Fabrication of Artificial Neuronal Circuit by In-Situ Guidance of Individual Neurites

Establishment of an artificial neuronal circuit, a simple in-vitro model that mimics the in-vivo architecture and function of neural circuits, are expected to facilitate the study of network properties of neurons in a brain and their computational role. Various attempts have been made to pattern neurons and their processes using pre-designed templates of polypeptides, proteins, or self-assembled monolayers. Yet arbitral fabrication of a neuronal circuit with defined connectivity has not been demonstrated with the conventional approaches, primarily due to the complexity of neurons, having two types of neurites, i.e., axons and dendrites. Moreover, excitatory or inhibitory neurons must be positioned preferentially in the circuit. Controlling inter-neuronal connectivity requires patterning of individual neurons and distinctive guidance of the neurites.

For the fabrication of a designed network of neurons, neurons need to be immobilized on preferred sites on a template, followed by connecting their neurites individually to other cells. This approach is akin to building an electronic circuit on a stripboard and enables us to design a living neuronal circuit by guiding a selected neurite to a preferred site of any target neuron with an arbitrary pathway. To make this, we investigate the feasibility of photocatalytic lithography of self-assembled monolayers deposited on a titanium dioxide film. Decomposition of cytophobic monolayers by ultra-violet irradiation allows individual cells to attach to the decomposed surface and to elongate their neurites on a subsequently decomposed line pattern. The photocatalytic lithography can be carried out not only in the atmosphere but also in a culture media in which neurons are being cultured. Using this technique, we intend to reconstruct local neuronal circuits on a chip and understand their functions by comparing with related mathematical models.


H.Yamamoto, K.Okano, T.Demura, Y.Hosokawa, H.Masuhara, T.Tanii, S.Nakamura: In-situ guidance of individual neuronal processes by wet femtosecond-laser processing of self-assembled monolayers, Appl. Phys. Lett. 99 (2011) 163701.


H.Yamamoto, T.Demura, M.Morita, G.Banker, T.Tanii, S.Nakamura: Differential neurite outgrowth is required for axon specification by cultured hippocampal neurons, Journal of Neurochemistry 123 (2012) 904-910.