Meditation and the Brain
by Martin Wuttke
Researchers have been studying the effects of meditation on the brain and body for over 50 years. One area of interest is the electroencephalograph (EEG) which is the measurement of the electrical activity of the brain (brain waves). The EEG is a direct indicator of states of consciousness and brain function and can be used to determine the effects of meditation on the brain. Different types of meditation produce different effects measured by the EEG but research has identified an important finding that appears in both Tibetan and Kriya yoga advanced meditators: as compared to non-meditators and other types of meditation, there is a significant increase in high frequency activity (referred to as gamma) in the frontal lobes of the brain common to both types of meditation. The frontal lobes are the seat of the brains executive functions such as concentration, focus, motivation, goal directed behavior, impulse control, and higher order reasoning. From an evolutionary standpoint, the frontal lobes were the last to develop, giving the human brain the ‘hardware’ for higher order intelligence. Other studies also reveal that the thickness of this region is actually greater in meditators versus controls.
In addition, EEG studies on Kriya yoga meditators have identified the following:
- There is a decrease in Alpha activity as Theta increases
This occurs with deeper meditation states and correlates with the emergence of theta brain waves as inner awareness is increased. Theta states in meditation are also associated with creativity and intuitive insight. Also correlating with theta is awareness of normally unconscious levels of the mind where the patterns and drives that influence our conscious mind and behaviors can be observed. With continued meditation practice the Meditator learns to dispassionately view the contents of this level and neutralize any negative tendencies (samskaras in Sanskrit).
- There is an increase in the EEG’s frequency called Beta activity
Beta brain waves are associated with activation and therefore, increased activity of brain locations where it is measured. In meditators this is found in brain pathways regulating attention, focus and concentration. In addition, when a Meditator has experiences that have a blissful or ecstatic component there is a large burst of beta in the left frontal lobe of the brain; an area associated with emotional regulation, positive mood and affect. With continued practice, the activation of this area of the brain contributes to feelings of well-being and emotional contentment that many meditators report.
- No alpha blocking to stimuli
Alpha brain waves indicate stillness and the brain in ‘neutral’. Normally, alpha activity is ‘blocked’ when the brain is activated by a stimulus. In meditators alpha remains present, and non-reactive regardless of external stimuli. In essence the reactive pathways in the brain are quieted and the sense, or location of influence shifts from an outer to an inner cause. This shift correlates with improvement in the immune systems function and greater regulation in both under and over acting immune problems.
- There is an overall increase in resting alpha amplitude and wider distribution throughout brain regions after meditation vs. before
A marker in the EEG of advanced meditators is that Alpha brain waves are more powerful and cover larger areas of the brain post meditation. From a functional perspective this indicates a quiet and clear mind. It also indicates more efficient use of energy and therefore greater stamina, endurance and mental capacity.
- Samadhi with increased amplitude high frequency activity known as Gamma
This is the aforementioned Gamma activity; indicating a heightening, or magnification, of consciousness. Gamma is also a ‘binding rhythm’. When it appears in the EEG the brain is connecting many different areas, binding them together, so that the whole brain is involved in the processing of perception. This is the mechanism that is crucial to learning and understanding. The presence of Gamma apparently relates to the gradual emergence of superconscious energies. This brings a greater awareness of oneself and like a spotlight it is impartial. In other words, Gamma exposes both the positive and negative aspects of our personal beliefs, behaviors and attitudes. Hence, the Meditator has the opportunity to neutralize negative aspects. In advanced meditators Gamma is more pronounced than in normals both during meditation and after. This finding has generated a great deal of scientific interest because of the potential to quantify higher states of consciousness from a neurologic perspective.
Findings such as these have generated a new field of study: Neurotheology. From this perspective, the human brain is the medium through which consciousness (God) is expressed. And according to esoteric teachings, the nervous system must undergo systematic refinement in order to process higher and more expanded states of consciousness. Therefore, it may be that the presence of Gamma is an indicator of this refinement process because it means that the brain has increased its capacity to accommodate greater amounts of awareness. This would also provide an explanation for the fact that our spiritual awakening comes from the development of our own innate capacities and that spiritual disciplines such as meditation, yoga, and various contemplative traditions are, in effect, methods that systematically direct and facilitate this refinement process.
SIDEBAR FOR TECHNICAL EXPLANATION:
Frequency is a measurement of the oscillations, or the cycles per second also called Hertz (Hz), of the brain waves. This electrical activity is hypothesized to emerge from vast aggregates of neurons as they communicate and process information. The source of this activity is considered to be the postsynaptic changes in electrical potential along the membrane of the dendrites. These changes are the result of the highly complex interchange of neurotransmitters in synaptic junctions between neurons. Both excitatory neurotransmitters that produce arousal and inhibitory neurotransmitters that decrease arousal are involved in the production of this electrical activity called the EEG.
Delta is the slowest frequency of brain wave activity. Delta is measured from .5 to about 4 cycles per second. Delta is only seen as the dominant rhythm in the adult EEG in the deep sleep state that occurs within the first two hours of the sleep cycle. If it is dominant in the waking state in an adult, it could indicate some type of abnormality. Serotonin is the neurotransmitter involved with delta rhythm and the appropriate regulation of our deep, rejuvenate, delta sleep cycle.
The next brainwave bandwidth is Theta. Theta occurs between 4 and 8 cycles per second. Theta in the adult EEG can indicate drowsiness and can also indicate some abnormalities. Sometimes people with head injuries will show excessive Theta activity either at the sight of the injury or other areas of the brain. Theta has also been found to be outside the norm in some children and adults with ADD and ADHD and sometimes in children with learning disabilities. Theta dominance can also be indicative of a certain meditative state where the individual is on the threshold of awareness of the normally subconscious and unconscious levels of the mind. Theta is associated with the neurotransmitter GABA and acts like a natural tranquilizer to counter stress chemicals in the brain. The temporal lobes, which help govern the frontal and parietal lobes of the brain, regulate emotions and memory and are the primary locations for GABA.
The next bandwidth is Alpha. The mental state of Alpha is similar to putting the clutch in before shifting the gears; it is a holding pattern. Alpha predominance essentially represents a brain that is quiet and at rest. Alpha ranges from 8 to 12 cycles per second. Alpha also regulates the efficiency of the brains processing and thinking speed and is associated with levels of the neurotransmitter acetylcholine in the parietal lobes.
Beta is between 13 cycles per second up to over 30 cycles per second. Low frequency Beta, between 13 and 15 cycles per second, has also been referred to as "sensory motor rhythm" and it appears to be a very important rhythm. When this rhythm is present in the EEG, it has the ability to organize and coordinate many pathways in the brain. It indicates quieting of the processing of incoming sensory information with the appropriate motor response. Sensory-motor rhythm is found to be very high in persons adept in Hatha Yoga while performing postures. Beta waves ranging from 15 to 20 hertz indicate external awareness and heightened states of attention. The neurotransmitter dopamine, which is responsible for our ‘drive’, energy and motivation is regulated by the frontal lobes and is associated with Beta. From 20 to 30 hertz, too much Beta activity can indicate states of hyper-arousal, anxiety or panic. However; from approximately 35 hertz on, this can be a very different indicator in the brain of the advanced meditators and is called Gamma. Gamma is considered in these cases to be evidence of ‘being more conscious’.