The effects of activation of nicotinic acetylcholine receptors (nAChRs) on glutamatergic transmission in the ventral lateral geniculate nucleus (LGNv) were examined in chick brain slices. Whole-cell recordings demonstrated that monosynaptic postsynaptic currents (PSCs) evoked in LGNv neurons by optic tract stimulation were blocked by glutamate receptor antagonists. Exogenously applied nicotine (0.5 µM), choline (1 mM) or acetylcholine (ACh, 100 µM) markedly increased (>3-fold) these evoked PSCs. Potentiation by ACh was dose-dependent and did not desensitize during a 5 min application. In a second set of experiments, the effect of releasing endogenous ACh by stimulating the lateral portion of the LGNv via a separate conditioning electrode prior to optic tract stimulation was examined. Conditioning stimulation trains increased PSCs by an average of 5.2-fold, an effect dependent on both the intensity and number of conditioning pulses. This increase in PSC amplitude was most likely due to released ACh activating 6- and/or 3-containing nAChRs since it was blocked by 100 nM -Conotoxin MII, 100 nM dihydro--erythroidine (DHE), and 0.1 - 1.0 µM methyllycaconitine (MLA). In contrast, exogenously applied ACh increased PSC amplitude by activating a pharmacologically different population of nAChRs since this effect was inhibited by 100 nM -bungarotoxin, 50 nM MLA, and a high concentration (30 µM) of DHE, indicating that 7- and/or 8-containing receptors were involved. The results are consistent with a model whereby 6- and/or 3-containing nAChRs on retinal ganglion cell nerve terminals are located preferentially at cholinergic synapses, while 7- and/or 8-containing receptors are primarily extrasynaptic.