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Kumbhaka and samadhi During kumbhaka the quantum of prana increases as the body, breath and mind are brought into a state of stillness. The stillness allows prana and consciousness to intensify, as in a pressure cooker - the intensity of energy and heat go up because they are not released from the body. This pressure is sustained while kumbhaka is maintained, allowing prana and consciousness to flow unimpeded throughout pranamaya kosha.
The expansion of prana also has a substantial effect on the mind. There is greater mental power and the awareness becomes acute. The capacity of the mind increases due to the stillness, as there are no fluctuations or disturbances. Just as light is transformed into a laser beam, the mind becomes totally focused and one-pointed. At this stage there is total cessation of the mental patterns. The dissipation of the mind ceases and the mental perception and the pranic structure sever their connection with the physical body. There is a total experience of intensity: intensity of stillness, intensity of mind, intensity of prana and intensity of practice. This intensity of practice enables one to hold the concentration and focus, and leads on to the path of samadhi.
The process can also be described physiologically. In kumbhaka the carbon dioxide levels in the brain increase. In reaction, the neurons begin firing nerve impulses in the brain to signal the body to breathe. Transmission of a nerve impulse involves more than one neuron; it needs a synapse (the point where an impulse passes from one neuron to another) and neurotransmitters, which are synthesized nerve cells. The longer the kumbhaka is held, the more nerve impulses are generated and transmitted.
While kumbhaka is maintained, this constant firing of impulses builds up an immense amount of nervous energy in the brain, forcing the creation of new neuronal pathways and the activation of dormant centres. The brain is literally illumined and awakened. In addition, the corpus callosum, a thin sheet of membrane between the two hemispheres of the brain, is
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