Senior Yoga Researcher Shirley Telles, PhD, and her colleagues have corroborated previous research to show that not only does breathing through one nostril effect the autonomic nervous system as established in previous studies–i.e., left nostril breathing stimulates parasympathetic activity for a calming effect while right nostril breathing stimulates sympathetic activity for a stimulating effect, but it also effects hemispheric dominance. In a study involving 29 male subjects that compared 45 minutes of left nostril, right nostril, alternate nostril, breath awareness and no special breathing on five consecutive days, the results suggest that right nostril yoga breathing facilitates the activity of the contralateral (left) hemisphere. After breathing through the right nostril, the subjects had more focused attention and could more easily discriminate between stimuli.
I asked Dr. Telles about this, because there is some controversy about whether the changes we have observed in other studies as a result of uninostril breathing are the result of autonomic shifts only or hemispheric dominance. Here is what she says:
“Our findings on uninostril breathing can be summarized like this: when we looked at midlatency auditory EPs which examine the neural centers from the ear till the first relay in the cortex we find IPSILATERAL changes. The first relay in the cortex just says whether a SOUND has OCCURRED or NOT.”
As I understand it, what this means is that the first response of the brain to noticing a stimuli like a sound occurs on the same side of the brain in which the breathing has been practiced.
However, Dr. Telles continues, “When the stimuli are cognitively processed this occurs in SECONDARY areas (which are needed to understand details about the stimuli such as WHAT is the STIMULUS? from WHERE is it coming?) Secondary processing occurs CONTRALATERALLY.”
What this means is that in the second phase of the brain’s response, i.e.when we become aware that the stimuli has occurred (details about the sound, for example whether the sound is a telephone ringing or a doorbell) requires cognitive processes which occur on the opposite side of the brain in which the breathing has been practiced.
So it seems to be correct to say that both sides of the brain are stimulated by uninostril and alternate nostrll breathing practices. However, cognition, which comes second, registers in the brain on the opposite side of the nostril breathing practice or “contralaterally.”
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