Table 1. Overview of Assay Endpoints Grouped by Activity Type.

The assay technology type (HCI or MEA), activity type, assay short name, cell type, functional process and endpoints evaluated, and then the expected possible assay response direction are briefly summarized.

Assay technology type	Activity Type	Assay short name	Cell type	Overview of functional processes and endpoints evaluated	Direction
HCI	Proliferation	MUNDY_HCI_hNP1_Pro	Human hNP1	Proliferation based on BrdU labeling, the intensity of this response, and number of nuclei per well (cytotoxicity).	Down
	Apoptosis	MUNDY_HCI_hNP1	Human hNP1	Apoptosis based on luminescent signal produced by detection of caspase 3/7 cleavage. The number of cells were measured based on the amount of ATP present in each well (cell viability).	Both
	Neurite outgrowth, hN2	MUNDY_HCI_hN2_NOG	Human hN2	Neurite outgrowth based on morphology of βII-tubulin labeled neurons. Measurements of neurite length, number of neurites, number of neurite branch points, and number of neurons per well (cytotoxicity).	Down
	Neurite outgrowth, rat	MUNDY_HCI_Cortical_NOG	Rat cortical
	Synaptogenesis and neurite maturation	MUNDY_HCI_Cortical_Synap&Neur_Matur_	Rat cortical	Synaptogenesis based on morphology of MAP2 and synapsin labeled neurons. Measurements of neurite length, number of neurites, number of neurite branch points, the number of pre-synaptic puncta in the cell body compartment or the neurite compartment, the total number of synapses, the number of neurite-associated puncta, and number of neurons pre well (cytotoxicity).	Down
MEA	Network formation activity: General	CCTE_Shafer_MEA_dev	Rat cortical	General activity based on measurements: mean firing rate, burst rate, number of active electrodes, and number of bursting electrodes.	Both
	Network formation activity: Bursting	CCTE_Shafer_MEA_dev	Rat cortical	Bursting activity based on measurements: interspike interval within a burst, number of spikes within a burst, mean duration of a burst, and mean interval between bursts.	Both
	Network formation activity: Network	CCTE_Shafer_MEA_dev	Rat cortical	Network activity based on measurements: number of spikes in a network spike, number of electrodes active at peak of network spike, mean spike duration, SD of network spike duration, mean interspike interval for spikes in network spikes, number of spikes in network spike, percent of spikes in network spike (out of total spikes), mean correlation between all electrodes, and mutual information between all electrodes.	Both
	MEA Cytotoxicity	CCTE_Shafer_MEA_dev	Rat cortical	Two measurements of cytotoxicity: alamarBlue (‘_AB) which detects metabolically active cells and lactate dehydrogenase activity assay (‘_LDH’) which detects LDH released into the cell culture medium upon damage to the plasma membrane. Due to the half-life of LDH and the length of time between media changes, total cellular LDH was measured as an indicator of remaining cells at DIV12.	Down