Synaptic Connectivity of a Low Density Patterned Neuronal Network Produced on the Poly-L-Lysine Stamped Microelectrode Array

Rectangular networks of rat hippocampal neurons have been produced on microelectrode arrays (MEAs). The crossing points of networks were located at the recording electrode sites by aligned microcontact printing (muCP) technique. Polydimethysiloxane (PDMS) stamp was fabricated to print fine poly-L-lysine (PLL) patterns of 2 mum-width lines for neurites and 20 mum-diameter circles for cell bodies. Different densities of neurons were applied on the PLL-stamped MEAs to find how a low density of neurons still has the functional connectivity. From the neural network applied with a density of 200 cells/mm² , we could observe signal propagation among spontaneous activities. Electrical responses were also evoked by 200 muA current pulse stimulation with 50 mus pulse width. Immunocytostaining was employed to identify dendrites, synapses, and nuclei in the patterned neurons