A Neurofeedback System to Decrease Chronic Musculoskeletal Pain.

The existing methods for treating chronic musculoskeletal (MSK) pain do not address the restoration of altered brain activity, referred to as maladaptive plasticity, resulting from the effects of chronic MSK pain. Using electroencephalography (EEG) an increase in event-related alpha power over the somatosensory cortex was previously observed during movement in chronic MSK pain. A low cost neurofeedback system was developed that focuses on decreasing event-related alpha power.

Topical capsaicin modulates the two-point discrimination threshold-Modulation depends on stimulation modality and intensity.

Background: Spatial acuity concerns the ability to localize and discriminate sensory input and is often tested using the two-point discrimination threshold (2PDT). Sensitization of the pain system can affect the spatial acuity, but it is unclear how 2PDTs of different testing modalities are affected. The aim was to investigate if the 2PDTs for mechanical and heat stimulation at different intensities were modulated by topical capsaicin sensitization.

EEG signatures of low back and knee joint pain during movement execution: a short report.

Chronic musculoskeletal pain has a high prevalence between European citizens, affecting their quality of life and their ability to work. The plastic changes associated with the occurrence of chronic musculoskeletal pain are still not fully understood. The current short report investigated the possible changes in brain activity caused by pain during movement in two of the most common musculoskeletal pain disorders in Denmark, knee pain and low back pain.

Influence of skin type and laser wavelength on laser-evoked potentials.

Background: Infrared laser stimulation is a valuable tool in pain research, its primary application being the recording of laser-evoked brain potentials (LEPs). Different types of laser stimulators, varying in their skin penetrance, are likely to have a large influence on the LEPs, when stimulating different skin types. The aim of this study was to investigate how LEPs depend on laser type and skin location.

The two-point discrimination threshold depends both on the stimulation noxiousness and modality.

The two-point discrimination threshold (2PDT) has been used to investigate the integration of sensory information, especially in relation to spatial acuity. The 2PDT has been investigated for both innocuous mechanical stimuli and noxious thermal stimuli; however, previous studies used different stimulation modalities to compare innocuous and noxious stimuli. This study investigated the 2PDT in 19 healthy participants, using both thermal (laser) and mechanical stimulation modalities.

New Insights into Cutaneous Laser Stimulation - Dependency on Skin and Laser Type.

Cutaneous laser stimulation is a proficient tool to investigate the function of the nociceptive system. However, variations in laser-skin interactions, causes by different skin anatomies and laser wavelength, affects the robustness of nociceptor activation. Thus, thoroughly understanding how the skin is heated by a laser pulse is important to characterize the thermal response properties of nociceptors.

Delayed muscle onset soreness in the gastrocnemius muscle attenuates the spinal contribution to interlimb communication.

Purpose: Delayed onset muscle soreness (DOMS) has been shown to induce changes in muscle activity during walking. The aim of this study was to elucidate whether DOMS also affects interlimb communication during walking by investigating its effect on short-latency crossed responses (SLCRs).

Methods: SLCRs were elicited in two recording sessions by electrically stimulating the tibial nerve of the ipsilateral leg, and quantified in the contralateral gastrocnemius muscle.

Evidence for a Supraspinal Contribution to the Human Crossed Reflex Response During Human Walking.

In humans, an ipsilateral tibial nerve (iTN) stimulation elicits short-latency-crossed-responses (SLCR) comprised of two bursts in the contralateral gastrocnemius lateralis (cGL) muscle. The average onset latency has been reported to be 57-69 ms with a duration of 30.4 ± 6.

A Novel Stimulation Paradigm to Limit the Habituation of the Nociceptive Withdrawal Reflex.

In gait rehabilitation, combining gait therapy with functional electrical stimulation based on the nociceptive withdrawal reflex (NWR) improves walking velocity and gait symmetry of hemiparetic patients. However, habituation of the NWR can affect the efficacy of training. The current study aimed at identifying the stimulation parameters that would limit, in healthy participants, the habituation of the NWR.

Technologically-advanced assessment of upper-limb spasticity: a pilot study.

Background: Spasticity is a muscle disorder associated with upper motor neuron syndrome occurring in neurological disorders, such as stroke, multiple sclerosis, spinal cord injury and others. It influences the patient's rehabilitation, interfering with function, limiting independence, causing pain and producing secondary impairments, such as contractures or other complications. Due to the heterogeneity of clinical signs of spasticity, there is no agreement on the most appropriate assessment and measurement modality for the evaluation of treatment outcomes.

Sensory Feedback in Interlimb Coordination: Contralateral Afferent Contribution to the Short-Latency Crossed Response during Human Walking.

A constant coordination between the left and right leg is required to maintain stability during human locomotion, especially in a variable environment. The neural mechanisms underlying this interlimb coordination are not yet known. In animals, interneurons located within the spinal cord allow direct communication between the two sides without the need for the involvement of higher centers.

The effect of crossed reflex responses on dynamic stability during locomotion.

In recent studies, we demonstrated that a neural pathway within the human spinal cord allows direct communication between muscles located in the opposing limb. Short-latency crossed responses (SLCRs) are elicited in the contralateral triceps surae at an onset of 40-69 ms following electrical stimulation of the ipsilateral tibial nerve (iTN). The SLCRs are significantly affected by lesions of the central nervous system where the patients are unable to attain normal walking symmetry.

Crossed reflex reversal during human locomotion.

During human walking, precise coordination between the two legs is required in order to react promptly to any sudden hazard that could threaten stability. The networks involved in this coordination are not yet completely known, but a direct spinal connection between soleus (SOL) muscles has recently been revealed. For this response to be functional, as previously suggested, we hypothesize that it will be accompanied by a reaction in synergistic muscles, such as gastrocnemius lateralis (GL), and that a reversal of the response would occur when an opposite reaction is required.

Motor adaptation following split-belt treadmill walking.

Malone L, Vasudevan E, and Bastian A (J Neurosci 31: 15136-15143, 2011) investigated the effects of different training paradigms on the day-by-day retention of learned motor patterns. In this Neuro Forum, a description and assessment of the methods used will be presented. The interpretation of the findings will be extended and the possible implications will be discussed.