Sensorimotor and Autonomic Contributions of the Brainstem in Physiological and Pathophysiological Conditions

Traditionally, the brainstem is considered a conduit which relays information descending and ascending between higher brain centers, the cerebellum and the spinal cord. However, the brainstem can be considered much more than a relay station. Key nuclei located within the brainstem are essential for integrating sensory and nociceptive feedback from the periphery, processing motor commands involved in coordination, gait and posture; as well as regulating autonomic functions, such as respiration, blood pressure and heart rate. In order to exert control over many basic functions, sites within the brainstem are well organized and are able to integrate multiple afferent inputs. These inputs are then translated to cranial motoneurons and reticulospinal neurons ensuring the appropriate outputs are achieved. One key example, is the brainstem nuclei that coordinate the integration of motor commands like movement initiation and execution from higher brain centers. They ensure appropriate levels of motor tone, fine-tuning the motor command and locomotion such as gait and posture, steering and turning. At the same time, these nuclei are involved in regulating the output of the autonomic nervous system to ensure that metabolic demands are met to maintain motor outputs. That is, these centers facilitate the integration of multiple inputs from higher brain centers, with feedback input from the spinal cord during motor tasks to ensure stable movement and metabolic demands.

Given the brainstem's importance in integrating and coordinating motor outputs, as well as sensory processing including nociception, the brainstem has become a focus on rehabilitative strategies to improve autonomic, motor and sensory function after neurological injury or disease. However, to develop and target effective therapeutic strategies for regaining sensorimotor and autonomic function, basic understanding of the micro-circuits that govern the integration of cortical and spinal cord inputs are needed. This will in turn further our understanding of how these circuits are disrupted following injury or disease.

In this Research Topic, we welcome manuscripts studying brainstem functions in health, disease and injury. We will consider both Original Research and timely Reviews focused on:

1) identifying and characterizing neuronal populations with the brainstem involved in sensorimotor and autonomic functions;

2) identifying afferent and efferent projection patterns of brainstem neurons;

3) examining synaptic integration within the brainstem;

4) plasticity of the brainstem following injury or disease;

5) reorganization of brainstem cells and nuclei following therapeutic strategies like rehabilitation or stimulation promoting functional recovery.

As the brainstem's structure and function is conserved across species, we encourage studies using any model from lower vertebrates to humans and using either traditional methods such as electrophysiology, electrical stimulation (TMS, DBS, microsimulation, peripheral nerve stimulation) or pharmacological and genetic approaches such as fluorescent and viral tract tracing techniques, optogenetics, pharmacogenetics, and calcium imaging. The wide array of models and methodology will provide insight into not only cell-to-cell but neural network connectivity