Which among the following poison acts as a spinal poison?

Strychnine competitively blocks ventral horn motor neuron postganglionic receptor sites in the spinal cord and prevents the effects of glycine. Widespread inhibition in the spinal cord results in 'release' excitation. The action is paicularly noted in the anterior horn cells. It stimulates the cerebral coex. Ref: The Essentials of Forensic Medicine and Toxicology by KS Narayan Reddy, 27th edition, Page 545.