Prof. J.P.N. Mishra
Skin resistance to electrical current provides a measure of autonomic nervous system reactivity. An increase in the skin resistance of meditators has been reported by several groups. Increase in skin resistance indicates a decrease in skin conduction and a reduction in its fluctuations. It is well established that skin resistance decreases in states of anxiety or stress, and increases during relaxation. The large increases in skin resistance of meditators found in these studies are impressive.
Galvanic skin response, or GSR, was used to measure recovery from stress; a study by Orme-Johnson (1973) showed that meditators recovered from stress more quickly than non-meditators. Specifically, habituation of the GSR to stress was faster for meditators than for controls, and meditators made fewer multiple responses during habituation, indicating greater stability in response to stress. In other experiments, meditators produced fewer spontaneous GSR than their non-meditating controls, both during and while out of meditation. Spontaneous GSR is defined as spontaneous fluctuations in skin resistance and the frequency of spontaneous GSR defines the lability of an individual to stress. For example, the frequency rises with anger, fear, and increased epinephrine and norepinephrine blood levels. Those individuals with lower frequencies of spontaneous GSR exhibit more effective behavior in a number of stressful situations, are less impulsive on motor tasks, and have quicker perceptions. Rapid GSR habituation and low levels of spontaneous GSR are reported in the literature to be correlated with physiological and behavioral characteristics associated with good mental health. Therefore, meditation benefits practitioners by decreasing the frequency of spontaneous GSR. In general, these studies indicate that meditators possess a more adaptive pattern of stress response than controls.
On another level, meditation produces specific neural activation patterns involving decreased limbic arousal in the brain (Schwartz 1975). Since the limbic system contains the hypothalamus, which controls the autonomic nervous system, reduction in limbic arousal may explain how meditation reduces stress and increases autonomic stability to stress. Ultimately, meditation strengthens and enhances the ability to cope with stress. In comparing meditation groups to resting controls, reports of increased galvanic skin resistance (GSR) and decreased spontaneous electro dermal response (EDR) are common (Goleman & Schwartz, 1976, Wallace and Benson, 1972 etc. This suggest decrease sympathetic activity and a move towards a relax state (Jevning, 1992), also the heart rate decrease during meditation (Holems 1980).
The researches shows activation in neurol structures involving attention (lateral prefrontal and padietal regions) (Herzog, 1990) and arousal/autonomic control (Pregenual anterior Singulate, amygdala, Midbrain and hypothalamus) (Lazar, et al, 2000).
