Journal of Gyansagar Science Foundation 2013 04 01

Author(s): Sanjeev Sogani, Vimal Jain
Publisher: Gyansagar Science Foundation

Page 64

Dr. Sudhir, Volume 1 Issue 1 April 2013
Most types of meditation, which involve an initial focusing of attention, are associated with increased regional blood flow or glucose metabolism in the prefrontal and cingulate cortex, areas that are important in selection of a mental task
⚫ The frontal lobes, especially the prefrontal regions help to organize, prioritize, plan and focus attention • During visualization regional blood flow increases in the "visual cortex" and visual association areas in the occipital lobes
• In contemplation of "self" the parietal lobes on both sides are activated
• Meditation appears to begin by activating prefrontal and cingulate cortex, associated with the will or intent to clear one's mind of thoughts or to focus on an object
• There also occurs deafferentation of PSPL, means a decrease in arrival of distracting stimuli to striate cortex and PSPL, enhancing sense of focus during meditation results in altered perception of selfexperience during spiritual or meditative practices • Thalamus is a relay station and filtering station for sensory information that reaches the cerebral cortex for further processing
• During meditation the thalamus filters sensory input to part of the parietal lobe (the posterior superior parietal lobule or PSPL), involved in "body awareness"
decreased activation of the PSPL
• Increased thalamic blood flow during meditation implies that this is an active process of filtering of information and processing of information about the body
• Some studies during meditation show increased activity in the Hippocampus or inner aspect of the temporal lobe
• Hippocampus has close functional connections with hypothalamus and autonomic nervous system
• During meditation, integration of autonomic nervous system activity with different parts of brain involved in meditation is increased
⚫ fMRI studies of Kundalini yoga support increased activity of hippocampus and amygdala in meditation
• Stimulation of right lateral amygdala results in stimulation of ventromedial hypothalamus and peripheral parasympathetic system associated with a subjective sensation, first of relaxation and later, a more profound sense of quiescence
Neurochemical effects
Meditation has been shown to increase serotonin
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production. Serotonin is an important neurotransmitter and neuropeptide that influences mood and behavior in many ways. Meditation has also been associated with increased melatonin availability. In general during meditation GABA is increased in dorsal raphae nuclei. Cortisol is decreased in paraventricular nucleus and B-endorphin diurnal rhythms are changed for better. i.e. peace and pleasure feelings.
Heart rate and breathing slows down during meditation and stress response is cut down. There is a relatively greater parasympathetic nervous system activity during meditation, so production of catecholamines are reduced. So the patients with hypertension, coronary disease and other stress related diseases are benefited.
Increased serotonin level helps improving mood of person with meditation. It is observed that there is increase skin resisitance with meditation. There is decreased limbic arousal, which in turn explains how, meditation strengthens and enhances the ability to cope with stress and reduces reactivity of a person. So these are the good effects on autonomic nervous system during meditation.
Effects of meditation on CNS is further seen as it accelerates neural conduction or augments the release of neurotransmitters, thereby decreasing synaptic time. This results in a change in muscle firing threshold and pattern. By inhibiting the left cortical hemisphere, the sense of time and logic no longer dominate consciousness during meditation. Therefore manifestation of ego is suppressed. The thoughts, desires, perceptions, perversions and duality all are reduced. As we know, these are all functions attributed to mind and hence the faculty of mind is reduced more and more with depth of meditation, particularly in long term practitioners. Once faculty of mind is reduced or controlled, the meditator enjoys enormous bliss and peace. This is because the root of our miseries is our own mind which is normally not in our control.
Recent Hypothesis in This Context
• When meditation acts as a constant repetitive stimulus, certain permanent qualitative and quantitative changes develop in nervous system. Neuro transmitters and neuro modulators may stimulate growth of dormant neurons to develop a centre higher than neocortex- God module.
• This higher centre will exert inhibitory control over present neocortex and thereby over mind as a wholethereby suppressing consciousness and all mental activities.