Proprioceptive Adaptation Research Articles

Self-Adhesive and Self-Sustainable Bioelectronic Patch for Physiological Feedback Electronic Modulation of Soft Organs.

Bionic electrical stimulation (Bio-ES) aims to achieve personalized therapy and proprioceptive adaptation by mimicking natural neural signatures of the body, while current Bio-ES devices are reliant on complex sensing and computational simulation systems, thus often limited by the low-fidelity of simulated electrical signals, and failure of interface information interaction due to the mechanical mismatch between soft tissues and rigid electrodes. Here, the study presents a flexible and ultrathin self-sustainable bioelectronic patch (Bio-patch), which can self-adhere to the lesion area of organs and generate bionic electrical signals synchronized vagal nerve envelope in situ to implement Bio-ES. It allows adaptive adjustment of intensity, frequency, and waveform of the Bio-ES to fully meet personalized needs of tissue regeneration based on real-time feedback from the vagal neural controlled organs. With this foundation, the Bio-patch can effectively intervene with excessive fibrosis and microvascular stasis during the natural healing process by regulating the polarization time of macrophages, promoting the reconstruction of the tissue-engineered structure, and accelerating the repair of damaged liver and kidney. This work develops a practical approach to realize biomimetic electronic modulation of the growth and development of soft organs only using a multifunctional Bio-patch, which establishes a new paradigm for precise bioelectronic medicine.

Bodily self-perception during voluntary actions: The causal contribution of premotor cortex and cerebellum

Voluntary actions are accompanied by the experience of controlling one's own movements (sense of agency) and the feeling that the moving body part belongs to one's self (sense of body ownership). So far, agency and body ownership have been investigated separately, leaving the neural underpinnings of the relation between the two largely unexplored. The aim of this study was to explore the causal role of two multisensory brain regions, that is the premotor cortex (PMc) and the cerebellum, in agency and body ownership concurrently on the same behavioral task, i.e., the moving Rubber Hand Illusion (mRHI). Participants watched a rubber hand while moving their hidden hand. The type of movement (active or passive) and posture of the rubber hand (congruent or incongruent) differed in three conditions (active congruent, passive congruent, active incongruent), so that agency and ownership could be elicited either separately or concurrently. Agency and ownership were measured by subjective report and proprioceptive drift. Sham and anodal transcranial direct current stimulation (tDCS) were delivered to the PMc (Experiment 1) or the cerebellum (Experiment 2) prior to the mRHI task. Independent of the site or type of tDCS, subjective reports revealed that both agency and ownership were evoked in the active congruent condition, ownership but not agency in the passive congruent condition, and agency but not ownership in the active incongruent condition. The proprioceptive drift was evoked in the active congruent and the passive congruent condition. Anodal tDCS over the PMc reduced the feeling of agency in the active congruent condition, while it enhanced proprioceptive drift when applied over the cerebellum. These findings suggest a specific causal contribution of the PMc and the cerebellum to bodily self-perception during voluntary movement, with the PMc mainly involved in awareness of action and the cerebellum in proprioceptive adaptation of body position in space.

Neural coordination of bilateral power and precision finger movements.

The dexterity of hands and fingers is related to the strength of control by cortico-motoneuronal connections which exclusively exist in primates. The cortical command is associated with a task-specific, rapid proprioceptive adaptation of forces applied by hands and fingers to an object. This neural control differs between "power grip" movements (e.g., reach and grasp of a cup) where hand and fingers act as a unity and "precision grip" movements (e.g., picking up a raspberry) where fingers move independently from the hand. In motor tasks requiring hands and fingers of both sides a "neural coupling" (reflected in bilateral reflex responses to unilateral stimulations) coordinates power grip movements (e.g., opening a bottle). In contrast, during bilateral precision movements, such as playing piano, the fingers of both hands move independently, due to a direct cortico-motoneuronal control, while the hands are coupled (e.g., to maintain the rhythm between the two sides). While most studies on prehension concern unilateral hand movements, many activities of daily life are tackled by bilateral power grips where a neural coupling serves for an automatic movement performance. In primates this mode of motor control is supplemented by a system that enables the uni- or bilateral performance of skilled individual finger movements.

Visual and Proprioceptive Adaptation of Arm Position in a Virtual Environment

ABSTRACTThe authors examined the resolution of a discrepancy between visual and proprioceptive estimates of arm position in 10 participants. The participants fixed their right shoulder at 0°, 30°, or 60° of transverse adduction while they viewed a video on a head-mounted display that showed their right arm extended in front of the trunk for 30 min. The perceived arm position more closely approached the seen arm position on the display as the difference between the actual and visually displayed arm positions increased. In the extreme case of a 90° discrepancy, the seen arm position on the display was very gradually perceived as approaching the actual arm position. The magnitude of changes in sensory estimates was larger for proprioception (20%) than for vision (< 10%).

Short-Term Adaptation of Joint Position Sense Occurs during and after Sustained Vibration of Antagonistic Muscle Pairs.

Proprioception is critical for the control of many goal-directed activities of daily living. While contributions from skin and joint receptors exist, the muscle spindle is thought to play an important role in allowing accurate judgments of limb position and movement to occur. The discharges elicited from muscle spindles can be degraded by simultaneous agonist-antagonist tendon vibration, causing proprioception to be distorted. Despite this, changes in limb perception that may result from sensory adaptation to this stimulus remain misunderstood. The purpose of this study was, therefore, to investigate short-term proprioceptive adaptation resulting from vibration of antagonistic muscle pairs. We measured elbow joint position sense in 21 healthy young adults while 80 Hz vibration was applied simultaneously to the distal tendons of the elbow flexor and extensor muscles. Matching errors were then analyzed during early and late adaptation phases to assess short-term adaptation to the vibration stimuli. Participants committed significant undershoot errors during the early adaptation phase, but were comparable to baseline measurements during the late adaptation phase. When we removed the vibration stimuli and conducted a second joint position matching task, matching variability increased significantly, and participants committed overshoot errors. These results bring into question the efficacy of simultaneous agonist-antagonist tendon vibration to degrade proprioceptive acuity.

Poster #T116 INTERACTION BETWEEN PARENTAL PSYCHOSIS AND DELAYS ON EARLY MOTOR DEVELOPMENTAL MILESTONES IN SCHIZOPHRENIA – THE NORTHERN FINLAND 1966 BIRTH COHORT STUDY

Voluntary actions are accompanied by the experience of controlling one's own movements (sense of agency) and the feeling that the moving body part belongs to one's self (sense of body ownership). So far, agency and body ownership have been investigated separately, leaving the neural underpinnings of the relation between the two largely unexplored. The aim of this study was to explore the causal role of two multisensory brain regions, that is the premotor cortex (PMc) and the cerebellum, in agency and body ownership concurrently on the same behavioral task, i.e., the moving Rubber Hand Illusion (mRHI). Participants watched a rubber hand while moving their hidden hand. The type of movement (active or passive) and posture of the rubber hand (congruent or incongruent) differed in three conditions (active congruent, passive congruent, active incongruent), so that agency and ownership could be elicited either separately or concurrently. Agency and ownership were measured by subjective report and proprioceptive drift. Sham and anodal transcranial direct current stimulation (tDCS) were delivered to the PMc (Experiment 1) or the cerebellum (Experiment 2) prior to the mRHI task. Independent of the site or type of tDCS, subjective reports revealed that both agency and ownership were evoked in the active congruent condition, ownership but not agency in the passive congruent condition, and agency but not ownership in the active incongruent condition. The proprioceptive drift was evoked in the active congruent and the passive congruent condition. Anodal tDCS over the PMc reduced the feeling of agency in the active congruent condition, while it enhanced proprioceptive drift when applied over the cerebellum. These findings suggest a specific causal contribution of the PMc and the cerebellum to bodily self-perception during voluntary movement, with the PMc mainly involved in awareness of action and the cerebellum in proprioceptive adaptation of body position in space.

The Role of Movement Synchronization with an Auditory Signal in Producing Prism Adaptation

The prism adaptation procedure is often used to study the plasticity of eye-hand coordination to misalignment of the visual and proprioceptive spatial maps. Misalignment can be resolved by adaptive change in spatial maps of either the eyes or hand or both. In this procedure, pacing pointing movements with a rhythmic auditory signal is usually employed to control movement speed, but the role of the auditory signal itself in producing adaptation has not been examined. The present experiment addressed this issue by testing three conditions: (i) exposure pointing was self-paced without an auditory signal; (ii) exposure pointing was paced by an auditory signal without synchronization; and (iii) exposure pointing was synchronized with the auditory signal. The first condition produced primarily proprioceptive adaptation. The second condition also produced primarily proprioceptive adaptation, but visual adaptation was also present. The third condition produced primarily visual adaptation. Results are discussed in terms of two possible roles for the auditory signal: (i) a rhythmic auditory signal may enhance overall activation of the adaptive neural network; and (ii) movement synchronization with a rhythmic auditory signal may enable multisensory integration, including auditory spatial information that selects the more reliable proprioceptive signal for movement control. Consequently, detection of the misalignment is localized and realignment occurs in the visual system.

Multisensory disintegration and the disappearing hand trick

Summary Successful multisensory integration is the cornerstone of corporeal awareness. Experimental investigations of body ownership usually require the embodiment of additional non-bodily objects [1,2]. In contrast, here we asked whether experimentally-induced disintegration of sensory signals could bring about loss of ownership and awareness for the real limb without the embodiment of an alternative representation. In three experiments, naive participants placed their hands inside a MIRAGE multisensory illusions box and reached across to touch their right hand with their left. In the crucial Disappearing Hand condition, we created a situation in which the right hand unexpectedly disappeared from vision and touch with the result that healthy participants reported the sensation that they had no right hand and that their hand was no longer part of their body. In two further experiments, physiological responses to threat towards the disappeared hand were absent and self-drawn representations of the limb terminated at the wrist. These results highlight the importance of bottom-up processes in the normal experience of body permanence and may provide the key to understanding neuropsychological disorders of body ownership.

Conflict with vision diminishes proprioceptive adaptation to muscle vibration

Muscle vibration excites muscle spindles and creates illusory movement of a body part in a blindfolded individual. It is followed by an aftereffect, an illusion of return movement when vibration stops. The aftereffect reflects adaptation in the proprioceptive system. This adaptation is susceptible to attentional manipulations (Seizova-Cajic and Azzi in Exp Brain Res 203(1):213-219, 2010), but it is not known whether it is open to cross-modal influences unaided by those manipulations. We attempted to answer this question by allowing vision of the vibrated, stationary arm. We asked our participants (n=20) to retain focus on the feeling of movement. They reported any illusory movement during 60-s biceps vibration (at 90Hz), as well as following its offset, when vision of the arm was removed. During vibration, the proprioceptive movement illusion persisted, although the stationary arm was visible, but its duration and strength were much reduced in comparison with the no-vision condition. The movement aftereffect, experienced in total darkness following vibration offset, was also substantially weaker. The results show that proprioceptive adaptation is strongly modulated by vision. We propose that two processes contribute: perceptual (cross-modal binding with conflicting vision reduces the proprioceptive movement signal) and attentional (view of a stationary arm distracts from the proprioceptive movement signal). Our finding that during vibration, participants felt movement in the arm they could see, which was stationary, shows that cross-modal binding partially failed. This happened because the two percepts were too discrepant. However, only one-the visual-appeared real, and we argue that such an outcome is consistent with general principles of intersensory integration.

Visual aftereffects of proprioceptive stimulation not due to proprioceptive adaptation

Illusory motion of a visual target can be elicited by vibratory stimulation of the neck muscles; after vibration stops, motion in the opposite direction is perceived (Biguer et al, 1988, Brain, 111, 1405–1424). This motion aftereffect could be due to adaptation exclusively at the proprioceptive level, or at a stage where visual and proprioceptive information are combined. To distinguish between these two possibilities, we applied vibratory stimulation to dorsolateral neck muscles for 15-sec periods alternating with 15-sec periods without vibration.Observers (N=26) used a hand-held tracker to indicate perceived motion of the target (an LED). In the critical condition, observers were in complete darkness during vibration, and the LED was only turned on in post-vibration periods. If adaptation was purely proprioceptive, illusory LED motion should have occurred in this condition, but it did not. In a follow-up experiment (N=9), we used a similar method to determine if there was a position aftereffect. The LED was presented intermittently during the test period (for 150 msec, with 1.35 sec of dark periods in between), such that its displacement, rather than motion, could readily be perceived. No aftereffect occurred. Both experiments show that there has to be a visual stimulus during the adaptation period for the aftereffect to occur, at least for the relatively brief adaptation periods used. Proprioceptive mechanisms did not adapt, and visual motion mechanisms were mainly responsible for the illusion. We conclude that they adapt more quickly than the proprioceptive mechanisms from which they receive input.

A visual distracter task during adaptation reduces the proprioceptive movement aftereffect

Visual processing of basic perceptual attributes depends on attention. This has been well documented since the surprising initial report on attentional modulation of the visual motion aftereffect (Chaudhuri 1990). Here, we investigate proprioception and show for the first time that attention modulates adaptation to perceived limb movement. We used biceps vibration to induce illusory forearm extension in 10 participants and measured the aftereffect-perceived movement in the opposite direction. The aftereffect was largest when participants focused on the illusory extension during the adaptation period. To divert attention away from the illusory extension, a rapid serial visual presentation task was performed during the adaptation. The aftereffect was much smaller in this condition, indicating interference between the visual task and proprioceptive adaptation. In tests of an analogous interaction between audition and vision, earlier research found no effect. We suggest that conscious proprioception requires more attention than conscious processing of visual or auditory input.

The perception of body verticality (subjective postural vertical) in peripheral and central vestibular disorders.

The perception of body verticality (subjective postural vertical, SPV) was assessed in normal subjects and in patients with peripheral and central vestibular lesions and the data were compared with conventional neuro-otological assessments. Subjects were seated with eyes closed in a motorized gimbal which executed cycles of tilt at low constant speed (1.5 degrees s-1), both in the frontal (roll) and sagittal (pitch) planes. Subjects indicated with a joystick when they entered and left verticality, thus defining a sector of subjective uprightness in each plane. The mean angle of tilt (identifying a bias of the SPV) and the width of the sector (defining sensitivity of the SPV) were then determined. In normal subjects, the angle of the "verticality' sector was 5.9 degrees for pitch and roll. Patients with bilateral absence of vestibular function, patients with vertigo, i.e. acute unilateral lesions, benign paroxysmal positional vertigo (BPPV) and Ménière's disease, and patients with positionally modulated up-/downbeat nystagmus all had enlarged sectors (i.e. loss in sensitivity). Mean sector angle in these groups ranged from 7.8 to 11 degrees and the abnormality was present both in pitch and roll, regardless of the direction of nystagmus or body sway. Patients with chronic unilateral peripheral vestibular lesions and those with position-independent vertical nystagmus had normal sensitivities. No significant bias of the SPV was found in any patient group, not even those with acute unilateral vestibular lesions who had marked tilts of the subjective visual vertical (SVV). Complementary experiments in normal subjects tested under galvanic vestibular or roll-plane optokinetic stimulation also failed to show biases of the SPV. In contrast, a significant bias in the SPV could be induced in normal subjects by asymmetric cycles of gimbals tilt, presumably by proprioceptive adaptation. The following conclusions can be drawn. (i) The perception of body verticality whilst seated is mainly dependent on proprioceptive/contact cues but these are susceptible to tilt-mediated adaptation. (ii) Vestibular input improves the sensitivity of the SPV, even in vestibular disorders, as long as the abnormality is stable. (iii) There can be marked dissociation between vestibulo-motor (ocular and postural) phenomena and the perception of body verticality, and between the SPV and SVV. (iv) The postural sway asymmetries in patients with peripheral and central vestibular lesions, like those induced by galvanic or optokinetic stimulation in normal subjects, are not consequences of changes of the SPV.

Effects of Movement Duration and Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement ever 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of the movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation.

While looking through laterally displacing prisms, subjects pointed 60 times straight ahead of their nose at a rate of one complete movement every 2 or 3 s, with visual feedback available early in the pointing movement or delayed until the end of the movement. Sagittal pointing was paced such that movement speed covaried with pointing rate. Aftereffect measures (obtained after every 10 pointing trials) showed that when the limb became visible early in a pointing movement, proprioceptive adaptation was greater than visual, but when visual feedback was delayed until the end of the movement, the reverse was true. This effect occurred only with the 3-s pointing rate, however. With the 2-s pointing rate, adaptation was predominately proprioceptive in nature, regardless of feedback availability. Independent of the availability of visual feedback, visual adaptation developed more quickly with 3-s pointing, whereas proprioceptive adaptation developed more rapidly with 2-s pointing. These results are discussed in terms of a model of perceptual-motor organization in which the direction of coordinative (guidance) linkage between eye-head (visual) and hand-head (proprioceptive) systems (and consequently the locus of discordance registration and adaptive recalibration) is determined jointly by pointing rate and feedback availability. An additional effect of pointing rate is to determine the rate of discordant inputs. Maximal adaptive recalibration occurs when the input (pointing) rate matches the time constant of the adaptive encoder in the guided system.

Effects on prism adaptation of duration and timing of visual feedback during pointing.

In two experiments, we investigated the effects of duration of visual feedback of the pointing limb and the time (early to late) in the movement when the limb first becomes visible (timing of visual feedback). Timing, rather than duration of visual feedback, proved to have the greater effect on the relative magnitude of visual and proprioceptive adaptation. Visual adaptation increased smoothly with feedback delay, but corresponding decreases in proprioceptive adaptation underwent an additional sharp change when feedback was delayed until about three-fourths of the way to the terminal limb position. These results are consistent with the idea that visual and proprioceptive adaptation are mediated by exclusive processes. Change in the limb position sense (i.e., proprioceptive adaptation) may be produced by visual guidance of the pointing limb, and view of the limb early in the pointing movement seems to be critical for such visual guidance. The limb may be ballistically released as it nears the terminal position, and, thereafter, any opportunity for visual guidance (i.e., view of the limb) is not effective. On the other hand, change in the eye position sense (i.e., visual adaptation) may be mediated by proprioceptive guidance of the eye; the eyes may track the imaged position of the nonvisible limb. Such proprioceptive guidance seems to be solely a function of the distance moved before the limb becomes visible.

Head posture effects in prism adaptation during hallway exposure.

Different groups of subjects walked nearer the left or right side of a hallway while looking through prisms that displaced the visual field in either the left or right direction. As predicted from the head posture required to view the apparently displaced hallway, adaptive pre-post change in felt head position was greater when head turning during exposure was expected to be greater (i.e., when the subject was walking on the prism base side of the hall). This finding supports a postural basis, but not a discordance basis, for change in felt head position. Visual adaptation was not explained either by the head position results or by the eye-in-head posture required to view the apparently displaced hallway, and was attributed to recalibration processes based on discordant input from other sensorimotor systems. Proprioceptive adaptation in the right hand was small and similar to the head position results, except for the group that experienced right-ward displacement and walked near the right wall. The substantial right-hand proprioceptive adaptation in this group was attributed to discordance between visual and proprioceptive systems when subjects visually anticipated an encounter between their arm or shoulder and the wall.

Cognitive interference in prism adaptation.

Visual and proprioceptive adaptation to optical displacement were found to decrease with increasing difficulty of mental arithmetic performed during hall exposure. The graded nature of such cognitive interference is consistent with the idea that limited-capacity central control processes are required to coordinate the discordant visual system with other sensorimotor systems. When central processing capacity is diverted to other tasks, the frequency of coordinated activity involving the discordant visual system is reduced, there are fewer occasions for the discordance to pose a problem, and there is less need for adaptive recalibration in any sensorimotor system.

Factors affecting proprioceptive adaptation to prismatic displacement.

Two prism displacement experiments were conducted to determine the effects of reducing proprioceptive feedback on resultant adaptation magnitude. In Experiment 1, proprioceptive reduction was produced by requesting subjects to employ passive Ivs. active) and/or fast- Ivs. slow-) paced arm movement during prism exposure. When both of these conditions were present, a significant reduction in the magnitude of proprioceptive adaptation and a significant increase in the magnitude of visual adaptation were produced. In Experiment 2, hypnotic anesthesia was employed to reduce felt sensation in an adapting limb during a prism displacement situation. This manipulation reduced proprioceptive adaptation to a nonsignificant level. The combined results of the two experiments reveal several conditions that can serve to reduce proprioceptive adaptation during prism displacement.

Proprioception and the production of adaptation and intermanual transfer to prismatic displacement

Proprioceptive adaptation to prismatic displacement and resultant intermanual transfer were investigated in two experiments. In Experiment 1, magnitude of adaptation and transfer were assessed as a result of the reduction of felt sensation via hypnotic anesthesia in an adapting limb. Such anesthesia reduced the magnitude of adaptation in that limb and resultant transfer in the nonadapting limb to a nonsignificant level. Such was not the case when the adapting limb was nonanesthetic. In Experiment 2, adaptation and transfer magnitude were assessed as the result of anesthetic induction in a nonadapting limb. When this was the case, adaptation was produced in the adapting limb but not in the anesthetized, nonadapting limb. The results of the two experiments generally point to proprioception as being the major source of input to the production of intermanual transfer in a prismatic adaptation task. 113 When subjects adapt to a prismatically displaced environment, a portion of the adaptation magnitude is represented by a component responsible for felt limb location or orientation (Harris, 1963, 1965; Hay & Pick, 1966; Redding, 1978; Redding & Wallace, 1976, 1978; Wallace, 1977; Wallace & Redding, 1979; Wilkinson, 1971). This adaptation component is gen­ erally assessed in a head-hand coordination task where subjects are required to localize the straight­ ahead position in space with an unseen limb before and after an exposure to prismatic displacement. The preexposure-postexposure localization difference value is termed a proprioceptive shift (PS) and post­ exposurepointing is typically in the direction opposite the exposure, prism-base orientation (Harris, 1965; Welch, 1974, 1978). Recently, it has been shown that PS is amenable to intermanual transfer (Choe & Welch, 1974; McLaughlin & Bower, 1965; Wallace, 1978; Wallace & Redding 1979; Melamed, Beckett, & Hill, Note 1). Specifically, PS can be measured for a nonadapting limb as well as for an adapting limb. As such, the recalibrated proprioceptive input appears to influence control of the unexposed limb. The experimental paradigm which appears to max­ imize intermanual transfer involves a situation where a subject is required to observe a limb perform a terminal, ballistic movement while being permitted some head movement to observe the pointing action (Wallace, 1978; Wallace & Redding, 1979). Terminal,

Additivity in adaptation to optical tilt.

Tests of proprioceptive adaptation (head-hand), visual adaptation (eye-head), and both components (eye-hand) were made during 15-min exposure to 20 degrees tilt in two experiments. In both experiments, subjects alternated exposures in which they explored hallways (hall) or viewed their active hand (hand), but in Experiment 2 subjects received two exposures to each condition, while in Experiment 1 only one exposure was given. Hall exposure produced greater visual change, and hand exposure produced greater proprioceptive change; but in both conditions, when order of conditions was controlled, the sum of performance on visual and proprioceptive tests was not statistically different from performance on the common test. In Experiment 2, adaptive components appeared to be inversely related, both within and between exposure conditions, thus providing some evidence of a reciprocal relationship, but a reliable negative correlation between components was not found. Finally, adaptation increased over alternation-repetition of exposure tasks in the second experiment, even though adaptation appeared limited within any given exposure. Results are interpreted in terms of the linear model, and the possible role of attentional factors in processing sensory inconsistencies is discussed.