Introduction to Alpha
Alpha (8-12 Hz) was the first brain wave discovered in 1929 by Hans Berger, the inventor of the EEG. Alpha lies in the middle of the five brain wave categories. It acts as a bridge between the slow waves of Theta and Delta and the faster waves of Beta. It is the dominant frequency in adults and the least contaminated by muscular artifacts. Alpha waves are generated throughout the brain and are strongest in the back of the brain in the occipital lobes.
Alpha Functions
Because Alpha power increases with eyes closed, Alpha was thought to represent an “idling” state for brain regions not engaged in sensory information processing. Current research shows that Alpha is more of a top-down inhibitory control process. EEG researchers now understand that Alpha inhibition goes up in the brain regions not required to execute a task and down in the areas that are focused on a task (Klimesch 1999).
For example, when attention is focused on the auditory portion of an audiovisual stimulus, Alpha power increases in the back of the brain where vision is processed (Klimesch 2012). Alpha can therefore be understood as an inhibitory filter, turning off brain regions that are distracting to a given task to create a greater Signal-to-Noise ratio in brain regions that are involved in the task.
In addition to focusing attention, Alpha also plays a key role in semantic memory performance. Semantic memory is a type of long-term memory that deals with our general world knowledge—such as facts, ideas, concepts, and the meanings of words. During semantic tasks, high Alpha (10-12 Hz) decreases (or desynchronizes) over the left hemisphere, which processes language and logic (Klimesch 1999).
Alpha Waves and Meditation
The Alpha frequency gets a lot of attention these days as the brain wave of meditation. While this view is oversimplified, Alpha increases are one of the most well-reported findings in the EEG meditation literature (Cahn and Polich 2006). Alpha can be thought of as the gateway frequency into meditation, as increasing Alpha for a stronger internal focus is one of the first steps along the path of meditative mastery.
The Alpha frequency band can be further broken down into two sub-bands:
- Alpha 1 (8-10 Hz): Otherwise known as low Alpha, this band dominates when we are in a peaceful state of relaxation with little awareness of our surroundings. Frontal Alpha 1 is rewarded in Transcendental Meditation and Quiet Mind meditation to promote a witness consciousness that transcends its own procedures. Alpha 1 is more related to attentional demands than Alpha 2.
- Alpha 2 (10-12 Hz): High Alpha is present when we are awake and alert with a generalized awareness of our surroundings. Alpha 2 is a better index of engagement in semantic memory tasks. Alpha 2 increases in the back of the brain during semantic memory retrieval and when one is tuning out the outside world.
A Closer Look at Alpha 1
Alpha 1 waves are generally associated with being relaxed and internally focused. Frontal Alpha 1 increases in meditations that non-reactively monitor thoughts and emotions, such as Vipassana and Zazen (Kakumanu & Nair et al. 2014, Huang & Lo 2009). Frontal Alpha 1 inhibits executive decision making in the front of the brain and therefore supports not reacting to thoughts. Posterior Alpha 1 increases are seen in OM (Open Monitoring) and Focus meditations. When posterior Alpha 1 increases, it suppresses sensory processing of the outside world, thereby supporting an internal focus.
In Body Scan meditations, Alpha 1 filters the processing of sensory inputs that are irrelevant to one’s focus. That is to say, Alpha 1 decreases in somatosensory regions that are involved in the center of one’s focus and increases elsewhere (Kerr et al. 2013). Advanced practitioners show the greatest Alpha 1 power increases during the practice, an indication of more efficient top-down modulation of irrelevant sensory information (Kakumanu et al. 2018).
Frontal Alpha Asymmetry
When frontal Alpha power is higher on one side of the brain than the other, it is closely linked to one’s emotional style. Higher left frontal Alpha is associated with negative mood and avoidant behavior. Higher right frontal Alpha is associated with positive mood, including optimism, happiness, and approach-oriented behavior. Protocols for Loving Kindness meditation aim to increase right frontal Alpha and decrease left frontal Alpha, thus decreasing negative emotions and bolstering the generation of positive emotions.
Remember Alpha is an inhibitory frequency band—thus, higher left frontal alpha indicates a brain that is more active on the right. So why would an active right brain be associated with negative mood and an active left brain be associated with positive mood? No one knows for sure, but to help you remember which is which, you can think of the stereotypes of the moody artist (the right brain is more artsy) and the bubbly talkative neighbor (speech is produced on the left side of the brain).
Alpha and Creativity
Broadly speaking, Alpha links the conscious and subconscious mind. Without Alpha, we wouldn’t remember our dreams or be in touch with what happened during our deepest meditative states (Wise 2002). If one meditates in Theta without the accompanying Alpha, all the subconscious insights made in Theta are inaccessible to the conscious mind.
Creatives benefit from increased frontal Alpha 1, particularly in the right hemisphere, as it supports a relaxed, broad, witness consciousness that can more easily tackle complex concepts where divergent thinking is required (Horan 2009). Alpha 2 also supports creativity by facilitating access to semantic memories that can be reconfigured into new insights.
Required reading: