Fig. 4.

Neurobiological read–write memory on multiple timescales. Sustained neural spiking activity has been viewed as a correlate of memory on short timescales. However, physiological processes other than the evolving membrane state provide dynamic variables for information storage on successively longer timescales. These include intrinsic plasticity, temporally extended synaptic currents, and short-term synaptic plasticity. Coupling of these processes to the membrane state creates read–write cycles where past information, held in slower dynamic variables (storage), is continuously folded back into the fast-changing, active network state (computation). The functional distinction between memory and computation is based on the timescales of dynamic variables.