Pathway-specific variations in neurovascular and neurometabolic coupling in rat primary somatosensory cortex

• Published in: Journal of cerebral blood flow and metabolism Vol. 29; no. 5; pp. 976 - 986
• Main Authors: Enager, Pia, Piilgaard, Henning, Offenhauser, Nikolas, Kocharyan, Ara, Fernandes, Priscilla, Hamel, Edith, Lauritzen, Martin
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-05-2009; Nature Publishing Group; Sage Publications Ltd
• Subjects: Animals; Biological and medical sciences; Cerebrovascular Circulation - physiology; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Electric Stimulation; Evoked Potentials, Somatosensory - physiology; gamma-Aminobutyric Acid - metabolism; Immunohistochemistry; Interneurons - metabolism; Interneurons - physiology; Laser-Doppler Flowmetry; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Neurons - metabolism; Neurons - physiology; Oxygen Consumption - physiology; Pyramidal Cells - metabolism; Pyramidal Cells - physiology; Rats; Rats, Wistar; Somatosensory Cortex - blood supply; Somatosensory Cortex - metabolism; Somatosensory Cortex - physiology; Synaptic Potentials - physiology; Vascular diseases and vascular malformations of the nervous system; synaptic activity; whisker barrel; oxygen tension; blood flow; glutamate; interneurons; Oxygen; Nervous system diseases; Rat; Rodentia; Glutamate; Cerebral disorder; Blood flow; Interneuron; Somatosensory cortex; Vertebrata; Mammalia; Animal; Central nervous system disease; Cerebrovascular disease
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1038/jcbfm.2009.23

Functional neuroimaging signals are generated, in part, by increases in cerebral blood flow (CBF) evoked by mediators, such as nitric oxide and arachidonic acid derivatives that are released in response to increased neurotransmission. However, it is unknown whether the vascular and metabolic responses within a given brain area differ when local neuronal activity is evoked by an activity in the distinct neuronal networks. In this study we assessed, for the first time, the differences in neuronal responses and changes in CBF and oxygen consumption that are evoked after the activation of two different inputs to a single cortical area. We show that, for a given level of glutamatergic synaptic activity, corticocortical and thalamocortical inputs evoked activity in pyramidal cells and different classes of interneurons, and produced different changes in oxygen consumption and CBF. Furthermore, increases in stimulation intensities either turned off or activated additional classes of inhibitory interneurons immunoreactive for different vasoactive molecules, which may contribute to increases in CBF. Our data imply that for a given cortical area, the amplitude of vascular signals will depend critically on the type of input, and that a positive blood oxygen level-dependent (BOLD) signal may be a consequence of the activation of both pyramidal cells and inhibitory interneurons.