Neurotoxicity studies are preclinical studies that are conducted to evaluate the potential adverse effects of a substance on the nervous system. These studies are typically conducted in laboratory animals, such as rats or mice, to assess the safety of a drug or other substance before testing in humans.

The primary objective of neurotoxicity studies is to identify any potential adverse effects of the substance on the structure or function of the nervous system, including changes in behavior, neurochemistry, neurophysiology, or histology. These studies can include a range of endpoints, such as neurobehavioral testing, histopathological examination of nervous tissue, and electrophysiological assessments.

Neurotoxicity studies can be further classified based on the exposure period and the endpoints evaluated:

1. Acute neurotoxicity studies: These studies are conducted to evaluate the potential effects of the substance on the nervous system after short-term exposure, usually for a few days to a few weeks.
2. Sub-chronic neurotoxicity studies: These studies are conducted to evaluate the potential effects of the substance on the nervous system after repeated exposure over a period of several weeks to several months.
3. Chronic neurotoxicity studies: These studies are conducted to evaluate the potential effects of the substance on the nervous system after repeated exposure over a period of several months to several years.

The results of neurotoxicity studies can help identify any potential adverse effects of the substance on the nervous system, and can help inform decisions about the safety of the substance for use in humans. These studies are an important part of the preclinical safety assessment of drugs and other substances, particularly those intended for long-term use or for use in populations with a higher risk of neurotoxicity.