Alterations in brain activation during Meditation

The electro-physiological activity of the brain changes through prolonged practice of Sahaja yoga mediation from typical fast waves during normal consciousness to a state of slow waves, similar but not identical to the sleep state (Matsuoka et al., 1990, Aftanas et al., 2001; link to Aftanas). The slow waves (the so called theta waves) are thought to be formed by the limbic system, which it is believed is activated during Sahaja Yoga meditation. Likewise, studies using high resolution brain imaging have shown that during meditation, activity in the frontal and other cortical brain regions (thought to be the areas that originate thought processes) are reduced, while activity in the limbic brain areas increases, especially in the hippocampus (Lou et al., 1999, Lazar et al., 2000), an area associated associated with the stress hormone cortisol.

The limbic system regulates emotion and motivation. It has traditionally been considered an evolutionarily lower brain centre than the cortex, which is responsible for higher level cognitive functions. However, the limbic system is essential for regulating our individual drives. Without this motivation no cognitive functions would be possible. Indeed, depressed patients, for example, with their lack of drive due to abnormal  activation of the limbic system, suffer from cognitive and attentional dysfunctions. Without the battery, i.e. the emotional and motivational centre of the brain, all other functions the brain is capable of are bereft of their motivational charge and ultimately cannot unfold to their full potential.

Meditation with its relaxation of the body and limbic system, provides the necessary energy sources for a full potential of cognitive functioning. Only when we are fully relaxed, motivated, satisfied and full of energy can we truly activate our full potential, whether it is cognitive or artistic. Interestingly, another brain region that appears to undergo increased activation as a result of meditation is the hippocampus, which is linked to the stressrelated hypothalamuspituitary- axis. Patients with post-traumatic stress disorder or depression show a reduced size in their hippocampi that may be related to increased stress-induced corticol levels (Bremner et al., 1998, 1999). An increase in hippocampus activation may thus be another indicator of stress reduction through meditation. Thoughts can indeed have a corresponding reaction at the physiological level. Anger, for example, has been shown to raise pulse rates and blood pressure and can even tear blood vessels, leading to heart infarction (Williams, 2001).