Intracellular Microelectrode Array (imea) and Synaptic Connectivity Mapping

– Intracellular recording offers exquisite access to the electrical interior of a neuron––detecting not only spikes but also the small synaptic signals that reflect synaptic connections and their properties––but it had been limited to only one cell at a time. In 2020, a CMOS nanoelectrode array broke this constraint and massively parallelized intracellular recording, opening a path to capturing synaptic signals across a neuronal network. This shift led us in 2021 to propose thecopyframework: population-scale intracellular recording is a process of copying a biological network, because the resulting data––rich with synaptic signals from across the network––reveal its synaptic connectivity map. In this Perspective, we revisit that framework because the recent CMOS intracellular microelectrode array (iMEA), building on the 2020 nanoelectrode array, transforms copy from a demanding demonstration into a practical, high-yield technology. By routinely recording intracellular signals across thousands of neurons, the iMEA uncovers synaptic organization with a breadth and clarity previously unreachable. We outline the development of the iMEA as an improved copy platform, what it now enables, and what must still be advanced to build a richer synaptic connectivity map––one that is indispensable to understanding how the brain functions, and provides a firmer foundation for neuromorphic models grounded in the brain’s own wiring.