Home > Soul > 14. Geon is Created by Alpha Waves

 

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Figure 14a. The ascending arousal system. The first branch involves LDT and PPT, projecting to the thalamus. The second branch extends to the basal forebrain (BF) which has direct connection with anterior cingulate cortex (ACC). Thalamus and ACC are the original generators of alpha waves. [Source: Schwartz and Roth, 2008]

During deep sleep and general anesthesia, our consciousness is lost. It implies that the geon is disintegrated, namely, the GR waves no longer bind together. To wake-up, or to regain consciousness, the geon must be re-created. Thus, neuroscience studies on consciousness may provide useful information about the creation of a geon. It turns out that the synchronized brain activities at the alpha band play a critical role.

Wakefulness is known to arise from the ascending arousal system which starts from the upper brainstem, and separates into two branches (Figure 14a). The first branch involves laterodorsal tegmental (LDT) and pediculopontine tegmental (PPT), projecting to the thalamus. The second branch extends to the basal forebrain (BF) which has direct connection with anterior cingulate cortex (ACC). Interestingly, thalamus and ACC are the original generators of alpha waves. The alpha waves originating from ACC propagate to the frontal regions of the brain. Those originating from the thalamus propagate mainly to the posterior parts.

The creation of a gravitational geon requires sufficient synchronized brain activities so that the generated GR waves may bind together. Experimentally, the degree of synchronization can be quantified by using functional magnetic resonance imaging (fMRI) to measure functional connectivity between brain areas. It has been demonstrated that consciousness is directly related to the functional connectivity between frontal and posterior regions (Figure 14b). Furthermore, the general anesthetic, ketamine, increases both gamma and theta oscillations, but reduces α rhythms. These observations support the view that consciousness arises from global synchronization of α rhythms.

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Figure 14b. Functional connectivity and consciousness. Left: reduced connectivity between frontal and temporal lobes leads to vegetative state. Right: general anesthetic propofol causes decreased connectivity between frontal and parietal lobes. [Source: Boly et al, 2013]