Neuronal networks for control of eye movement

动眼肌基底神经节中稳定物体价值的鲁棒表征：我们的目光倾向于指向先前与奖励相关的物体。这些对象值可以灵活变化或保持稳定。在这里，我们提出的证据表明，猴子基底神经节的网状黑质（SNr）代表稳定的，而不是灵活的，物体值。经过一整天的客体联想学习后，信噪比神经元逐渐对惊人多的视觉客体表现出反应偏倚：对高价值客体的抑制和对低价值客体的兴奋。许多神经元被显示投射到同侧上丘。即使在没有进一步学习的情况下，这种神经元偏差在100天后仍然完好无损。与神经元偏见平行的是，猴子倾向于看高价值的物体。即使在测试过程中没有价值相关，神经元和行为偏差也存在。这些结果表明，信噪比神经元倾向于将目光投向那些在个人历史中始终与高价值相关的物体。

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.