title: Modulation of prism adaptation by a shift of background in the monkey.
abstract: Recent human behavioral studies have shown that the position of a visual target is instantly represented relative to the background (e.g., a large square) and used for evaluating the error in reaching the target. In the present study, we examined whether the same allocentric mechanism is shared by the monkey. We trained two monkeys to perform a fast and accurate reaching movement toward a visual target with a square in the background. Then, a visual shift (20mm or 4.1°) was introduced by wedge prisms to examine the process of decreasing the error during an exposure period (30 trials) and the size of the error upon removal of the prisms (aftereffect). The square was shifted during each movement, either in the direction of the visual displacement or in the opposite direction, by an amount equal to the size of the visual shift. The ipsilateral shift of the background increased the asymptote during the exposure period and decreased the aftereffect, i.e., prism adaptation was attenuated by the ipsilateral shift. By contrast, a contralateral shift enhanced adaptation. We further tested whether the shift of the square alone could cause an increase in the motor error. Although the target did not move, the shift of the square increased the motor error in the direction of the shift. These results were generally consistent with the results reported in human subjects, suggesting that the monkey and the human share the same neural mechanisms for representing a target relative to the background.
authors.affiliation: Department of Neurophysiology, Juntendo University School of Medicine, Bunkyo, Tokyo 113-8421, Japan; Dynamic Brain Network Laboratory, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan. Electronic address: msinoue@nict.go.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Inoue
authors.affiliation: Department of Neurophysiology, Juntendo University School of Medicine, Bunkyo, Tokyo 113-8421, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Harada
authors.affiliation: Department of Neurophysiology, Juntendo University School of Medicine, Bunkyo, Tokyo 113-8421, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fujisawa
authors.affiliation: Dynamic Brain Network Laboratory, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Motoaki
authors.initials: M
authors.lastname: Uchimura
authors.affiliation: Dynamic Brain Network Laboratory, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan; Department of Brain Physiology, Graduate School of Medicine, Osaka University, 1-3 Suita, Osaka 565-0871, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Suita, Osaka 565-0871, Japan. Electronic address: kitazawa@fbs.osaka-u.ac.jp.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kitazawa
mesh_terms: D000222:Adaptation, Physiological; D000223:Adaptation, Psychological; D000818:Animals; D007839:Functional Laterality; D007909:Lenses; D008251:Macaca; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance; D011601:Psychophysics; D014796:Visual Perception
keywords: Allocentric coordinate; Background coordinate; Nonhuman primate; Prism adaptation