The relationship between neck muscle electromyography (EMG) and torsional head rotation (about the nasooccipital axis) is difficult to assess during normal gaze behaviors with the head upright. Here, we induced acute head tilts similar to cervical dystonia (torticollis) in two monkeys by electrically stimulating 20 interstitial nucleus of Cajal (INC) sites or inactivating 19 INC sites by inject...

Neck proprioceptive input, as elicited by muscle vibration, can produce destabilizing effects on stance and locomotion. Neck muscle fatigue produces destabilizing effects on stance, too. Our aim was to assess whether neck muscle fatigue can also perturb the orientation in space during a walking task. Direction and amplitude of the path covered during stepping in place were measured in 10 blindf...

The role of skin and muscle vascular beds in baroreceptor-mediated alterations of peripheral vascular resistance was evaluated in six normal subjects in whom the skin circulation in one forearm was temporarily suppressed by epinephrine iontophoresis. Baroreceptor activity was enhanced by application of negative pressure to the neck (neck suction) and inhibited by application of lower body negat...

We have shown previously that head-down neck flexion (HDNF) in humans elicits increases in muscle sympathetic nerve activity (MSNA). The purpose of this study was to determine the effect of neck muscle afferents on MSNA. We studied this question by measuring MSNA before and after head rotation that would activate neck muscle afferents but not the vestibular system (i.e., no stimulation of the o...

In this study a common yet very strenuous construction work activity, was evaluated biomechanically by studying electromyography (EMG) of the major neck muscles. The muscles studied were the sternocleidomastoid and the upper trapezius. Fifteen healthy participants (10 males and 5 females) with no history of musculoskeletal abnormalities participated in this study. The participants lifted 25%, 5...

We report neck muscle activity and head movements evoked by electrical stimulation of the superior colliculus (SC) in head-unrestrained monkeys. Recording neck electromyography (EMG) circumvents complications arising from the head's inertia and the kinetics of muscle force generation and allows precise assessment of the neuromuscular drive to the head plant. This study served two main purposes....