Protocol

Dynamic Brain Imaging

Volume 489 of the series METHODS IN MOLECULAR BIOLOGY™ pp 93-109

Astrocytic Calcium Signaling: Mechanism and Implications for Functional Brain Imaging

  • Xiaohai WangAffiliated withCenter for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center
  • , Takahiro TakanoAffiliated withCenter for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center
  • , Maiken NedergaardAffiliated withCenter for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical Center

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Abstract

Astrocytes are electrically non-excitable cells that, on a slow time scale of seconds, integrate synaptic transmission by dynamic increases in cytosolic Ca2+. A number of groups have recently shown that astrocytic Ca2+ signaling regulates vascular tones and that astrocytes play a central role in functional hyperemia by Ca2+-dependent release of Prostaglandin E2 (PGE2). Astrocytes are, however, not simple detectors of excitatory transmission, since a number of neuromodulator and hormones trigger elevations in astrocytic Ca2+ independently of synaptic transmission. Furthermore, astrocytes exhibit ex vivo intrinsic Ca2+ excitability, or spontaneous increases in Ca2+ that are not triggered by receptor activation. The notion that astrocytes can regulate vascular tone independently of synaptic transmission challenges the notion that changes in the blood oxygenation level dependent (BOLD) signal is directly proportional to neuronal activity and may thus require a reevaluation of the large body of data accumulated using functional magnetic resonance imaging (fMRI).

Key words

Photolysis 2-photon imaging functional brain imaging