Noise-enhanced kinaesthesia: a psychophysical and microneurographic study

Abstract

We first explored whether the ability of subjects to detect the direction of slow ramp imposed movements may be improved by the application of mechanical noise to muscle tendons. Movements were plantar/dorsal flexion of the ankle at 0.04°/s, and the amplitude was just sub-threshold for each subject. A white noise signal (random vibration), low-pass filtered to 100 Hz and distributed uniformly in amplitude, was applied to both the extensor and the flexor ankle muscle tendons with four different mean amplitudes (20, 30, 100, 280 μm). The population of subjects was observed to exhibit clear stochastic-type behaviour: their ability to determine the direction of sub-threshold movements significantly increased when the two lower levels of noise were added and subsequently decreased when the noise magnitude was enhanced. Second, using microneurography, we explored the response of 9 primary muscle spindle afferents and 8 cutaneous afferents to the same imposed movements with and without noise application. While these conditions of ankle mobilisation were too small to induce a response in most of the recorded afferents, two muscle afferents exhibited responses that were characteristic of aperiodic stochastic resonance behaviour: the unit movement response was either triggered or improved by the application of an optimal level of noise. All cutaneous afferents were unresponsive to the imposed movements with or without noise application. We conclude that ankle movement sense can be significantly improved by adding an optimal level of mechanical noise to ankle muscle tendons and discuss the optimisation of the response of movement-encoding receptors that may account for this improvement. The application of a mechanical noise on ankle muscle tendons may constitute a means of improving postural stability in subjects with sensory deficits.

Cortical correlates of response time slowing in older adults: ERP and ERD/ERS analyses during passive ankle movement

“…More specifically, anesthetic procedures have indicated that such potentials are associated with the activation of muscle spindles, with little (if any) contribution from cutaneous and joint receptors (Abbruzzese et al, 1985;Starr et al, 1991;Mima et al, 1996). In addition, microneurographic techniques have shown that the essential proprioceptive sources of kinesthetic information of limb movement are the muscle spindles (Burgess et al, 1982;Burke et al, 1988), whereas cutaneous afferents have been shown to be partially active (Aimonetti et al, 2007) or even inactive (Ribot-Ciscar et al, 2013) during passive movement. In this sense, the N1 component observed in the present study must have been triggered by the discharges of muscle spindles from the triceps surae muscles.…”

“…As measurements of performance, both are limited in quantifying possible proprioceptive impairment per se (e.g., proprioceptive loss due to aging or neuropathy) since both measurements can be also influenced by cognitive and motor factors. A promising approach for investigating the neurophysiological aspects of proprioceptive function is the association of passive joint movement to different techniques such as microneurography (Burke et al, 1988;Ribot-Ciscar et al, 2013), electroencephalography (EEG) (Cassim et al, 2001;Lewis and Byblow, 2002;Seiss et al, 2002;Keinrath et al, 2006), and transcranial magnetic stimulation (TMS) (Lewis et al, 2001;Lewis and Byblow, 2002). The combination of these techniques can be very useful in the study of how different stages of information transmission and processing are involved in a cognitive sensorimotor task.…”

Improving postural control by applying mechanical noise to ankle muscle tendons

“…More specifically, the application of an optimal-amplitude random mechanical vibration to both the extensor and flexor ankle muscle tendons was shown to improve the detection of imposed ankle movements that were initially subthreshold. In addition, microneurographic recordings revealed improved muscle spindle responses during the application of an optimal level of mechanical vibration to muscle tendons (Cordo et al 1996;Ribot-Ciscar et al 2013). In the present study, mechanical noise was applied to both the gastrocnemius/soleus (GS) muscles and the tibialis anterior (TA) muscle to optimize ankle proprioceptive cues.…”

“…We used this method because the effects of mechanical stimulation on neuromuscular function have been accurately described and provide a solid basis for understanding the potential postural effects. Indeed, improved movement detection due to the induction of stochastic resonance by mechanical stimulation was recently demonstrated for the first time (Ribot-Ciscar et al 2013). More specifically, the application of an optimal-amplitude random mechanical vibration to both the extensor and flexor ankle muscle tendons was shown to improve the detection of imposed ankle movements that were initially subthreshold.…”

Gradual mechanics-dependent adaptation of medial gastrocnemius activity during human walking

“…Patients may also have a reduced ability to use afferent feedback to drive the gradual adaptation we observed in uninjured participants. If this is found to be true, then enhancing proprioceptive feedback with techniques such as white noise tendon vibration (Ribot-Ciscar et al 2013) may hold promise for improving function, similar to the beneficial effects of foot sole vibration on balance (Priplata et al 2006). …”