A researcher is interested in discovering if one part of the brain, the orbitofrontal cortex, connects directly to another part of the brain, the amygdala. Which of the following experimental methods would be the most appropriate for this purpose?
A) Inject horseradish peroxidase into a rat's amygdala and then see if cells in the orbitofrontal cortex are stained.
B) Inject a human volunteer with a radioactive glucose and see what part of his brain is active while viewing an emotionally charged set of pictures using a PET scan.
C) Look at a human brain with fMRI to see if the orbitofrontal cortex and amygdala are active at the same times.
D) Stimulate the orbitofrontal cortex of a human volunteer during neurosurgery.

Question

Quizplus · Accepted Answer

Injecting horseradish peroxidase into a rat's amygdala and then observing if cells in the orbitofrontal cortex of the rat are stained is the best method for discovering if the two brain parts are connected directly. This technique is called the retrograde tracing method and is used to trace the connections between brain regions. The other options do not directly test for a direct connection between the two brain regions. PET scans and fMRI can show activity in different regions of the brain, but they cannot confirm a direct connection between two brain regions. Stimulating the orbitofrontal cortex during neurosurgery is an invasive technique and would not necessarily show a direct connection between the two regions.

A Researcher Is Interested in Discovering If One Part of the Brain