Short-Term Synaptic Plasticity and Persistent Activity in the Prefrontal Cortex

Abstract

Persistent activity of cue-representing neurons in the prefrontal cortex (PFC) is regarded as a neural basis for working memory. Contribution of short-term synaptic plasticity (STP) at different types of synapses comprising the cortical network to persistent activity, however, remains unclear. Upon characterization of STP at synapses of the PFC network, PFC synapses were found to exhibit distinct STP patterns according to presynaptic and postsynaptic identities. Excitatory synapses from corticopontine (Cpn) neurons were well sustained throughout continued activity, with stronger depression at synapses onto fast-spiking interneurons than those onto pyramidal cells. Inhibitory postsynaptic currents were sustained at a weaker level compared to excitatory postsynaptic currents from Cpn synapses. Computational modeling of a balanced network incorporating empirically observed STP revealed that little depression at recurrent excitatory synapses, combined with stronger depression at other synapses, could provide the PFC with a unique synaptic mechanism for the generation and maintenance of persistent activity.