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A startle stimulus has been shown to elicit a ballistic response in a reaction time (RT) task at very short latencies without involvement of the cerebral cortex (J. Valls-Sole, J. C. Rothwell, F. Gooulard, G. Cossu, & E. Munoz, 1999). The present authors examined the nature of the startle response. A simple RT task was used in which 8 participants performed(More)
To document the activity of cutaneous mechanoreceptors in the glabrous skin of the foot sole, tungsten microelectrodes were inserted through the popliteal fossa and into the tibial nerve of thirteen healthy human subjects. A total of 104 cutaneous mechanoreceptors were identified in the glabrous skin of the foot. This sample consisted of 15 slow adapting(More)
Quick voluntary responses to environmental stimuli are required of people on a daily basis. These movements have long been thought to be controlled via cortical loops involving processing of the stimulus and generation of a suitable response. Recent experiments have shown that in simple reaction time (RT) tasks, the appropriate response can be elicited much(More)
This study examines the contribution of the vestibular system during different magnitudes of galvanic vestibular stimulation (GVS) during human walking. Anodal threshold levels of GVS were determined for right and left sides for each subject. Seven conditions were tested (no stimulation, left and right anode stimulation) at one, two and three times(More)
Recent experiments pairing a startling stimulus with a simple reaction time (RT) task have shown that when participants are startled, a prepared movement may be triggered earlier in comparison to voluntary initiation (Carlsen et al. 2003, in press; Siegmund et al. 2001; Valls-Solé et al. 1999). The use of this paradigm in experiments may provide new(More)
Prior knowledge of potentially slippery conditions has been shown to alter normal human gait in slip and fall experiments. Here we quantify the effects of two aspects of prior knowledge - awareness of a possible slip and prior slip experience - on normal gait. Sixty-eight subjects (40F, 28M) each walked over 48 high-friction surfaces (control trials) and 12(More)
The purpose of this study was to examine the effect of bilateral labyrinthectomy on quiet stance in the freely-standing cat. Since loss of the vestibular end organs produces marked deficits in motor behaviour, including ataxia and problems with balance, we hypothesized that labyrinthectomized animals would show impairment in quantitative measures of stance.(More)
Recent studies using a reaction time (RT) task have reported that a preprogrammed response could be triggered directly by a startling acoustic stimulus (115-124 dB) presented along with the usual "go" signal. It has been suggested that details of the upcoming response could be stored subcortically and are accessible by the startle volley, directly eliciting(More)
Stochastic vestibular stimulation (SVS) can be used to study the postural responses to unpredictable vestibular perturbations. The present study seeks to determine if stochastic vestibular stimulation elicits lower limb muscular responses and to estimate the frequency characteristics of these vestibulo-motor responses in humans. Fourteen healthy subjects(More)