Abstract:

PURPOSE: One paradox in primate vision concerns the increasing complexity of encoded features while spatial frequency (SF) selectivity decreases drastically along the visual hierarchy. We know V1 holds the highest SF selectivity for ?ne spatial analysis, however the comparative SF processing in di?erent functional stripes of V2 as well as in the downstream V4 is less clear.
METHODS: By simultaneous intrinsic optical imaging of macaque V1, V2 and V4, we quantitatively measured the population responses across these visual areas to sine-wave gratings with various SFs. The population responses of V1, V2, and V4 were subsequently con?rmed by single-unit recordings in awake macaques.
RESULTS: As expected we found that the SF selectivity was the highest in V1 while most regions in V4 exhibited the lowest SF selectivity. Compared with V1 and V4, V2 exhibited the strongest population response magnitude. We further investigated the SF selectivity across V2 functional stripes and found that the SF selectivity in thick stripes were lower than that in both thin and pale stripes. No signi?cant SF di?erence was found between the thin and pale stripes.
CONCLUSIONS: Our findings on the distinct SF selectivity across simultaneously imaged V1, V2, and V4 sheds lights on the spatial analysis along the visual hierarchy, which help to further our understanding and electrophysiological studies as well as computational modelling of the integration of local spatial features to form global representations.

Key words: Spatial vision, Non-human primate, ventral pathway