>
> A neural basis for benefits of meditation
>
> February 13th, 2013 in Psychology & Psychiatry
> Magnetoencephalographic studies show that people who have been trained in
> mindfulness have quicker and larger changes in alpha wave amplitude when they
> shift focus. Credit: Mike Cohea/Brown University Credit: Mike Cohea/Brown
> University
>
> Why does training in mindfulness meditation help patients manage chronic
> pain and depression? In a newly published neurophysiological review, Brown
> University scientists propose that mindfulness practitioners gain enhanced
> control over sensory cortical alpha rhythms that help regulate how the brain
> processes and filters sensations, including pain, and memories such as
> depressive cognitions.
>
> The proposal, based on published experimental results and a validated
> computer simulation of neural networks, derives its mechanistic framework
> from the intimate connection in mindfulness between mind and body, since
> standardized mindfulness meditation training begins with a highly localized
> focus on body and breath sensations. This repeated localized sensory focus,
> the scientists write, enhances control over localized alpha rhythms in the
> primary somatosensory cortex where sensations from different body are
> "mapped" by the brain.
>
> In effect, what the researchers propose in their paper in Frontiers in Human
> Neuroscience, is that by learning to control their focus on the present
> somatic moment, mindfulness meditators develop a more sensitive "volume knob"
> for controlling spatially specific, localized sensory cortical alpha rhythms.
> Efficient modulation of cortical alpha rhythms in turn enables optimal
> filtering of sensory information. Meditators learn not only to control what
> specific body sensations they pay attention to, but also how to regulate
> attention so that it does not become biased toward negative physical
> sensations such as chronic pain. The localized attentional control of
> somatosensory alpha rhythms becomes generalized to better regulate bias
> toward internally focused negative thoughts, as in depression.
>
> "We think we're the first group to propose an underlying neurophysiological
> mechanism that directly links the actual practice of mindful awareness of
> breath and body sensations to the kinds of cognitive and emotional benefits
> that mindfulness confers," said lead author Catherine Kerr, assistant
> professor (research) of family medicine at the Alpert Medical School and
> director of translational neuroscience for the Contemplative Studies
> Initiative at Brown.
>
> Experimental evidence
>
> In experiments that Kerr and neuroscientist co-authors Stephanie Jones and
> Christopher Moore have published over the last few years, the team has used a
> brain imaging technology called magnetoencephalography (MEG) to show that
> alpha rhythms in the cortex correlate with sensory attention and that the
> ability to regulate localized alpha brainwaves on a millisecond scale is more
> distinct in people who have had standardized mindfulness training than in
> those who have not. The trio led these experiments at the Massachusetts
> Institute of Technology, Harvard, and Massachusettes General Hospital before
> they all came to Brown in 2011.
>
> In one experiment published in the Journal of Neuroscience in 2010, they
> observed that when people focused their attention on sensations in the left
> hand, the corresponding "map" for the hand in the cortex showed a marked drop
> in alpha wave amplitude (as if to reduce filtering there). When the subjects'
> attention shifted away from that body part, the alpha rhythm amplitude in the
> corresponding brain map went back up (as if restoring the alpha filter).
> Other research groups have shown this to be the case for other kinds of
> attention-related tasks including focusing spatial attention and working
> memory.
>
> Then in 2011 in Brain Research Bulletin, the team published another paper.
> They randomized subjects to eight weeks of mindfulness training versus a
> control group. In MEG, they asked members of each group to focus attention on
> sensations in their hand and then to switch their attention to their foot.
> The people trained in mindfulness displayed quicker and larger changes in
> alpha wave amplitude in their brain's hand map when they made the attentional
> shift than the six people who did not have mindfulness training.
>
> Mindful computational model
>
> In addition to the emerging experimental evidence, the research framework is
> also informed by a computer model that Jones has developed to simulate the
> alpha brainwaves through reciprocal interactions between the cortex, which
> processes information and thoughts, and the thalamus, which is like a
> switchboard that mediates information flow from the rest of the brain to the
> cortex. The model is well validated in that it produces alpha rhythms that
> closely match those observed in live MEG scans of real subjects.
>
> Jones, assistant professor (research) of neuroscience, did not originally
> develop the model to aid meditation research.
>
> "We were investigating what are the brain mechanisms that can create this
> prominent alpha rhythm and mediate its impact on sensory processing," Jones
> said. "The model simulates the electrical activity of neural networks and
> makes very specific predictions about how this rhythm is generated. Once we
> understand the brain processes regulating alpha rhythm expression, we can
> better understand how it can be modulated with mindfulness practice and why
> this is beneficial."
>
> Among the most important predictions is one that could explain how gaining
> control of alpha rhythms not only enhances sensory focus on a particular area
> of the body, but also helps people overcome persistent competing stimuli,
> such as depressive thoughts or chronic pain signals.
>
> To accomplish this, the model predicts, meditators must achieve proper
> control over the relative timing and strength of alpha rhythms generated from
> two separate regions of the thalamus, called thalamic nuclei, that talk to
> different parts of the cortex. One alpha generator would govern the local
> "tuning in," for instance of sensations in a hand, while the other would
> govern the broader "tuning out" of other sensory or cognitive information in
> the cortex.
>
> It's a bit like focusing a telescope by precisely aligning the position of
> two different lenses. The authors' framework hypothesizes that experienced
> meditators gain the ability to turn that proverbial focus knob to align those
> different rhythms.
>
> Working with the framework
>
> In the new paper the authors propose that training chronic pain patients in
> the standardized mindfulness techniques of focusing on and then focusing away
> from pain, should result in MEG-measurable, testable improvements in alpha
> rhythm control.
>
> "By this process of repeatedly engaging and disengaging alpha dynamics across
> the body map, according to our alpha theory, subjects are re-learning the
> process of directly modulating localized alpha rhythms," they wrote. "We
> hypothesize that chronic pain patients trained in mindfulness will show
> increased ability to modulate alpha in an anticipatory tactile attention
> paradigm similar to that used in [the 2011 study]."
>
> Many such experiments are yet to be done, Kerr acknowledges, and her group
> can only do so many.
>
> "There are a number of hypotheses in this framework that can be tested," Kerr
> said. "That's one of the reasons we wanted to put this out as a framework. It
> is beyond our ability to test all of these ideas. We wanted to make this
> available to the scientific field and present this unified view."
>
> Provided by Brown University
>
>
> "A neural basis for benefits of meditation." February 13th, 2013.
> http://medicalxpress.com/news/2013-02-neural-basis-benefits-meditation.html
>
