4-MTA hydrochloride is primarily used in research settings to study its effects on serotonin and dopamine systems in the brain. It serves as a tool for investigating neurotransmitter release, receptor interactions, and behavioral responses in animal models. Due to its psychoactive properties, it has been explored in studies related to substance abuse and addiction mechanisms. Additionally, it is sometimes examined for its potential impact on mood regulation and cognitive functions. However, its use is strictly limited to controlled laboratory environments due to its potent and potentially harmful effects.