Cortical control of erector spinae muscles during arm abduction in humans.

Abduction of one arm preferentially activates erector spinae muscles on the other side to stabilise the body. We hypothesise that the corticospinal drive to the arm abductors and the erector spinae may originate from the same hemisphere. In 18 subjects, transcranial magnetic stimulation (TMS) was applied using an angle double-cone coil placed symmetrically over the vertex.

Quantitative sensory tests (perceptual thresholds) in patients with spinal cord injury.

This article was presented at the Premeeting Workshop on Outcome Measures at the American Spinal Injury Association (ASIA) Annual Scientific Meeting in Dallas, Texas, in May 2005. The article summarizes preliminary findings of three quantitative sensory tests that were evaluated as part of the International Spinal Research Trust Clinical Initiative study: perceptual thresholds to electrical, vibration, and thermal stimulation. The results gathered so far suggest that the three tests are simple, reproducible, and applicable in a clinical setting.

Review of physiological motor outcome measures in spinal cord injury using transcranial magnetic stimulation and spinal reflexes.

This article reviews methods that have been developed as part of a clinical initiative on improving outcome measures for motor function assessment in subjects with spinal cord injury (SCI). Physiological motor outcome measures originally developed for limbs-transcranial magnetic stimulation (TMS) of the motor cortex to elicit motor-evoked potentials (MEPs) and mechanical stimulation to elicit spinal reflexes-have been extended to muscles of the trunk. The impetus for this development is the lack of a motor component in the American Spinal Injury Association clinical assessment for the thoracic myotomes.

Corticospinal excitability in patients with chronic low back pain.

Objective: This study was designed to investigate corticospinal excitability of lumbar muscles using transcranial magnetic stimulation (TMS) in patients with chronic low back pain and correlate this with self-rated measures of disability and pain.

Methods: Twenty-four patients with chronic low back pain and 11 healthy control subjects were used in this study. TMS was delivered through an angled double-cone coil, with its cross-over on the vertex and a posterior-to-anterior current flow in the brain.

Estimation of cortical silent period following transcranial magnetic stimulation using a computerised cumulative sum method.

The cortical silent period (CSP) following transcranial magnetic stimulation (TMS) of the motor cortex can be used to measure intra-cortical inhibition and changes in a number of important pathologies affecting the central nervous system. The main drawback of this technique has been the difficulty in accurately identifying the onset and offset of the cortical silent period leading to inter-observer variability. We developed an automated method based on the cumulative sum (Cusum) technique to improve the determination of the duration and area of the cortical silent period.

Corticospinal activation of internal oblique muscles has a strong ipsilateral component and can be lateralised in man.

Trunk muscles receive corticospinal innervation ipsilaterally and contralaterally and here we investigate the degree of ipsilateral innervation and any cortical asymmetry in pairs of trunk muscles and proximal and distal limb muscles. Transcranial magnetic stimulation (TMS) was applied to left and right motor cortices in turn and bilateral electromyographic (EMG) recordings were made from internal oblique (IO; lower abdominal), deltoid (D; shoulder) and first dorsal interosseus (1DI; hand) muscles during voluntary contraction in ten healthy subjects. We used a 7-cm figure-of-eight stimulating coil located 2 cm lateral and 2 cm anterior to the vertex over either cortex.

Human corticospinal excitability in microgravity and hypergravity during parabolic flight.

Introduction: Spontaneous electromyographic (EMG) activity in the soleus muscle of the rat varies with the changing gravitational force in parabolic flight, presumably in an appropriate way to resist the load. We investigated how decreased and increased gravitational force affects EMG in human back and arm muscles and to what extent the motor cortex is responsible for any modulation seen.

Methods: Three healthy subjects stood during 10 parabolas consisting of periods (duration 20-25 s) of 1.

Corticospinal excitability in patients with unilateral sciatica.

Patients suffering from sciatica may develop altered patterns of corticospinal drive to muscles of the leg. Electromyographic recordings were made bilaterally from tibialis anterior and lateral gastrocnemius muscles during transcranial magnetic stimulation of the motor cortex from nine patients with unilateral sciatica and seven healthy controls. The mean thresholds for eliciting motor evoked potentials (MEPs) and the silent period were higher in the patients than in the control subjects.

Stability of corticospinal excitability and grip force in intrinsic hand muscles in man over a 24-h period.

The maximum voluntary muscle force can vary throughout the day; typically being low in the morning and high in the evening. The nature of this possible variation has been investigated with respect to corticospinal excitability. Six healthy subjects were studied.

Fatigue-induced change in corticospinal drive to back muscles in elite rowers.

This study examined post-exercise changes in corticospinal excitability in five 'elite' rowers and six nonrowers. Transcranial magnetic stimulation (TMS) was delivered to the motor cortex and bilateral electromyographic (EMG) recordings were made from erector spinae (ES) muscles at L3/L4 spinal level and from the first dorsal interosseous (FDI) muscle of the dominant hand. Each subject completed two exercise protocols on a rowing ergometer: a light exercise protocol at a sub-maximal output for 10 min and an intense exercise protocol at maximum output for 1 min.

Activation of back muscles during voluntary abduction of the contralateral arm in humans.

Study Design: Motor-evoked responses to transcranial magnetic stimulation of the motor cortex were recorded from erector spinae and deltoid muscles while the arm was abducted voluntarily in 10 normal subjects.

Objective: To understand the neuronal substrate for the activation of the contralateral erector spinae muscle when the opposite arm is abducted.

Background Data: When a standing individual abducts an arm, the center of gravity is altered; to avoid falling, trunk muscles become activated on the contralateral side.

Musical beat influences corticospinal drive to ankle flexor and extensor muscles in man.

Body movements in man are frequently observed in relation to musical rhythms. In this study we have investigated the effect of strongly rhythmic music on corticospinal drive to the ankle extensor and flexor muscles involved in foot tapping. Surface electromyographic (EMG) recordings were made from tibialis anterior (TA) and lateral gastrocnemius (LGN) muscles in 12 normal subjects.