AUTHOR=Madadi Asl Mojtaba , Valizadeh Alireza , Tass Peter A. 

TITLE=Dendritic and Axonal Propagation Delays May Shape Neuronal Networks With Plastic Synapses

JOURNAL=Frontiers in Physiology

VOLUME=Volume 9 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01849

DOI=10.3389/fphys.2018.01849

ISSN=1664-042X

ABSTRACT=‎Biological neuronal networks are highly adaptive and plastic‎. ‎For instance‎, ‎spike-timing-dependent plasticity (STDP) is a core mechanism which adapts the synaptic strengths based on the relative timing of pre‎- ‎and postsynaptic spikes‎. ‎In various fields of physiology‎, ‎time delays cause a plethora of biologically relevant dynamical phenomena‎. ‎However‎, ‎time delays increase the complexity of model systems together with the computational and theoretical analysis burden‎. ‎Accordingly‎, ‎in computational neuronal network studies propagation delays were often neglected‎. ‎As a downside‎, ‎a classic STDP rule in oscillatory neurons without propagation delays is unable to give rise to bidirectional synaptic couplings‎, ‎i.e‎. ‎loops or uncoupled states‎. ‎This is at variance with basic experimental results‎.  In this mini review, we focus on recent theoretical studies focusing on how things change in the presence of propagation delays‎. ‎Realistic propagation delays may lead to the emergence of neuronal activity and synaptic connectivity patterns‎, ‎which cannot be captured by classic STDP models‎. ‎In fact‎, ‎propagation delays determine the inventory of attractor states and shape their basins of attractions‎. ‎The results reviewed here enable to overcome fundamental discrepancies between theory and experiments‎. ‎Furthermore‎, ‎these findings are relevant for the development of therapeutic brain stimulation techniques aiming at shifting the diseased brain to more favorable attractor states‎.