Viewing Target Distance Influences the Vestibulo-Ocular Reflex Gain when Assessed Using the Video Head Impulse Test.

Gaze stabilization during head movements is provided by the vestibulo-ocular reflex (VOR). Clinical assessment of this reflex is performed using the video Head Impulse Test (vHIT). To date, the influence of different fixation distances on VOR gain using the vHIT has not been explored.

Locomotor adaptation is modulated by observing the actions of others.

Observing the motor actions of another person could facilitate compensatory motor behavior in the passive observer. Here we explored whether action observation alone can induce automatic locomotor adaptation in humans. To explore this possibility, we used the "broken escalator" paradigm.

Head-Jolting Nystagmus: Occlusion of the Horizontal Semicircular Canal Induced by Vigorous Head Shaking.

Importance: We report a new syndrome, which we are calling head-jolting nystagmus, that expands the differential diagnosis of head movement-induced paroxysmal vertigo.

Observations: Two male patients (65 and 58 years old) described rotational vertigo after violent and brief (1- to 2-second) oscillations of the head (head jolting) that triggered intense horizontal nystagmus lasting 45 seconds. Accelerations of the head required to induce these episodes could only be achieved by the patients themselves.

Does outstretching the arms improve postural stability?

We spontaneously outstretch our arms when standing upon challenging surfaces, yet the effect of stretching the arms upon postural stability is unknown. We investigated whether stretching out the arms laterally improves postural control during tandem stance on a narrow beam. Twelve healthy participants stood upon a beam, right foot in front of the left foot, for 30s with arms outstretched or down to the side, with eyes open and closed.

Ocular tremor in Parkinson's disease is due to head oscillation.

Background: We investigated the origin of a recently reported ocular microtremor in patients with Parkinson's disease (PD).

Methods: Eye movements were recorded in 2 unselected patients with PD. Two recording techniques were used to control for artifacts: infrared video-oculography and infrared scleral reflection techniques.