[Physiological basis of functional MRI].
Afferent neurotransmission of a given neuronal group and its subsequent dendritic activity are followed by a transient hemodynamic response such as an increase of the local blood flow and of the intravascular level of oxygen. This neurovascular regulation involves neurons, astrocytes, interneurons and various transmitter substances. The resulting changes in the magnetic susceptibility is then detected by the MRI machine which can specifically localize regional brain activity. Blood oxygenation level dependent contrast reflects afferent inputs and their post-synaptic (dendritic) processing, rather than the output from the concerned cerebral zone (spiking). In other words, this contrast depends on local informational treatment of an active zone without implying any effective influence upon its targets.
Habas
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Service Central de Biophysique et de Médecine Nucléaire, Pr A. Aurengo, Hôpital Pitié-Salpêtrière, 83 boulevard de l'Hôpital, Paris, France. christophe.habas@libertysurf.fr
D000344:Afferent Pathways / Q000378:metabolism / Q000503:physiopathology; D001253:Astrocytes / Q000378:metabolism; D001923:Brain Chemistry; D002560:Cerebrovascular Circulation; D003712:Dendrites / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D006439:Hemodynamics; D006706:Homeostasis; D006801:Humans; D002534:Hypoxia, Brain / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D007395:Interneurons / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010101:Oxygen Consumption; D009435:Synaptic Transmission
D005947:Glucose