Brainstem control of deglutition: Swallowing pattern generator

Abstract

Deglutition, one of the most elaborate motor functions in mammals, depends on a CPG located in the medulla oblongata, which involves several brainstem motor nuclei and two main groups of interneurons. The DSG, located in a primary sensory nucleus, namely the NTS, contains the generator neurons involved in triggering, shaping and timing the sequential or rhythmic swallowing pattern. The VSG, located in the ventrolateral medulla, contains switching neurons that distribute the swallowing drive to the various pools of motoneurons. Both peripheral sensory inputs and supramedullary influences, such as the cortical ones, may shape the CPG activity in order to adapt the output of the network to the motor pattern required. Interestingly, signalling pathways involved in the control of food intake do also exert modulatory infl uences on the CPG. As regard the mechanisms at work in the CPG, they depend, very probably, on the pattern of intrinsic connections, with a crucial role of the inhibitory ones in shaping the sequential firing, as well as on the intrinsic cellular properties of swallowing neurons. Recent data indicate that the CPG may show some degree of fl exibility, with neurons participating to the activity of other brainstem CPGs, providing interesting neuroplasticity capabilities.