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We studied the effects of horizontal smooth pursuit on the ocular tracking responses to brief perturbations of a textured background in humans. When the subject was fixating a stationary spot, a brief perturbation (60 degrees/s, 40 ms) of the background in any one of four directions (right, left, up, down) elicited a small tracking response. When the(More)
Chemical lesions of the brain stem region containing glycinergic omnipause neurons (OPNs) cause saccade slowing with no change in latency. To explore the mechanisms responsible for this deficit, simulation studies were performed with a conductance-based model of premotor excitatory burst neurons (EBNs) that incorporated multiple membrane channels, including(More)
Psychophysical evidence indicates that visual motion can be sensed by low-level (energy-based) and high-level (feature-based) mechanisms. The present experiments were undertaken to determine which of these mechanisms mediates the initial ocular following response (OFR) that can be elicited at ultra-short latencies by sudden motion of large-field images. We(More)
Tremor disorders pose fundamental questions about disease mechanisms, and challenges to successful neurotherapeutics: What causes motor circuits to oscillate in disorders in which the central nervous system otherwise seems normal? How does inheritance 'determine' the clinical phenotype in familial tremor disorders? Here, we address these questions.(More)
Saccadic oscillations threaten clear vision by causing image motion on the retina. They are either purely horizontal (ocular flutter) or multidimensional (opsoclonus). We propose that ion channel dysfunction in the burst cell membrane is the underlying abnormality. We have tested this hypothesis by simulating a neuromimetic computational model of the burst(More)
To study the initial part of the mouse optokinetic response, OKR (approximately 500 ms from the onset of visual stimulus motion), we recorded the ocular response to a vertical sinusoidal grating moving at a constant velocity. We found that the magnitude of the response monotonically increased as the stimulus contrast increased. The response showed a narrow(More)
Ocular following responses (OFRs) were elicited in monkeys at short latencies ( approximately 50ms) by applying motion in the form of successive 1/4-wavelength steps to each of two overlapping vertical sine-wave gratings that had different spatial frequencies. In the first experiment, the two sine waves had spatial frequencies in the ratio 3:5 and moved in(More)
We studied the effect of the probability of required tracking on the gain of visuomotor transmission for pursuit initiation in monkeys. We recorded the ocular responses to a brief movement (perturbation) of a target located at an eccentric position from the central fixation spot. As soon as the central fixation spot went off, the animal was required to make(More)