TY - JOUR
T1 - Optokinetic and vestibular stimulation determines the spatial orientation of negative optokinetic afternystagmus in the rabbit
AU - Pettorossi, Vito Enrico
AU - Errico, Pierangelo
AU - Ferraresi, Aldo
AU - Barmack, Neal H.
PY - 1999/2/15
Y1 - 1999/2/15
N2 - Prolonged binocular optokinetic stimulation (OKS) in the rabbit induces a high-velocity negative optokinetic afternystagmus (OKAN II) that persists for several hours. We have taken advantage of this uniform nystagmus to study how changes in static head orientation in the pitch plane might influence the orientation of the nystagmus. After horizontal OKS, the rotation axis of the OKAN II remained almost constant in space as it was kept aligned with the gravity vector when the head was pitched by as much as 80°up and 35°down. Moreover, during reorientation, slow-phase eye velocity decreased according to the head pitch angle. Thereafter, we analyzed the space orientation of OKAN II after optokinetic stimulation during which the head and/or the OKS were pitched upward and downward. The rotation axis of OKAN II did not remain aligned with an earth vertical axis nor a head vertical axis, but it tended to be aligned with that of the OKS respace. The slow-phase eye velocity of OKAN II was also affected by the head pitch angle during OKS, because maximal OKAN II velocity occurred at the same head pitch angle as that during optokinetic stimulation. We suggest that OKAN II is coded in gravity-centered rather than in head-centered coordinates, but that this coordinate system may be influenced by optokinetic and vestibular stimulation. Moreover, the velocity attenuation of OKAN II seems to depend on the mismatch between the space-centered nystagmus rotation axis orientation and that of the 'remembered' head-centered optokinetic pathway activated by OKS.
AB - Prolonged binocular optokinetic stimulation (OKS) in the rabbit induces a high-velocity negative optokinetic afternystagmus (OKAN II) that persists for several hours. We have taken advantage of this uniform nystagmus to study how changes in static head orientation in the pitch plane might influence the orientation of the nystagmus. After horizontal OKS, the rotation axis of the OKAN II remained almost constant in space as it was kept aligned with the gravity vector when the head was pitched by as much as 80°up and 35°down. Moreover, during reorientation, slow-phase eye velocity decreased according to the head pitch angle. Thereafter, we analyzed the space orientation of OKAN II after optokinetic stimulation during which the head and/or the OKS were pitched upward and downward. The rotation axis of OKAN II did not remain aligned with an earth vertical axis nor a head vertical axis, but it tended to be aligned with that of the OKS respace. The slow-phase eye velocity of OKAN II was also affected by the head pitch angle during OKS, because maximal OKAN II velocity occurred at the same head pitch angle as that during optokinetic stimulation. We suggest that OKAN II is coded in gravity-centered rather than in head-centered coordinates, but that this coordinate system may be influenced by optokinetic and vestibular stimulation. Moreover, the velocity attenuation of OKAN II seems to depend on the mismatch between the space-centered nystagmus rotation axis orientation and that of the 'remembered' head-centered optokinetic pathway activated by OKS.
KW - Eye movement
KW - Head position
KW - Inertial coordinates
KW - Optokinetic afternystagmus
KW - Optokinetic stimulus
KW - Slow-phase eye velocity
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U2 - 10.1523/jneurosci.19-04-01524.1999
DO - 10.1523/jneurosci.19-04-01524.1999
M3 - Article
C2 - 9952428
AN - SCOPUS:0033557629
SN - 0270-6474
VL - 19
SP - 1524
EP - 1531
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 4
ER -