Alpha block on EEG is seen during which of the folllowing activities?
Sleep
Seizures
Concentrating
None of the above
When attention is focused on something, the alpha rhythm is replaced by an irregular 13-30 Hz low-voltage activity, the beta rhythm. This phenomenon is called alpha block and can be produced by any form of sensory stimulation or mental concentration, such as solving arithmetic problems. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 15.