Mammalian axons are specialized for transmitting action potentials to targets within the central and peripheral nervous system. A growing body of evidence suggests that, besides signal conduction, axons play essential roles in neural information processing, and their malfunctions are common hallmarks of neurodegenerative diseases. The technologies available to study axonal function and structure integrally limit the comprehension of axon neurobiology. 

Complementary-metal-oxide-semiconductor (CMOS) -based high-density microelectrode arrays (HD-MEAs) have been designed to record extracellular action potentials from neuronal cultures and allow tracking axonal signals across hundreds of microelectrodes. Thanks to a low-noise CMOS-design, HD-MEAs enable detection of APs across entire arbors of cortical axons. HD-MEAs provide noninvasive access to axonal action potentials and impose no constraints on the duration of the recording sessions. Here we present extracellular electrical activity recorded from rat's primary neurons using CMOS-based HD-MEA system (MaxWell Biosystems AG). Datasets comprise electrophysiological recordings obtained from primary motor and cortical neurons. Recorded signals were up-sampled to 200 kHz following the Whitaker-Shannon interpolation formula. Recorded signals were spike-sorted and spike-trigger averaged across an entire array (26400 electrodes). Such signal representation is referred to as ‘axonal electrical image’.