Vaughan G. Macefield

Learn More
The most obvious impairments associated with spinal cord injury (SCI) are loss of sensation and motor control. However, many subjects with SCI also develop persistent neuropathic pain below the injury which is often severe, debilitating and refractory to treatment. The underlying mechanisms of persistent neuropathic SCI pain remain poorly understood.(More)
Unexpected pulling and pushing loads exerted by an object held with a precision grip evoke automatic and graded increases in the grip force (normal to the grip surfaces) that prevent escape of the object; unloading elicits a decrease in grip force. Anesthesia of the digital nerves has shown that these grip reactions depend on sensory signals from the(More)
A debilitating consequence of complete spinal cord injury (SCI) is the loss of motor control. Although the goal of most SCI treatments is to re-establish neural connections, a potential complication in restoring motor function is that SCI may result in anatomical and functional changes in brain areas controlling motor output. Some animal investigations show(More)
1. The discharge behaviour of fourteen single sympathetic vasoconstrictor efferents was studied using a tungsten microelectrode inserted percutaneously into a motor fascicle of the radial or peroneal nerve in eight awake supine subjects. Units were classified as vasoconstrictor because their firing properties correlated appropriately to changes in cardiac(More)
It has been known for some time that populations of cutaneous and muscle afferents can provide short-latency facilitation of motoneuron pools. Recently, it has been shown that the input from individual low-threshold mechanoreceptors in the glabrous skin of the hand can modulate ongoing activity in muscles acting on the fingers via spinally mediated(More)
Firing properties of single sudomotor axons were studied via tungsten microelectrodes inserted percutaneously into cutaneous fascicles of the peroneal nerve in awake subjects. Sweating was induced by radiant heat and measured by changes in skin electrical resistance within the innervation territory on the dorsum of the foot. Eight units were classified as(More)
1. The firing of single sympathetic neurones was recorded via tungsten microelectrodes in cutaneous fascicles of the peroneal nerve in awake humans. Studies were made of 17 vasoconstrictor neurones during cold-induced cutaneous vasoconstriction and eight sudomotor neurones during heat-induced sweating. Oligounitary recordings were obtained from 8 cutaneous(More)
Modulation of motor unit activation rate is a fundamental process by which the mammalian nervous system encodes muscle force. To identify how rate coding of force may change as a consequence of fatigue, intraneural microstimulation of motor axons was used to elicit twitch and force-frequency responses before and after 2 min of intermittent stimulation(More)
1. Single motor axons innervating human toe extensor muscles were selectively stimulated through a tungsten microelectrode inserted percutaneously into the peroneal nerve. Twitch and tetanic forces were measured from a strain gauge over the proximal phalanx of the toe generating the greatest force. Twitch data were obtained from 19 single motor units in(More)
All pain is unpleasant, but different perceptual and emotional qualities are characteristic of pain originating in different structures. Pain of superficial (cutaneous) origin usually is sharp and restricted, whereas pain of deep origin (muscle/viscera) generally is dull and diffuse. Despite the differences it has been suggested previously that all pain is(More)