It has been demonstrated that in gap pursuit tasks, smooth pursuit latency is reduced. This 'gap effect' is modified by factors such as gap duration and task context. We have now investigated whether it is also modified by an important visual parameter--the contrast of the pursuit and fixation targets. We found that while pursuit target contrast is an important determinant of pursuit latency, f...

PURPOSE To identify and explain the effects of eye and head position on smooth pursuit eye movements in normal humans. METHODS Horizontal and vertical smooth pursuit were measured in different eye-in-orbit positions in normal subjects, using a magnetic search coil technique with sinusoidal and step-ramp stimuli. Pursuit also was tested in different horizontal head-on-trunk positions. RESULT...

We compared horizontal and vertical smooth pursuit eye movements in five healthy human subjects. When maintenance of pursuit was tested using predictable waveforms (sinusoidal or triangular target motion), the gain of horizontal pursuit was greater, in all subjects, than that of vertical pursuit; this was also the case for the horizontal and vertical components of diagonal and circular tracking...

Eye-head gaze pursuit-related activity was recorded in rostral portions of the nucleus reticularis tegmenti pontis (rNRTP) in alert macaques. The head was unrestrained in the horizontal plane, and macaques were trained to pursue a moving target either with their head, with the eyes stationary in the orbits, or with their eyes, with their head voluntarily held stationary in space. Head-pursuit-r...

BACKGROUND Evidence of reliable smooth visual pursuit is crucial for both diagnosis and prognosis in prolonged disorders of consciousness (PDOC). However, a mirror is more likely than an object to elicit evidence of smooth pursuit. Our objective was to identify the physiological and/or cognitive mechanism underlying the mirror benefit. METHODS We recorded eye-movements while healthy participa...

During maintenance of smooth pursuit eye movements, the brain must keep track of pursuit velocity to reconstruct target velocity from motion of retinal images. Although a recent study showed that corollary discharge signals through the thalamus to the cortex are used for internal monitoring of saccades, it remains unknown whether signals in the thalamus also contribute to monitoring and on-line...

Visual short-term memory (VSTM) was probed while observers performed smooth pursuit eye movements. Smooth pursuit keeps a moving object stabilized in the fovea. VSTM capacity for position was reduced during smooth pursuit compared with a condition with eye fixation. There was no difference between a condition in which the items were approximately stabilized on the retina because they moved with...

The effects of an optokinetic background on pursuit eye movements was studied in four normal human subjects and seven patients with impaired pursuit and/or optokinetic nystagmus (OKN). Eye movements were recorded by DC electro-oculography and eye movement velocity was analyzed by a digital, microprocessor system. Tracking of a small laser target was performed against a featureless, white screen...

It has been demonstrated in normal subjects that smooth pursuit latency is reduced in gap pursuit tasks. We have now measured smooth pursuit latency in a group of schizophrenic subjects in both gap and non-gap conditions. In non-gap tasks pursuit latency was longer in the schizophrenic subjects than in controls. While the addition of gaps produced reductions in pursuit latency in the schizophre...