Activity of pursuit-related neurons in medial superior temporal area (MST) during static roll-tilt.
Recent studies have shown that rhesus macaques can perceive visual motion direction in earth-centered coordinates as accurately as humans. We tested whether coordinate frames representing smooth pursuit and/or visual motion signals in medial superior temporal area (MST) are earth centered to better understand its role in coordinating smooth pursuit. In 2 Japanese macaques, we compared preferred directions (re monkeys' head-trunk axis) of pursuit and/or visual motion responses of MSTd neurons while upright and during static whole-body roll-tilt. In the majority (41/51 = 80%) of neurons tested, preferred directions of pursuit and/or visual motion responses were not significantly different while upright and during 40° static roll-tilt. Preferred directions of the remaining 20% of neurons (n = 10) were shifted beyond the range expected from ocular counter-rolling; the maximum shift was 14°, and the mean shift was 12°. These shifts, however, were still less than half of the expected shift if MST signals are coded in the earth-centered coordinates. Virtually, all tested neurons (44/46 = 96%) failed to exhibit a significant difference between resting discharge rate while upright and during static roll-tilt while fixating a stationary spot. These results suggest that smooth pursuit and/or visual motion signals of MST neurons are not coded in the earth-centered coordinates; our results favor the head- and/or trunk-centered coordinates.
Fujiwara
Keishi
K
Department of Physiology, Hokkaido University School of Medicine, Sapporo 060-8638, Japan. kikuro@med.hokudai.ac.jp
Akao
Teppei
T
Kurkin
Sergei
S
Fukushima
Kikuro
K
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D008251:Macaca; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009483:Neuropsychological Tests / Q000592:standards; D010775:Photic Stimulation / Q000379:methods; D011698:Pursuit, Smooth / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology*; D018667:Tilt-Table Test / Q000379:methods