Funding provided by: National Institute of Neurological Disorders and StrokeCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000065Award Number: R01NS101353Funding provided by: National Institute of Neurological Disorders and StrokeCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000065Award Number: R01NS078168Funding provided by: American Heart AssociationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000968Award Number: 935961Funding provided by: National Institute of Neurological Disorders and StrokeCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000065Award Number: U19NS128613Funding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeAward Number: R01NS101353Funding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeAward Number: R01NS078168Funding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeAward Number: U19NS128613Funding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeAward Number: R01NS101353Funding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeFunding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and StrokeFunding provided by: U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and Stroke

In the adult sensory cortex, increases in neural activity elicited by sensory stimulation usually drive vasodilation mediated by neurovascular coupling. However, whether neurovascular coupling is the same in neonatal animals as adults is controversial, as both canonical and inverted responses have been observed. We investigated the nature of neurovascular coupling in unanesthetized neonatal mice using optical imaging, electrophysiology, and BOLD fMRI. We find in neonatal (postnatal day 15, P15) mice, sensory stimulation induces a small increase in blood volume/BOLD signal, often followed by a large decrease in blood volume. An examination of arousal state of the mice revealed that neonatal mice were asleep a substantial fraction of the time, and that stimulation caused the animal to awaken. As cortical blood volume is much higher during REM and NREM sleep than the awake state, awakening occludes any sensory-evoked neurovascular coupling. When neonatal mice are stimulated during an awake period, they showed relatively normal (but slowed) neurovascular coupling, showing that that the typically observed constriction is due to arousal state changes. These result show that sleep-related vascular changes dominate over any sensory-evoked changes, and hemodynamic measures need to be considered in the context of arousal state changes.