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The role of the FEF/FPA and SEF in oculomotor prediction was investigated using psychophysics, functional MRI (fMRI) and TMS. The separate contribution of advance knowledge of target direction and target timing to predictive saccades, and neural activity in frontal oculomotor structures was first investigated. The greatest proportion of predictive saccades were elicited when subjects had advance knowledge of both target direction and target timing; advance knowledge of target direction increased the proportion of predictive saccades, while advance knowledge of target timing decreased saccade latencies without increasing predictive saccades. Activity was greater in the FEF for all saccade tasks with a predictable component than reflexive saccades. Activity in the FEF was higher in tasks for which saccade latencies were lower. These data suggest that target direction and target timing independently reduce saccade latencies, and that this information converges in the FEF to allow the generation of predictive saccades. In the SEF, activity was greater only in the condition when both target direction and target timing were predictable. This finding may reflect a role of the SEF in oculomotor sequencing rather than in prediction per se. / In order to assess whether the FEF play a general role in oculomotor prediction, and not just in saccades, the role of the FPA in predictive pursuit was evaluated by applying TMS to the FPA and SEF during sinusoidal pursuit. TMS of the FPA modulated eye velocity both at peak target velocity and at the target turnaround. The induced changes in eye velocity occurred with a short latency, that is, before visual signals could travel from the retina to brainstem. This would suggest that TMS of the FPA likely increased the gain of the transformation of predictive signals, rather than visual signals, to motor commands. Stimulation of the SEF increased eye velocity only when applied at the target turnaround. Previous studies have demonstrated that stimulation of SEF increases eye velocity during pursuit initiation. Our finding that this facilitation also occurs at the target turnaround may berelated to similarities between pursuit initiation and the turnaround, including the necessity to rapidly increase eye velocity from zero.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 7 uppsatser.

Thesis (Ph. D.)--University of Florida, 1988. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 115-122).

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Psychology, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND HUMANITIES / Bibliography: leaves 36-40. / by Douglas Allen Whittington. / Ph.D.

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This paper describes an electro-oculometer and analyzes the electronic circuits required to process the signal. This electro-oculometer is a passive, two-channel device which detects the eye orientation using commercially available electrodes attached near the eyes. The electro-oculometer is composed of a special amplifier followed by a parabolic filter. The amplifier has high common mode rejection ratio, low drift, and low input bias current. Both DC and AC analyses of the electro-oculometer have been performed. The common mode rejection ratio (CMRR) of the input stage of the device is computed both at low and high frequencies. The experimental data were then compared with theoretical results. A parabolic low pass filter was designed and implemented as part of the electro-oculometer. A parabolic filter was chosen because it gives a minimum overshoot step response. The input stage (preamplifier) of the electro-oculometer is modified so as to prevent a latch up problem. This latch up is a saturated state of the system. When the output of the system reaches saturation, the system cannot reset itself. The new configuration of the preamplifier does not require any extra active elements.

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