Neurocomputing 65–66 (2005) 859–868 Study on the role of GABAergic synapses in synchronization Ho Young Jeong à , Boris Gutkin Gatsby Computational Neuroscience Unit, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK Available online 15 December 2004 Abstract GABAergic synapses play an important role in the control of neural activity as well as the formation of neural circuitry. In particular, the reversal potential of GABAergic synapses can change significantly during development along with the intrinsic neuronal properties. In this report, we study the influence of such synaptic changes on synchrony in neural circuits. We use phase reduction methods to study the stability of synchrony. Numerical simulations of a conductance-based model based on the analysis exhibit the various firing conditions. We also extend the analysis to large globally coupled neuronal networks. r 2004 Elsevier B.V. All rights reserved. Keywords: Synchronization; GABAergic synapses; Afterhyperpolarization 1. Introduction GABA (g-aminobutyric acid) synaptic transmission plays an important role in the construction of developing neuronal circuitry as well as sculpting the activity in the adult brain. Early in development GABAergic synapses are formed before glutamate neurotransmission appears. During this stage, the activity of the GABAergic synapses is excitatory due to high intracellular concentration of chloride ion, promoting neural growth and synapse formation [1,2]. For example, fluorometric ARTICLE IN PRESS www.elsevier.com/locate/neucom 0925-2312/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.neucom.2004.10.063 à Corresponding author. Tel.: +442076791176. E-mail address: jeonghy@gatsby.ucl.ac.uk (H.Y. Jeong).