Tachykinin ligands have been extensively studied and determined to be functionally linked to the control of affective phenotypes in a complex physiological manner. Epilepsy is a broad category of disorders with varying types of severity and presented symptoms. Neurokinins have been experimentally determined as possible predictor in the generation of certain forms of epilepsy. Experimentally when substance P is injected into the rat hippocampus, it significantly lowers the initiation threshold for seizures induced in a dose-dependent manner. Experimental data thus has indicated a pro-convulsant role for the "Pre-protachykinin-1" gene and thus substance P and neurokinin A.