Cognitive challenges trigger a slight oxygen deficit in hippocampal pyramidal neurons. This increases the production of erythropoietin (Epo) and its receptors in the active neurons, stimulating neighboring precursor cells to form new neurons and enhancing connectivity.
Increased potassium currents were responsible for hyperactivity of CA3 neurons. When exposed to potassium channel blockers, the hyperactivity disappeared. However, when exposed to lithium, the drug not only reversed hyperactivity but reduced potassium currents at the same time. The findings strengthen the case that potassium currents play a role in bipolar disorder.