c-Fos is a protein that functions as a transcription factor, which means it helps regulate the expression of specific genes. It is often used as a marker for neuronal activity, as its levels increase in response to various stimuli, such as stress or learning. Researchers study c-Fos to understand how the brain processes information and responds to different experiences. In the context of neuroscience, c-Fos is valuable for mapping brain activity. When neurons are activated, they can produce c-Fos, allowing scientists to visualize which areas of the brain are involved in particular behaviors or responses. This makes c-Fos an important tool in studies related to neurobiology and psychology.