Sensory neurons located in your fingertips perform mathematical calculations that provide us with geometric information about objects we touch, a new study has found. This exciting discovery is titillating neuroscientists because it was long believed that such computations were reserved for neurons in the brain. The work has been published in Nature Neuroscience.
Touch, or tactile, perception is part of the somatosensory system; this complex system receives information from the environment via specialized receptors and relays this data to the central nervous system. The tactile system includes nerves called first-order neurons that extend into the skin and process touch. These neurons are heavily branched, meaning they receive information from many highly sensitive zones on the skin. Furthermore, according to the new research, this arrangement also allows individual neurons to identify geometric features of the objects that we touch.
During the study, researchers from Umeå University, Sweden, observed that the first-order tactile neurons that are packed into the skin of our fingertips are able to signal information about the edge orientation of a touched object to the brain. They also found that this sensitivity to edge orientation was dependent on the layout of the neuron’s highly sensitive zones.
According to lead author Andrew Pruszynski, their findings suggest that these tactile neurons are not only capable of signaling information about when and how intensely objects are touched, but they also glean and transmit information about the shape of an object.
The results were particularly surprising because it was assumed that these feature extraction calculations were mainly performed by nerves located in the outer layer of the brain called the cerebral cortex.
“Somewhat simplified, it means that our touch experiences are already processed by neurons in the skin before they reach the brain for further processing,” said Pruszynski.