Figure 2.

Voltage-dependent changes of synaptic strength. A–E, Time courses of Ca²⁺ concentration (A), CaMKII activity (B), PP1 activity (C), PKA activity (D), and CaN activity (E) at PSD in response to 100 prespikes at 1 Hz with the indicated voltage clamp of somatic membrane potential during the stimulation. Colors correspond to the voltage as indicated in E. Arrowheads indicate the onset of stimulation. The inset in A shows its time courses by a single prespiking. F, Voltage-dependent Ca²⁺ concentration at PSD. The black and gray lines indicate the mean and maximal amplitude of Ca²⁺ concentration, respectively. G, Voltage-dependent CaN, PKA, PP1, and CaMKII activities. Integrated PP1 activity (red; normalized with the maximal activity, 0.33), integrated PKA activity (dark blue; normalized by 3.68), integrated CaN activity (green; normalized by 1.75), and final CaMKII activity (light blue) against the indicated membrane potentials are plotted. H, Time courses of changes of synaptic conductance. I, Voltage-dependent changes of synaptic conductance. Data were taken at 2 and 60 min after the onset of stimulation (Obs 1 and Obs 2, respectively) as indicated in H.