Activation Of Proprioceptors Research Articles

Differential encoding of mammalian proprioception by voltage-gated sodium channels.

Animals that require purposeful movement for survival are endowed with mechanosensory neurons called proprioceptors that provide essential sensory feedback from muscles and joints to spinal cord circuits, which modulates motor output. Despite the essential nature of proprioceptive signaling in daily life, the mechanisms governing proprioceptor activity are poorly understood. Here, we have identified distinct and nonredundant roles for two voltage-gated sodium channels (NaVs), NaV1.1 and NaV1.6, in mammalian proprioception. Deletion of NaV1.6 in somatosensory neurons (NaV1.6cKO mice) causes severe motor deficits accompanied by complete loss of proprioceptive transmission, which contrasts with our previous findings using similar mouse models to target NaV1.1 (NaV1.1cKO). In NaV1.6cKO animals, loss of proprioceptive feedback caused non-cell-autonomous impairments in proprioceptor end-organs and skeletal muscle that were absent in NaV1.1cKO mice. We attribute the differential contribution of NaV1.1 and NaV1.6 in proprioceptor function to distinct cellular localization patterns. Collectively, these data provide the first evidence that NaV subtypes uniquely shape neurotransmission within a somatosensory modality.

Symbiotic electroneural and musculoskeletal framework to encode proprioception via neurostimulation: ProprioStim

Peripheral nerve stimulation in amputees achieved the restoration of touch, but not proprioception, which is critical in locomotion. A plausible reason is the lack of means to artificially replicate the complex activity of proprioceptors. To uncover this, we coupled neuromuscular models from ten subjects and nerve histologies from two implanted amputees to develop ProprioStim: a framework to encode proprioception by electrical evoking neural activity in close agreement with natural proprioceptive activity. We demonstrated its feasibility through non-invasive stimulation on seven healthy subjects comparing it with standard linear charge encoding. Results showed that ProprioStim multichannel stimulation was felt more natural, and hold promises for increasing accuracy in knee angle tracking, especially in future implantable solutions. Additionally, we quantified the importance of realistic 3D-nerve models against extruded models previously adopted for further design and validation of novel neurostimulation encoding strategies. ProprioStim provides clear guidelines for the development of neurostimulation policies restoring natural proprioception.

Rehabilitative training paired with peripheral stimulation promotes motor recovery after ischemic cerebral stroke

Spontaneous recovery of ischemic stroke is very limited and often results in the loss of motor and sensory function. Till now, rehabilitative training is the most widely accepted therapy to improve long-term outcome. However, its effectiveness is often suboptimal, largely due to a sharp decline of neuroplasticity in adults. In this study, we hypothesized that a combination of proprioceptive stimulation and rehabilitative training will promote neuroplasticity and functional recovery post injury. To test this hypothesis, we first established a photothrombotic stroke model that lesions the hindlimb sensorimotor cortex. Next, we demonstrated that injecting Cre-dependent AAV-retro viruses into the dorsal column of PV-Cre mice achieves specific and efficient targeting of proprioceptors. With chemogenetics, this method enables chronic activation of proprioceptors. We then assessed effects of combinatorial treatment on motor and sensory functional recovery. Our results showed that pairing proprioceptive stimulation with rehabilitative training significantly promoted skilled motor, but not tactile sensory functional recovery. This further led to significant improvement when compared to rehabilitation training or proprioceptor stimulation alone. Mechanistically, combinatorial treatment promoted cortical layer V neuronal mTOR activity and sprouting of corticospinal axon into the area where proprioceptive afferents terminate in the denervated side of the spinal cord. Serving as a proof of principle, our study thus provided novel insights into the application of combining proprioceptive stimulation and rehabilitative training to improve functional recovery of ischemic stroke and other traumatic brain or spinal cord injuries.

An asymmetric mechanical code ciphers curvature-dependent proprioceptor activity.

A repetitive gait cycle is an archetypical component within the behavioral repertoire of many animals including humans. It originates from mechanical feedback within proprioceptors to adjust the motor program during locomotion and thus leads to a periodic orbit in a low-dimensional space. Here, we investigate the mechanics, molecules, and neurons responsible for proprioception in Caenorhabditis elegans to gain insight into how mechanosensation shapes the orbital trajectory to a well-defined limit cycle. We used genome editing, force spectroscopy, and multiscale modeling and found that alternating tension and compression with the spectrin network of a single proprioceptor encodes body posture and informs TRP-4/NOMPC and TWK-16/TREK2 homologs of mechanosensitive ion channels during locomotion. In contrast to a widely accepted model of proprioceptive “stretch” reception, we found that proprioceptors activated locally under compressive stresses in-vivo and in-vitro and propose that this property leads to compartmentalized activity within long axons delimited by curvature-dependent mechanical stresses.

Compact oscillatory stimulation device for evaluation and activation of proprioceptors

Compact oscillatory stimulation device for evaluation and activation of proprioceptors

Characterization of Proprioceptive System Dynamics in Behaving Drosophila Larvae Using High-Speed Volumetric Microscopy

SUMMARYProprioceptors provide feedback about body position that is essential for coordinated movement. Proprioceptive sensing of the position of rigid joints has been described in detail in several systems; however, it is not known how animals with a flexible skeleton encode their body positions. Understanding how diverse larval body positions are dynamically encoded requires knowledge of proprioceptor activity patterns in vivo during natural movement. Here we used high-speed volumetric swept confocally aligned planar excitation (SCAPE) microscopy in crawling Drosophila larvae to simultaneously track the position, deformation, and intracellular calcium activity of their multidendritic proprioceptors. Most proprioceptive neurons were found to activate during segment contraction, although one subtype was activated by extension. During cycles of segment contraction and extension, different proprioceptor types exhibited sequential activity, providing a continuum of position encoding during all phases of crawling. This sequential activity was related to the dynamics of each neuron’s terminal processes, and could endow each proprioceptor with a specific role in monitoring different aspects of body-wall deformation. We demonstrate this deformation encoding both during progression of contraction waves during locomotion as well as during less stereotyped, asymmetric exploration behavior. Our results provide powerful new insights into the body-wide neuronal dynamics of the proprioceptive system in crawling Drosophila, and demonstrate the utility of our SCAPE microscopy approach for characterization of neural encoding throughout the nervous system of a freely behaving animal.

Sense of extension force and angle of the knee joint are correlated between two generations of men

ABSTRACTNumerous motor abilities depend on the activity of proprioceptors, which has been suggested to be genetically determined. To test this hypothesis, the control of torque generated by knee extensors and knee position was studied in 30 father–son pairs both before and immediately after running. After stabilisation of the participant in a sitting position, the knee joint of his dominant leg was flexed to 90°, and the maximal voluntary torque (MVT) of the dominant knee extensors under static conditions was measured. The participant then tried five times to produce 50% of the MVT. Next, the participant extended the knee to 45° five times without visual control. Significant correlations between the reproducibility of successive trials for groups of fathers and their sons were found. The correlation coefficients for the repeatability of the knee extension torque were 0.69 (confidence interval [CI] = 0.45–0.84; P < 0.01) and 0.75 (CI = 0.54–0.87; P < 0.01) before and after the fatiguing exercise, respectively, whereas the coefficient for the reproducibility of positioning the knee was 0.49 (CI = 0.16–0.72; P < 0.01) after the fatiguing exercise. Our results indicate a significant influence of hereditary factors on the control of limb torque and position.

Dynamic High-Cadence Cycling Improves Motor Symptoms in Parkinson's Disease.

Individuals with Parkinson's disease (PD) often have deficits in kinesthesia. There is a need for rehabilitation interventions that improve these kinesthetic deficits. Forced (tandem) cycling at a high cadence improves motor function. However, tandem cycling is difficult to implement in a rehabilitation setting. To construct an instrumented, motored cycle and to examine if high cadence dynamic cycling promotes improvements in motor function. This motored cycle had two different modes: dynamic and static cycling. In dynamic mode, the motor maintained 75-85 rpm. In static mode, the rider determined the pedaling cadence. UPDRS Motor III and Timed Up and Go (TUG) were used to assess changes in motor function after three cycling sessions. Individuals in the static group showed a lower cadence but a higher power, torque and heart rate than the dynamic group. UPDRS score showed a significant 13.9% improvement in the dynamic group and only a 0.9% improvement in the static group. There was also a 16.5% improvement in TUG time in the dynamic group but only an 8% improvement in the static group. These findings show that dynamic cycling can improve PD motor function and that activation of proprioceptors with a high cadence but variable pattern may be important for motor improvements in PD.

How Actions Alter Sensory Processing

Our vestibular organs are simultaneously activated by our own actions as well as by stimulation from the external world. The ability to distinguish sensory inputs that are a consequence of our own actions (vestibular reafference) from those that result from changes in the external world (vestibular exafference) is essential for perceptual stability and accurate motor control. Recent work in our laboratory has focused on understanding how the brain distinguishes between vestibular reafference and exafference. Single-unit recordings were made in alert rhesus monkeys during passive and voluntary (i.e., active) head movements. We found that neurons in the first central stage of vestibular processing (vestibular nuclei), but not the primary vestibular afferents, can distinguish between active and passive movements. In order to better understand how neurons differentiate active from passive head motion, we systematically tested neuronal responses to different combinations of passive and active motion resulting from rotation of the head-on-body and/or head-and-body in space. We found that during active movements, a cancellation signal was generated when the activation of proprioceptors matched the motor-generated expectation.

Effects of 4 Weeks of Stretching on Active Torque Development

Stretching is common in recreational and athletic settings in an attempt to reduce the passive stiffness of muscles and reduce injury risk. One proposed mechanism by which stretching can reduce muscle stiffness is by decreasing alpha motor neuron activity and decreasing the output from, or sensitivity to, muscle and joint proprioceptors. However, the resultant reduced motor neuron and proprioceptor activity, as well as reduced stiffness, may have a negative impact on muscle force generation. PURPOSE: To determine if muscle force, power, and optimum length are affected by 4 weeks of static or ballistic stretching. METHODS: Twenty nine, recreationally active, aged 18–60yr., males who had not undergone routine flexibility training in the past 6 months were participants in this study. Prior to completing the stretching program and following habituation, measures of peak torque (PT), rate of torque development (RTD), work (W), and peak torque angle (PTA) were assessed in the hip extensors. All measures were completed on a isokinetic dynamometer at 1.05rad·s−1 (60deg·s−1) and involved hip extension from a flexed position. Then, participants completed 4 weeks of either static or ballistic flexibility training of the hip extensors for a total stretching duration of 3,600s. Following the 4 weeks of training and two days without stretching, assessment of active torque development was repeated. Comparisons between variables prior to and post-training were made using repeated measures analysis of variance. RESULTS: After training, PT increased by 5.3 ± 19.0% in the static group, 7.8 ± 12.7% in the ballistic group, and 6.1 ± 17.9% in the control group (p = .94). RTD increased by 4.8 ± 22.7% in the static group, 3.6 ± 28.0% in the ballistic group and by 9.7 ± 24.0% in the control group (p = .85). W increased by 3.9 ± 7.0% in the static group, 14.7 ± 27.4% in the ballistic group, and 5.5 ± 9.5% in the control group (p = .35). PTA changed little with a −1.6 ± 6.6% decrease in the static group, and increases of 0.86 ±4.1% in the ballistic and 0.18 ± 8.7% in the control groups (p = .80). There were no statistical differences between groups for any measures. CONCLUSIONS: These data suggest that 4 weeks of stretching have little effect on parameters of active torque development. There were no changes in optimal muscle length (PTA) that would suggest that a lengthening of the muscle occurred with stretching. Furthermore, there were no significant differences in these measures between either static or ballistic stretching modalities. These data indicate that engaging in a moderate duration stretching program does not adversely affect the generation of muscle force or power. Supported by NIH grant P20 RR16462

Primary afferent depolarization induced by cyclically modulated natural hind limb proprioceptor activity in cats

Primary afferent depolarization (PAD), developing during passive movements of the ankle with a frequency of 0.14–5.0 Hz was investigated in decerebrate cats. An increase in the dorsal root potential, the amplitude of which was used to judge the intensity of PAD, was observed during both extension and flexion of the joint. Parallel with waves of the dorsal root potential, changes in amplitude of the N component of the dorsal cord potential in response to stimulation of a cutaneous nerve during different phases of the limb movement cycle were recorded. These changes were periodic in character and opposite in phase to oscillations of dorsal root potential. The mechanisms of the observed changes in the PAD level and also the functional significance of these changes during cyclic motor acts are discussed.

Effect of thyrotoxicosis on skeletal muscle proprioceptor activity

The effect of prolonged administration of thyroid hormones on the discharges from muscle spindles of the cat soleus was investigated. In animals with thyrotoxicosis the response of the primary spindle endings to a constantly acting and to a sudden rapid stretching increased considerably in both the dynamic and the static phase. The discharge frequency of the secondary endings remained substantially unchanged. It is postulated that the observed changes in activity of the primary endings are connected with disturbances of metabolism in the muscle and also with its atrophy.

Studies on the nervous system of an isopod crustacean, Ligia oceanica

1. 1. Each pereiopod is innervated by two branches of the segmental nerve. The activity from vibration sensitive units can be recorded from the anterior branch and proprioceptor activity from the posterior branch. Motor activity is also carried in these branches. 2. 2. Three vibration sensitive units were found experimentally responding to 100–150 c/s; 150–400 c/s; and 2 kc/s. 3. 3. Simultaneous recording from the anterior and posterior branches revealed evidence of a reflex pathway at the segmental level. 4. 4. Recordings from the nerve cord showed that sensory activity from pereiopod proprioceptors was detectable in the ipsilateral connective but not beyond adjacent ganglia.

Influence of proprioceptor activity in the ventilatory response to exercise.

ArticleInfluence of proprioceptor activity in the ventilatory response to exercise.J H Sipple, and R GilbertJ H Sipple, and R GilbertPublished Online:01 Jan 1966https://doi.org/10.1152/jappl.1966.21.1.143MoreSectionsPDF (682 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEffects of exercise modality on patterns of ventilation and respiratory timingRespiration Physiology, Vol. 90, No. 2Ventilatory responses during varied stride and pedal frequenciesRespiration Physiology, Vol. 78, No. 2Interrelation of Respiratory Responses to $$ \dot V $$ co2, Pedal Rate and Loading Force During Cycle ExerciseRespiratory Control During Exercise1 January 2011Ventilatory Response to Muscular ExerciseAbnormal Respiratory Control in Acquired DysautonomiaNew England Journal of Medicine, Vol. 285, No. 7Effect of body temperature on the ventilatory response to exerciseRespiration Physiology, Vol. 8, No. 3Sauerstoffaufnahme, Pulsfrequenz und Ventilation bei Variation von Tretgeschwindigkeit und Tretkraft bei aerober ErgometerarbeitPfl�gers Archiv f�r die Gesamte Physiologie des Menschen und der Tiere, Vol. 298, No. 3 More from this issue > Volume 21Issue 1January 1966Pages 143-6 https://doi.org/10.1152/jappl.1966.21.1.143PubMed5903901History Published online 1 January 1966 Published in print 1 January 1966 Metrics

The Co-Ordination of Limb Movements in the Amphibia

ABSTRACT Well-defined myotactic reflexes (retractor-extensor thrusts) can be elicited from the retractor and extensor musculature when these muscles contract against an external resistance. A de-afferentated limb cannot exert a retractor-extensor thrust. A retractor-extensor thrust arising in a forelimb evokes an extensor response in the diagonal hindlimb and a protractor response in the contralateral forelimb. In order that these responses should display themselves with regularity it is necessary to de-afferentate the responding limb; in an intact limb they are often masked by the control exerted by the limb’s own proprioceptive mechanism. In an intact animal a retractor-extensor thrust in a forelimb evokes a ‘placing reaction’ from the ipsilateral hindlimb. This phenomenon is only partially displayed if the hindlimb is de-afferentated. When an intact forelimb responds, by protraction, to passive stretch, the contralateral hindlimb flexes and the ipsilateral hindlimb extends if the latter limbs have been de-afferentated. The individual proprioceptor limb responses integrate to form an adequate picture of the co-ordinated limb movements seen when an intact toad ceases to swim and begins to walk on land. The role of proprioceptor activity in the maintenance of an ambulatory rhythm in a single limb is discussed.