title: Oblique effect in visual area 2 of macaque monkeys.
abstract: The neural basis of an oblique effect, a reduced visual sensitivity for obliquely oriented stimuli, has been a matter of considerable debate. We have analyzed the orientation tuning of a relatively large number of neurons in the primary visual cortex (V1) and visual area 2 (V2) of anesthetized and paralyzed macaque monkeys. Neurons in V2 but not V1 of macaque monkeys showed clear oblique effects. This orientation anisotropy in V2 was more robust for those neurons that preferred higher spatial frequencies. We also determined whether V1 and V2 neurons exhibit a similar orientation anisotropy soon after birth. The oblique effect was absent in V1 of 4- and 8-week-old infant monkeys, but their V2 neurons showed a significant oblique effect. This orientation anisotropy in infant V2 was milder than that in adults. The results suggest that the oblique effect emerges in V2 based on the pattern of the connections that are established before birth and enhanced by the prolonged experience-dependent modifications of the neural circuitry in V2.
authors: College of Optometry, University of Houston, Houston, TX, USA.
authors: Guofu
authors: G
authors: Shen
authors: Xiaofeng
authors: X
authors: Tao
authors: Bin
authors: B
authors: Zhang
authors: Earl L
authors: EL
authors: Smith
authors: Yuzo M
authors: YM
authors: Chino
mesh_terms: D000818:Animals; D008253:Macaca mulatta; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology
keywords: V1; V2; macaque monkeys; oblique effect; orientation tuning; radial bias