Unique structure of elephant whiskers give them built-in sensing 'intelligence'

Source: Ars Technica

Elephant trunk whiskers and sensory intelligence

An elephant’s trunk is a marvelous organ: flexible enough to bend and stretch while foraging, yet stiff enough to grasp delicate objects like peanuts or a tortilla chip. This versatility stems from the trunk’s high tactile sensitivity. Scientists have determined that the whiskers lining the trunk are crucial for that sensitivity thanks to their unique structure, amounting to a kind of innate “material intelligence,” according to a new paper published in Science.

Whisker research in other mammals

As previously reported, there is a long history of studying whiskers (vibrissae) in mammals. Rats, cats, tree squirrels, manatees, harbor seals, sea otters, polecats, shrews, tammar wallabies, sea lions, and naked mole‑rats all share strikingly similar basic whisker anatomies, according to various prior studies. Among other potential applications, such research could one day enable scientists to:

• Build artificial whiskers as tactile sensors in robotics
• Learn more about human touch

Structure and function of whiskers

Whiskers are much more complex than one might think, both in structure and function. Rats, for instance, have about 30 large whiskers and dozens of smaller ones, forming a complex “scanning sensorimotor system” that enables diverse tasks such as texture analysis, active touch for path finding, pattern recognition, and object location—simply by scanning the terrain with their whiskers.

Technically, whiskers are hairs, a collection of dead keratin cells. It’s what they’re attached to that makes them as sensitive as human fingertips. Each rat whisker is inserted into a follicle that connects it to a “barrel” made up of as many as 4,000 densely packed neurons. Together, these barrels form a grid or array that serves as a topographic “map,” informing the rat’s brain about the presence and movement of objects in its immediate environment. The barrels are wired together into a neural network, providing multidimensional cues.

Rat whiskers also resonate at certain frequencies; shorter whiskers near the nose and longer ones further back enable rats to create a kind of “frequency map” by probing their surroundings.