Inter-regional Dynamics in Hippocampal Sub-Networks Co-cultured on Microelectrode Arrays and Connected via Micro-Tunnels

Different pairs of adjacent sub-regions of rat hippocampal neurons were co-cultured within two-well devices on micro-electrode arrays (MEAs). Micro-tunnels allowed passage of axons, strong structural connectivity, and information transmission between wells. Paired-pulse stimuli were delivered at each electrode to increase the probability of the excitation without overstimulation. Because of the micro-channel construction, the electrodes inside these tunnels pick up more activity than those within each well. In particular, the strong axonal inputs from the sources of native feed-forward EC-DG and CA3-CA1 co-cultures evoked more target activity than the feed-back networks. In contrast, the evoked target activity in the native feed forward DG-CA3 networks was lower than the reverse flow of information.