Peter W. Van Gelder

Associate Professor, Department of Psychiatry

Keywords
eye movements and biomedical imaging
Summary

Schizophrenic patients perform smooth pursuit eye movement poorly. A similar finding in relatives of schizophrenic patients has prompted hundreds of studies characterizing the finding and searching for a cause, without a resulting consensus. We find a wide range of competence in both normal subjects and schizophrenic patients, but both groups improve dramatically when the target becomes interesting. This improvement occurs when eliminating anticipatory saccades (fast eye movements), which are produced while attending unnaturally to the quality of smooth pursuit. Our current effort is to document velocity differences between anticipatory and the more common catchup saccades in pursuit and to establish the differences in pursuit processes. In taking the point of gaze ahead of the pursuit target, anticipatory saccades also show predictive pursuit of global properties of the trajectory, where smooth eye movement after the saccade is adjusted to meet the target at the trajectory endpoint (see Figure).

Additionally, we have developed a versatile and easily used program called Multimodal Image Display and Analysis System (MIDAS), now commercially available and used at other institutions, for the extraction of quantitative data from images of brain function (photon emission tomography and single photo emission computerized tomography) and structure (magnetic resonance imaging and computerized tomography). MIDAS can be used to coregister images of the same modality as well as images of different modalities, so that, for example, the metabolic activity of selected brain structures can be assessed. It has many tools to define and analyze regions and volumes of interest. Images can be displayed in any orthogonal or oblique orientation; volume rendering allows surface features to aid the definition of volumes of interest.

 

These focus areas and their associated publications are derived from medical subject headings from PubMed.
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Associate Professor, Department of Psychiatry

Lebedev, S V; Van Gelder, P W; Tsui, W H

Nuclear medicine communications. 2002 Feb; 23(2):181-185

Drawing movements as an outcome of the principle of least action

Lebedev, Sergey; Tsui, Wai Hon; Van Gelder, Peter

Journal of mathematical psychology. 2001 Feb; 45(1):43-52

Dumas, F; Frank, S; Koebnik, R; Maillet, E; Lustig, A; Van Gelder, P

Journal of molecular biology. 2000 Jul 21; 300(4):687-695

Target velocity information required for predictive saccade accuracy and for the transition to accurate smooth pursuit [Meeting Abstract]

Van Gelder P; Lebedev S; Tsui WH; Singh A

Abstracts (Society for Neuroscience). 1999 23-28 Oct; 25(1-2):1399-1399

Van Gelder, P; Lebedev, S; Tsui, W H

Experimental brain research. 1997 Sep; 116(2):201-215

Square-root relations between main saccadic parameters

Lebedev, S; VanGelder, P; Tsui, WH

Investigative ophthalmology & visual science. IOVS. 1996 Dec; 37(13):2750-2758

van Gelder P; Lebedev S; Tsui WH

Journal of neurophysiology. 1995 Sep; 74(3):1358-1361

Van Gelder P; Lebedev S; Liu PM; Tsui WH

Vision research. 1995 Mar; 35(5):667-678