Cortical processing of global form, motion and biological motion under low light levels

Abstract

'Cortical processing of global form, motion and biological motion under low light levels.', Vision research., 121. pp. 39-49. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. however, global form thresholds were relatively more impaired than those for global motion or biological motion. VEP responses to coherent global form and motion were reduced in low light, and motion responses showed a shift in topography from the midline to more lateral locations. Contrast sensitivity measures confirmed that basic visual processing was also affected by low light. However, comparison with CSF reductions achieved by optical blur indicated that these were insufficient to explain the pattern of results, although the temporal properties of the rod system may also play a role.Overall, mid-level processing in extra-striate areas is differentially affected by light level, in ways that cannot be explained in terms of low-level spatiotemporal sensitivity. A topographical shift in scotopic motion VEP responses may reflect either changes to inhibitory feedback mechanisms between V1 and extra-striate regions or a reduction of input to the visual cortex. These results provide insight into how higher-level cortical vision is normally organised in absence of cone input, and provide a basis for comparison with patients with cone dystrophies, before and after treatments aiming to restore cone function.

The Effect of Luminance Condition on Form, Form-from-Motion and Motion Perception

“…temporal summation). This issue has also been confirmed by recent findings [18] measuring steady state visual evoked potentials. However, when considering global motion detection, involving high order motion processing (MT area), at a relatively low velocity (from 3.2°/sec to 8.0°/sec), failed to confirm a clear motion deficit under scotopic condition [19].…”

“…Form perception has rarely been studied in condition of low-light level, such as in low mesopic or scotopic conditions [18,19]. The biological motion perception was studied by different scientific authors [18,19,20].…”

“…The biological motion perception was studied by different scientific authors [18,19,20]. All the cited studies show that both form and biological motion perception are highly defected in scotopic conditions.…”

“…in roddominated vision) and have demonstrated that motion perception is affected in scotopic light level [18,19,20,22,23,24,25,26,27]. However, the rod disadvantage in motion perception seemed to rely on the difficulty in extracting temporal changes.…”

Dissociations in Coherence Sensitivity Reveal Atypical Development of Cortical Visual Processing in Congenital Achromatopsia

“…We have attempted to simulate these effects with normal observers by testing global form and motion sensitivity with a diffusing screen that acts as a low-pass filter for spatial frequencies 37 and iovs.arvojournals.org j ISSN: 1552-5783 by testing under scotopic levels of illumination. 38 Both methods have been used and reported in previous studies: blur [39][40][41] and scotopic illumination. [42][43][44][45] Our recent study of global form, motion, and biological motion processing 38 with healthy controls (the same data provide a comparison for ACHM subjects in this paper) found greater impairments in global form perception under low light relative to global motion and biological motion.…”