What are the brain frequencies?

What are the brain frequencies?

Brain frequencies or Brain States Like Delta, Theta, Alpha and Beta are terms that medicine
and scientists uses to indicate the rates of brain cell firing and the corresponding mental states associated with them.

The instruments measure the neuron firing rates of groups of brain cells, The Name Of These instruments is (electroencephalographs) and They are commonly used by medical people to evaluate The Brain states.  These firing rates are commonly thought to control mental states.

The Delta State

The Delta brain state of mind involves frequencies from approximately 0.1Hz to 4Hz. Is commonly experienced during deep sleep. 

 The natural amplitudes are large in size. These brain frequencies are the least researched and are common in very deep trance states.

The Theta State 

The theta state is commonly experienced in deepened states of meditation, at the onset and in lighter parts of sleep. It is believed by some scientists that high amplitude Theta frequencies accompany most ( if not all) psychic activity.
 It is characterized by frequencies from 4.0Hz to 7.9Hz.

The Alpha State

The alpha brain state is the one you experience whilst doing a mundane repetitive task with nothing particular on your mind. 
The alpha brain state of mind involves frequencies from 8.0 to 12.9Hz. The natural amplitudes tend to be larger than beta. 

The Beta State 

Beta brain states above 20 Hz are generally classed as higher beta or gamma.
 Beta brain state is that state of mind that you experience when awake and active during the day. It includes any brain wave with a frequency greater than or equal to 13 Hz. 
This is the state of mind in which 
you commonly deal with your daily routines. 
 The low beta state involves frequencies from 13Hz to 20Hz.

 The higher beta brain state, often referred to as the gamma state, is experienced while wide awake and highly aroused.