Cortisol-induced effects on human cortical excitability.

Background: Cortisol may fulfill all criteria for a neuromodulator. However, it is not known whether it may rapidly influence motor system activity in humans.

Objective: Circulating cortisol levels were manipulated by administration of a single intravenous dose of hydrocortisone or saline solution, on separate days, to study changes in corticospinal and motor cortical excitability.

Adaptive changes in postural strategy selection in chronic low back pain.

Chronic low back pain (CLBP) patients achieve postural stability during challenging stance conditions by increasing sway speed. We investigated the mechanisms underlying this behavior, and whether postural strategy selection may be influenced by short-term experience of postural perturbation. Thirteen CLBP patients and thirteen age-matched controls underwent posturography tests.

Influences of chemically-induced muscle pain on power output of ballistic upper limb movements.

Objective: To analyse the conditioning effects of localised acute muscle pain on power output during ipsi- and contra-lateral ballistic arm extensions.

Methods: Eight male subjects performed right arm (ipsilateral) and left arm (contra-lateral) bench press movements. The power output (and force and velocity) of the concentric phase of movement was measured before and during muscle pain induced by a standardised intramuscular injection of levo-ascorbic acid in the right pectoralis major muscle (prime mover muscle) and in the lateral head of the right triceps brachii muscle (synergist).

Effects of gonadal steroids on the input-output relationship of the corticospinal pathway in humans.

Most of our knowledge about gonadal steroid effects on the nervous system come from studies of limbic structures, while virtually nothing is known about the action of these hormones on the motor system. We carried out experiments on six healthy volunteer males to determine the threshold and gain of the input-output relationship (i.e.

Early somatosensory processing during tonic muscle pain in humans: relation to loss of proprioception and motor 'defensive' strategies.

Objective: It is known that tonic muscle pain induced by a Levo-Ascorbic (L-AS) solution injected in a foot muscle can transiently modify both regional proprioception and stimulus perception. These findings are paralleled by changes of middle-latency lower-limb somatosensory evoked potentials (SEPs). However, little is known on the behaviourally relevant aspect whether eventual SEP pain-induced changes could be partly due to a sort of 'motor strategy' of subjects in the frame of a self-protective reaction towards the noxious stimulus.