The effect of blur on cortical responses to global form and motion

Burton, E.A.; Wattam-Bell, J.; Rubin, G.S.; Atkinson, J.; Braddick, O.; Nardini, M.

Abstract

Global form and motion sensitivity undergo long development in childhood with motion sensitivity rather than form being impaired in a number of childhood disorders and both impaired in adult clinical populations. This suggests extended development and vulnerability of extrastriate cortical areas associated with global processing. However, in some developmental and clinical populations, it remains unclear to what extent impairments might reflect deficits at earlier stages of visual processing, such as reduced visual acuity and contrast sensitivity. To address this, we investigated the impact of degraded spatial vision on cortical global form and motion processing in healthy adults. Loss of high spatial frequencies was simulated using a diffuser to blur the stimuli. Participants completed behavioral and EEG tests of global form and motion perception under three levels of blur. For the behavioral tests, participants' form and motion coherence thresholds were measured using a two-alternative, forced-choice procedure. Steady-state visual evoked potentials were used to measure cortical responses to changes in the coherence of global form and motion stimuli. Both global form and global motion perception were impaired with increasing blur as measured by elevated behavioral thresholds and reduced cortical responses. However, form thresholds showed greater impairment in both behavioral and EEG measures than motion thresholds at the highest levels of blur. The results suggest that high spatial frequencies play an important role in the perception of both global form and motion but are especially significant for global form. Overall, the results reveal complex interactions between low-level factors and global visual processing, highlighting the importance of taking these factors into account when investigating extrastriate function in low vision populations.

Citation

Burton, E., Wattam-Bell, J., Rubin, G., Atkinson, J., Braddick, O., & Nardini, M. (2015). The effect of blur on cortical responses to global form and motion. Journal of Vision, 15(15), 1-14. https://doi.org/10.1167/15.15.12

• Journal Article Type: Article
• Acceptance Date: Oct 16, 2015
• Publication Date: Nov 1, 2015
• Deposit Date: Oct 16, 2015
• Journal: Journal of Vision
• Electronic ISSN: 1534-7362
• Publisher: Association for Research in Vision and Ophthalmology
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 15
• Article Number: 12
• Pages: 1-14
• DOI: https://doi.org/10.1167/15.15.12
• Keywords: Cortical vision, Optical blur, Global form and motion, Low vision.
• Public URL: https://durham-repository.worktribe.com/output/1420347
• Publisher URL: http://jov.arvojournals.org/article.aspx?articleid=2472922