Amyotrophic lateral sclerosis (ALS) is a form of motor neuron disease characterized by loss of motor neurons in the brain and spinal cord. These cells are involved in movements, which are generated by the sequential activity of cells in three regions of the central nervous system: they are planned by the activity of neurons in the premotor cortex (whose activity is monitored by brain-computer interfaces), and executed when this activity is relayed to motor neurons in the ventral horn of the spinal cord, via the cells in the primary motor cortex.