Deciphering micro-and mesoscale dynamics in ALS patient-derived motor neuron networks

Amyotrophic lateral sclerosis (ALS) causes degeneration of vulnerable motor neurons leading to progressive paralysis and death. However, there is mounting evidence that the disease causes changes in brain functional connectivity prior to the emergence of motor symptoms. An important unanswered question is how these early changes in network dynamics contribute to pathology. Using high density multielectrode arrays (HD-MEAs) and induced pluripotent stem cell (IPSC)-derived motor neurons, we show that both healthy motor neurons and motor neurons derived from an ALS patient with an expansion mutation in C9orf72 self-organise into networks with high computationally capacity. However, ALS networks show classical TDP-43 cytopathology alongside dysfunctional microscale features and mesoscale compensatory dynamics, including increased network centralisation. Our findings demonstrate that ALS pathology leads to a sub-optimal network organisation which increases the overall metabolic cost of the network. This is the first study to show endogenously altered functional connectivity in in vitro neural networks derived from a patient with confirmed neurodegenerative disease. We further show that this organisation makes the network more vulnerable to perturbation by selectively induced chemical hypoxia in complex microfluidic MEAs.