Postsynaptic potentials in layer IV pyramidal cells in response to thalamic stimulation. A, Typical responses of the thalamocortical PSPs in layer IV pyramidal cells of wt (left) and tg (right) mice, with increments of the stimulus intensity. B, Vertical expansion of the thalamocortical PSPs with the 400 μA stimulus intensity, which are identical to those in A. Note that the thalamic stimulation with 400 μA intensity evoked transient depolarization followed by long-lasting hyperpolarization in wt mice (top) but long-lasting depolarization in tg mice (bottom). The early transient depolarization is indicated by Peak, whereas the late long-lasting hyperpolarization and depolarization are indicated by arrowheads. The membrane potentials before the stimulation were set to −60 mV by current injection. Stimulus artifacts were truncated. C, Time course profiles of thalamocortical PSPs with 400 μA stimulus intensity in wt and tg mice. PSP values were calculated as membrane potentials at each time point after stimulation minus those just before stimulation. Peak amplitudes of the early transient depolarization (indicated by Peak) were searched from 2 to 7 ms after stimulation in individual preparations. The time course profiles were significantly different between wt and tg mice (p < 0.02, two-way repeated-measures ANOVA). *p < 0.05, **p < 0.01, Bonferroni’s test between genotype at each time point. D, Stimulus intensity profiles of thalamocortical PSPs at 40 ms after stimulation. The stimulus intensity profiles were significantly different between wt and tg mice (p < 0.03, two-way repeated-measures ANOVA). *p < 0.05, **p < 0.01, Bonferroni’s test between genotypes at each stimulus intensity.