Oscillatory Working Memory in Networks with Short-Term Synaptic Facilitation
Experimental studies have recently reported the existence of a rich variety of activity-dependent patterns of synaptic transmission in pre-frontal cortex. In particular, strong, short-term facilitation of synaptic efficacy at inter-pyramidal synapses has been found. By using dynamical system modeling, we investigate the effects of short-term facilitation on the activity patterns exhibited by a simple network model. In a suitable region for synaptic transmission parameters (consistent with experiment), the network exhibits bi-stability between a fixed point solution (to be identified with a 'spontaneous activity' state) and a limit cycle solution (to be identified with a 'working memory' state). We carried out numerical simulations to verify that the qualitative results obtained from the simple model remain valid in more 'realistic' networks of spiking neurons. Finally, we discuss some of the implications of this mode of activity on working memory function.