Thomas Eggert

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Three experiments were performed to determine how an error signal for driving saccadic adaptation is derived from visual information processing. The first experiment demonstrated that an intrasaccadic displacement of a visual background does not influence saccadic adaptation when a small foveal target is used. The second experiment showed that when a(More)
This study investigated whether the cerebellum is essential for rapid saccade adaptation. Saccade adaptation was elicited by 30% backward target steps during the primary saccade. Patients with cerebellar lesions adapted less than normal subjects, but saccade adaptation was most impaired in the group of patients with cerebellar degeneration. As the(More)
A shift of the visual attention focus is known to precede saccades. However, how the metrics of both this presaccadic attention shift and the saccade are coupled is still unclear. We altered the saccade size by short-term saccadic adaptation to determine whether the attention focus would still be shifted to the location of the saccade target or to the(More)
Downbeat nystagmus (DN), a fixation nystagmus with the fast phases directed downward, is usually caused by cerebellar lesions, but the precise etiology is not known. A disorder of the smooth-pursuit system or of central vestibular pathways has been proposed. However, both hypotheses fail to explain why DN is usually accompanied by gaze-holding nystagmus,(More)
Gilles de la Tourette's syndrome (GTS) is presumed to be an inherited disorder with an unclear pathophysiology. An involvement of the basal ganglia is suspected. Besides vocal tics, one of the main symptoms is the presence of motor tics. As eye movements are a specialized part of the motor system, we investigated whether they differed in some typical way in(More)
To investigate the effect of the visual stimulus configuration on localization when oculomotor performance is excluded, we evaluated the errors made when subjects compare the horizontal location of two sequentially presented peripheral targets while looking at a visual or memorized fixation spot. Eye position was monitored by means of an infrared eye(More)
Reaching movements are often used to study the effectiveness of motor control processes with respect to the final position of arm and hand. Empirical evidence shows that different targets can be grasped with similar final position accuracy. However, movements that achieve similar accuracy at their final position may nevertheless be controlled differently.(More)
The way in which saccadic eye movements are elicited influences their latency and accuracy. Accordingly, different tasks elicit different types of saccades. Using the tasks steps, gap, memory, scanning and antisaccade, we analyzed combined eye and hand movements to determine whether both motor systems share control strategies. Errors and latencies were(More)
Eye-hand coordination was investigated with the global effect paradigm. In this paradigm, saccades typically land in between the target and a nearby presented distractor, the configuration's center of gravity. This so-called global effect, or spatial averaging, is attributed to incomplete target selection. Four experiments demonstrated a similar effect for(More)
We tested the ability of normal subjects to make changes in the conjugacy of their saccades. Subjects dichoptically viewed a grid the size of which was 10% larger in one eye. The grids were centred onto a flat screen at 57 cm or 1 m from the subject. Horizontal saccades immediately became larger in the eye viewing the larger grid. For some subjects this(More)