Altanserin hydrochloride is primarily used in neuroscience research as a radioligand for positron emission tomography (PET) imaging. It selectively binds to serotonin 5-HT2A receptors in the brain, allowing researchers to map receptor distribution and density in vivo. This application is valuable in studying psychiatric and neurological disorders such as schizophrenia, depression, and Alzheimer's disease. Due to its high affinity and specificity, it helps assess changes in serotonin receptor activity in response to drug treatments or disease progression. Altanserin hydrochloride is also used in preclinical studies to validate new compounds targeting the 5-HT2A receptor.