Figure 7

Model for K ⁺ channel regulation during induction of homeostatic intrinsic plasticity. TTX application rapidly blocks spontaneous action potential firing, causing an initial decrease in Ca²⁺ influx through NMDARs in dissociated hippocampal neurons cultured at high density. The subsequent transcriptional down-regulation of multiple K⁺ channel genes leads to a reduction in the protein expression of K⁺ channels at the neuronal plasma membrane. By 48 h, a decrease in currents through these K⁺ channels regulates AP and passive properties of hippocampal neurons, resulting in a homeostatic increase in the AP firing rates. The representative AP traces in the insets are from Figure 1A.