過去曾有人提出，當(dāng)動物執(zhí)行簡單的刺激-反應(yīng)任務(wù)時(shí),，在多巴胺能中腦中所觀察到的階段性活動代表著對即將到來的獎(jiǎng)賞的一種預(yù)期?，F(xiàn)在，Ann Graybiel及其同事演示了紋狀體中一種不同形式的與獎(jiǎng)賞有關(guān)的多巴胺信號作用,。采用循環(huán)伏安法,，他們發(fā)現(xiàn)穿越迷宮來獲得獎(jiǎng)賞的動物的多巴胺信號延長了。這些反應(yīng)隨動物與其目標(biāo)的接近在穩(wěn)定增加,，同時(shí)也隨獎(jiǎng)賞的距離和大小按比例變化,。這些信號可能代表著(對于獲得獎(jiǎng)賞的)驅(qū)動力，有助于我們認(rèn)識多巴胺在長時(shí)間的,、由目標(biāo)引導(dǎo)的行動中所起作用,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi:10.1038/nature12475
Prolonged dopamine signalling in striatum signals proximity and value of distant rewards
Mark W. Howe,Patrick L. Tierney,Stefan G. Sandberg, Paul E. M. Phillips & Ann M. Graybiel
Predictions about future rewarding events have a powerful influence on behaviour. The phasic spike activity of dopamine-containing neurons, and corresponding dopamine transients in the striatum, are thought to underlie these predictions, encoding positive and negative reward prediction errors. However, many behaviours are directed towards distant goals, for which transient signals may fail to provide sustained drive. Here we report an extended mode of reward-predictive dopamine signalling in the striatum that emerged as rats moved towards distant goals. These dopamine signals, which were detected with fast-scan cyclic voltammetry (FSCV), gradually increased or—in rare instances—decreased as the animals navigated mazes to reach remote rewards, rather than having phasic or steady tonic profiles. These dopamine increases (ramps) scaled flexibly with both the distance and size of the rewards. During learning, these dopamine signals showed spatial preferences for goals in different locations and readily changed in magnitude to reflect changing values of the distant rewards. Such prolonged dopamine signalling could provide sustained motivational drive, a control mechanism that may be important for normal behaviour and that can be impaired in a range of neurologic and neuropsychiatric disorders.
