Brain Mechanisms Supporting the Modulation of Pain by Mindfulness Meditation

1. Brain Mechanisms Supporting the Modulation of Pain by Mindfulness Meditation By: Zeidan, Martucci, Kraft, Gordon, McHaffie, and Coghill

2. “Mindfulness is a state of present awareness. A relaxed state of mind, in which we are conscious of our experience, including sensations, thoughts and feelings, breathing, and surroundings, all with an attitude of non-resistance, peace and acceptance. This does not imply passivity or lack of emotion. Mindfulness engenders faith in the perfection of the moment, and allows each new experience to be felt fully, without the reactive, self-critical, controlling mind.”

3. Meditation is not a religion but simply a method of mental training • You don’t have to sit cross legged on the floor.. You can meditate anywhere • Patience and persistence are required but the practice of meditation does not take a long time • Meditation is not complicated, nor is it about success or failure • It will not deaden your mind or turn your into a “hippie” but rather it helps cultivate a deep and compassionate awareness that allows you to assess your goals and find the optimum path towards realizing your deepest values

4. Introduction • Our perception of the sensory environment is shaped by our own unique past experiences, current cognitive state, and future expectations. • Best example of this is the subjective experience of pain- while noxious stimuli initiates physiological and neurophysiological changes within our bodies, its effects are highly malleable and subject to modification. • The nature of our mental activity can be manipulated through the practice of mindfulness meditation.

5. Shamatha (focused attention) is a form of mindfulness meditation used in this study. • Focused attention is the cognitive practice of sustaining attention on the changing sensations of the breath, monitoring changing events as they arise, disengaging from these events without affective reaction and redirecting attention back to the breath. • This allows you to observe your thoughts as they arise in your mind and little by little, to let go of struggling with them.

6. The authors believed that given that mindfulness meditation can reduce the subjective experience of pain, brain regions involved in meditation must somehow interact with those involved with nociceptive processing • The specific brain mechanisms associated with mindfulness meditation were poorly characterized • How the brain mechanisms could potentially influence pain related brain activity was unknown • Therefore the authors investigated how meditation affects pain related brain processes using an emerging functional magnetic resonance imaging technique (FMRI) and pulsed arterial spin labeled (PASL) MRI

7. THE STUDY: • Hypothesized that in addition to reducing psychophysical pain ratings, meditation would modulate brain regions associated with constructing the pain experience. • Specifically that meditation would engage brain regions such as the prefrontal cortex, anterior cingulate cortex, and the anterior insula which are known for their role in attentional control and affective processing. • They further sought to determine whether meditation related activation of these brain regions was directly associated with pain modulation.

8. Materials and Methods: • Fifteen healthy volunteers, six males and nine females(age range 22-35) completed the study. • Subjects participated in a psychophysical training session- initially familiarizing them with 32 5 second duration stimuli (35-49 degrees C/95- 120.2 degrees F) to provide experience with the visual analog scales (VAS). They then received 5 min and 55 seconds of stimulation. A 15 cm plastic sliding VAS scale was used to quantify pain intensity and unpleasantness. The minimum rating was represented as “no pain sensation/not at all unpleasant” whereas the maximum was “most intense imaginable/most unpleasant imaginable”

9. MRI session 1: Subjects were positioned in the MRI scanner, a pulse oximeter was attached to a subjects left index finger to assess heart rate and a transducer was placed around the chest to gauge respiration rate. Noxious thermal stimuli were delivered to the right calf. The heat condition consisted of alternating patterns of 49 and 35 degrees C with 12 second durations at each temperature for 5 mins and 55 seconds total. The neutral series consisted of only 35 degrees C for 5 mins and 55 seconds. • After each series, subjects evaluation of pain intensity and unpleasantness was acquired with the VAS scale. • In this session four functional series (two heat, two neutral) were separated by a structural acquisition scan. In the first half of the experiment, subjects were instructed to keep their eyes closed and restrict movement (rest). After the image was obtained, they were instructed to meditate by focusing on breathing (ATB)

10. Mindfulness based mental training: • Mindfulness based mental training was performed in four separate, 20 minute sessions conducted by a facilitator with over 10 years of experience • Subjects were taught to focus on the changing sensations of the breath. They were also taught that discursive thoughts were to be acknowledged without affective reaction and to let go by redirecting their focus back on breath sensations. • In sessions 3 and 4, sounds of the MRI scanner were introduced to the subjects to familiarize them with the MRI environment

11. MRI session 2: • Occurred after successful completion of meditation training • Session consisted of eight function series (four heat, four neutral). • After completion of the first four rest series (reduce eye movement and close eyes) subjects were again instructed to meditate by focusing on the changing sensations of the breath at which point the anatomical scan was conducted. Subjects continued to meditate across blocks of noxious stimulation and pain ratings were again assessed after each block.

12. Results • Before meditation training: • There was no change in pain intensity when subjects attended to their breathing • There was no significantly greater brain activation when focusing on breath as contrasted to the rest condition, however there was significantly greater default-mode- related brain activation (medial PFC )in the rest condition compared with the ATB condition suggesting they were actively engaged in a cognitive task when instructed to focus on breath sensations • When compared with neutral stimulation, pain related brain activity was detected in the ACC, bilateral insula, secondary Somatasensory cortex (SII) and SI corresponding to the noxious thermal stimulation on the leg

13. Post meditation training/MRI 2: • Meditation produced a 40% reduction in VAS pain intensity ratings compared with rest. Pain intensity ratings were lower in MRI session 2 compared with MRI session 1. Meditation also significantly reduced pain unpleasantness ratings by 57% • Meditation related brain activity: • Meditating produced bilateral activation of the posterior insula, secondary somatosensory cortex (SII), anterior insula, and the anterior cingulate cortex which are associated with the cognitive modulation of pain (these areas were also activated when compared with neutral stimulation)

14. Somatosensory cortex activation corresponding to the stimulation site significantly decreased during mediation when compared with rest • Individuals with the greatest reductions in pain intensity ratings exhibited the largest meditation induced activation of the right anterior insula and bilateral anterior cingulate cortex • Individuals with the greatest reductions in pain unpleasantness ratings exhibited the greatest activation of the orbitofrontal cortex and the greatest deactivation of the thalamus • After meditation training, brain activity was more pronounced in the frontal pole, thalamus, medial prefrontal cortex, and the anterior cingulate cortex compared with before training

16. Discussion: • In the present investigation, meditation reduced all subject’s pain intensity and unpleasantness ratings with decreases ranging from 11 to 70% and 20 to 93% respectively. • Meditation related pain relief was directly related to brain regions associated with the cognitive modulation of pain providing unique insights into the manner that mediation alters the subjective experience of pain.

17. Meditation reduces pain through multiple brain mechanisms • 1) Significantly reduced pain related afferent processing in the somatosensory cortex • 2) The magnitude of decreased pain intensity ratings was associated with anterior cingulate cortex and right anterior insula activation • 3) Orbitofrontal cortex activation was associated with decreases in pain unpleasantness ratings- may reflect altered executive level reappraisals to consciously process reward and hedonic experiences (meditation directly improves mood and positive mood reduces pain ratings)