Vibration sensitive afferents rather than spatial acuity determine tactile roughness discrimineration

The human hand is a wondrous instrument that serves us extremely well in a multitude of applications. In every day life, we frequently explore surfaces with our fingertips to estimate different aspects of their physics. We use our hands to identify objects and surface textures with high accuracy. Tactile information tells a person how much force to use when grasping objects, which range from rigid, such as a steel marble to delicate, such as a tomato. Researchers are currently working on developing prosthetic systems that incorporate touch-sensitive feedback. Understanding the neurobiology of roughness perception could be revolutionary to the utility of hand prosthetics. In this thesis, a psychophysical method to estimate roughness threshold with the sandpaper set was developed and validated. Secondarily, we examined the relative contribution of remote mechanoreceptors to perception of roughness versus spatial acuity in various conditions that affect innervation of the index finger differently as carpal tunnel syndrome or surgically repaired complete traumatic median nerve section at the wrist. In conclusion, all studies indicated that vibration sensitive afferents rather than spatial acuity determine roughness discrimination. These investigations have important implications for the development of technologies that may provide prosthetic hand users with a realistic restoration of sensory feedback systems.