James P Newton

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The effect of ageing on the threshold firing rate of motor units from the first dorsal interosseous muscle was investigated. Two groups of 9 healthy male subjects between the ages of 20-29 and 60-69 years took part in the study. The threshold firing rate of motor units in young subjects showed close agreement with previous observations. However, a(More)
The effects of ageing and dental state on the cross-sectional area and density of two jaw muscles, the masseter and medial pterygoid, were investigated using computed tomography. The study involved 84 male and 70 female subjects between the ages of 20 and 90 years. The cross-sectional area of both muscles showed a significant reduction with age; values for(More)
The effect of ageing on the contractile properties of the first dorsal interosseous muscle was investigated. A group of 42 healthy male subjects between the ages of 10 and 80 years took part in the study. The time to peak tension was significantly prolonged with increasing age but no evidence was found of an extension of the half relaxation time. When left(More)
In humans, inhibitory jaw reflexes can be depressed by painful stimulation of remote parts of the body. The underlying mechanisms may involve diffuse noxious inhibitory controls (DNIC). Animal experiments have shown that the neurons which may mediate DNIC show spatial encoding (i.e. their responses vary in relation to the size of the body area being(More)
The effects on activity in the masseter muscle of applying electrical stimuli to discrete areas within the mouth or on peri-oral skin were studied electromyographically in 8 subjects. In all subjects, the intra-oral stimuli produced two phases of depressed masseteric activity with mean latencies of 14 ms and 47 ms. By contrast, this shorter latency response(More)
Reflex responses of the jaw-closing system to innocuous mechanical stimulation of the tongue and palate were examined in a group of 25 girls aged 7-8 years and in a group of 25 women aged 70-80 years. Responses were measured both as changes in background biting force and from bilateral recordings of masseter EMGs. For comparative purposes, results from an(More)
OBJECTIVE In humans, stimulation of nerves in or around teeth can evoke inhibitory jaw reflexes. Previous studies had suggested that there may be subtle differences in the timings of the responses. The aim of the present study was to investigate this by comparing reflexes evoked by electrical stimulation of a tooth and of the adjacent tissues in individual(More)