Wednesday, February 20, 2013

Moving your mind instead of your body

I found this paper earlier today, Mindfulness starts with the body: somatosensory attention and top-down modulation of cortical alpha rhythms in mindfulness meditation, and planned to comment on it a bit, but became sidetracked by the CRPS paper.

Serendipitously Todd Hargrove beat me to it, and produced this wonderful blogpost! Meditation and Pain. Thank you Todd - you saved me piles of time!

What I thought might be fun would be to compare and contrast, speculate a bit on the possibilities presented by this new (unrelated) paper by Luczak et al. from NatureReviewsNeuroscience, Gating of Sensory Input by Spontaneous Cortical Activitywhich proposes a mechanism by which rostral centers might "control" sensory input. It was about auditory input, but I'm thinking, this could maybe be extrapolated to other kinds of sensory input. Nature Reviews Neuroscience commented and suggested reading this paper as well, from a few years ago, Cortical state and attention, (Harris et al) in which the authors describe how selective attention can affect input into cortical columns. This sentence from the abstract is particularly delicious: 
"We suggest that selective attention involves processes that are similar to state change, and that operate at a local columnar level to enhance the representation of otherwise non-salient features while suppressing internally generated activity patterns."
The NRN post about these two papers, titled "A gate for sensory responses," and behind a paywall, says, "In a new study, Harris and colleagues show that one role for irregular spontaneous activity may be to allow higher-order structures to control the representation of sensory stimuli... Harris and colleagues show that one role for irregular spontaneous activity may be to allow higher-order structures to control the representation of sensory stimuli." There are references to brain neuronal functions called "activity packets," (which are spontaneous) , and "Population activity fluctuations were strong in synchronized states — that is, there were clear activity packets — whereas population activity seemed more evenly distributed in desynchronized states..  both during silent periods and during sustained tone presentation, suggesting that cortical state influences the structure of activity packets more than does an auditory stimulus... [in that] activity packets are triggered by corticocortical rather than thalamocortical connections, the authors propose that activity packets in primary auditory cortex reflect the top-down opening of a ‘gate’ that allows input from lower auditory regions to be processed by primary auditory cortex." (My bold)

OK, that's a bit dense, but I think it means that the cortex has final call on what goes on in the brain, or at least where to put a boundary between itself and what it has to sift from its inner and outer environments somewhere in the cortical columns (processors) of the brain. And I think that sifts right back to the paper from PLoS1 that Todd blogged about, an excerpt from which is here: 
"Using a common set of mindfulness exercises, mindfulness based stress reduction (MBSR) and mindfulness based cognitive therapy (MBCT) have been shown to reduce distress in chronic pain and decrease risk of depression relapse.

Paying attention to interoception in a safe context might be all it takes. Really, it's looking that way. 
Last word to Todd: 
"Meditation seems like powerful medicine indeed, perhaps second only to general exercise in its health benefits. I find it fascinating that this all purpose mental muscle can be developed by something as simple as focusing attention on bodily sensations.So don’t just sit there!Pay attention to just sitting there! You might get better at playing the mental movies you want to watch."

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