Simultaneous multi-electrode array recording and two-photon calcium imaging of neural activity

A complete understanding of how brain circuits function will require measurement techniques which monitor large-scale network activity simultaneously with the activity of local neural populations at a small scale. Here we present a useful step towards achieving this aim: simultaneous two-photon calcium imaging and multi-electrode array (MEA) recordings. The primary challenge of this method is removing an electrical artifact from the MEA signals that is caused by the imaging laser. Here we show that artifact removal can be achieved with a simple filtering scheme. As a demonstration of this technique we compare large-scale local field potential signals to single-neuron activity in a small-scale group of cells recorded from rat acute slices under two conditions: suppressed vs. intact inhibitory interactions between neurons.

Research highlights▶ Combining two-photon imaging with simultaneous multi-electrode array (MEA) recording requires the removal of an electrical artifact from the MEA data caused by the imaging laser. ▶ We present a simple method to remove the laser artifact based on frequency domain filtering. ▶ Simultaneous two-photon imaging and multi-electrode array recording of cortical neural populations supports the idea that inhibition is required for maintaining diverse population dynamics.