Figure 3.

Induction of thalamic LTP is dependent on presynaptic NMDA receptors. A, Graph plotting the amplitude of EPSCs evoked by activation of thalamic afferents (y-axis) as a function of time (x-axis). Circles and triangles show experiments in which HFS was applied in the absence or presence of APV, respectively. B, Time dependence of NMDA receptor block by intracellular MK-801. CNQX (20 μm) and picrotoxin (100 μm) were present in Mg²⁺-free aCSF. MK-801 (1 mm) was present in pipette solution. B1, NMDA responses evoked by electrical activation of thalamic afferents (left; Thal Stim.) or pressure application of glutamate via a patch pipette positioned close to recorded soma (right; Glutamate Puff). The numbers on left indicate time (in seconds) from first stimulus. B2, Graph plotting NMDA response amplitudes (y-axis) as a function of time (x-axis) for responses evoked by endogenous (triangles) and exogenous (circles) glutamate. Same experiment as in B1. C, Effect of intracellular MK-801 on thalamic LTP. See details in Results. Graph plotting the amplitude of EPSCs evoked by activation of thalamic (filled circles) or BL (empty circles) afferents (y-axis) as a function of time (x-axis). HFS was applied at the time indicated by the downward arrow. Data were normalized to baseline response amplitudes. Error bars represent SE.