2013/02/25 榎本

Dopamine encoding of pavlovian incentive stimuli diminishes with extended training.
Clark JJ, Collins AL, Sanford CA, Phillips PE.
J Neurosci. 2013 Feb 20;33(8):3526-32.

　ラット、ドパミン、ボルタメトリー。古典的条件付け課題でCS→US連合学習。オーバートレーニングでドパミンのCS応答はぐんぐん小さくなるのだけれど、学習しているのはイベントの時間間隔なんかも含めたコンテクストで、じっさいCSを早めに出したりすれば、ドパミンはたくさんでる。

　いぜんのNature論文にあったSign-trackingラットだけ使用（Goal-trackingなやつらは除いてる）。あと薬物注入したり。

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おまけ

Genetic origins of social networks in rhesus macaques.
Brent LJ, Heilbronner SR, Horvath JE, Gonzalez-Martinez J, Ruiz-Lambides A, Robinson AG, Skene JH, Platt ML.
Sci Rep. 2013;3:1042. doi: 10.1038/srep01042.

2013/02/25 野々村

Differential effects of amygdala, orbital prefrontal cortex, and prelimbic cortex lesions on goal-directed behavior in rhesus macaques.
Rhodes SE, Murray EA.
J Neurosci. 2013 Feb 20;33(8):3380-9.

We assessed the involvement of the orbital prefrontal cortex (PFo), the prelimbic region of the medial prefrontal cortex (PL), and the amygdala in goal-directed behavior. Rhesus monkeys were trained on a task in which two different instrumental responses were linked to two different outcomes. One response, called “tap,” required the monkeys to repeatedly touch a colored square on a video monitor to produce one kind of food reward. The other response, called “hold,” required persistent contact of an identical stimulus, and it produced a different kind of food reward. After training, we assessed the effects of sensory-specific reinforcer devaluation as a way to probe each monkey's use of goal-directed behavior. In this procedure, monkeys were allowed to consume one of the two foods to satiety and were then tested for tap/hold preference under extinction. Unoperated control monkeys showed a reduction in the response associated with obtaining the devalued food, called the “devaluation effect,” a hallmark of goal-directed behavior. Monkeys with bilateral lesions of PFo or the amygdala exhibited significantly reduced devaluation effects. Results from monkeys with PL lesions were equivocal. We conclude that both PFo and the amygdala play a significant role in goal-directed behavior in monkeys. Notably, the findings for PFo challenge the idea that orbital and medial prefrontal regions are exclusively dedicated to object- and action-based processes, respectively.

2013/02/12 春野

Neural correlates of reinforcement learning and social preferences in competitive bidding.
van den Bos W, Talwar A, McClure SM.
J Neurosci. 2013 Jan 30;33(5):2137-46.

In competitive social environments, people often deviate from what rational choice theory prescribes, resulting in losses or suboptimal monetary gains. We investigate how competition affects learning and decision-making in a common value auction task. During the experiment, groups of five human participants were simultaneously scanned using MRI while playing the auction task. We first demonstrate that bidding is well characterized by reinforcement learning with biased reward representations dependent on social preferences. Indicative of reinforcement learning, we found that estimated trial-by-trial prediction errors correlated with activity in the striatum and ventromedial prefrontal cortex. Additionally, we found that individual differences in social preferences were related to activity in the temporal-parietal junction and anterior insula. Connectivity analyses suggest that monetary and social value signals are integrated in the ventromedial prefrontal cortex and striatum. Based on these results, we argue for a novel mechanistic account for the integration of reinforcement history and social preferences in competitive decision-making.

2013/02/12 田中

Social network modulation of reward-related signals.
Fareri DS, Niznikiewicz MA, Lee VK, Delgado MR.
J Neurosci. 2012 Jun 27;32(26):9045-52.

The potential role of the striatum in antisocial behavior and psychopathy.
Glenn AL, Yang Y.
Biol Psychiatry. 2012 Nov 15;72(10):817-22.

セミナーでは以下の論文を紹介します。
同じ報酬でも、誰と共に得るかで、嬉しさの程度が変わるという、報酬に対する主観のmodulationに関わる論文と、共感能力が低いとされるpsychopathyに分類されるヒトの線条体に関するreviewをかいつまんで紹介させて頂きます。
よろしくお願いします。

2013/02/04 鮫島

Concurrent activation of striatal direct and indirect pathways during action initiation.
Cui G, Jun SB, Jin X, Pham MD, Vogel SS, Lovinger DM, Costa RM.
Nature. 2013 Jan 23

Rui Costaのところから出たdirect/indirect を記録し分けた論文を紹介します。

2013/02/04 渡邊言也

The emergence and representation of knowledge about social and nonsocial hierarchies.

Kumaran D, Melo HL, Duzel E.

Neuron. 2012 Nov 8;76(3):653-66.

社会的ヒエラルキーに関するfMRIを用いた研究です。

扁桃体が社会的ヒエラルキーの構造を学習する課題特異的に関与しているということと、

社会的ランクの情報を使う課題を行うと、そのランクの順位情報が扁桃体で表現されているというお話です。