rostral

They analyzed the fossils’ rostral denticles, the spikes that jut from the sides of a sawfish’s snout to aid in foraging and self-defense.

Rostral denticles look like teeth, but they’re actually specialized body scales.

Although rostral denticles didn’t become teeth themselves—sawfish ancestors already had teeth—this discovery indicates that scales like the ones on a fish’s bodily surface have the capacity to evolve a toothlike internal structure, and they could have done so at least once before.

The placebo effect increased activity in an area called the rostral ventromedial medulla, which relays pain information, and decreased activity in the periaqueductal gray, which helps the body suppress pain.

Peter Strick, a neuroscientist at the University of Pittsburgh, injected the virus into rat stomachs and discovered vagal pathways that lead to the rostral insula, a poorly understood region thought to process sensations from internal organs and regulate emotions.