Skin strain patterns provide kinaesthetic information to the human central nervous system (original) (raw)
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Movement illusions evoked by ensemble cutaneous input from the dorsum of the human hand
The Journal of physiology, 1996
1. In this study we tested the hypothesis that ensemble activity in human cutaneous sensory afferents evoked by the stretching of skin over and around the finger joints contributes to the conscious perception of movement of the fingers. 2. In nineteen normal adults, ensembles of cutaneous afferents were activated either by electrical stimulation, delivered through an array of electrodes on the dorsum of the hand and fingers, or by mechanical stretching of the skin over and around the joints. The stretching was applied through an array of threads stuck to the skin, in such a way as to avoid or minimize moving the underlying joints and to avoid applying pressure to underlying tendons and ligaments. Perceived movements were mimicked by voluntary movements of the fingers of the contralateral hand. 3. By way of comparison, kinaesthetic illusions were also evoked by activation of muscle receptors by vibration. 4. Illusions of movement were elicited with each type of stimulus. Electrical s...
Movement detection at the distal joint of the human thumb and fingers
Experimental Brain Research, 1998
To determine whether proprioceptive acuity is the same at all digits, particularly when postured as in à grasp', we imposed 10 movements at the distal joint of the thumb, index and ring finger, at three velocities; 1.25/s, 2.5/s and 5/s. The test joint was initially flexed by 25 and the joints proximal to the test joint were maintained in a standard posture for each study. When in a grasp posture that disengaged the extensor muscles at the distal joint of the finger, movement detection at the thumb was superior to that at the fingers for all velocities. However, when the fingers were positioned so that all proprioceptive inputs were able to contribute (i.e. cutaneous, joint and both flexor and extensor muscle afferents), proprioceptive acuity was similar for the three digits. Loss of local cutaneous (and joint) inputs by digital anaesthesia significantly impaired performance at all digits, suggesting a critical role for cutaneous input in normal proprioceptive sensibility at all distal joints of the digits. Anaesthesia of the extensor muscle afferents innervating the thumb did not affect its proprioceptive acuity. Thus, for the thumb, the extensor muscle afferents do not provide critical information. The greater change in muscle fascicle length for the thumb's long flexor muscle (3% per 10) compared with that in the finger flexor muscles (e.g. 0.1% per 10) could contribute to the thumb's performance. There appears to be less redundancy of muscle and non-muscle signals for the fingers than for the thumb, because a reduction in either cutaneous or muscle input significantly impaired acuity at the fingers. Overall, when the hand is in a grasping posture, irrespective of the contribution of local cutaneous inputs, the long flexor acting on the thumb may contribute more to its proprioceptive acuity than the long finger flexors contribute to acuity at the fingers.
Proprioceptive Localization of the Hand Changes When Skin Stretch around the Elbow Is Manipulated
Frontiers in psychology, 2016
Cutaneous information has been shown to influence proprioceptive position sense when subjects had to judge or match the posture of their limbs. In the present study, we tested whether cutaneous information also affects proprioceptive localization of the hand when moving it to a target. In an explorative study, we manipulated the skin stretch around the elbow by attaching elastic sports tape to one side of the arm. Subjects were asked to move the unseen manipulated arm to visually presented targets. We found that the tape induced a significant shift of the end-points of these hand movements. Surprisingly, this shift corresponded with an increase in elbow extension, irrespective of the side of the arm that was taped. A control experiment showed that this cannot be explained by how the skin stretches, because the skin near the elbow stretches to a similar extent on the inside and outside of the arm when the elbow angle increases and decreases, respectively. A second control experiment ...
Cutaneous Receptors Contribute to Kinesthesia at the Index Finger, Elbow, and Knee
Journal of Neurophysiology, 2005
The neural mechanisms underlying the sense of joint position and movement remain controversial. While cutaneous receptors are known to contribute to kinesthesia for the fingers, the present experiments test the hypothesis that they contribute at other major joints. Illusory movements were evoked at the interphalangeal (IP) joints of the index finger, the elbow, and the knee by stimulation of populations of cutaneous and muscle spindle receptors, both separately and together. Subjects matched perceived movements with voluntary movements of homologous joints on the contralateral side. Cutaneous receptors were activated by stretch of the skin (using 2 intensities of stretch) and vibration activated muscle spindle receptors. Stimuli were designed to activate receptors that discharge during joint flexion. For the index finger, vibration was applied over the extensor tendons on the dorsum of the hand, to evoke illusory metacarpophalangeal (MCP) joint flexion, and skin stretch was delivered around the IP joints. The strong skin stretch evoked the illusion of flexion of the proximal IP joint in 6/8 subjects (12 Ϯ 5°, mean Ϯ SE). For the group, strong skin stretch delivered during vibration increased the perceived flexion of the proximal IP joint by eight times with a concomitant decrease in perceived flexion of the MCP joint compared with vibration alone (P Ͻ 0.05). For the elbow, vibration was applied over the distal tendon of triceps brachii and skin stretch over the dorsal forearm. When delivered alone, strong skin stretch evoked illusory elbow flexion in 5/10 subjects (9 Ϯ 4°). Simultaneous strong skin stretch and vibration increased the illusory elbow flexion for the group by 1.5 times compared with vibration (P Ͻ 0.05). For the knee, vibration was applied over the patellar tendon and skin stretch over the thigh. Skin stretch alone evoked illusory knee flexion in 3/10 subjects (8 Ϯ 4°) and when delivered during vibration, perceived knee flexion increased for the group by 1.4 times compared with vibration (P Ͻ 0.05). Hence inputs from cutaneous receptors, muscle receptors, and combined inputs from both receptors likely subserve kinesthesia at joints throughout the body.
The detection of human finger movement is not facilitated by input from receptors in adjacent digits
The Journal of Physiology, 2003
It is well established that muscle, joint and cutaneous receptors can contribute to the sensations of limb position and movement. This derives from two key observations. First, these receptors are activated when joints are moved. Secondly, this discharge can influence the perception of limb position and movement, based on psychophysical studies in which the discharge is abolished (for example by anaesthesia) or enhanced artificially (for example by electrical stimulation). The first observation goes back to early recordings of afferent discharge in animals (e.g.
Journal of neurophysiology, 2015
It is not known how changes in skin mechanics affect the responses of cutaneous mechanoreceptors in the finger pads to compression forces. We used venous occlusion to change the stiffness of the fingers and investigated whether this influenced the firing of low-threshold mechanoreceptors to surfaces of differing stiffness. Unitary recordings were made from 10 SAI, 10 FAI and 9 SAII units via tungsten microelectrodes inserted into the median nerve at the wrist. A servo-controlled stimulator applied ramp-and-hold forces (1, 2, 4 N) at a constant loading and unloading rate (2 N/s) via a flat 2.5 cm-diameter silicone disc over the centre of the finger pad. Nine silicone discs (objects), varying in compliance, were used. Venous occlusion, produced by inflating a sphygmomanometer cuff around the upper arm to 40 ± 5 mmHg, was used to induce swelling of the fingers and increase the compliance of the finger pulp. Venous occlusion had no effect on the firing rates of the SAI afferents, nor on...
The role of cutaneous sensation in the motor function of the hand
Journal of Orthopaedic Research, 2004
We studied the effect of abolishing cutaneous sensation (by infiltrating local anaesthetic around the median nerve at the wrist) on the ability of 10 healthy volunteers (a) to maintain a submaximal isometric pinch-grip force for 30 s without visual feedback, and (b) to perform a fine finger-manipulation 'handwriting' task. Blocking cutaneous sensation had no effect on ability to maintain pinch force, suggesting that muscle afferents have the major role in force-control feedback. However, a near-linear fall in force, present with or without block (mean slope = -1.3 & 0.2%) s-'), which cannot be attributed to motor fatigue, reveals a shortcoming of the afferent feedback system. Blocking cutaneous sensation did impair ability to perform the more demanding writing task, as judged by an 18 2 6% increase in the length of the path between target points, a 22 k 9% increase in the duration of the movement and a 63 k 24% in 'normalised averaged rectified jerk', an averaged time-derivative of acceleration (all significantly nonzero, P < 0.04).
Experimental Brain Research, 1990
The responses of non-cutaneous receptors in the human hand to normal digit movements were studied using single afferent recordings from the radial nerve. Eight joint-related afferents had thresholds of 50 mN or less. All responded to passive flexion movements within the physiological range of joint rotation and showed predominantly static response sensitivity; none increased its discharge during passive extension. However, only two of these eight afferents showed the same response pattern during active movements; three discharged only during the extension phase whereas the other three discharged both during extension and flexion. No highthreshold, joint-related mechanoreceptive afferents were encountered in a population of 148 afferents recorded from the cutaneous portion of the radial nerve indicating a scarcity of such afferents on the dorsal aspect of finger joints. Seven high-threshold, subcutaneous mechanoreceptive units not related to joints had thresholds for indentations of 50 mN or more and lacked responses to finger movements. Low-threshold mechanoreceptive afferents related to joints in the human hand may thus provide kinematic information in the physiological midrange of both passive and active movements. Joint position cannot, however, be derived unambiguously from their discharge since the receptor responses may be dramatically altered by muscle activity.