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| Home > Publications Database > Hemodynamic responses in the rat hippocampus are simultaneously controlled by at least two independently acting neurovascular coupling mechanisms |
| Home > Publications Database > Hemodynamic responses in the rat hippocampus are simultaneously controlled by at least two independently acting neurovascular coupling mechanisms |
| Journal Article | DZNE-2024-00300 |
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2024
Sage
London
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Please use a persistent id in citations: doi:10.1177/0271678X231221039
Abstract: We combined electrical perforant pathway stimulation with electrophysiological and fMRI recordings in the hippocampus to investigate the effects of neuronal afterdischarges (nAD) on subsequent fMRI BOLD signals in the presence of isoflurane and medetomidine. These two drugs already alter basal hemodynamics in the hippocampus, with isoflurane being mildly vasodilatory and medetomidine being mildly vasoconstrictive. The perforant pathway was stimulated once for 8 seconds with either continuous 20 Hz pulses (continuous stimulation) or 8 bursts of 20 high-frequency pulses (burst stimulation). Burst stimulation in the presence of medetomidine elicited long-lasting nAD that coincided with a brief positive BOLD response and a subsequent long-lasting decrease in BOLD signals. Under isoflurane, this stimulation elicited only short-lasting nAD and only a short-lasting decline in BOLD signals. In contrast, continuous stimulation under isoflurane and medetomidine caused a similar duration of nAD. Under isoflurane, this caused only a sharp and prolonged decline in BOLD signals, whereas under medetomidine, again, only a brief positive BOLD response was elicited, followed by a shorter and moderate decline in BOLD signals. Our results suggest that nAD simultaneously activate different neurovascular coupling mechanisms that then independently alter local hemodynamics in the hippocampus, resulting in an even more complex neurovascular coupling mechanism.
Keyword(s): Animals (MeSH) ; Neurovascular Coupling: physiology (MeSH) ; Neurovascular Coupling: drug effects (MeSH) ; Isoflurane: pharmacology (MeSH) ; Hippocampus: physiology (MeSH) ; Hippocampus: drug effects (MeSH) ; Hippocampus: blood supply (MeSH) ; Medetomidine: pharmacology (MeSH) ; Male (MeSH) ; Magnetic Resonance Imaging (MeSH) ; Rats (MeSH) ; Hemodynamics: drug effects (MeSH) ; Hemodynamics: physiology (MeSH) ; Electric Stimulation (MeSH) ; Anesthetics, Inhalation: pharmacology (MeSH) ; Rats, Wistar (MeSH) ; Perforant Pathway: physiology (MeSH) ; Perforant Pathway: drug effects (MeSH) ; Cerebrovascular Circulation: physiology (MeSH) ; Cerebrovascular Circulation: drug effects (MeSH) ; BOLD-fMRI ; dentate gyrus ; in vivo electrophysiology ; negative BOLD response ; neuronal afterdischarges
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