Stress Management
Method
For this particular experiment, eighteen participants were recruited in this study. During the psychological training, one person was removed for low sensitivity and one for hypersensitivity to heat stimulation. A third was dismissed for falling asleep during the course of the meditation intervention. Therefore, fifteen healthy volunteers, six males and nine females aged between the ages of 22-35 years completed the study. All of the participants were right-handed, 13 Caucasian, one Asian and one Hispanic. They all had given written consent knowing that they would experience painful,heat stimuli, all the methods were clearly explained and they were free to withdraw from the study without prejudice.
Psychophysical training.
The participants were all in a room at 35–49°C and had to sit there for almost 6 minutes. A 15cm plastic sliding was used to quantify pain intensity and unpleasantness.
MRI session 1.
Subjects were positioned in the MRI scanner, a pulse oximeter was attached to each subject's left index finger to assess heart rate, and a transducer was placed around the chest to gauge respiration rate. The “heat” condition consisted of thermal stimuli that were administered in alternating patterns of heat (49°C) and neutral (35°C) with 12 s durations at each temperature (5 minutes and 55 s total duration per MRI series). They were instructed that their ratings should reflect the overall experience of the entire series.
In MRI session 1, four functional series (two heat; two neutral) were separated by a structural acquisition scan. In the first half of the experiment, participants were instructed to keep their eyes closed and restrict movement across conditions. After the structural image was obtained, participants were instructed to “meditate by focusing on the changing sensations of the breath.”
Mindfulness-based mental training.
Mindfulness-based mental training was performed in four separate, 20 min sessions conducted by a facilitator with >10 years of experience leading similar meditation regimens. Participants had no previous meditative experience and were informed that such training was secular and taught as the cognitive practice of mindfulness meditation. Each training session was held with one to three participants.
On mindfulness meditation training day 1, subjects were encouraged to sit with a straight posture, eyes closed, and to focus on the changing sensations of the breath occurring at the tips of their nostrils. Instructions emphasised acknowledging discursive thoughts and feelings and to return their attention back to the breath sensation without judgement or emotional reaction whenever such discursive events occurred. On training day 2, participants continued to focus on breath-related nostril sensations and were instructed to “follow the breath,” by mentally noting the rise and fall of the chest and abdomen. The last 10 minutes were held in silence so subjects could develop their meditative practice. On training day 3, the same basic principles of the previous sessions were reiterated. However, an audio recording of MRI scanner sounds was introduced during the last 10 minutes of meditation to familiarise subjects with the sounds of the scanner. On the final training session (day 4), subjects received minimal meditation instruction but were required to lie in the supine position and meditate with the audio recording of the MRI sounds to simulate the scanner environment.
MRI session 2.
After successful completion of meditation training, subjects participated in MRI session 2. This session consisted of eight functional series (four heat; four neutral). After completion of the first four “rest” series, subjects were again instructed to “meditate by focusing on the changing sensations of the breath,” at which point the anatomical scan was conducted. Subjects were instructed to meditate until the end of the experiment. Four minutes after the anatomical scan, functional acquisition was resumed, and four meditation series were obtained. Evaluation of pain ratings and experimental procedures were identical to MRI session 1.
Results
Mean (SEM) psychophysical pain ratings across each session. Meditation, after training, significantly reduced pain intensity ratings and pain unpleasantness ratings when compared with rest *p < 0.05.
Brain activations and deactivations illustrate the main effects of ATB and pain in the MRI session before training. In the main effect of pain, there was greater activation in SI corresponding to the stimulation site, ACC, SII, left putamen, and bilateral insula. There was no ATB-related brain activity, but the deactivations for the main effect of meditation were found in the medial PFC, posterior cingulate cortex, thalamus, and paracingulate gyrus. Slice locations correspond to standard stereotaxic space.
References
Zeidan, F, Martucci, K.T., Kraft, R.A., Gordon, N.S., McHaffie, J.G. and Coghill, R.C. (2011) Brain Mechanisms supporting the Modulation of Pain by Mindfulness Meditation. The Journal of Neuroscience, 31(14), 5540-5448.
- Fadel Zeidan
- Katherine T. Martucci
- Robert A. Kraft
- Nakia S. Gordon
- John G. Mc Haffe
- Robert C. Coghill
