Alpha

Alpha ( α ) activity: Electromagnetic waves ranging between 8 and 13 Hz in frequency, and between 30 and 50 μV in amplitude. 

Best expressed in the occipital area, the Alpha wave is the strongest source of neural signal in the EEG [most informative and dominative wave in EEG

The alpha rhythm can reach its highest amplitude in the state of calm relaxed waking state, especially with eyes closed.

EEG Studies

A number of EEG studies further revealed that EEG alpha activity is sensitive to creativity-related demands of tasks (more alpha in task showing higher as compared to lower free-associative, divergent thinking.

These findings suggest that creative cognition is reliably associated with increased alpha power levels in the brain task requires that attention is continuously directed to the processing of external information or no

These imaginative processes include the generation and manipulation of mental images of possible uses. The generation of ideas in form of mental images (i.e., visual mental imagery; Kosslyn, Ganis, and Thompson (2001)) can be conceived as a very sensitive cognitive process that may be easily interfered by irrelevant sensory stimulation coming from the visual stream, and thus to benefit from task-focused attention

Inhibition vs. Exhibition

' InhibitionAlpha Block'

Considering evidence from fMRI studies, right-parietal alpha power increases may correspond to a deactivation of the right temporoparietal junction, reflecting an inhibition of the ventral attention network. Inhibition of this region is thought to prevent reorienting to irrelevant stimulation during goal-driven, top-down behavior, which may serve the executive function of task shielding during demanding cognitive tasks such as idea generation and mental imagery.

When thinking, blinking, or otherwise stimulated, α waves disappear. This is known as an alpha block. This type of periodic wave is produced in the parietal and occipital regions of the brain when in a state of consciousness, quiet, or at rest. 

beta waves are associated with active, busy or anxious thinking and active concentration

Measuring high alpha during environmental stimuli may indicate distraction Attentional tasks that required observation of environmental stimuli (intake tasks)

Exhibition EEG alpha activity correlated wakeful relaxing with closed eyes

Tasks such as mental arithmetic that require attention be paid to internal processing (rejection tasks)

Alpha Band Cognition

Alpha-band oscillations have two roles:

• Inhibition and
• Timing

Closely linked to two fundamental functions of attention

• Suppression and
• Selection

which enable controlled knowledge access and semantic orientation (the ability to be consciously oriented in time, space, and context).

As such, alpha-band oscillations reflect one of the most basic cognitive processes and can also be shown to play a key role in the coalescence of brain activity in different frequencies

.

Alpha Findings

Alpha band is predominant in a relaxed adult, while theta band is prominent in light sleep.

Important role for attention by supporting processes within the attentional focus and blocking processes outside its focus.

Alpha activity reflects attentional demands and is higher for tasks with internal attention focus than for tasks with external attention focus.

Power Findings

Alpha power increases in right-parietal cortex reflect a gradual response corresponding to the strength of task-focused attention or task shielding

alpha activity reflects attentional demands and is higher for tasks with internal attention focus than for tasks with external attention focus. Alpha power is lower in sensory-intake tasks as compared to intake-rejection tasks

Table 2: EEG brainwave frequency bands  https://www.hindawi.com/journals/apm/2015/614723/tab2/

Meditation induced changes in EEG brainwaves.

https://www.hindawi.com/journals/apm/2015/614723/tab1/