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<p>Meditative practices typically require several coordinated cognitive activities. This study measured changes in cerebral blood flow during "verbal" based meditation by Franciscan nuns involving the internal repetition of a particular phrase. These results are compared with those we previously described in eight Buddhist meditators who use a type of "visualization" technique. Three experienced practitioners of verbal meditation were injected via i.v. at rest with 260 MBq of Tc-99m HMPAO and scanned 30 min. later on a triple head SPECT camera for 45 min. Following the baseline scan, subjects meditated for approximately 40 min. at which time they were injected with 925 MBq of HMPAO while they continued to meditate for 10 min. more (total of 50 min. of meditation). The injection during meditation was designed not to disturb practice. Subjects were scanned 20 min. later for 30 min. Counts were obtained for regions of interest for major brain structures and normalized to whole-brain blood flow. Compared to baseline, mean verbal meditation scans showed increased blood flow in the prefrontal cortex (7.1%), inferior parietal lobes (6.8%), and inferior frontal lobes (9.0%). There was a strong inverse correlation between the blood flow, change in the prefrontal cortex and in the ipsilateral superior parietal lobe (p<.01). This study on a limited number of subjects demonstrated the feasibility of studying different types of meditation with neuroimaging techniques, suggested that several coordinated cognitive processes occur during meditation, and also raised important methodological issues.</p>
<p>Using brain imaging techniques, investigators measured brain activity of an advanced Tibetan Buddhist meditator. The results showed an increase of blood flow during the peak of meditation to the left prefrontal area of the brain. Other areas which showed increase in activity were the right and left thalamus, and caudate nucleus. Areas which showed a deficit in activity were the right sensory-motor cortex and the left hippocampus (with the latter showing a marked decrease). The lateral parietal lobe on the right showed an decrease in activity while the left showed an increase. The results were in accord with a theory of brain activation during meditation from earlier studies.</p>
<p>Note that SPECT (Single-Photon Emission Computerized Tomography) is a brain imaging technique that uses radioactive dyes to track metabolic activity in the brain. (Zach Rowinski 2005-03-05)</p>
<p>Blood flow in the cerbral cortex of Tibetan Buddhist meditators was observed using Single Photon Emission Computed Tomography (SPECT), a brain imaging technique which measures metabolic activity in the brain. The results showed a significant increase in activity (P < .05) in the cingulate gyrus, inferior and orbital frontal cortex, as well as the dorsolateral prefrontal cortex and thalamus. The authors speculate a correlated change in the dorsolateral prefrontal cortex and the superior parietal lobe may account for the feeling of an altered sense of space during meditation. (Zach Rowinski 2005-03-05)</p>
<p>Meditation is a complex mental process involving changes in cognition, sensory perception, affect, hormones, and autonomic activity. Meditation has also become widely used in psychological and medical practices for stress management as well as a variety of physical and mental disorders. However, until now, there has been limited understanding of the overall biological mechanism of these practices in terms of the effects in both the brain and body. We have previously described a rudimentary neuropsychological model to explain the brain mechanisms underlying meditative experiences. This paper provides a substantial development by integrating neurotransmitter systems and the results of recent brain imaging advances into the model. The following is a review and synthesis of the current literature regarding the various neurophysiological mechanisms and neurochemical substrates that underlie the complex processes of meditation. It is hoped that this model will provide hypotheses for future biological and clinical studies of meditation.</p>