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Brief neuronal afterdischarges in the rat hippocampus lead to transient changes in oscillatory activity and to a very long-lasting decline in BOLD signals without inducing a hypoxic state.
Arboit, Alberto; Ku, Shih-Pi; Krautwald, Karla; Angenstein, Frank.
Affiliation
  • Arboit A; Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany.
  • Ku SP; Department Functional Architecture of Memory, Leibniz Institute for Neurobiology (LIN), Magdeburg 39118, Germany.
  • Krautwald K; Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany.
  • Angenstein F; Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany; Department Functional Architecture of Memory, Leibniz Institute for Neurobiology (LIN), Magdeburg 39118, Germany; Center for Behavior and Brain Sciences (CBBS), Mag
Neuroimage ; 245: 118769, 2021 12 15.
Article in En | MEDLINE | ID: mdl-34861394
ABSTRACT
The effects of hippocampal neuronal afterdischarges (nAD) on hemodynamic parameters, such as blood-oxygen-level-dependent (BOLD) signals) and local cerebral blood volume (CBV) changes, as well as neuronal activity and metabolic parameters in the dentate gyrus, was investigated in rats by combining in vivo electrophysiology with functional magnetic resonance imaging (fMRI) or 1H-nuclear magnetic resonance spectroscopy (1H-NMRS). Brief electrical high-frequency pulse-burst stimulation of the right perforant pathway triggered nAD, a seizure-like activity, in the right dentate gyrus with a high incidence, a phenomenon that in turn caused a sustained decrease in BOLD signals for more than 30 min. The decrease was associated with a reduction in CBV but not with signs of hypoxic metabolism. nAD also triggered transient changes mainly in the low gamma frequency band that recovered within 20 min, so that the longer-lasting altered hemodynamics reflected a switch in blood supply rather than transient changes in ongoing neuronal activity. Even in the presence of reduced baseline BOLD signals, neurovascular coupling mechanisms remained intact, making long-lasting vasospasm unlikely. Subsequently generated nAD did not further alter the baseline BOLD signals. Similarly, nAD did not alter baseline BOLD signals when acetaminophen was previously administered, because acetaminophen alone had already caused a similar decrease in baseline BOLD signals as observed after the first nAD. Thus, at least two different blood supply states exist for the hippocampus, one low and one high, with both states allowing similar neuronal activity. Both acetaminophen and nAD switch from the high to the low blood supply state. As a result, the hemodynamic response function to an identical stimulus differed after nAD or acetaminophen, although the triggered neuronal activity was similar.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Seizures / Magnetic Resonance Imaging / Brain Waves / Neuroimaging / Proton Magnetic Resonance Spectroscopy / Electrocorticography / Neurovascular Coupling / Hippocampus Limits: Animals Language: En Journal: Neuroimage Journal subject: DIAGNOSTICO POR IMAGEM Year: 2021 Document type: Article Affiliation country: Germany

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Seizures / Magnetic Resonance Imaging / Brain Waves / Neuroimaging / Proton Magnetic Resonance Spectroscopy / Electrocorticography / Neurovascular Coupling / Hippocampus Limits: Animals Language: En Journal: Neuroimage Journal subject: DIAGNOSTICO POR IMAGEM Year: 2021 Document type: Article Affiliation country: Germany