No description available.

No description available.

No description available.

No description available.

No description available.

The perception of isometric forces was examined under normal conditions, during sustained constant force contractions, and during vibration of the muscle tendon. In these experiments a contralateral limb matching procedure was employed, and force and the brachial biceps and triceps electromyogram (EMG) were recorded from each arm. Under normal conditions it was found that smaller forces were consistently overestimated in magnitude. During sustained constant force contractions the matching forces exerted by the unfatigued arm increased linearly as did the EMG of the fatiguing muscle. These results are consistent with force judgements being made with respect to the excitatory input to the reference muscle. It was further determined that during fatigue subjects were unable to dissociate the force of exertion from the motor command generating the contraction. Muscle tendon vibration increased the variability of force judgements and resulted in the overestimation of forces. This appeared to be due to co-contraction of the antagonist triceps muscle during vibration of the contracting biceps. The increase in the perceived magnitude of force during vibration is again consistent with the centrally-mediated theory of force perception.

Thesis (B.A. Hons. 1978) from the Depatment of Psychology, University of Adelaide.

Thesis (B.A. (Hons.)) -- University of Adelaide, Department of Psychology, 1970.

Thesis (Ph.D.)--Texas Christian University, 2006. / Title from dissertation title page (viewed Sept. 11, 2006). Includes abstract. Includes bibliographical references.

Reduction from a more to a less noxious stimulus intensity produces a disproportionate but transient decrease in perceived pain. Although the relationship between the central nervous system and this offset analgesia has come under investigation using brain imaging, whether offset analgesia is primarily mediated by central rather than peripheral mechanisms has not been established. Here we investigate this question in healthy volunteers using thermal stimuli while recording continuous pain ratings. We constructed a composite stimulus using one Peltier thermode to deliver a constant painful test stimulus while a separate thermode coincidentally delivered a shorter but more intense conditioning stimulus at a distinct location. Three spatial configurations were investigated all delivering stimulation to the ventral forearm either proximally or distally from one another on the same forearm or with thermodes on opposing forearms. We demonstrate a decrease in test stimulus pain levels following offset of an ipsilateral but not contralateral conditioning stimulus. This decrease is comparable in magnitude to that observed during a single thermode classic offset analgesia stimulation. The manifestation of analgesia in one sensory field following cessation of stimulation in a distinct sensory field shows antinociceptive adaptation of primary afferent neurons is unnecessary to produce offset analgesia, and demonstrates central mechanisms are sufficient to achieve temporal filtering of nociceptive information during stimulus offset. / 2017-08-01