Retinotopic and Lateralized Processing of Spatial Frequencies in Human Visual Cortex during Scene Categorization

• Published in: Journal of cognitive neuroscience 2013-08, Vol.25 (8), p.1315-1331
• Main Authors: Musel, Benoit, Bordier, Cécile, Dojat, Michel, Pichat, Cédric, Chokron, Sylvie, Le Bas, Jean-François, Peyrin, Carole
• Format: Article
• Language: English
• Subjects: Adult; Brain; Brain Mapping; Cancer; Computer Science; Engineering Sciences; Female; Functional Laterality - physiology; Humans; Image Processing, Computer-Assisted; Life Sciences; Magnetic Resonance Imaging; Male; Medical Physics; Neurobiology; Neurons and Cognition; Neurosciences; NMR; Nuclear magnetic resonance; Oxygen; Pattern Recognition, Visual - physiology; Photic Stimulation; Physics; Reaction Time; Recognition (Psychology); Signal and Image Processing; Space Perception - physiology; Visual Cortex - blood supply; Visual Cortex - physiology; Visual Fields - physiology; Visual Pathways - blood supply; Visual Pathways - physiology; Young Adult
• ISSN: 0898-929X; 1530-8898
• DOI: 10.1162/jocn_a_00397

Using large natural scenes filtered in spatial frequencies, we aimed to demonstrate that spatial frequency processing could not only be retinotopically mapped but could also be lateralized in both hemispheres. For this purpose, participants performed a categorization task using large black and white photographs of natural scenes (indoors vs. outdoors, with a visual angle of 24° × 18°) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and nonfiltered scenes, in block-designed fMRI recording sessions. At the group level, the comparison between the spatial frequency content of scenes revealed first that, compared with HSF, LSF scene categorization elicited activation in the anterior half of the calcarine fissures linked to the peripheral visual field, whereas, compared with LSF, HSF scene categorization elicited activation in the posterior part of the occipital lobes, which are linked to the fovea, according to the retinotopic property of visual areas. At the individual level, functional activations projected on retinotopic maps revealed that LSF processing was mapped in the anterior part of V1, whereas HSF processing was mapped in the posterior and ventral part of V2, V3, and V4. Moreover, at the group level, direct interhemispheric comparisons performed on the same fMRI data highlighted a right-sided occipito-temporal predominance for LSF processing and a left-sided temporal cortex predominance for HSF processing, in accordance with hemispheric specialization theories. By using suitable method of analysis on the same data, our results enabled us to demonstrate for the first time that spatial frequencies processing is mapped retinotopically and lateralized in human occipital cortex.