Touch, Proprioception and Vision

Provides pre-movement information Provides feedback about the movement in progress Provides post-movement information about action goal achievement

Skin receptors Mechanoreceptors located in the dermis layer of skin Greatest concentration in finger tips Provide CNS with temperature, pain, tactile and movement info

Touch, vision, and proprioception

Compare performance of task involving finger(s) before and after anesthetizing finger(s)

Movement accuracy Movement consistency Movement force adjustments

Proprioception: The sensory system’s detection and reception of movement and spatial position of limbs, trunk, and head

proprioceptors Located in muscles, tendons, ligaments, and joints

Muscle spindles Golgi tendon organs Joint receptors

In most skeletal muscles in a capsule of specialized muscle fibers and sensory neurons Intrafusal fibers [see Fig. 6.2] Lie in parallel with extrafusal muscle fibers Mechanoreceptors that detect changes in muscle fiber length (i.e. stretch) and velocity (i.e. speed of stretch) Enables detection of changes in joint angle Function as a feedback mechanism to CNS to maintain intended limb movement position, direction, and velocity

In skeletal muscle near insertion of tendon Detect changes in muscle tension (i.e. force) Poor detectors of muscle length changes

Several types located in joint capsule and ligaments Mechanoreceptors that detect changes in Force and rotation applied to the joint, Joint movement angle, especially at the extreme limits of angular movement or joint positions

Surgical deafferentation Deafferentation due to sensory neuropathy Temporary deafferentation Tendon vibration technique

“Nerve block technique” – Inflate blood-pressure cuff to create temporary disuse of sensory nerves Techniques to Investigate the Role of Propioception in Motor Control

Afferent neutral pathways associated with movements of interest have been surgically removed or altered

Sometimes called “peripheral neuropathy” Large myelinated fibers of the limb are lost, leading to a loss of all sensory information except pain and temperature