Section: Reading

Question 61 of 111


61) Read the following paragraph and answer the question at the bottom:

 1.Electroencephalograph (EEG) is a tool used for gauging and recording brain
 2.waves. In 1929, Hans Berger, the German psychiatrist, published the results of
 3.his experiments using the electroecenphalograph in recording human brain
 4.waves.
 
 5.Four major brain waves exist: alpha has a frequency that ranges from 8 to 14
 6.cycles per second (cps) and is found in the occipital part of the brain. Beta
 7.covers 14 to 30 cps. Delta wave includes frequencies that are below 5 cps. Theta
 8.wave covers the range between 5 and 8 cps. Alpha waves are more active
 9.during relaxation and light sleep. Nonetheless, their function is altered by deep
10.mental activities. Beta waves, on the other hand, appear during mental
11.concentration periods.
 
12.In 1935, the findings of collaborators Frederic Gibbs, William Lennox, and
13.Hallowelle Davis from Harvard on the use of EEG in epilepsy was published.
14.Since EEG poses no pain or side effects, it is broadly included as a medium for
15.identifying brain irregularities. The EEG is instrumental in discovering a host
16.of brain wave abnormalities. Persons who suffer from grand mal epilepsy have
17.brain wave patterns that resemble spikes, while those with petit mal epilepsy
18.have arch-shaped brain waves. Brain waves respond to physiological and
19.chemical stimuli. For instance, the use of drugs will result in low-amplitude,
20.high frequency brain waves. When we are asleep, the waves' pattern changes a
21.few times. Dreaming frequently happens when the brain waves have high
22.frequency but low amplitude.

In line 14, the word "it" refers to which of the following?