Li Yuhong, Lindemann Christoph, Goddard Matthew J, Hyland Brian I
Department of Physiology, Otago School of Medical Sciences, Brain Health Research Centre, University of Otago, and the Brain Research New Zealand Centre of Research Excellence, Dunedin 9054, New Zealand.
Department of Physiology, Otago School of Medical Sciences, Brain Health Research Centre, University of Otago, and the Brain Research New Zealand Centre of Research Excellence, Dunedin 9054, New Zealand
J Neurosci. 2016 Mar 23;36(12):3567-78. doi: 10.1523/JNEUROSCI.1107-15.2016.
Midline thalamus is implicated in linking visceral and exteroceptive sensory information with behavior. However, whether neuronal activity is modulated with temporal precision by cues and actions in real time is unknown. Using single-neuron recording and a Pavlovian visual-cue/liquid-reward association task in rats, we discovered phasic responses to sensory cues, appropriately timed to modify information processing in output targets, as well as tonic modulations within and between trials that were differentially reward modulated, which may have distinct arousal functions. Many of the cue-responsive neurons also responded to repetitive licks, consistent with sensorimotor integration. Further, some lick-related neurons were activated only by the first rewarded lick and only if that lick were also part of a conditioned response sequence initiated earlier, consistent with binding action decisions to their ensuing outcome. This rich repertoire of responses provides electrophysiological evidence for midline thalamus as a site of complex information integration for reward-mediated behavior.
Disparate brain circuits are involved in sensation, movement, and reward information. These must interact in order for the relationships between cues, actions, and outcomes to be learned. We found that responses of single neurons in midline thalamus to sensory cues are increased when associated with reward. This output may amplify similar signals generated in parallel by the dopamine system. In addition, some neurons coded a three-factor decision in which the neuron fired only if there was a movement, if it was the first one after the reward becoming available, and if it was part of a sequence triggered in response to a preceding cue. These data highlight midline thalamus as an important node integrating multiple types of information for linking sensation, actions, and rewards.
中线丘脑与将内脏和外感受性感觉信息与行为联系起来有关。然而，尚不清楚神经元活动是否会被线索和动作实时精确地调节。通过在大鼠中进行单神经元记录和巴甫洛夫视觉线索/液体奖励关联任务，我们发现了对感觉线索的相位反应，其时间恰到好处，可改变输出靶点中的信息处理，以及试验内和试验间的紧张性调节，这些调节受到不同的奖励调节，可能具有不同的唤醒功能。许多对线索有反应的神经元也对重复舔舐有反应，这与感觉运动整合一致。此外，一些与舔舐相关的神经元仅在第一次获得奖励的舔舐时被激活，并且只有当该舔舐也是较早启动的条件反应序列的一部分时才被激活，这与将动作决策与其随后的结果联系起来一致。这种丰富的反应库为中线丘脑作为奖励介导行为的复杂信息整合位点提供了电生理证据。
不同的脑回路参与感觉、运动和奖励信息。为了学习线索、动作和结果之间的关系，这些回路必须相互作用。我们发现，当与奖励相关联时，中线丘脑单个神经元对感觉线索的反应会增强。这种输出可能会放大多巴胺系统并行产生的类似信号。此外，一些神经元编码了一个三因素决策，即只有当有动作、如果这是奖励可用后的第一个动作以及如果它是响应先前线索触发的序列的一部分时，神经元才会放电。这些数据突出了中线丘脑作为整合多种类型信息以连接感觉、动作和奖励的重要节点。
