Effects of attention on MT and MST neuronal activity during pursuit initiation
Effects of attention on MT and MST neuronal activity during pursuit initiation
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DOI：
10.1152/jn.2000.83.2.777
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发表时间：
2000-02-01
影响因子：
2.5
通讯作者：
Wurtz, RH
中科院分区：
文献类型：
--
作者：
Recanzone, GH;Wurtz, RH
猴子纹外区MT（中颞）和MST（内侧上级颞）的神经元的反应，以及扫视和追求眼球运动的初始指标，已经：以前被证明是更好地预测向量平均或赢家通吃模型，这取决于刺激条件。为了研究注意对神经元活动的潜在影响，我们测量了在相同刺激条件下，当两个移动刺激之一是追踪眼球运动的目标时，单个MT和MST神经元的反应。我们发现，当两个刺激移动通过神经元的感受野（RF）和刺激运动至少450毫秒到达RF的中心之前启动时，神经元之间的注意力调制最大。这些条件与赢者通吃模型更好地预测眼球运动和潜在神经元活动的条件相同。这种调节几乎总是活性的增加，在MT和MST中的频率大致相同。在类似于41%的MT神经元和27%的MST神经元中观察到>50%的调节。对所有运动方向的响应都进行了调制，以便在有人值守和无人值守的条件下的方向调谐曲线相似。背景活动与目标选择的变化很小，不太可能解释所观察到的注意力调节。与此相反，当刺激在运动开始后150 ms到达RF中心时，注意力神经元反应几乎没有变化，这也是向量平均模型更好地预测初始眼球运动和神经元活动的条件。这些结果与注意力的竞争模型是一致的，在该模型中，自上而下的注意力作用于由自下而上的外周刺激输入激活的两个竞争神经元群体之一的活动。他们认为，在注意力作用于一个种群之前，种群之间需要有一个最小的分离，类似于在追求初始化中产生赢家通吃的行为模式所需的分离。目前的实验还表明，这种自上而下的注意力效应需要几百毫秒的时间。
The responses of neurons in monkey extrastriate areas MT (middle temporal) and MST (medial superior temporal), and the initial metrics of saccadic and pursuit eye movements, have: previously been shown to be better predicted by vector averaging or winner-take-all models depending on the stimulus conditions. To investigate the potential influences of attention on the neuronal activity, we measured the responses of single MT and MST neurons under identical stimulus conditions when one of two moving stimuli was the target for a pursuit eye movement. We found the greatest attentional modulation across neurons when two stimuli moved through the receptive field (RF) of the neuron and the stimulus motion was initiated at least 450 ms before reaching the center of the RF. These conditions were the same as those in which a winner-take-all model better predicted both the eye movements and the underlying neuronal activity. The modulation was almost always an increase of activity, and it was about equally frequent in MT and MST. A modulation of >50% was observed in similar to 41% of MT neurons and 27% of MST neurons. Responses to all directions of motion were modulated so that the direction tuning curves in the attended and unattended conditions were similar. Changes in the background activity with target selection were small and unlikely to account for the observed attentional modulation. In contrast, there was little change in the neuronal response with attention when the stimulus reached the RF center 150 ms after motion onset, which was also the condition in which the vector average model better predicted the initial eye movements and the activity of the neurons. These results are consistent with a competition model of attention in which top-down attention acts on the activity of one of two competing populations of neurons activated by the bottom-up input from peripheral stimuli. They suggest that there is-a minimal separation of the populations necessary before attention can act on one population, similar to that required to produce a winner-take-all mode of behavior in pursuit initiation. The present experiments also suggest that it takes several hundred milliseconds to develop this top-down attention effect.