Increased excitability of both principal neurons and interneurons during associative learning

In this review, we highlight several studies indicating that the modulation of intrinsic neuronal excitability is key for successful memory formation. Specifically, we will focus our discussion on our hypothesis that the postburst afterhyperpolarization (a key regulator of intrinsic excitability) is an essential cellular mechanism used by both principal and inhibitory neurons to change their neuronal activity as memory is formed. In addition, we propose that these intrinsic excitability changes occur first in principal neurons, followed by changes in inhibitory neurons, thus maintaining the balance of network activity among neurons for successful encoding and readout of memory.