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. Author manuscript; available in PMC: 2013 Jan 16.
Published in final edited form as: Brain Res Rev. 2009 Dec 21;62(2):233–244. doi: 10.1016/j.brainresrev.2009.12.004

Figure 2. Schematic representation of hippocampal BOLD response in frequently studied behavioral tasks.

Figure 2

Three different scenarios are described along with the predicted BOLD signal. All comparisons are made relative to a “true” hippocampal baseline task, or tasks that do not directly require the hippocampus (such as making odd-even number judgments). In the first situation, “rest” results in increased blood flow due to the involvement of the hippocampus in the default network, resulting in increased activity relative to an “inactive” baseline. In the second situation, tasks not involving the hippocampus (such as familiarity judgments) result in no net BOLD change because two inactive tasks result in no net change. In the final situation, a weakly positive BOLD change arises because hippocampal metabolism may outpace blood flow. Note that if situation #1 were used as baseline for situation #3, as applied in many cases previously, hippocampal negative BOLD changes result.