Ideally a brain can sustain a state of slow dominance when, for example, listening to music, watching a movie or looking for a new idea. Ideally it can shift out and stay out of the state when there are tasks at hand.
When a brain is using a slow-dominant state—or when locked in it—we can describe how that person is likely to appear or feel. There is a relationship between my brain’s frequency activation patterns and my mental and emotional state.
Internal Locus of Awareness: Slow-dominant brains live in an inner world. They can push their attention out for brief periods, but they can’t sustain it. Their concentration fails by falling inside.
Image-Based Processing: They think in pictures—not words. Reading/listening for detail and organizing thoughts in written or spoken form are often areas of difficulty. Hands-on or visual-based tasks can be a strength.
Leap to Decisions: Choices are made intuitively, so they can’t be explained. Sequential processes and hierarchies don’t make sense. Slow brains don’t plan or organize.
Low energy Moods: Moods tend toward sadness, helplessness, depressive feelings.
Disconnected socially: Living in an inner world complicates social contacts. Often introverted and shy, but can also be the clown in social situations. Easily disappears into the internet or video games, etc.
Visionary thinker: Sees distant big picture, but limited in ability to see and deal with details and steps.
Non-restorative sleep: Sleeps easily and deeply but may never feel rested; slow to awaken. Bed-wetting in childhood is not uncommon.
Learning difficulties: Sensory processing can be disrupted. Difficulty maintaining attention, poor memory recall of facts and categories are common. May be very fast calculators but unable to “show their work”.
Delta (1.5-4 Hz) is the slowest/lowest EEG frequency band. It is the frequency of a coma, of deep dreamless sleep. It is the frequency of the unconscious mind. Delta is produced in the brain stem. It is, in a sense, the brain’s lowest common denominator. It can appear very strongly in areas where white-matter head injuries have torn an area of neurons away from its connections—leaving them alive but not receiving or sending.
Theta (4-8 Hz) contains the twilight states of brain activity. Theta is the frequency of the subconscious mind—feelings and memories. For training purposes, we divide theta into Slow (4-6 Hz) and Fast (6-8 Hz.)
Slow theta is much like delta. They are often combined in a band called Thelta (2-6 Hz). Thelta is a very internal state, unmotivated to do much in the “outside” world.
We pay special attention to sudden surges of 3 Hz activity. These can be indicators that the brain is falling asleep—or entering a state of “abreaction” where old traumatic experiences are re-experienced.
Fast Theta, however is quite different. 7 Hz is the frequency of visualization—a way of programming the subconscious source of most of our habits of action and reaction.
The 7 Hz central frequency of Fast Theta is produced in the brain’s hippocampus—the memory center. It is commonly found when we are accessing memories.
It is also the so-called “crossover” frequency at which we can be consciously aware of our own sub-conscious processes.
When and where
Slow frequencies are produced below the cortex, the “thinking” layer of the brain. They are broadcast from rhythm generators in the brainstem, thalamus and the hippocampus. They are considered “Global” frequencies, because they tend to appear everywhere when they appear. When the brain is in a twilight (theta) or unconscious (delta) state, it’s that way throughout.
Slow activity is more common and more useful over the right hemisphere and the back of the brain, where material is integrated, than over frontal and left-side sites, where more processing is done. It is expected to reduce with eyes open and at task.
Involvement of slow frequencies is central to sleep. Stage1 sleep is a shifting of neuron pools from faster alpha and beta speeds down into Theta. Stage3 sleep involves shifting from theta down into Delta, the deepest sleep state, related with physical restoration.