Development of an objective index, neural activity score (NAS), reveals neural network ontogeny and treatment effects on microelectrode arrays

Passaro AP, Aydin O, Taher M, Saif A and Stice SL

Scientific Reports, 2021


The Axion microelectrode array (MEA) system is a valuable tool for electrophysiological analysis of neural networks or neural populations in vitro.  MEA systems provide a large dataset of many activity parameters which are often simplified to overall activity (firing rate). With the use of multi-well microplates, even more data can be collected simultaneously.  Additional analysis will allow for the reporting of network parameters such as burst characteristics or synchrony.  

Mouse embryonic stem cells were differentiated into mixed neuronal co-cultures of excitatory and inhibitory neurons, and glial cells.  Spontaneous activity was recorded over days from the developing neural co-culture. Initially sporadic spikes were recorded, then sporadic bursts and finally synchronous network activity. 

A principal component analysis (PCA) was used to reduce the complexity of information from MEA in neural development and toxicity studies.  This analysis showed that the first principal correlated to time and therefore neural culture development.  This could become a single index score called neural activity score reflecting the network maturity.  This analysis and score was applied to a variety of treatments and consistently reported the network health.