Seeberger Teri, Noto Christopher, Robinson Farrel
Department of Biological Structure, and Regional Primate Research Center, University of Washington, Seattle, WA 98195-7420, USA.
Brain Res. 2002 Nov 29;956(2):374-9. doi: 10.1016/s0006-8993(02)03577-1.
Recent experiments have characterized the dependence of saccade gain adaptation on the characteristics of the visual error following inaccurate saccades. We currently know little about the potential role of non-visual information in driving saccade adaptation. The brain could use non-visual signals from the saccade burst generator or extraocular muscle (EOM) proprioceptors to determine if the eye had rotated the appropriate distance to aim at a target. Both saccade-related burst signals and EOM proprioceptive information reach the posterior vermis of the cerebellum, a brain area strongly implicated in saccade adaptation. In the experiment described here we determined if non-visual information has a significant affect on saccade adaptation. We made monkey saccades hypometric with intra-saccade target movements and then tested the recovery of saccade gain toward normal under three conditions: (1) when the target was continuously visible, (2) when the target extinguished for 1000 ms beginning during the saccade, and (3) when the monkey remained in the dark. In the first condition both visual and non-visual indications of hypometria were available. In the second, only non-visual information was available. In the third, the monkey made no visually guided saccades and very few spontaneous saccades in the dark so neither visual nor non-visual information could drive adaptation. We found that, though it was hypometric, saccade size during recovery changed the same small amount when monkeys made saccades to extinguishing targets or remained in the dark. Saccade size changed significantly (approximately 5x) more during recovery when the monkey tracked continuously visible targets. Thus non-visual information has no influence on adaptation and visual post-saccade error is the only known driver of saccade adaptation.
最近的实验已经明确了扫视增益适应对不准确扫视后视觉误差特征的依赖性。目前，我们对非视觉信息在驱动扫视适应中的潜在作用知之甚少。大脑可以利用来自扫视爆发发生器或眼外肌（EOM）本体感受器的非视觉信号来确定眼睛是否旋转了适当的距离以瞄准目标。与扫视相关的爆发信号和EOM本体感受信息都到达小脑的后蚓部，这是一个与扫视适应密切相关的脑区。在本文所述的实验中，我们确定了非视觉信息是否对扫视适应有显著影响。我们通过在扫视过程中进行目标运动使猴子的扫视幅度变小，然后在三种条件下测试扫视增益恢复到正常的情况：（1）目标持续可见时；（2）目标在扫视开始时熄灭1000毫秒；（3）猴子处于黑暗中。在第一种条件下，视觉和非视觉的欠幅指示都可用。在第二种条件下，只有非视觉信息可用。在第三种条件下，猴子在黑暗中既没有进行视觉引导的扫视，也很少有自发扫视，因此视觉和非视觉信息都无法驱动适应。我们发现，尽管扫视幅度变小，但当猴子对熄灭的目标进行扫视或处于黑暗中时，恢复过程中的扫视大小变化量相同且很小。当猴子跟踪持续可见的目标时，恢复过程中的扫视大小变化显著更大（约5倍）。因此，非视觉信息对适应没有影响，视觉扫视后误差是已知的唯一驱动扫视适应的因素。
