Factors Influencing Polychronous Group Sustainability as a Model of Working Memory

Working memory is the system that underlies the temporary storage and manipulation of information. However, the exact biological basis and neural mechanisms of cognitive function and working memory has yet to be fully uncovered. The temporary storage of information has been correlated with enhanced spiking activity in the form of persistent reverbaration for several seconds, as shown in vivo experiments. Several computational models have been designed to help our understanding of the conditions under which persistent activity can be sustained in cortical circuits. Here, we will focus on one such model that has shown promise, that uses polychronisation and short term synaptic dynamics to achieve this reverberation, and explore it with respect to different physiological parameters in the brain, including size of the network, number of synaptic connections, small-world connectivity, maximum axonal conduction delays, and type of cells (excitatory or inhibitory). We show that excitation and axonal conduction delays greatly affect the sustainability of spatio-temporal patterns of spikes called polychronous groups, even though the large variance in some of our results suggest that further exploration is needed on a larger scale of neuronal populations.