Retinal and cortical patterns of spatial anisotropy in contrast sensitivity tasks.
It has often been postulated that asymmetries in performance within the visual field (VF) are not characteristic of early visual processing. Here, human retinal (naso/temporal), cortical (left/right) and superior/inferior patterns of asymmetry were explored with achromatic contrast sensitivity (CS) tasks, that probed distinct spatiotemporal frequency channels. Low spatial, high temporal frequency stimuli (illusory frequency-doubling (FD)) yielded superior and temporal field disadvantage. Independent right and nasal visual hemifield patterns of disadvantage were found when probing an intermediate spatial frequency (ISF) channel, with stationary sinusoidal gratings. These findings show that asymmetries in spatial vision are explained by independent retinal and cortical mechanisms.
Silva
Maria Fatima
MF
Centre for Opthalmology, Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, Az. de Sta Comba, 3000-354 Coimbra, Portugal.
Maia-Lopes
Susana
S
Mateus
Catarina
C
Guerreiro
Manuela
M
Sampaio
Joana
J
Faria
Pedro
P
Castelo-Branco
Miguel
M
D000328:Adult; D016880:Anisotropy; D015350:Contrast Sensitivity / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012160:Retina / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology