title: Optical monitoring of progressive synchronization in dentate granule cells during population burst activities.
abstract: Monitoring multiple neurons is essential for understanding neuronal network activities. While calcium imaging from a population of cells is an effective method to study the network dynamics of a neural structure, it has been difficult to image from densely packed structures, such as the granule cell layer of the dentate gyrus, due to overlap of the cells. We have developed a novel method to label multiple granule cells with a Ca(2+) indicator in rat hippocampal slices using Oregon Green 488 BAPTA-1 (OGB-1) AM. Synchronized burst activities (0.3-1.4 Hz), which were induced by applying 50 microm 4-aminopyridine, were monitored extracellularly with a glass electrode placed at the granule cell layer in the dentate gyrus. During the burst activities, spontaneously occurring action potential-induced Ca(2+) transients from multiple (4-12) granule cells were monitored with a cooled CCD camera with single-cell resolution. Temporal structures of firing patterns from the multiple neurons were determined from Ca(2+) transients. In each single-burst-event recorded from the extracellular electrode, each neuron fired synchronously within a 200 ms time window. The latency and its variance from the onset time of the single-burst-events to one of the Ca(2+) transients decreased over time (< 7.5 min). These results indicate that the synchrony of the action potentials within a single-burst-event was enhanced as the burst activities proceeded. This progressive synchronization may be a key feature in making self-organizing neuronal networks.
authors: Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors: Masanori
authors: M
authors: Murayama
authors: Kenichi
authors: K
authors: Miyazaki
authors: Yoshihisa
authors: Y
authors: Kudo
authors: Hiroyoshi
authors: H
authors: Miyakawa
authors: Masashi
authors: M
authors: Inoue
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002264:Carboxylic Acids / Q000493:pharmacokinetics; D002452:Cell Count / Q000379:methods; D018891:Dentate Gyrus / Q000166:cytology*; D003952:Diagnostic Imaging / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D004558:Electric Stimulation / Q000379:methods; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008991:Monitoring, Physiologic / Q000379:methods*; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D011188:Potassium / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects
chemical_list: D002264:Carboxylic Acids; D018691:Excitatory Amino Acid Antagonists; C436864:Oregon Green 488 carboxylic acid; D026902:Potassium Channel Blockers; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015761:4-Aminopyridine; D011188:Potassium; D002118:Calcium