Electroencephalogram (EEG) is an important method measuring the brain waves and the electrical activities of the brain. The slowest waves (about 0.5-2 cycles/second) are called delta waves. Those that cycle about 8-12 times/second are alpha waves. Those that cycle about 4-7 times/second are theta waves. Those that cycle about 14-30 times/second are beta waves. Those that cycle about 30-50 times/second are gamma waves.
Different mental conditions may have different brain waves. For example, relaxed and attentive conditions are related to alpha waves. A state in deep sleep may have delta waves. During day-dreams and relaxed states, theta waves may be shown. The states of stress or excitement may be shown as beta waves. Quick responses may be related to the gamma waves. During meditation, the brain waves are likely to synchronize, referring to a more ordered and tranquilized state.
Studies using single photon emission computed tomography (SPECT) imaging on experienced Buddhist meditators have shown that the frontal lobe of the brain has elevated activities during meditation. This region of the brain is usually related to concentration and focused attention. On the other hand, reduced activities have been observed in the parietal lobe, the region that is related to the sense of space and time. However, this does not mean the loss of sense of space and time during meditation.
Meditation can also influence the neurotransmitters by improving the response time. These findings are consistent with the idea that meditation can be a good method for the cultivation of concentration. Even though some meditation practice such as focusing on the breath may sound boring to some people, continuous practice can improve the ability of concentration and make it interesting. However, studies about meditation may have problems such as being subjective. More objective methods to study meditation are still needed.