title: Size-dependent regulation of synchronized activity in living neuronal networks.
abstract: We study the effect of network size on synchronized activity in living neuronal networks. Dissociated cortical neurons form synaptic connections in culture and generate synchronized spontaneous activity within 10 days in vitro. Using micropatterned surfaces to extrinsically control the size of neuronal networks, we show that synchronized activity can emerge in a network as small as 12 cells. Furthermore, a detailed comparison of small (∼20 cells), medium (∼100 cells), and large (∼400 cells) networks reveal that synchronized activity becomes destabilized in the small networks. A computational modeling of neural activity is then employed to explore the underlying mechanism responsible for the size effect. We find that the generation and maintenance of the synchronized activity can be minimally described by: (1) the stochastic firing of each neuron in the network, (2) enhancement in the network activity in a positive feedback loop of excitatory synapses, and (3) Ca-dependent suppression of bursting activity. The model further shows that the decrease in total synaptic input to a neuron that drives the positive feedback amplification of correlated activity is a key factor underlying the destabilization of synchrony in smaller networks. Spontaneous neural activity plays a critical role in cortical information processing, and our work constructively clarifies an aspect of the structural basis behind this.
authors: Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan.
authors: Hideaki
authors: H
authors: Yamamoto
authors: Graduate School of Science and Engineering, Yamagata University, Yamagata 992-8510, Japan.
authors: Shigeru
authors: S
authors: Kubota
authors: Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
authors: Yudai
authors: Y
authors: Chida
authors: School of Fundamental Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors: Mayu
authors: M
authors: Morita
authors: Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
authors: Satoshi
authors: S
authors: Moriya
authors: Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
authors: Hisanao
authors: H
authors: Akima
authors: Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
authors: Shigeo
authors: S
authors: Sato
authors: Graduate School of Biomedical Engineering, Tohoku University, 980-8579 Sendai, Japan.
authors: Ayumi
authors: A
authors: Hirano-Iwata
authors: School of Fundamental Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors: Takashi
authors: T
authors: Tanii
authors: Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
authors: Michio
authors: M
authors: Niwano
mesh_terms: D000200:Action Potentials; D000818:Animals; D005246:Feedback; D008959:Models, Neurological; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D013569:Synapses / Q000378:metabolism