Project 451326

Repetitive movements like walking, breathing and chewing insure vital functions and are produced by more primitive areas of the brain. Although these movements are executed with a high level of automaticity, as all movements, they need to be constantly adjusted to the conditions of the outside world. How would we know otherwise if we are walking on a slippery surface and need to adjust our gate? Information from the outside world reaches the brain through our senses, but little is known about the mechanisms and circuits that enable interaction between sensory inputs and motor commands. To achieve their tasks in any brain circuit, neurons need to communicate to one another using an electrical language which pattern constitutes their code for communication. A circuit that programs a repetitive movement needs to generate a rhythmic activity pattern. In this proposal, we examine how a nervous circuit in the brainstem generates the rhythmic motor command for chewing and how sensory inputs change the pattern of this command. In addition to neurons, we also consider astrocytes in the circuit that we examine. Astrocytes, another sort of cell in the brain are traditionally considered to play only a support role for neurons, but our recent findings show that they play a key role in shaping the pattern of electrical activity of neurons. Here we propose to examine how sensory information arriving to the brainstem interacts with astrocytes and modulates their behavior. This should help understand how sensory information can drive movement. Because these mechanisms are not unique to the circuit responsible for chewing, but are shared by other circuits that generate rhythmic movements, we believe that they may help devising strategies to restore movements after injuries. More importantly, we think that they may help understand what goes wrong in pathologies like Parkinson's or epilepsy, where similar mechanisms are involved and generate an uncontrolled rhythmic activity.