The hemodynamic initial-dip consists of both volumetric and oxymetric changes reflecting localized spiking activity

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dc.contributor.authorZaidi, Ali Danish
dc.contributor.authorBirbaumer, Niels
dc.contributor.authorFetz, Eberhard
dc.contributor.authorLogothetis, Nikos
dc.contributor.authorSitaram, Ranganatha
dc.date.accessioned2025-01-20T20:10:48Z
dc.date.available2025-01-20T20:10:48Z
dc.date.issued2023
dc.description.abstractThe initial-dip is a transient decrease frequently observed in functional neuroimaging signals, immediately after stimulus onset, believed to originate from a rise in deoxy-hemoglobin (HbR) caused by local neural activity. It has been shown to be more spatially specific than the hemodynamic response, and is believed to represent focal neuronal activity. However, despite being observed in various neuroimaging modalities (such as fMRI, fNIRS, etc), its origins are disputed, and its precise neuronal correlates are unknown. Here we show that the initial-dip is dominated by a decrease in total-hemoglobin (HbT). We also find a biphasic response in deoxy-Hb (HbR), with an early decrease and later rebound. Both the HbT-dip and HbR-rebound were strongly correlated to highly localized spiking activity. However, HbT decreases were always large enough to counter the spiking-induced increase in HbR. We find that the HbT-dip counters spiking induced HbR increases, imposing an upper-limit to HbR concentration in the capillaries. Building on our results, we explore the possibility of active venule dilation (purging) as a possible mechanism for the HbT dip.
dc.fuente.origenWOS
dc.identifier.doi10.3389/fnins.2023.1170401
dc.identifier.eissn1662-453X
dc.identifier.urihttps://doi.org/10.3389/fnins.2023.1170401
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/92097
dc.identifier.wosidWOS:001003355900001
dc.language.isoen
dc.revistaFrontiers in neuroscience
dc.rightsacceso restringido
dc.subjectfunctional neuroimaging
dc.subjectnear infra-red spectroscopy
dc.subjectneurovascular coupling
dc.subjectelectrophysiology
dc.subjectvisual cortex
dc.subjectprimate
dc.subjecthemodynamics
dc.subjectinitial dip reflects spiking activity
dc.subject.ods03 Good Health and Well-being
dc.subject.odspa03 Salud y bienestar
dc.titleThe hemodynamic initial-dip consists of both volumetric and oxymetric changes reflecting localized spiking activity
dc.typeartículo
dc.volumen17
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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