1. A method for identifying an agent for treating a neurodegenerative condition associated with degeneration of motor neurons caused by soluble factors released by astrocytes carrying a SOD1 G93A mutation, comprising: i. subjecting embryonic stem cells to retinoic acid and sonic hedgehog agonist in vitro, for five days, to produce a-motor neuron cells; ii. plating the motor neuron cells in neurobasal medium containing 2% heat inactivated horse serum, B27 supplement, 0.5 mM glutamine, 25 μM 2-mercaptoethanol, and penicillin/streptomycin and adding a degeneration-promoting astrocyte carrying a SOD1 G93A mutation or a conditioned medium produced by a culture of degeneration-promoting astrocytes carrying a SOD1 G93A mutation, so as to establish a culture system comprising the motor neuron and a degeneration-promoting astrocyte carrying a SOD1 G93A mutation or a conditioned medium produced by a culture of degeneration-promoting astrocytes carrying a SOD1 G93A mutation; iii. adding the agent to the culture system; iv. subjecting the culture system to a time period of culturing of at least 2 days; v. evaluating whether the motor neuron in the culture system degenerates in the presence of the agent, wherein the evaluation of degeneration is relative to a control culture system comprising identically produced motor neurons subjected to the same time period of culturing in the absence of the agent; and vi. determining if the agent reduces degeneration of the motor neurons by comparing the number of dead neurons present in the culture system containing the agent to the number of dead neurons in the control culture system.