A neural correlate of motivational conflict in the superior colliculus of the macaque
A neural correlate of motivational conflict in the superior colliculus of the macaque
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DOI：
10.1152/jn.90275.2008
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发表时间：
2008-09-01
影响因子：
2.5
通讯作者：
Hikosaka, Okihide
中科院分区：
文献类型：
--
作者：
Isoda, Masaki;Hikosaka, Okihide
行为既受外部指令的控制，也受内部动机的控制，但每种动机要求的行动可能不同。这种冲突的一个常见后果是决策和随后的马达反应的延迟。然而，动机冲突和相关反应延迟背后的神经机制尚不清楚。为了回答这个问题，我们记录了猕猴在执行视觉引导的、不对称奖励的扫视任务时，上丘(SC)中的单个神经元的活动。两个相对位置之一处的外围光点被照亮以指示扫视目标。在给定的一组试验中，一个职位与大奖励有关，而另一个职位与小奖励相关。高额奖励的职位在不同街区轮换。行为分析表明，小额奖励试验在指示跳跃到一个位置和内部动机但无效的跳跃到相反位置之间造成了冲突。我们发现，在与其运动场相反的小奖赏目标出现后，SC中的运动神经元在时间上表现出爆发性活动。这一瞬时活动预测了即将到来的扫视的响应延迟量。我们的数据表明，动机冲突激活了两个丘脑的运动神经元，从而通过丘间抑制相互作用延迟了眼跳的启动。
Behavior is controlled by both external instructions and internal motives, but the actions demanded by each may be different. A common consequence of such a conflict is a delay in decision making and subsequent motor responses. It is unknown, however, what neural mechanisms underlie motivational conflict and associated response delay. To answer this question, we recorded single-neuron activity in the superior colliculus (SC) as macaque monkeys performed a visually guided, asymmetrically rewarded saccade task. A peripheral spot of light at one of two opposing positions was illuminated to indicate a saccade target. In a given block of trials, one position was associated with a big reward and the other with a small reward. The big-reward position was alternated across blocks. Behavioral analyses revealed that small-reward trials created a conflict between the instructed saccade to one position and the internally motivated, yet invalid saccade to the opposite position. We found that movement neurons in the SC temporally exhibited bursting activity after the appearance of the small-reward target opposite their movement field. This transient activity predicted the amount of response delay for upcoming saccades. Our data suggest that motivational conflict activates movement neurons in both colliculi, thereby delaying saccade initiation through intercollicular inhibitory interactions.