Decreased neuronal synchronization during experimental seizures.
Synchronization between CA1 pyramidal neurons was studied using dual-cell patch-clamp techniques simultaneous with an extracellular measurement of network activity. We explored various linear and nonlinear methods to detect weak synchronization in this network, using cross-correlation, mutual information in one and two dimensions, and phase correlation in both broad and narrow band. The linear and nonlinear methods demonstrated different patterns of sensitivity to detect synchrony in this network, depending on the dynamical state of the network. Bursts in 4-amino-pyridine (4AP) were highly synchronous events. Unexpectedly, seizure-like events in 4AP were desynchronous events, both in comparison with interictal periods preceding the seizure without bursts (cut Schaffer collateral tract) and in comparison with bursts preceding the seizures (intact Schaffer collateral tract). The finding that seizure-like events are associated with desynchronization in such networks is consistent with recent theoretical work, suggesting that asynchrony is necessary to maintain a high level of activity in neuronal networks for sustained periods of time and that synchrony may disrupt such activity.
Netoff
Theoden I
TI
Krasnow Institute for Advanced Studies, George Mason University, Fairfax, Virginia 22030, USA.
Schiff
Steven J
SJ
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D003344:Cortical Synchronization; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009415:Nerve Net / Q000187:drug effects / Q000503:physiopathology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D009435:Synaptic Transmission / Q000187:drug effects
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine; D011188:Potassium