Definition: Post-stimulus undershoot refers to the transient drop of the oxygenated hemoglobin signal below baseline level after the stimulation ends. It is subject to a range of physiological factors and is likely mostly driven by an increase in the cerebral metabolic rate of oxygen (CMRO
). Other physiological factors that partly also contribute include post-arterial cerebral blood volume (CBV
) and cerebral blood flow post-stimulus undershoot (CBF-PSU). These are more dependent on the interplay of brain region and stimulus length and type. A default form of post-stimulus undershoot is modeled in the canonical hemodynamic response function for BOLD analyses.
Category: Neuroscience
Related terms: blood-oxygenation level-dependent (BOLD) post-stimulus undershoot, hemodynamic response, hemodynamic response function, cerebral metabolic rate of oxygen
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References: https://doi.org/10.1016/j.neuroimage.2005.09.048; https://doi.org/10.1016/j.mri.2005.12.034https://doi.org/10.1016%2Fj.neuroimage.2012.01.029
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