Neuronal activity in substantia nigra pars reticulata during target selection
Neuronal activity in substantia nigra pars reticulata during target selection
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DOI：
10.1523/jneurosci.22-05-01883.2002
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发表时间：
2002-03-01
影响因子：
5.3
通讯作者：
Wurtz, RH
中科院分区：
文献类型：
--
作者：
Basso, MA;Wurtz, RH
复杂的视觉场景要求从多个可能的目标中选择用于即将发生的扫视眼睛运动的目标。我们研究了是否改变刺激的数量，从该目标将被确定改变黑质网状部（SNr）的基底神经节（BG）的神经元的活动，以及如何这种变化可能有助于我们以前观察到的变化，在上级丘（SC）。一个，两个，四个或八个视觉刺激出现在随机试验中，而猴子固定在一个位于中心的点。在延迟之后，阵列中的一个刺激改变亮度，表明它是扫视目标。我们发现，SNr神经元有一个暂停的紧张性活动后，目标发病，当眼跳的目标表现出调制的活动过程中的多目标任务。由于阵列中的刺激数量从一个增加到八个，视觉刺激开始后的初始停顿减少了。预选延迟期间的活动减少，但与可能存在的目标数量无关。当其中一个刺激被确定为眼跳目标，但在眼跳之前，我们发现活动急剧下降。这种下降与猴子选择目标有关，而不是识别目标的亮度变化，因为在错误试验中，当亮度变化但没有对目标进行扫视时，活动并没有下降。首选目标地点的下降也伴随着邻近地点的较小下降。我们的研究结果表明，SNr活动的变化与目标的选择，因为它与眼跳启动，SNr可以作出实质性的，直接的贡献，在这两个时间的SC。SNr活动与目标选择的暂停与BG为所需运动的选择提供去抑制的假设一致。
Complex visual scenes require that a target for an impending saccadic eye movement be selected from a number of possible targets. We investigated whether changing the number of stimuli from which a target would be identified altered the activity of substantia nigra pars reticulata (SNr) neurons of the basal ganglia (BG) and how such changes might contribute to changes we observed previously in the superior colliculus (SC). One, two, four, or eight visual stimuli appeared on random trials while monkeys fixated a centrally located spot. After a delay, one of the stimuli in the array changed luminance, indicating that it was the saccade target. We found that SNr neurons that had a pause in tonic activity after target onset and when the saccade was made to the target showed a modulation of activity during the multitarget task. Because the number of stimuli in the array increased from one to eight, the initial pause after the onset of the visual stimulus decreased. Activity during the preselection delay was reduced but was independent of the number of possible targets present. When one of the stimuli was identified as the saccade target, but before the saccade was made, we found a sharp decline in activity. This decline was related to the monkey's selecting the target rather than the luminance change identifying the target, because on error trials, when the luminance changed but a saccade was not made to the target, the activity did not decline. The decline for the preferred target location was also accompanied by a lesser decline for adjacent locations. Our findings indicate that SNr activity changes with target selection as it does with saccade initiation and that the SNr could make substantial, direct contributions to the SC at both times. The pause in SNr activity with target selection is consistent with the hypothesis that BG provide a disinhibition for the selection of desired movements.