Neuronal networks for control of eye movement

稳定的对象值在眼基底神经节的鲁棒表示：我们的目光往往是针对以前与奖励相关的对象。这些目标值灵活变化或保持稳定。在这里，我们提出的证据表明，猴子黑质网状部（SNr）在基底神经节代表稳定的，而不是灵活的，对象的价值观。经过一天的学习后，SNr神经元逐渐表现出对许多视觉对象的反应偏好：对高价值对象的抑制和对低价值对象的兴奋。这些神经元中有许多投射到同侧的上级丘。即使在100天后没有进一步的学习，这种神经元的偏见仍然完好无损。与神经元的偏好平行，猴子倾向于看高价值的物体。即使在测试过程中没有相关的值，也存在神经元和行为偏差。这些结果表明，SNr神经元会将目光偏向于那些在历史上一直与高价值相关的物体。 灵长类动物腹侧苍白球编码期望奖励值并调节运动动作：当期望奖励值高时，运动动作容易进行。据推测，有神经元编码预期的奖励值，以调节即将发生的行动，并可能代表动机信号。在这里，我们提出的证据表明，腹侧苍白球（VP）可能参与这一过程。我们记录了单个神经元活动的猴子VP使用眼跳任务与方向依赖性奖励偏见。根据预期奖励的数量，VP神经元增加或减少其活动，直到奖励被传递，无论是同向还是逆向眼跳。预期奖励值的变化也与眼跳表现（潜伏期和速度）的变化相关。此外，双侧蝇蕈醇诱导的VP失活消除了扫视潜伏期的奖励依赖性变化。这些数据表明，VP提供了预期的奖励值信号，用于促进或抑制运动动作。 灵长类动物前背隔区神经元对奖赏不确定性的选择性和分级编码： 自然环境不确定。情绪结果的不确定性可以引起焦虑和提高警惕，促进和信号学习的机会，调节经济选择和调节风险寻求。在这里，我们表明，灵长类动物的隔膜（ADS）的前背区域的神经元的一个子集主要致力于以高度特定的方式处理不确定性。这些神经元选择性地被视觉线索激活，这些视觉线索表明奖励的概率（例如，25%，50%和75%的奖励），而不对指示某些结果（0%和100%奖励）的线索做出反应。平均ADS不确定性反应与奖励不确定性的大小分级，并选择性地表示奖励而不是惩罚的不确定性。ADS中许多神经元编码的关于奖励不确定性的选择性和分级信息可能是调节价值和感觉运动相关区域的不确定性以调节目标导向行为的基础。 灵长类动物尾状尾中视觉反应的奖励值相关变化与视觉技能相关：针对激励结果的目标导向动作，如果重复，则成为可以自动启动的技能。我们现在报告尾状核（CDt）的尾部可能用于控制视觉技能。猴子观察许多分形物体，其中一半总是与大奖励（高价值物体）相关，另一半则与小奖励（低价值物体）相关。经过几次日常训练后，他们产生了一种凝视偏见，即使没有奖励，他们也会看高价值的物体。CDt神经元产生了反应偏差，通常对高价值的物体表现出更强的反应。相比之下，当物体的价值经常被颠倒时，它们的反应没有变化，尽管猴子表现出强烈的凝视偏见，以目标导向的方式看着高价值的物体。CDt神经元的偏性活动可能会传递到眼区，使动物能够基于稳定的奖励经验自动选择高价值的物体。

Robust representation of stable object values in the oculomotor basal ganglia: Our gaze tends to be directed to objects previously associated with rewards. Such object values change flexibly or remain stable. Here we present evidence that the monkey substantia nigra pars reticulata (SNr) in the basal ganglia represents stable, rather than flexible, object values. After across-day learning of objectreward association, SNr neurons gradually showed a response bias to surprisingly many visual objects: inhibition to high-valued objects and excitation to low-valued objects. Many of these neurons were shown to project to the ipsilateral superior colliculus. This neuronal bias remained intact even after 100 d without further learning. In parallel with the neuronal bias, the monkeys tended to look at high-valued objects. The neuronal and behavioral biases were present even if no value was associated during testing. These results suggest that SNr neurons bias the gaze toward objects that were consistently associated with high values in ones history. The primate ventral pallidum encodes expected reward value and regulates motor action: Motor actions are facilitated when expected reward value is high. It is hypothesized that there are neurons that encode expected reward values to modulate impending actions and potentially represent motivation signals. Here, we present evidence suggesting that the ventral pallidum (VP) may participate in this process. We recorded single neuronal activity in the monkey VP using a saccade task with a direction-dependent reward bias. Depending on the amount of the expected reward, VP neurons increased or decreased their activity tonically until the reward was delivered, for both ipsiversive and contraversive saccades. Changes in expected reward values were also associated with changes in saccade performance (latency and velocity). Furthermore, bilateral muscimol-induced inactivation of the VP abolished the reward-dependent changes in saccade latencies. These data suggest that the VP provides expected reward value signals that are used to facilitate or inhibit motor actions. Selective and graded coding of reward uncertainty by neurons in the primate anterodorsal septal region: Natural environments are uncertain. Uncertainty of emotional outcomes can induce anxiety and raise vigilance, promote and signal the opportunity for learning, modulate economic choice and regulate risk-seeking. Here we demonstrate that a subset of neurons in the anterodorsal region of the primate septum (ADS) are primarily devoted to processing uncertainty in a highly specific manner. Those neurons were selectively activated by visual cues indicating probabilistic delivery of reward (for example, 25%, 50% and 75% reward) and did not respond to cues indicating certain outcomes (0% and 100% reward). The average ADS uncertainty response was graded with the magnitude of reward uncertainty and selectively signaled uncertainty about rewards rather than punishments. The selective and graded information about reward uncertainty encoded by many neurons in the ADS may underlie modulation of uncertainty of value- and sensorimotor-related areas to regulate goal-directed behavior. Reward value-contingent changes of visual responses in the primate caudate tail associated with a visuomotor skill: A goal-directed action aiming at an incentive outcome, if repeated, becomes a skill that may be initiated automatically. We now report that the tail of the caudate nucleus (CDt) may serve to control a visuomotor skill. Monkeys looked at many fractal objects, half of which were always associated with a large reward (high-valued objects) and the other half with a small reward (low-valued objects). After several daily sessions, they developed a gaze bias, looking at high-valued objects even when no reward was associated. CDt neurons developed a response bias, typically showing stronger responses to high-valued objects. In contrast, their responses showed no change when object values were reversed frequently, although monkeys showed a strong gaze bias, looking at high-valued objects in a goal-directed manner. The biased activity of CDt neurons may be transmitted to the oculomotor region so that animals can choose high-valued objects automatically based on stable reward experiences.