Theta activity and meditative states: spectral changes during concentrative meditation

Brain oscillatory activity is associated with different cognitive processes and plays a critical role in meditation. In this study, we investigated the temporal dynamics of oscillatory changes during Sahaj Samadhi meditation (a concentrative form of meditation that is part of Sudarshan Kriya yoga). EEG was recorded during Sudarshan Kriya yoga meditation for meditators and relaxation for controls. Spectral and coherence analysis was performed for the whole duration as well as specific blocks extracted from the initial, middle, and end portions of Sahaj Samadhi meditation or relaxation. The generation of distinct meditative states of consciousness was marked by distinct changes in spectral powers especially enhanced theta band activity during deep meditation in the frontal areas. Meditators also exhibited increased theta coherence compared to controls. The emergence of the slow frequency waves in the attention-related frontal regions provides strong support to the existing claims of frontal theta in producing meditative states along with trait effects in attentional processing. Interestingly, increased frontal theta activity was accompanied reduced activity (deactivation) in parietal–occipital areas signifying reduction in processing associated with self, space and, time.     

Control over experience? Magnitude of the attentional blink depends on meditative state

The information processing capacity of the human mind is limited, as is evidenced by the so-called ‘attentional-blink’ deficit. This deficit is believed to result from competition between stimuli for limited attentional resources. We examined to what extent advanced meditators can manipulate their attentional state and control performance on an attentional blink task. We compared the magnitude of the attentional blink between states of focused attention meditation (in which one focuses tightly on an object) and states of open monitoring meditation (in which one is simply aware of whatever comes into experience) in a sample of experienced meditators. We found a smaller attentional blink during open monitoring compared to focused attention meditation due to reduced T1 capture. Of note, this effect was only found for very experienced meditators (on average 10,704 h of experience). These data may suggest that very advanced practitioners can exert some control over their conscious experience.     

Meditation,well-being and cognition in heartfulness meditators – A pilot study

Meditative practices can vary considerably in technique as well as their effects. Heartfulness is a popular meditation technique that includes in its repertoire, a unique passive form of meditation. We carried out a pilot study recruiting male heartfulness meditators (proficient n = 24, with 6–28 years of meditation experience; novice n = 24, 5 to 16 months of experience) and subsequently recruited matched controls (n = 15). We examined well-being, and carried out high-density EEG recordings to examine indices of meditation and cognition in these groups. Well-being scores were significantly higher for the proficient meditators as compared to novice and intermediate for the controls. We did not find any group differences in cognitive processing. During meditation, enhanced occipital gamma was found in proficient meditators as compared to controls. We discuss the findings from this pilot study and suggest avenues for future research.     

Occipital gamma activation during Vipassana meditation

Long-term Vipassana meditators sat in meditation vs. a control rest (mind-wandering) state for 21 min in a counterbalanced design with spontaneous EEG recorded. Meditation state dynamics were measured with spectral decomposition of the last 6 min of the eyes-closed silent meditation compared to control state. Meditation was associated with a decrease in frontal delta (1–4 Hz) power, especially pronounced in those participants not reporting drowsiness during meditation. Relative increase in frontal theta (4–8 Hz) power was observed during meditation, as well as significantly increased parieto-occipital gamma (35–45 Hz) power, but no other state effects were found for the theta (4–8 Hz), alpha (8–12 Hz), or beta (12–25 Hz) bands. Alpha power was sensitive to condition order, and more experienced meditators exhibited no tendency toward enhanced alpha during meditation relative to the control task. All participants tended to exhibit decreased alpha in association with reported drowsiness. Cross-experimental session occipital gamma power was the greatest in meditators with a daily practice of 10+ years, and the meditation-related gamma power increase was similarly the strongest in such advanced practitioners. The findings suggest that long-term Vipassana meditation contributes to increased occipital gamma power related to long-term meditational expertise and enhanced sensory awareness.     

Cerebral blood flow differences between long-term meditators and non-meditators

We have studied a number of long-term meditators in previous studies. The purpose of this study was to determine if there are differences in baseline brain function of experienced meditators compared to non-meditators. All subjects were recruited as part of an ongoing study of different meditation practices. We evaluated 12 advanced meditators and 14 non-meditators with cerebral blood flow (CBF) SPECT imaging at rest. Images were analyzed with both region of interest and statistical parametric mapping. The CBF of long-term meditators was significantly higher (p < .05) compared to non-meditators in the prefrontal cortex, parietal cortex, thalamus, putamen, caudate, and midbrain. There was also a significant difference in the thalamic laterality with long-term meditators having greater asymmetry. The observed changes associated with long-term meditation appear in structures that underlie the attention network and also those that relate to emotion and autonomic function.     

Mindfulness meditation and relaxation training increases time sensitivity

Two experiments examined the effect of mindfulness meditation and relaxation on time perception using a temporal bisection task. In Experiment 1, the participants performed a temporal task before and after exercises of mindfulness meditation or relaxation. In Experiment 2, the procedure was similar than that used in Experiment 1, except that the participants were trained to mediate or relax every day over a period of several weeks. The results showed that mindfulness meditation exercises increased sensitivity to time and lengthened perceived time. However, this temporal improvement with meditation exercises was primarily observed in the experienced meditators. Our results also showed the experienced meditators were less anxious than the novice participants, and that the sensitivity to time increased when the level of anxiety decreased. Our results were explained by the practice of mindfulness technique that had developed individuals’ abilities in devoting more attention resources to temporal information processing.     

A single session of meditation reduces of physiological indices of anger in both experienced and novice meditators

The goal of the present study was to explore how anger reduction via a single session of meditation might be measured using psychophysiological methodologies. To achieve this, 15 novice meditators (Experiment 1) and 12 practiced meditators (Experiment 2) completed autobiographical anger inductions prior to, and following, meditation training while respiration rate, heart rate, and blood pressure were measured. Participants also reported subjective anger via a visual analog scale. At both stages, the experienced meditators’ physiological reaction to the anger induction reflected that of relaxation: slowed breathing and heart rate and decreased blood pressure. Naïve meditators exhibited physiological reactions that were consistent with anger during the pre-meditation stage, while after meditation training and a second anger induction they elicited physiological evidence of relaxation. The current results examining meditation training show that the naïve group’s physiological measures mimicked those of the experienced group following a single session of meditation training.     

Coherence between emotional experience and physiology: does body awareness training have an impact?

Two fundamental issues in emotion theory and research concern: (a) the role of emotion in promoting response coherence across different emotion systems; and (b) the role of awareness of bodily sensations in the experience of emotion. The present study poses a question bridging the two domains; namely, whether training in Vipassana meditation or dance, both of which promote attention to certain kinds of bodily sensations, is associated with greater coherence between the subjective and physiological aspects of emotion. We used lag correlations to examine second-by-second coherence between subjective emotional experience and heart period within individuals across four different films. Participants were either: (a) experienced Vipassana meditators (attention to visceral sensations), (b) experienced dancers (attention to somatic sensations), and (c) controls with no meditation or dance experience. Results indicated a linear relationship in coherence, with meditators having highest levels, dancers having intermediary levels, and controls having lowest levels. We conclude that the coherence between subjective and cardiac aspects of emotion is greater in those who have specialized training that promotes greater body awareness.     

Trait lasting alteration of the brain default mode network in experienced meditators and the experiential selfhood

Based on the finding in novices that four months of meditation training significantly increases frontal default mode network (DMN) module/subnet synchrony while decreasing left and right posterior DMN modules synchrony, the current study tested the prediction whether experienced meditators (those who are practising meditation intensively for several years) had a change in the DMN “trinity” of modules as a baseline trait characteristic and whether this change is in a similar direction as in the novice trainees who practised meditation for only four months. Comparison of functional connectivity within DMN subnets (measured by electroencephalogram operational synchrony in the three separate DMN modules) between five experienced meditators and 10 naïve participants (who were about to start the meditation training) fully support the prediction. Interpretation that links such DMN subnets changes to the three-dimensional components of the experiential selfhood was proposed.     

Effects of long-term meditation practice on attentional biases towards emotional faces: An eye-tracking study

Attentional biases towards affective stimuli reflect an individual balance of appetitive and aversive motivational systems. Vigilance in relation to threatening information reflects emotional imbalance, associated with affective and somatic problems. It is known that meditation practice significantly improves control of attention, which is considered to be a tool for adaptive emotional regulation. In this regard, the main aim of the present study was to evaluate the influence of meditation on attentional bias towards neutral and emotional facial expressions. Eyes were tracked while 21 healthy controls and 23 experienced meditators (all males) viewed displays consisting of four facial expressions (neutral, angry, fearful and happy) for 10 s. Measures of biases in initial orienting and maintenance of attention were assessed. No effects were found for initial orienting biases. Meditators spent significantly less time viewing angry and fearful faces than control subjects. Furthermore, meditators selectively attended to happy faces whereas control subjects showed attentional biases towards both angry and happy faces. In sum we can conclude that long-term meditation practice adaptively affects attentional biases towards motivationally significant stimuli and that these biases reflect positive mood and predominance of appetitive motivation.     

The happy face of mindfulness: Mindfulness meditation is associated with perceptions of happiness as rated by outside observers

The last decade has witnessed an enormous increase in research examining the effects of mindfulness meditation. One of the basic assumptions guiding this research is that meditation ultimately makes people happier. In this article, in two studies we tested whether meditators actually look happier. To address this question, outside raters judged the happiness of meditators and non-meditators based on a 15-s video clip of their behaviour. Study 1 demonstrated that novice meditators looked happier after an intensive 9-day meditation retreat (as compared to before the retreat), while Study 2 demonstrated that experienced mindfulness meditators looked happier as compared to controls. The interpersonal implications of these findings are discussed.     

Brainwave classification without the help of limb movement and any stimulus for character-writing application

Recently, Brain-Computer Interfaces (BCIs) have been extensively popular for employing Electroencephalography (EEG) signals to control devices with different applications. The use of BCIs currently involves for lots of applications to help the disabilities who cannot communicate with other people, as it is an alternative way for communication by passing the need of speech. Although the applications to spell the character with BCI systems (e.g., P300-speller, SSVEP-speller, Hex-O-spell) have been already developed, but these techniques are not flexible in the real scenarios because they require the stimulus all the time or stopping the activity to focus on the limb movement in order to provide the accuracy of brain responses. In this paper, the feasibility of brainwave classification for the applications of character-writing by considering only the EEG signals without the need of stimulus unlike the literature is newly introduced. This paper adopts a classification technique named Artificial Neural Network (ANN) and focuses on two different characters; straight line and circle. From the experimental results, the suitable position of electrodes are the pair of electrodes (F3 and F4) at the frontal lobe, which provide the best result as compared to other areas due to its important role in perception, maintenance and revival of the information. The experimental results indicate that the classification accuracy of the proposed technique is about 70%, which in turn leads to a significant achievement for the development of character-writing applications.     

Measuring mindfulness—the Freiburg Mindfulness Inventory (FMI)

Mindfulness, a concept originally derived from Buddhist psychology, is essential for some well-known clinical interventions. Therefore an instrument for measuring mindfulness is useful. We report here on two studies constructing and validating the Freiburg Mindfulness Inventory (FMI) including a short form. A preliminary questionnaire was constructed through expert interviews and extensive literature analysis and tested in 115 subjects attending mindfulness meditation retreats. This psychometrically sound 30-item scale with an internal consistency of Cronbach alpha = .93 was able to significantly demonstrate the increase in mindfulness after the retreat and to discriminate between experienced and novice meditators. In a second study we broadened the scope of the concept to 86 subjects without meditation experience, 117 subjects with clinical problems, and 54 participants from retreats. Reducing the scale to a short form with 14 items resulted in a semantically robust and psychometrically stable (alpha = .86) form. Correlation with other relevant constructs (self-awareness, dissociation, global severity index, meditation experience in years) was significant in the medium to low range of correlations and lends construct validity to the scale. Principal Component Analysis suggests one common factor. This short scale is sensitive to change and can be used also with subjects without previous meditation experience.     

Just a minute meditation: Rapid voluntary conscious state shifts in long term meditators

Meditation induces a modified state of consciousness that remains under voluntary control. Can meditators rapidly and reversibly bring about mental state changes on demand? To check, we carried out 128 channel EEG recordings on Brahma Kumaris Rajayoga meditators (36 long term: median 14240 h meditation; 25 short term: 1095 h) and controls (25) while they tried to switch every minute between rest and meditation states in different conditions (eyes open and closed; before and after an engaging task). Long term meditators robustly shifted states with enhanced theta power (4–8 Hz) during meditation. Short term meditators had limited ability to shift between states and showed increased lower alpha power (8–10 Hz) during eyes closed meditation only when pre and post task data were combined. Controls could not shift states. Thus trained beginners can reliably meditate but it takes long term practice to exercise more refined control over meditative states.     

Perceptual visual grouping under inattention: electrophysiological functional imaging

Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were recorded from 22 scalp electrodes and source current density estimations were conducted for the net response to the task-irrelevant background patterns, using low-resolution electromagnetic tomography (LORETA). Although participants’ subjective reports indicated that neither type of organization induced awareness, electrophysiological results showed they both evoked significant activation in occipital, parieto-temporal and frontal brain areas. Behavioral results demonstrated that only grouping of the simple pattern arose under inattention. In contrast to the complex pattern, the processing of the simple pattern was associated with an initially longer latency and higher activation beginning at 130 ms. These results support the distinction of grouping patterns differing in complexity of shape formation.     

Bicartesian Coherence

Coherence is demonstrated for categories with binary products and sums, but without the terminal and the initial object, and without distribution. This coherence amounts to the existence of a faithful functor from a free category with binary products and sums to the category of relations on finite ordinals. This result is obtained with the help of proof-theoretic normalizing techniques. When the terminal object is present, coherence may still be proved if of binary sums we keep just their bifunctorial properties. It is found that with the simplest understanding of coherence this is the best one can hope for in bicartesian categories. The coherence for categories with binary products and sums provides an easy decision procedure for equality of arrows. It is also used to demonstrate that the categories in question are maximal, in the sense that in any such category that is not a preorder all the equations between arrows involving only binary products and sums are the same. This shows that the usual notion of equivalence of proofs in nondistributive conjunctive-disjunctive logic is optimally defined: further assumptions would make this notion collapse into triviality.     

关于城市居民心理凝聚感与压力源关系的研究

使用问卷测试方式对城市居民的心理凝聚感和压力源之问的关系进行研究。结果发现,在7种压力源因子和压力源总分中,经济收支和工作压力、家庭生活事件、知识技能更新3个压力源因子和压力源总分在三个级别的心理凝聚感组之间存在显著差异,心理凝聚感水平高的被试,对外界工作生活事件产生了最低的压力评价。职业、经济收入不同的群体在心理凝聚感的得分上存在显著的差异,经济收入高的个体有较高的心理凝聚感。说明不同心理凝聚感水平的被试面对相同的工作生活压力,其压力认知评价存在差异。     

Studies in the Peripheral Retina: II. The Purkinje After-Image on the Near Foveal Area of the Retina

Although true second-order conditioning has, apparently, not previously been demonstrated in any American laboratory, it was found that by using electrodes implanted in the occipital sensory areas of hens, second-order limb responses could be readily established in approximately 33% of a group of 51 subjects developing first-order conditioned responses. In a number of subjects, the second-order responses remained stable for hundreds of trials and were highly resistant to extinction. Electrolytic damage at the sites of the cerebral reinforcing electrodes had no discernible effect on the stability of the second-order conditioned responses. They could also be evoked when direct current which temporally overlapped the cerebral conditioned stimuli was passed between or adjacent to the signal electrodes.     

不同心理一致感个体压力情境下的情绪特点研究

以46名大学生为被试,利用“九洞仪”创设实验室压力情境,考察不同心理一致感个体压力情境下的情绪反应及恢复特点。结果表明：（1）压力情境下,高、低心理一致感个体的情绪反应存在显著性差异。高心理一致感个体出现较多的积极情绪,低心理一致感个体则以消极情绪体验为主。（2）低心理一致感压力情境诱发出的消极情绪显著多于积极情绪,消极情绪的诱发量较大。（3）压力任务后,高心理一致感个体在情绪恢复量上显著多于低心理一致感个体,心理健康的自我康复力较大。（4）压力任务前后,低心理一致感个体的消极情绪诱发量显著高于恢复量,在消极情绪变化上表现出“诱发多,恢复少”的特点。