ENHANCED VISUAL RESPONSES IN CAT DLGN - POTENTIATION BY PRIMING WITH EXCITATORY AMINO-ACIDS

SUSTAINED iontophoresis of NMDA potentiated visual responses for minut es after the application in 16 of 38 cells (42%), peaking 3 min after the end of the application and declining to control levels within 12 m in. Potentiation was also seen after application of ACPD (36%, n = 14) and AMPA (29%, n = 14), but not after application of ACh (n = 20). AC h also excites dLGN cells, but does not interact with amino acid recep tors, and ACh receptors are not directly involved in the transmission of visual information. We suggest that this modulation is a form of vi sually induced potentiation which permits dynamic modification of the strength of visual information to be relayed to the cortex depending u pon the history of previous activity levels.