Brainstem: neural networks vital for life

The brainstem is critically important for the survival of an animal. It lies between higher centres and the spinal cord and constitutes one of the oldest parts of our brains. Respiratory and cardiovascular systems fail and death ensues after circumscribed injury to the brainstem. Its neurons create the rhythm of inspiration and expiration, which starts in utero, and continues until the moment of death. How do brainstem circuits provide commands that are so inexorable that you cannot decide to commit suicide by holding your breath (although you can do so by fasting)? The brainstem also regulates blood pressure, second by second, to ensure that the blood supply to the cerebral cortex is always adequate, for example, in the face of gravity, as you get up from bed, or during strenuous exercise, when much of the blood flow is diverted to skeletal muscles. In spite of its role in these and many other essential bodily functions, the study of the brainstem has been neglected compared with research made on structures such as the cortex, hippocampus, cerebellum, retina, basal ganglia and spinal cord.