During a space flight, cosmonauts have to adapt to new unique environmental conditions. As a result, they accumulate changes to their bodily systems that can eventually cause undesirable consequences potentially detrimental to the success of the mission. The review examines research papers investigating functional and structural changes occurring in the brain in the context of a spaceflight. Microgravity is believed to be the main factor behind the said changes: it causes redistribution of fluid in the body and conditions adaptive neural rearrangements at the microstructural level. Other elements peculiar to a spaceflight that can have this or that effect on the brain are also considered. In addition, this review scopes publications that allow assumptions about the specific causes of the registered morphofunctional alterations in the brain of cosmonauts.