Our hands and fingertips are sensitive to texture in a unique way. We can easily differentiate coarse sandpaper from smooth glass or surface, but we also pick up more subtle differences across an extensive range of textures, like the slick sheen of silk or the soft give of cotton.
Information about texture is dispatched from sensors in the skin and through the nerves to the somatosensory cortex, the part of the brain responsible for understanding the sense of touch. The latest research by neuroscientists at the University of Chicago shows that as neurons in this part of the brain comprehend and process this information, they each respond in a different way to various features of a surface, creating a high-dimensional model of texture in the brain.
“Objects can have textures that we can explain in simple terms like rough or soft or hard. But they can also be velvety or cottony or furry or silky ,” said Sliman Bensmaia, PhD, associate professor of organismal biology and anatomy at University of Chicago and senior author of the study. “The variety of different adjectives you can use to tell about texture just highlights that it’s a rich sensory space. So, it makes sense that you need to have a rich neural space in the brain to interpret that and understand what’s going on.
The study was published this week in the Proceedings of the National Academy of Sciences (PNAS). Bensmaia is an expert on how the brain and nervous system interpret the sense of touch, including texture or feelings. In a 2013 study from PNAS, his lab showed how various kinds of nerve fibers respond to different aspects of texture. Some nerves respond primarily to spatial elements of coarse textures, like the raised bumps of a Braille script that create a pattern when pressed against the skin.
Others respond to vibrations developed when the skin rubs across fine textures, like fabrics, which account for the vast majority of textures we deal with in the real world.
The study “High-dimensional representation of texture in the somatosensory cortex of primates,” was aided by the National Institute of Neurological Disorders and Stroke.