Methodological Approaches
Electrocortical Measures
Intensive long-term meditation practice has the potential to alter the patterns of interaction among the varied regions and systems of the brain. Repeated detection of distraction and redirecting and focusing of attention during meditation is what, in part, constitutes the “practice” during meditation. Such practice, over time, engages and reengages brain networks to an extent that may induce changes in how we think and pay attention to what occurs in our external and internal environments. This practice can have a wide range of effects, which include more vivid perceptions, greater voluntary focus, and changes in our emotional responses to stressful or upsetting challenges. In the Shamatha Project, a longitudinal study, we address these possibilities by analyzing dense channel array (88 channel) electroencephalography (EEG) recordings taken from retreatants and wait-listed controls at three distinct time points throughout a 3-month retreat period (the control group was tested again during their subsequent retreat). Testing sessions included two blocks of time devoted to meditation (mindfulness of breathing and compassion) and a variety of cognitive and attentional tasks. The tasks used include a response inhibition task (RIT), a Stroop task, a continuous performance vigilance task (CPT), an attentional blink task, emotion-potentiated startle, and emotion-eliciting film-viewing tasks. This rich collection of behavioral and electrocortical data is fertile ground for testing hypotheses about how long-term, intensive meditation practices alter functional neural networks that subserve attention, emotion, and cognition.To increase the quality and value of our unique EEG data, we use state-of-the-art artifact rejection procedures that allow us to maximize the signal-to-noise ratio in our datasets. We apply a Second-Order Blind Source Identification (SOBI) algorithm and remove artifacts based on a Semi-Automated Artifact Removal Tool (SMART) output display that was developed in-house (Saggar et al, 2012; http://web.stanford.edu/~saggar/Software.html). The resultant reconstructed data has markedly reduced contributions from artifactual sources such as eye blinks and scalp muscle tension. With EEG data that has been ‘cleaned’ in this way, we are confident that our results more accurately reflect veritable electrocortical activity compared with data that has been pre-processed using traditional artifact rejection methods, a concern that has been raised in the literature (e.g. McMenamin et al, 2010).We use two broad classes of approach to the analysis of EEG data – the examination of ongoing oscillatory activity and of event-related potentials (ERPs). Regional analysis of oscillatory activity allows for inferences to be made about the spatial distribution and coarse time course of regional cortical activation patterns that may occur in the absence of repeated stimuli – for instance during the inter-stimulus interval, meditation practice, or long duration picture viewing. ERPs are used to investigate the post-stimulus neural activation time course of repeated stimuli. We use a variety of approaches to investigate these event-related responses – quantification of single trial and averaged responses, source estimation procedures, and topographic analyses.Currently we are conducting two comprehensive studies examining the electrophysiology of sustained attention longitudinaly. In the first, we focus on the detection of rare hard to discriminate perceptual events (termed vigilance) and in the second we focus on sustained attention to inhibiting habitual responses (thought to be related to executive control).
Biomarkers of Stress & Well-being
Research suggests that many health-relevant biomarkers are related to psychological and emotional well-being. Given that intensive meditation practice is believed to have adaptive psychological effects, such relations between biological and psychological factors may provide another avenue through which intensive meditation practice affects measurable changes in practitioners. To test this, we’ve measured baseline values of biomarkers related to physiological stress, social affiliation, and well-being alongside questionnaire measures of psychological functioning in two retreat and control cohorts. In the Shamatha Project, blood samples were collected from practitioners and a wait-listed control group at three time points: before, during, and after a three-month shamatha retreat. From these samples, we measured levels of telomerase (Jacobs et al, 2013), BDNF, and the cytokines IL-6 and IL-10 in order to investigate the impact of meditation on stress physiology. We also measured oxytocin and arginine vasopressin, neuropeptides known to be involved in social affiliation. Additionally, we collected saliva samples, which allow us to assess cortisol (Jacobs et al, 2013) and DHEA levels, were collected from both groups. In a separate but related study in collaboration with Spirit Rock Meditation Center, we are analyzing telomere length as well as blood levels of telomerase, cytokines, oxytocin, vasopressin, and gene expression from a group of individuals who participated in a one-month, silent, vipassana retreat and from a meditation-experienced control group. This work is conducted in collaboration with a number of colleagues at Davis, UCSF and Stanford.
Behavioral Measures of Cognitive Control, Perception & Attention
We are also deeply interested in how aspects of attention (dividing, shifting, and sustaining attention) and executive control (maintaining information in working memory and inhibiting task-inappropriate behavior) change over the course of long-term meditation training (Sahdra et al, 2011; Zanesco et al, 2013). Using computer-based cognitive experiments, we examine performance accuracy and reaction time on tests designed to measure different aspects of attention and cognition. One primary domain of research is exploring how meditation training affects an individual’s capacity to sustain their attention over long periods of time, in particular whether or not such training reduces the vigilance decrement, a commonly observed decline in performance that occurs when attention must be sustained over time (MacLean et al 2009, 2010). Furthermore, we are interested in meditation training's relationship to the frequency of mind wandering (i.e., distraction) when given a task on which to focus.
Comprehensive Interviews & Surveys
Another important component of our research involves capturing practitioners’ own accounts of their lives and experiences. We ask practitioners to describe the meditative process, as well as the role meditation has in their lives, through semi-structured interviews and self-recorded audio diaries. This allows us insights into individuals' experiences that cannot be obtained through traditional laboratory tasks. These descriptions are then coded to reveal patterns of themes that may arise and change over time. In addition, we administer batteries of questionnaires containing previously validated measures of various adaptive and maladaptive constructs (Sahdra et al, 2011), as well as measures of perceived impact of training. In some cases, most notably the Shamatha Project, we have also conducted interviews and given questionnaires to participants’ close family and friends, in order to get their perspective on how meditation and participation in a retreat may have affected their loved one. Our analysis of the data involves applying cutting-edge statistical techniques and network analytic approaches to analyze the complex dynamics between psychological and experiential components collected from participants.
Daily Mood, Experience & Dream Diaries
We are also committed to investigating the richness of individuals' daily experiences through the use of self-report questionnaire instruments that are completed at the end of each day of a meditation retreat. We use these instruments to examine fluctuations in participants' affect and mood, as they may change frequently over the course of a long-term retreat. Furthermore, these instruments let us quantify the duration and types of meditative practices and activities that participants engage in while on retreat.
Intensive long-term meditation practice has the potential to alter the patterns of interaction among the varied regions and systems of the brain. Repeated detection of distraction and redirecting and focusing of attention during meditation is what, in part, constitutes the “practice” during meditation. Such practice, over time, engages and reengages brain networks to an extent that may induce changes in how we think and pay attention to what occurs in our external and internal environments. This practice can have a wide range of effects, which include more vivid perceptions, greater voluntary focus, and changes in our emotional responses to stressful or upsetting challenges. In the Shamatha Project, a longitudinal study, we address these possibilities by analyzing dense channel array (88 channel) electroencephalography (EEG) recordings taken from retreatants and wait-listed controls at three distinct time points throughout a 3-month retreat period (the control group was tested again during their subsequent retreat). Testing sessions included two blocks of time devoted to meditation (mindfulness of breathing and compassion) and a variety of cognitive and attentional tasks. The tasks used include a response inhibition task (RIT), a Stroop task, a continuous performance vigilance task (CPT), an attentional blink task, emotion-potentiated startle, and emotion-eliciting film-viewing tasks. This rich collection of behavioral and electrocortical data is fertile ground for testing hypotheses about how long-term, intensive meditation practices alter functional neural networks that subserve attention, emotion, and cognition.To increase the quality and value of our unique EEG data, we use state-of-the-art artifact rejection procedures that allow us to maximize the signal-to-noise ratio in our datasets. We apply a Second-Order Blind Source Identification (SOBI) algorithm and remove artifacts based on a Semi-Automated Artifact Removal Tool (SMART) output display that was developed in-house (Saggar et al, 2012; http://web.stanford.edu/~saggar/Software.html). The resultant reconstructed data has markedly reduced contributions from artifactual sources such as eye blinks and scalp muscle tension. With EEG data that has been ‘cleaned’ in this way, we are confident that our results more accurately reflect veritable electrocortical activity compared with data that has been pre-processed using traditional artifact rejection methods, a concern that has been raised in the literature (e.g. McMenamin et al, 2010).We use two broad classes of approach to the analysis of EEG data – the examination of ongoing oscillatory activity and of event-related potentials (ERPs). Regional analysis of oscillatory activity allows for inferences to be made about the spatial distribution and coarse time course of regional cortical activation patterns that may occur in the absence of repeated stimuli – for instance during the inter-stimulus interval, meditation practice, or long duration picture viewing. ERPs are used to investigate the post-stimulus neural activation time course of repeated stimuli. We use a variety of approaches to investigate these event-related responses – quantification of single trial and averaged responses, source estimation procedures, and topographic analyses.Currently we are conducting two comprehensive studies examining the electrophysiology of sustained attention longitudinaly. In the first, we focus on the detection of rare hard to discriminate perceptual events (termed vigilance) and in the second we focus on sustained attention to inhibiting habitual responses (thought to be related to executive control).
Biomarkers of Stress & Well-being
Research suggests that many health-relevant biomarkers are related to psychological and emotional well-being. Given that intensive meditation practice is believed to have adaptive psychological effects, such relations between biological and psychological factors may provide another avenue through which intensive meditation practice affects measurable changes in practitioners. To test this, we’ve measured baseline values of biomarkers related to physiological stress, social affiliation, and well-being alongside questionnaire measures of psychological functioning in two retreat and control cohorts. In the Shamatha Project, blood samples were collected from practitioners and a wait-listed control group at three time points: before, during, and after a three-month shamatha retreat. From these samples, we measured levels of telomerase (Jacobs et al, 2013), BDNF, and the cytokines IL-6 and IL-10 in order to investigate the impact of meditation on stress physiology. We also measured oxytocin and arginine vasopressin, neuropeptides known to be involved in social affiliation. Additionally, we collected saliva samples, which allow us to assess cortisol (Jacobs et al, 2013) and DHEA levels, were collected from both groups. In a separate but related study in collaboration with Spirit Rock Meditation Center, we are analyzing telomere length as well as blood levels of telomerase, cytokines, oxytocin, vasopressin, and gene expression from a group of individuals who participated in a one-month, silent, vipassana retreat and from a meditation-experienced control group. This work is conducted in collaboration with a number of colleagues at Davis, UCSF and Stanford.
Behavioral Measures of Cognitive Control, Perception & Attention
We are also deeply interested in how aspects of attention (dividing, shifting, and sustaining attention) and executive control (maintaining information in working memory and inhibiting task-inappropriate behavior) change over the course of long-term meditation training (Sahdra et al, 2011; Zanesco et al, 2013). Using computer-based cognitive experiments, we examine performance accuracy and reaction time on tests designed to measure different aspects of attention and cognition. One primary domain of research is exploring how meditation training affects an individual’s capacity to sustain their attention over long periods of time, in particular whether or not such training reduces the vigilance decrement, a commonly observed decline in performance that occurs when attention must be sustained over time (MacLean et al 2009, 2010). Furthermore, we are interested in meditation training's relationship to the frequency of mind wandering (i.e., distraction) when given a task on which to focus.
Comprehensive Interviews & Surveys
Another important component of our research involves capturing practitioners’ own accounts of their lives and experiences. We ask practitioners to describe the meditative process, as well as the role meditation has in their lives, through semi-structured interviews and self-recorded audio diaries. This allows us insights into individuals' experiences that cannot be obtained through traditional laboratory tasks. These descriptions are then coded to reveal patterns of themes that may arise and change over time. In addition, we administer batteries of questionnaires containing previously validated measures of various adaptive and maladaptive constructs (Sahdra et al, 2011), as well as measures of perceived impact of training. In some cases, most notably the Shamatha Project, we have also conducted interviews and given questionnaires to participants’ close family and friends, in order to get their perspective on how meditation and participation in a retreat may have affected their loved one. Our analysis of the data involves applying cutting-edge statistical techniques and network analytic approaches to analyze the complex dynamics between psychological and experiential components collected from participants.
Daily Mood, Experience & Dream Diaries
We are also committed to investigating the richness of individuals' daily experiences through the use of self-report questionnaire instruments that are completed at the end of each day of a meditation retreat. We use these instruments to examine fluctuations in participants' affect and mood, as they may change frequently over the course of a long-term retreat. Furthermore, these instruments let us quantify the duration and types of meditative practices and activities that participants engage in while on retreat.
