Article Summary

Title : Hyperpolarization-activated graded persistent activity in the prefrontal cortex
Authors : Milena Winograd, Alain Destexhe and Maria V Sanchez-Vives
Year : 2008
Journal : Proceeding of the national academy of science of the USA
Volume : 105
Pages : 7298-7303


We describe a phenomenon of hyperpolarization-activated graded persistent activity (HAGPA) in prefrontal cortex neurons. Succes- sive hyperpolarizing pulses induced increasingly higher rates of tonic ?ring that remained stable for tens of seconds, allowing the neuron to retain a memory of the previous history of stimulation. This phenomenon occurred at the cellular level and in the absence of neuromodulators. Neurons with HAGPA had a sag during hyperpolarization, and blocking h-current eliminated the sag and prevented HAGPA, suggesting that the activation of this hyper- polarization-activated cationic current was necessary for the oc- currence of the phenomenon. A single-neuron biophysical model including h-currentmodulation by intracellular calciumwas able to display HAGPA. This form of neuronal memory not only allows the transformation of inhibition into an increase of ?ring rate, but also endows neurons with a mechanism to compute the properties of successive inputs into persistent activity, thus solving a dif?cult computational problem.