Supporting Figures

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Fig. 6. Single-burst long-term potentiation (LTP) requires NMDA receptors (NMDARs) and L-type voltage-gated calcium channels (VGCCs). (A) Examples of whole-cell current-clamp responses to single-burst stimuli [five pulses at 100 Hz delivered to stratum radiatum (SR); each trace represents a recording obtained from a different cell] recorded in three different pharmacological conditions: Control, NMDAR blockade with 50 mM AP-5 and 20 mM MK-801, and blockade of L-type VGCC with 10 mM nimodipine. (B) No. of somatic spikes observed after single-burst stimulation of SR (*, P < 0.01; one-way ANOVA). (C) EPSP amplitude in control conditions (filled circles) and NMDAR blockade (open circles). (D) EPSP amplitude in control conditions (filled circles) and L-type VGCC blockade (open circles). (E) Potentiation observed in control conditions, NMDAR blockade, and L-type VGCC blockade (*, P < 0.01; ANOVA, Tukey's multiple comparison test). Twenty minutes after stimulation, the average EPSP amplitudes in NMDAR blockade and L-type VGCC blockade remain significantly potentiated compared with baseline (baseline: control, 7.2 ± 0.3 mV; NMDAR blockade, 7.5 ± 0.5 mV; L-type VGCC blockade, 7.0 ± 0.6 mV. Twenty minutes: control, 11.5 ± 0.5 mV; NMDAR blockade, 8.3 ± 0.7 mV; L-type VGCC blockade, 8.2 ± 0.8 mV; paired t test, P < 0.05). The number of experiments in each condition is indicated at bottom of the respective bar. Data are presented as mean ±SEM.

Fig. 7. Single-burst stimulation potentiates perforant path synapses less robustly. (A) (Left) Recording configuration with whole-cell somatic patch-clamp recording and two stimulation electrodes, one placed in SR and one more distally in stratum lacunosum-moleculare (SLM; at least 200 mm away from the dendrite). For excitatory postsynaptic potential (EPSP) monitoring, pathways were alternately stimulated at 0.05 Hz. (Right) Three sample traces showing somatic whole-cell responses to single-burst stimuli (5 pulses at 100 Hz) delivered to perforant path (PP) in SLM. (B) Mean EPSP amplitudes recorded before and after single-burst stimulation of PP (PP induction) or Schaffer collaterals (SC induction). The stimulus intensity was set to elicit large EPSPs in the test pathways, which received the single-burst stimulus (filled symbols) and smaller EPSPs in the control pathways (no stimulus; open symbols). (C) Potentiation ratios after single-burst stimulation of SC (n = 7) and after single-burst stimulation of PP in SLM (n = 8). Note that SC synapses potentiate robustly (**, P < 0.01, paired t test), whereas the more distally situated PP synapses exhibit a less pronounced potentiation (*, P < 0.05, paired t test). The number of experiments in each condition is indicated at bottom of the respective bars. Data are presented as mean ±SEM.