Dedication

Abstract

Conditioning stimulation of afferent fibers in hippocampal area CA1 produced heterosynaptic, posttetanic depression (PTD) of responses evoked by stimulation of an indpendent set of afferent fibers. PTD was present within 5 s of conditioning stimulation, amounted to a 60–80% reduction of excitatory postsynaptic potentials (EPSPs), and required a period of 3–5 min for recovery. Antagonists of A1 adenosine receptors substantially reduced PTD. Adenosine released into, or formed in, the extracellular space during conditioning stimulation may diffuse within the slice to depress evoked release of glutamate.