A new method to measure higher visual functions in an immersive environment

Zito, Giuseppe Angelo; Müri, René; Mosimann, Urs Peter; Nyffeler, Thomas; Nef, Tobias (2014). A new method to measure higher visual functions in an immersive environment. Biomedical engineering online, 13, p. 104. BioMed Central 10.1186/1475-925X-13-104

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BACKGROUND: Higher visual functions can be defined as cognitive processes responsible for object recognition, color and shape perception, and motion detection. People with impaired higher visual functions after unilateral brain lesion are often tested with paper pencil tests, but such tests do not assess the degree of interaction between the healthy brain hemisphere and the impaired one. Hence, visual functions are not tested separately in the contralesional and ipsilesional visual hemifields. METHODS: A new measurement setup, that involves real-time comparisons of shape and size of objects, orientation of lines, speed and direction of moving patterns, in the right or left visual hemifield, has been developed. The setup was implemented in an immersive environment like a hemisphere to take into account the effects of peripheral and central vision, and eventual visual field losses. Due to the non-flat screen of the hemisphere, a distortion algorithm was needed to adapt the projected images to the surface. Several approaches were studied and, based on a comparison between projected images and original ones, the best one was used for the implementation of the test. Fifty-seven healthy volunteers were then tested in a pilot study. A Satisfaction Questionnaire was used to assess the usability of the new measurement setup. RESULTS: The results of the distortion algorithm showed a structural similarity between the warped images and the original ones higher than 97%. The results of the pilot study showed an accuracy in comparing images in the two visual hemifields of 0.18 visual degrees and 0.19 visual degrees for size and shape discrimination, respectively, 2.56° for line orientation, 0.33 visual degrees/s for speed perception and 7.41° for recognition of motion direction. The outcome of the Satisfaction Questionnaire showed a high acceptance of the battery by the participants. CONCLUSIONS: A new method to measure higher visual functions in an immersive environment was presented. The study focused on the usability of the developed battery rather than the performance at the visual tasks. A battery of five subtasks to study the perception of size, shape, orientation, speed and motion direction was developed. The test setup is now ready to be tested in neurological patients.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > University Psychiatric Services > University Hospital of Geriatric Psychiatry and Psychotherapy
10 Strategic Research Centers > ARTORG Center for Biomedical Engineering Research > ARTORG Center - Gerontechnology and Rehabilitation
04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DCR Unit Sahli Building > Forschungsgruppe Neurologie
04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Zito, Giuseppe Angelo; Müri, René Martin; Mosimann, Urs Peter; Nyffeler, Thomas and Nef, Tobias

Subjects:

600 Technology > 610 Medicine & health
600 Technology > 620 Engineering

ISSN:

1475-925X

Publisher:

BioMed Central

Language:

English

Submitter:

Vanessa Vallejo

Date Deposited:

23 Sep 2014 15:54

Last Modified:

09 Mar 2016 12:48

Publisher DOI:

10.1186/1475-925X-13-104

PubMed ID:

25069675

Uncontrolled Keywords:

Computer-based test, Distortion algorithm, Hemispherical projection, Unilateral brain lesion, Visual perception

BORIS DOI:

10.7892/boris.58724

URI:

https://boris.unibe.ch/id/eprint/58724

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