NMDA-RECEPTORS AND POTENTIATION IN AN AREA OF AVIAN BRAIN ESSENTIAL FOR LEARNING

THE intermediate medial part of the hyperstriatum ventrale (IMHV), par t of the avian forebrain, is essential for early learning in the domes tic chick. Persistent potentiation (PP) can sometimes be induced in th e IMHV in vitro. One can predict success from events which occur durin g the stimulation (1 min at 5 Hz) which is used for induction: the ori ginal response must be transiently replaced by a later, slower respons e (the LPSR). The LPSR has a comparatively high threshold of activatio n, its rate of development is inversely related to magnesium concentra tion and it can be eliminated by NMDA antagonists, as can the inductio n of PP. PP in the IMHV is therefore dependent upon NMDA receptors and the LPSR represents the activation of these receptors.