Open AccessImaging extrasynaptic glutamate dynamics in the brain
Author(s) -
Yohei Okubo,
Hiroshi Sasaki,
Shigeyuki Namiki,
Hirokazu Sakamoto,
Sho Iinuma,
Miwako Yamasaki,
Masahiko Watanabe,
Keikichi Hirose,
Masamitsu Iino
Publication year - 2010
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0913154107
Subject(s) - glutamate receptor , neuroscience , excitatory postsynaptic potential , neurotransmission , glutamatergic , sensory system , crosstalk , biology , chemistry , physics , inhibitory postsynaptic potential , receptor , biochemistry , optics
Glutamate is the major neurotransmitter in the brain, mediating point-to-point transmission across the synaptic cleft in excitatory synapses. Using a glutamate imaging method with fluorescent indicators, we show that synaptic activity generates extrasynaptic glutamate dynamics in the vicinity of active synapses. These glutamate dynamics had magnitudes and durations sufficient to activate extrasynaptic glutamate receptors in brain slices. We also observed crosstalk between synapses—i.e., summation of glutamate released from neighboring synapses. Furthermore, we successfully observed that sensory input from the extremities induced extrasynaptic glutamate dynamics within the appropriate sensory area of the cerebral cortex in vivo. Thus, the present study clarifies the spatiotemporal features of extrasynaptic glutamate dynamics, and opens up an avenue to directly visualizing synaptic activity in live animals.