To be considered a nootropic, a substance must meet all of the following characteristics:
- Enhance learning and memory.
- Increase the resistance of learned behaviors and memories to conditions which tend to disrupt them (e.g. electroconvulsive shock, hypoxia).
- Protect the brain from physical or chemical injury. (e.g. concussions, barbituates, scopalamine).
- Enhance the tonic control mechanisms of the cortex on the subcortical level mechanisms (positively effect how neurons fire)
- Exhibit few side effects and extremely low toxicity, while lacking the pharmacology of typical psychotropic drugs.