MCQ MAHE 2000 Physiology Answer 15

The Correct Answer is B

Alpha waves are those between 7.5 and thirteen(13) waves per second (Hz). Alpha is usually best seen in the posterior regions of the head on each side, being higher in amplitude on the dominant side. It is brought out by closing the eyes and by relaxation, and abolished by eye opening or alerting by any mechanism (thinking, calculating). It is the major rhythm seen in normal relaxed adults - it is present during most of life especially beyond the thirteenth year when it dominates the resting tracing.

Beta activity is 'fast' activity. It has a frequency of 14 and greater Hz. It is usually seen on both sides in symmetrical distribution and is most evident frontally. It is accentuated by sedative-hypnotic drugs especially the benzodiazepines and the barbiturates. It may be absent or reduced in areas of cortical damage. It is generally regarded as a normal rhythm. It is the dominant rhythm in patients who are alert or anxious or who have their eyes open.

Theta activity has a frequency of 3.5 to 7.5 Hz and is classed as "slow" activity. It is abnormal in awake adults but is perfectly normal in children upto 13 years and in sleep.

Delta activity is 3 Hz or below. It tends to be the highest in amplitude and the slowest waves. It is quite normal and is the dominant rhythm in infants up to one year and in stages 3 and 4 of sleep.

Category: MAHE 2000 MCQs