A Comparative Study of Shape Representation in Macaque Visual Areas V2 and V4 Export

@article{citeulike:1225954, abstract = {We compared aspects of shape representation in extrastriate visual areas V2 and V4, which are both implicated in shape processing and belong to different hierarchical levels. We recorded responses of cells in awake, fixating monkeys to matched sets of contour and grating stimuli of low or intermediate complexity. These included simple stimuli (bars and sinusoids) and more complex stimuli (angles, intersections, arcs, and non-Cartesian gratings), all scaled to receptive field size. The responses of cells within each area were substantially modulated by each shape characteristic tested, with substantial overlap between areas by many response measures. Our analyses revealed many clear and reliable differences between areas in terms of the effectiveness of, and response modulation by, various shape characteristics. Grating stimuli were on average more effective than contour stimuli in V2 and V4, but the difference was more pronounced in V4. As a population, V4 showed greater response modulation by some shape characteristics (including simple shape characteristics) and V2 showed greater response modulation by many others (including complex shape characteristics). Recordings from area V1 demonstrated complex shape selectivity in some cells and relatively modest population differences in comparison with V2. Altogether, the representation of 2-dimensional shape characteristics revealed by this analysis varies substantially among the 3 areas. But surprisingly, the differences revealed by our analyses, individually or collectively, do not parallel the stepwise organization of the anatomical hierarchy. Commonalities of visual shape representation across hierarchical levels may reflect the replication of neural circuits used in generating complex shape representations at multiple spatial scales. 10.1093/cercor/bhl020}, author = {Hegde, Jay and Van Essen, David C.}, citeulike-article-id = {1225954}, citeulike-linkout-0 = {http://dx.doi.org/10.1093/cercor/bhl020}, citeulike-linkout-1 = {http://cercor.oxfordjournals.org/content/17/5/1100.abstract}, citeulike-linkout-2 = {http://cercor.oxfordjournals.org/content/17/5/1100.full.pdf}, citeulike-linkout-3 = {http://cercor.oxfordjournals.org/cgi/content/abstract/17/5/1100}, citeulike-linkout-4 = {http://www.ingentaconnect.com/content/oup/cercor/2007/00000017/00000005/art01100}, citeulike-linkout-5 = {http://view.ncbi.nlm.nih.gov/pubmed/16785255}, citeulike-linkout-6 = {http://www.hubmed.org/display.cgi?uids=16785255}, day = {19}, doi = {10.1093/cercor/bhl020}, issn = {1047-3211}, journal = {Cereb. Cortex}, keywords = {shape, v2, v4}, month = {June}, number = {5}, pages = {bhl020--1116}, posted-at = {2009-11-10 22:40:14}, priority = {2}, publisher = {Oxford University Press}, title = {A Comparative Study of Shape Representation in Macaque Visual Areas V2 and V4}, url = {http://dx.doi.org/10.1093/cercor/bhl020}, volume = {17}, year = {2006} }

TY - JOUR ID - citeulike:1225954 L3 - citeulike-article-id:1225954 N2 - We compared aspects of shape representation in extrastriate visual areas V2 and V4, which are both implicated in shape processing and belong to different hierarchical levels. We recorded responses of cells in awake, fixating monkeys to matched sets of contour and grating stimuli of low or intermediate complexity. These included simple stimuli (bars and sinusoids) and more complex stimuli (angles, intersections, arcs, and non-Cartesian gratings), all scaled to receptive field size. The responses of cells within each area were substantially modulated by each shape characteristic tested, with substantial overlap between areas by many response measures. Our analyses revealed many clear and reliable differences between areas in terms of the effectiveness of, and response modulation by, various shape characteristics. Grating stimuli were on average more effective than contour stimuli in V2 and V4, but the difference was more pronounced in V4. As a population, V4 showed greater response modulation by some shape characteristics (including simple shape characteristics) and V2 showed greater response modulation by many others (including complex shape characteristics). Recordings from area V1 demonstrated complex shape selectivity in some cells and relatively modest population differences in comparison with V2. Altogether, the representation of 2-dimensional shape characteristics revealed by this analysis varies substantially among the 3 areas. But surprisingly, the differences revealed by our analyses, individually or collectively, do not parallel the stepwise organization of the anatomical hierarchy. Commonalities of visual shape representation across hierarchical levels may reflect the replication of neural circuits used in generating complex shape representations at multiple spatial scales. 10.1093/cercor/bhl020 IS - 5 JF - Cereb. Cortex SN - 1047-3211 EP - 1116 TI - A Comparative Study of Shape Representation in Macaque Visual Areas V2 and V4 PB - Oxford University Press VL - 17 SP - bhl020 KW - shape KW - v2 KW - v4 AU - Hegde, Jay AU - Van Essen, David PY - 2006/06/19/ UR - http://dx.doi.org/10.1093/cercor/bhl020 ER -