Different toxins affect the nervous system; there are many sources of neurotoxicants. A lot of the venoms from spiders and snakes as well as plants are neurotoxicants as well. Neurotoxicants are compounds that will injure or interfere with functions of the nervous system: they can act just in the brain, the spinal cord, or the periphery. We don"t know the mechanism of action for all the neurotoxicants. Some neurotoxins can incapacitate you right away while others are more subtle and you won"t know that it"s a neurotoxin until later on. It"s hard to extrapolate between other species and humans, i. e. cognitive function so it"s hard to find good models for neurotoxins. Acute vs. chronic toxicity: chronic toxicity in the nervous system is harder to pin down and can be quite subtle. We don"t know the pathogenesis of these diseases. The nervous system is vulnerable in a variety of specialized ways.