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| Zoran Josipovic |
Our cerebral cortex is generally regarded as having two broad functional systems, one "task positive" and "external" concerned with sensory and motor systems and tasks, and the other "task negative", "default" or "intrinsic" and unrelated to tasks. The "intrinsic" system includes our old friends the PCC and the medial prefrontal cortex (mPFC) and the related elements in the default mode network (DMN) as defined by Andrews-Hannah, et. al.
The consistent observation has been that these two systems are "anti-correlated", i.e when one is "on", the other is "off", even when there is no stimulus and no tasking, as in rest, sleep or under anesthesia. This "antagonistic" relationship is somehow maintained by the cortical organization.
The "intrinsic" network has been delineated by efforts like those of Andrews-Hannah by using "selfing" tasks that activate different regions (DMN). Problem solving has also been investigated to ascertain which particular regions are involved. As discussed previously, there appears to be a significant difference in the activation of the DMN/"selfing" network and the regions involved in problem solving.
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| Andrews-Hannah default mode network inter-connectivity |
There is much research on how closely correlated, and presumably functionally connected, elements are in the "intrinsic" network. The Andrews-Hannah graphic at the left determines the diameter of the lines between any two centers by how often the centers "worked together"/were operating at the same time. This made possible a separation of the centers into "self and other" (green) and "self through time" (blue) sub-networks, which had some useful implications.
This interconnectivity approach has proven useful in psychopathology as well and has extended to Alzheimer's disease, autism spectrum disorders, attention deficit hyperacivity disorder (ADHD), sleep, hypnosis, sedation, etc. If the "normal" functional interconnections between regions are degraded, or weakened, as discussed in an earlier blog on autism spectrum disorders, then the conditions manifest.
The intriguing prospect that arises is that perhaps meditation, as revealed through many studies over the ages, can selectively engage these two antagonistic "external" and "internal" networks, or parts of them, or even potentially integrate them.
The Josipovic team used three different Tibetan Buddhist meditations to evaluate this possibility. The 24 subjects were experienced in the specific Tibetan Buddhist meditation practices used. All were from Buddhist meditation centers in the US with from 4,000 to 37,000 hrs of practice. Only 7 had experiences in other approaches. The earlier Brewer, et. al paper used Theravadin Buddhists and meditations, which are different. It is VERY critical that we understand exactly what directions were given to meditators in these studies, as a FEW key words can change the meditation, and presumably the results, very significantly.
The three meditations used were:
a) Fixation - "Keep your gaze on the fixation point and allow your mind to wander naturally, and avoid engaging in any type of meditation".
b) Focused attention (FA) - "Keep a steady focus on the object of meditation, the fixation point, to the exclusion of other mental content, and if thoughts arise do not follow them but remain focused on the fixation point. If your mind wanders off, bring it back gently to the object of focus."
c) Non-dual awareness (NDA) - "Rest in reflexive NDA, equally aware of inside and outside of your body, allowing experiences to arise and subside of their own accord." Meditators were told to avoid "fixing attention exclusively on either external or internal experience or trying to keep one's mind empty of thoughts and feelings through holding effortful focus."
In discussing this paper w/Zoran, he explained "reflexive" in the NDA instructions as "the Buddhist concept "svasamveda" or self-knowing, i.e. nondual awareness (or pure awareness or pure consciousness) knows itself to be conscious without using any intermediary cognitive process - this is its auto-knowing property. He did not intend for there to be a focus to consciously balance the inside and outside of the body.
One fascinating aspect of this study was that the regions of interest (ROI) were determined for each individual by using functional and anatomical criteria revealed in watching a movie clip during fMRI scanning. There is a detailed description of this approach, very different from that used by Andrews-Hannah. Every participant had different center regions and sizes for their ROIs. These are the "standard" functional centers, but they are individually experimentally defined.
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| Correlations between Intrinsic (y-axis) and Extrinsic (x-axis) for A (Fixation), B (Focused attention) and C (Non-dual awareness) Individual results |
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| Aggregate Inter-Area Correlations for Three Different Meditations |
The importance of this finding is that previously it was generally believed that the extrinsic and intrinsic networks were fundamentally and structurally evolved to be antagonistic as a cortical organization principle. This supports the "if you're tasking, the internal network will be shut down, if you're not tasking, the internal network will be active". However, this ex-OR-in process extends to even when tasking is not being done, like in rest, sleep and while under anesthesia.
This study showed that non-dual awareness as defined in the Tibetan Buddhist tradition, with a balanced awareness of both internal and external, does somehow mediate the inherent antagonistic cognitive structure. These results are supported by many studies and contradicted by others to some extent. The bottom line is that non-dual awareness is clearly not like concentration in that it appears to balance somewhat, competing and antagonistic cognitive networks.
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