What, exactly, does it mean to say that a brain region is 'active' in a functional imaging experiment?
A) The region is critical for performing some aspect of that experiment.
B) The neurons in that region have an excitatory response during the experiment.
C) The region has a rapid response to some aspect of that experiment.
D) The haemodynamic response in that region is greater than in some other condition(s)

Question

Quizplus · Accepted Answer

Functional imaging techniques such as fMRI measure changes in blood flow to infer neural activity. An active brain region is one that has a greater haemodynamic response (i.e. increased blood flow) compared to some other condition. This increase in blood flow is assumed to indicate increased neural activity in that region. Thus, option D is the correct answer. Option A is incorrect because a region may be active even if it is not critical for performing the task. Option B is incorrect because an excitatory response does not necessarily translate to increased blood flow. Option C is incorrect because a rapid response may not necessarily result in increased blood flow.

What, Exactly, Does It Mean to Say That a Brain