ABSTRACT
Many models exist to help the medical student learn how to suture at a competency level required to progress to suturing on patients. However, these models do not readily simulate the qualities of live human tissue. We propose a simple intraoperative high-fidelity model that places the excised autologous patient tissue (eg, panniculectomy and breast reduction) on a sterile side table to allow the trainee to practice their skills alongside the staff surgeon on comparable tissue for the remainder of the case. We believe that the adoption of this practice allows a unique opportunity for medical students to advance their suturing techniques in a low-stress environment with staff surgeon guidance, further preparing them to perform high-quality closures on live patients.
ABSTRACT
Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.
