Answer:
Electroencephalography ( EEG )
Step-by-step explanation:
Electroencephalography -
It is one of the method which helps to detect any electrical activity in the brain , by using some metal discs attached to the scap of the person , is referred to as Electroencephalography .
This method can be used during the sleep time of the person , as the brain cells are always active and generates electrical impulse.
The method is used to detect -
Hence , from the given scenario of the question ,
The correct answer is Electroencephalography .