Which type of fibers are responsible for carrying signals in the FAST pain pathway?

The type of fibers responsible for carrying signals in the FAST pain pathway are Aδ fibers. These fibers are myelinated and have a larger diameter compared to unmyelinated fibers, which allows them to transmit pain signals rapidly. The Aδ fibers are primarily associated with the immediate, sharp sensation of pain that occurs quickly after a painful stimulus, often referred to as "first pain." This rapid transmission is crucial in providing an alert to the body that there is potential harm, prompting a quick protective response.

In contrast, other fiber types, such as C fibers, are associated with slower pain pathways, carrying signals related to dull, throbbing, or lingering pain sensations. Alpha motor neurons are involved in motor function rather than pain transmission, and Aβ fibers are primarily responsible for carrying touch and pressure sensations rather than pain. Therefore, the role of Aδ fibers in rapid pain signaling makes them integral to the FAST pain pathway.