2018/02/23 春野

Shared neural coding for social hierarchy and reward value in primate amygdala

Jérôme Munuera, Mattia Rigotti & C. Daniel Salzman
Nat Neurosci. 2018 Mar;21(3):415-423. doi: 10.1038/s41593-018-0082-8.

Abstract

The social brain hypothesis posits that dedicated neural systems process social information. In support of this, neurophysiological data have shown that some brain regions are specialized for representing faces. It remains unknown, however, whether distinct anatomical substrates also represent more complex social variables, such as the hierarchical rank of individuals within a social group. Here we show that the primate amygdala encodes the hierarchical rank of individuals in the same neuronal ensembles that encode the rewards associated with nonsocial stimuli. By contrast, orbitofrontal and anterior cingulate cortices lack strong representations of hierarchical rank while still representing reward values. These results challenge the conventional view that dedicated neural systems process social information. Instead, information about hierarchical rank—which contributes to the assessment of the social value of individuals within a group—is linked in the amygdala to representations of rewards associated with nonsocial stimuli.

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2018/2/14 木村

Multiple systems for emotion-based action selection in the amygdala

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Htr2a-Expressing Cells in the Central Amygdala Control the Hierarchy between Innate and Learned Fear

Tomoko Isosaka, Tomohiko Matsuo, Takashi Yamaguchi, Kazuo Funabiki, Shigetada Nakanishi, Reiko Kobayakawa, Ko Kobayakawa
Cell. 2015 Nov 19;163(5):1153-1164. doi: 10.1016/j.cell.2015.10.047.

Highlights

• A hierarchical relationship exists between innate- and learned-fear responses 
• Innate but not learned-fear stimuli suppress the activity of CeA Htr2a+ cells 
• CeA Htr2a+ cell inhibition up/downregulates innate/learned freezing, respectively 
• CeA Htr2a+ cells act as a hierarchy generator prioritizing innate over learned fear

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A competitive inhibitory circuit for selection of active and passive fear responses

Jonathan P. Fadok, Sabine Krabbe, Milica Markovic, Julien Courtin, Chun Xu, Lema Massi, Paolo Botta, Kristine Bylund, Christian Müller, Aleksandar Kovacevic, Philip Tovote & Andreas Lüthi
Nature. 2017 Feb 2;542(7639):96-100. doi: 10.1038/nature21047.

Abstract

When faced with threat, the survival of an organism is contingent upon the selection of appropriate active or passive behavioural responses. Freezing is an evolutionarily conserved passive fear response that has been used extensively to study the neuronal mechanisms of fear and fear conditioning in rodents. However, rodents also exhibit active responses such as flight under natural conditions. The central amygdala (CEA) is a forebrain structure vital for the acquisition and expression of conditioned fear responses, and the role of specific neuronal sub-populations of the CEA in freezing behaviour is well-established. Whether the CEA is also involved in flight behaviour, and how neuronal circuits for active and passive fear behaviour interact within the CEA, are not yet understood. Here, using in vivo optogenetics and extracellular recordings of identified cell types in a behavioural model in which mice switch between conditioned freezing and flight, we show that active and passive fear responses are mediated by distinct and mutually inhibitory CEA neurons. Cells expressing corticotropin-releasing factor (CRF+) mediate conditioned flight, and activation of somatostatin-positive (SOM+) neurons initiates passive freezing behaviour. Moreover, we find that the balance between conditioned flight and freezing behaviour is regulated by means of local inhibitory connections between CRF+ and SOM+ neurons, indicating that the selection of appropriate behavioural responses to threat is based on competitive interactions between two defined populations of inhibitory neurons, a circuit motif allowing for rapid and flexible action selection.

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2018/2/14 榎本

Amygdala inputs to prefrontal cortex guide behavior amid conflicting cues of reward and punishment

Burgos-Robles A, Kimchi EY, IzadmehrEM, PorzenheimMJ, Ramos-GuaspWA, NiehEH, Felix-Ortiz AC, NamburiP, LepplaCA, PresbreyKN, AnandalingamKK, Pagan-Rivera PA, AnahtarM, BeyelerA, TyeKM.
Nat Neurosci. 2017 Jun;20(6):824-835. doi: 10.1038/nn.4553.

報酬＋嫌悪条件下において扁桃体BLAと内側前頭前野PL（前辺縁皮質）領域との相互神経連絡がもつ行動情報。砂糖水も貰えるけれどもフットショックもくるアンビバレントな課題。ラットで電気生理実験と相互相関解析、オプトジェネティクスやDREADDなんかも用いて、BLA→PL投射がショックを予告する刺激に対してフリージングを引き起こすに必要十分であることを示しています。機械学習で（いちおう）行動予測もできる。

PLはIL（下辺縁皮質）とも相互連絡があり、どちらも腹側海馬から入力を受けて扁桃体や側坐核に投射しています。かねてより恐怖学習・消去、薬物依存などのパラダイムで役割の違いなどについて調べられており、ここ数年でその神経回路メカニズムが明らかになりつつあります。PL・ILはヒトやサルにおける帯状皮質の一部ですので、そのへんの対応関係にも注意してまとめてみたいと思います。つづく。

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参考文献

Prefrontal control of fear: more than just extinction.
Sotres-Bayon F, Quirk GJ.
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Long-range connectivity defines behavioral specificity of amygdala neurons.
Senn V, Wolff SB, Herry C, Grenier F, Ehrlich I, Gründemann J, Fadok JP, Müller C, Letzkus JJ, Lüthi A.
Neuron. 2014 Jan 22;81(2):428-37. doi: 10.1016/j.neuron.2013.11.006.

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Functional Connectivity between Amygdala and Cingulate Cortex for Adaptive Aversive Learning

Oded Klavir, Rotem Genud-Gabai, Rony Paz
Neuron. 2013 Dec 4;80(5):1290-300. doi: 10.1016/j.neuron.2013.09.035.

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Selective inhibitory control of pyramidal neuron ensembles and cortical subnetworks by chandelier cells.
Lu J, Tucciarone J, Padilla-Coreano N, He M, Gordon JA, Huang ZJ.
Nat Neurosci. 2017 Oct;20(10):1377-1383. doi: 10.1038/nn.4624.

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Combined Social and Spatial Coding in a Descending Projection from the Prefrontal Cortex.
Murugan M, Jang HJ, Park M, Miller EM, Cox J, Taliaferro JP, Parker NF, Bhave V, Hur H, Liang Y, Nectow AR, Pillow JW, Witten IB.
Cell. 2017 Dec 14;171(7):1663-1677.e16. doi: 10.1016/j.cell.2017.11.002.

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