meditators are more experienced in attending to their inner processes. Two Libet-type tasks were performed; one in which participants were asked to press a button at a moment of their own decision, and the other one in which participants' attention was directed towards their inner processes of decision making regarding the intended movement which lead them to press the button. Meditators revealed a consistent readiness potential (RP) between the two tasks with correlations between the subjective intention time to act and the slope of the early RP. However, non-meditators did not show this consistency. Instead, elicited introspection of inner processes of movement initiation changed early brain activity that is related to voluntary movement processes. Our findings suggest that compared to non-meditators, meditators are more able to access the emergence of negative deflections of slow cortical potentials (SCPs), which could have fundamental effects on initiating a voluntary movement with awareness.

Subjective expansion of extended time-spans in experienced meditators.

Experienced meditators typically report that they experience time slowing down in meditation practice as well as in everyday life. Conceptually this phenomenon may be understood through functional states of mindfulness, i.e., by attention regulation, body awareness, emotion regulation, and enhanced memory. However, hardly any systematic empirical work exists regarding the experience of time in meditators. In the current cross-sectional study, we investigated whether 42 experienced mindfulness meditation practitioners (with on average 10 years of experience) showed differences in the experience of time as compared to 42 controls without any meditation experience matched for age, sex, and education. The perception of time was assessed with a battery of psychophysical tasks assessing the accuracy of prospective time judgments in duration discrimination, duration reproduction, and time estimation in the milliseconds to minutes range as well with several psychometric instruments related to subjective time such as the Zimbardo Time Perspective Inventory, the Barratt Impulsivity Scale and the Freiburg Mindfulness Inventory. In addition, subjective time judgments on the current passage of time and retrospective time ranges were assessed. While subjective judgements of time were found to be significantly different between the two groups on several scales, no differences in duration estimates in the psychophysical tasks were detected. Regarding subjective time, mindfulness meditators experienced less time pressure, more time dilation, and a general slower passage of time. Moreover, they felt that the last week and the last month passed more slowly. Overall, although no intergroup differences in psychophysical tasks were detected, the reported findings demonstrate a close association between mindfulness meditation and the subjective feeling of the passage of time captured by psychometric instruments.

Electroencephalogram activity induced by magnetic stimulation on heart meridian.

Many studies on the effects of acupuncture on brain activity have been concerned with the stimulation of specific acu-points. However, research on brain activity with the stimulation of the body-meridian line is still quite novel. The hypothesis of the present study is that heart meridian stimulations with different directions of line-magnet poles would elicit different effects on EEG activity. Twenty-three healthy young adults between the age of 19 and 22 years old participated in the experiment. Two tiny NEO line-magnets were applied to stimulate the heart meridian. EEG activities were changed significantly between different treatments on the heart meridian using line-magnet with different directions of magnetic poles (p<0.05). The present study shows that the stimulation of the heart meridian with the line-magnets has an effect on brain activity associated with the direction of the line-magnet pole.