The stimuli which lead to emesis are received and processed in the brain. It is thought that a number of loosely organized neuronal networks within the medulla oblongata probably interact to coordinate the emetic reflex.[9] Some of the brain stem nuclei which have been identified as important in the coordination of the emetic reflex include the parvicellular reticular formation, the Bötzinger complex and the nucleus tractus solitarii.[22] The nuclei coordinating emesis had formerly been referred to as the vomiting complex, but it is no longer thought to represent a single anatomical structure.[9][22]