A brainstem circuit for the expression of defensive facial reactions in rat

Chemoreceptors in the nasal epithelium can trigger an apneic reaction and a grimace in response to airborne irritants. Callado Perez et al. find that the underlying circuit does not involve olfaction. Rather, activation of neurons in the muralis subnucleus of the spinal trigeminal complex will inhibit the Pre-Bötzinger inhalation oscillator.