<Li> Nucleus: Nucleus ambiguus and nucleus retro ambiguus . </Li> <Li> Function: It generally causes expiration but can cause either expiration or inspiration depending upon which neuron in the group is stimulated . It sends inhibitory impulse to the apneustic center . </Li> <P> In the pons, the pontine respiratory group includes the pneumotaxic and apneustic centers . These have connections between them, and from both to the solitary nucleus . </P> <P> The pneumotaxic center is located in the upper part of the pons . Its nuclei are the subparabrachial nucleus and the medial parabrachial nucleus . The pneumotaxic center controls both the rate and the pattern of breathing . The pneumotaxic center is considered an antagonist to the apneustic center, (which produces abnormal breathing during inhalation) cyclically inhibiting inhalation . The pneumotaxic center is responsible for limiting inspiration, providing an inspiratory off - switch (IOS). It limits the burst of action potentials in the phrenic nerve, effectively decreasing the tidal volume and regulating the respiratory rate . Absence of the center results in an increase in depth of respiration and a decrease in respiratory rate . </P>

Centers for respiratory and cardiovascular control are found in this part of the brain