In-cell recordings by extracellular microelectrodes.

Current extracellular multisite recordings suffer from low signal-to-noise ratio, limiting the monitoring to action potentials, and preclude detection of subthreshold synaptic potentials. Here we report an approach to induce Aplysia californica neurons to actively engulf protruding microelectrodes, providing 'in-cell recordings' of subthreshold synaptic and action potentials with signal-to-noise ratio that matches that of conventional intracellular recordings. Implementation of this approach may open new vistas in neuroscience and biomedical applications.