7. During the long-lasting potentiation there was an increase in the excitability of the post-synaptic cells and, on some but not all occasions, an increase in the extracellular current flow produced directly by synaptic action. 358

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8. The data suggest that there is a selective mechanism for passive K+ transport in an electrochemical gradient within brain tissue that results in higher K+ fluxes than could be supported by ionic mobility in the extracellular fluid. This mechanism exists not only at the surface but within the brain parenchyma and may involve current flow through glial cells.

SUMMARY1. The flux of K+ produced by electric current across the pia-arachnoid surface of the neocortex of anaesthetized rats has been studied with K+-selective electrodes in a cup at the surface and with flame photometry.2. The potential differences developed across three regions of the rat brain (neocortex, cerebellum, hippocampus) have been measured as [K+]

No abstract