The electrical stimulation hardware consisted of an MEA interfacing headstage, a digital to analog conversion board, a router circuitry, and a controlling PC (Lenovo). Plexon MHP64 headstage was used for interfacing MEAs which was designed for the 64 channel MEA layouts. A custom designed router circuitry was employed for directing analog stimulation signals to selected channel or channels from 64 alternatives. Digital stimulation signals were converted to analog voltages using National Instruments (NI) 6001 board, at a sampling rate of 5 kHz. Digital to analog conversion and router circuitry were controlled with a custom software written in MATLAB (Mathworks Inc.) incorporating Data Acquisition Toolbox (Mathworks Inc.) and utilizing the NI drivers and libraries. All stimulation signals were voltage controlled biphasic pulses and the stimulation parameters were adapted from previous studies [17 (link)–19 (link)]. The pulse durations and the amplitudes that elicit stable and reproducible responses were empirically adjusted in the ranges of 100–500 μs and 1–3 V, respectively.
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