New Model Of Whiskers Provides İnsight İnto Sense Of Touch

Researchers at Northwestern University have developed a model that will allow them to simulate how rats use their whiskers to sense objects around them. The model enables further research that may provide insight into the human sense of touch. Hundreds of papers are published each year that use the rat whisker system as a model to understand brain development and neural processing. Rats move their whiskers rhythmically against objects to explore the environment by touch. Using only tactile information from its whiskers, a rat can determine all of an object's spatial properties, including size, shape, orientation and texture.

But there is a big missing piece that prevents a full understanding of the neural signals recorded in these studies: no one knows how to represent the "touch" of a whisker in terms of mechanical variables.

"We don't understand touch nearly as well as other senses," says Mitra Hartmann, associate professor of biomedical engineering and mechanical engineering at the McCormick School of Engineering and Applied Science. "We know that visual and auditory stimuli can be quantified by the intensity and frequency of light and sound, but we don't fully understand the mechanics that generate our sense of touch."

To create a model that starts to quantify these mechanics, Hartmann's team first studied the structure of the rat whisker array – the 30 whiskers arranged in a regular pattern on each side of a rat's face. By analyzing them in both two- and three-dimensional scans, they defined the relationship between the size and shape of each whisker and its placement on the face of the rat.

Using this information, the team created a model that quantifies the full shape and structure of the rat head and whisker array. The model now allows the team to simulate the rat "whisking" against different objects and to predict the full pattern of inputs into the whisker system as a rat encounters an object. The simulations can then be compared against real behavior.