Discussion

One of the major challenges in phenotypic screening is to maintain relevance to the intact organism while striving to achieve a higher throughput. In studies of the central nervous system (CNS), this involves the ability to test network activity and plasticity in higher-throughput assays. Primary neuronal cell cultures are considered to be relevant in vitro models of functional activity but even though neuronal viability is commonly used as the endpoint for phenotypic assays, viability per se may not truly reflect neuronal dysfunction in neurodegenerative diseases. Rather, functional changes, such as excitability, structural changes and/or synapse strength alterations occur much earlier than cell death. Such alterations may thus serve as more relevant read-outs. Therefore, assays that enable identification of compounds affecting such events are highly desired. We investigate the neuronal response to electric field stimulation, EFS, and to this aim, we use an electrode array to simultaneously excite neurons in all wells of a microplate. At the same time, the entire plate is imaged dynamically. Here, we demonstrate an assay in which we can electrically excite primary CNS neurons and monitor their excitability as well as their synaptic function. A case study will be presented where compound effects on those crucial events are investigated.