The following statements all refer to the human brain when mental activity is occurring. Which statement is correct?
A) In order to detect electric currents in the brain, you must open the skull and make direct electrical contact with the brain.
B) The electric currents in the brain can be detected outside the brain by detecting the magnetic fields they produce.
C) The electric currents in the brain can be mapped by shaving a person's head and dropping iron filings on the head.
D) The electric currents in the brain produce an aura that can be detected visually.
E) The electric currents in the brain cannot be detected by any means.

Question

Quizplus · Accepted Answer

The electric currents in the brain can be detected outside the brain by detecting the magnetic fields they produce. This is done through a technique called magnetoencephalography (MEG). Opening the skull to make direct electrical contact with the brain (A) is not a common or safe method of measurement. Mapping brain activity through iron filings on the head (C) is not a valid technique. The electric currents in the brain cannot produce a visible aura (D). Finally, it is not true that electric currents in the brain cannot be detected at all (E), as they can be detected via MEG, as mentioned in choice B.

The Following Statements All Refer to the Human Brain When