Alpha block on EEG is seen during which of the folllowing activities?: (A) Sleep, (B) Seizures, (C) Concentrating, (D) None of the above
Answer is C. 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.