Regulation of dietary choice by the decision-making circuitry

Antonio Rangel
Nature Neuroscience 16, 1717–1724 (2013)


To advance our understanding of how the brain makes food decisions, it is essential to combine knowledge from two fields that have not yet been well integrated: the neuro-computational basis of decision-making and the homeostatic regulators of feeding. This Review integrates these two literatures from a neuro-computational perspective, with an emphasis in describing the variables computed by different neural systems and how they affect dietary choice. We highlight what is unique about feeding decisions, the mechanisms through which metabolic and endocrine factors affect the decision-making circuitry, why making healthy food choices is difficult for many people, and key processes at work in the obesity epidemic.


What's better for me? Fundamental role for lateral habenula in promoting subjective decision biases

Colin M Stopper & Stan B Floresco
Nature Neuroscience (2013) doi:10.1038/nn.3587

Lateral habenula (LHb) の活動を抑制すると、「コスト(報酬の遅延や不確実性)と利益に基づく意思決定」ができなくなる。
→ LHbは「利益とコスト計算して選択肢の価値を評価する」ことに関わっている。

The lateral habenula (LHb) is believed to convey an aversive or 'anti-reward' signal, but its contribution to reward-related action selection is unknown. We found that LHb inactivation abolished choice biases, making rats indifferent when choosing between rewards associated with different subjective costs and magnitudes, but not larger or smaller rewards of equal cost. Thus, instead of serving as an aversion center, the evolutionarily conserved LHb acts as a preference center that is integral for expressing subjective decision biases.


Distinct contributions of the amygdala and parahippocampal gyrus to suspicion in a repeated bargaining game.

Bhatt MA, Lohrenz T, Camerer CF, Montague PR.
Proc Natl Acad Sci U S A. 2012 May 29;109(22):8728-33.

Bargaining GameのfMRI研究。

Humans assess the credibility of information gained from others on a daily basis; this ongoing assessment is especially crucial for avoiding exploitation by others. We used a repeated, two-person bargaining game and a cognitive hierarchy model to test how subjects judge the information sent asymmetrically from one player to the other. The weight that they give to this information is the result of two distinct factors: their baseline suspicion given the situation and the suspicion generated by the other person's behavior. We hypothesized that human brains maintain an ongoing estimate of the credibility of the other player and sought to uncover neural correlates of this process. In the game, sellers were forced to infer the value of an object based on signals sent from a prospective buyer. We found that amygdala activity correlated with baseline suspicion, whereas activations in bilateral parahippocampus correlated with trial-by-trial uncertainty induced by the buyer's sequence of suggestions. In addition, the less credible buyers that appeared, the more sensitive parahippocampal activation was to trial-by-trial uncertainty. Although both of these neural structures have previously been implicated in trustworthiness judgments, these results suggest that they have distinct and separable roles that correspond to their theorized roles in learning and memory.


Safety Signals in the Primate Amygdala

Rotem Genud-Gabai, Oded Klavir, and Rony Paz
J. Neurosci. 2013;33 17986-17994


The ability to distinguish danger from safety is crucial for survival. On the other hand, anxiety disorders can result from failures to dissociate safe cues from those that predict dangerous outcomes. The amygdala plays a major role in learning and signaling danger, and recently, evidence accumulates that it also acquires information to signal safety. Traditionally, safety is explored by paradigms that change the value of a previously dangerous cue, such as extinction or reversal; or by paradigms showing that a safe cue can inhibit responses to another danger-predicting cue, as in conditioned-inhibition. In real-life scenarios, many cues are never paired or tested with danger and remain neutral all along. A detailed study of neural responses to unpaired conditioned-stimulus (CS−) can therefore indicate whether information on safety-by-comparison is also acquired in the amygdala. We designed a multiple-CS study, with CS− from both visual and auditory modalities. Using discriminative aversive-conditioning, we find that responses in the primate amygdala develop for CS− of the same modality and of a different modality from that of the aversive CS+. Moreover, we find that responses are comparable in proportion, sign (increase/decrease), onset, and magnitude. These results indicate that the primate amygdala actively acquires signals about safety, and strengthen the hypothesis that failure in amygdala processing can result in failure to distinguish dangerous cues from safe ones and lead to maladaptive behaviors.


Changing Social Norm Compliance with Noninvasive Brain Stimulation

C. C. Ruff, G. Ugazio, E. Fehr,
Science 25 October 2013: Vol. 342 no. 6157 pp. 482-484


All known human societies have maintained social order by enforcing compliance with social norms. The biological mechanisms underlying norm compliance are, however, hardly understood. We show that the right lateral prefrontal cortex (rLPFC) is involved in both voluntary and sanction-induced norm compliance. Both types of compliance could be changed by varying the neural excitability of this brain region with transcranial direct current stimulation, but they were affected in opposite ways, suggesting that the stimulated region plays a fundamentally different role in voluntary and sanction-based compliance. Brain stimulation had a particularly strong effect on compliance in the context of socially constituted sanctions, whereas it left beliefs about what the norm prescribes and about subjectively expected sanctions unaffected. Our findings suggest that rLPFC activity is a key biological prerequisite for an evolutionarily and socially important aspect of human behavior.


Single-Neuron Mechanisms Underlying Cost-Benefit Analysis in Frontal Cortex

Takayuki Hosokawa, Steven W. Kennerley, Jennifer Sloan, and Jonathan D. Wallis
J. Neurosci. 2013;33 17385-17397

→ これらの部位は「意思決定における価値」ではなく「状況のカテゴリー分け」に関わっているのでは?

Effective decision-making requires consideration of costs and benefits. Previous studies have implicated orbitofrontal cortex (OFC), dorsolateral prefrontal cortex (DLPFC), and anterior cingulate cortex (ACC) in cost-benefit decision-making. Yet controversy remains about whether different decision costs are encoded by different brain areas, and whether single neurons integrate costs and benefits to derive a subjective value estimate for each choice alternative. To address these issues, we trained four subjects to perform delay- and effort-based cost-benefit decisions and recorded neuronal activity in OFC, ACC, DLPFC, and the cingulate motor area (CMA). Although some neurons, mainly in ACC, did exhibit integrated value signals as if performing cost-benefit computations, they were relatively few in number. Instead, the majority of neurons in all areas encoded the decision type; that is whether the subject was required to perform a delay- or effort-based decision. OFC and DLPFC neurons tended to show the largest changes in firing rate for delay- but not effort-based decisions; whereas, the reverse was true for CMA neurons. Only ACC contained neurons modulated by both effort- and delay-based decisions. These findings challenge the idea that OFC calculates an abstract value signal to guide decision-making. Instead, our results suggest that an important function of single PFC neurons is to categorize sensory stimuli based on the consequences predicted by those stimuli.


アメリカで歯医者 Vol. 1



加入している保険は「Delta Dental PPO」。







麻酔 → 歯を削る → 根幹を掃除 → 薬を詰めて仮止めをするという感じで、一時間弱で終わりました。





Atypical Combinations and Scientific Impact

Brian Uzzi, Satyam Mukherjee, Michael Stringer, Ben Jones,
Science 25 October 2013: Vol. 342 no. 6157 pp. 468-472


Novelty is an essential feature of creative ideas, yet the building blocks of new ideas are often embodied in existing knowledge. From this perspective, balancing atypical knowledge with conventional knowledge may be critical to the link between innovativeness and impact. Our analysis of 17.9 million papers spanning all scientific fields suggests that science follows a nearly universal pattern: The highest-impact science is primarily grounded in exceptionally conventional combinations of prior work yet simultaneously features an intrusion of unusual combinations. Papers of this type were twice as likely to be highly cited works. Novel combinations of prior work are rare, yet teams are 37.7% more likely than solo authors to insert novel combinations into familiar knowledge domains.


War, space, and the evolution of Old World complex societies

Peter Turchin, Thomas E. Currie, Edward A. L. Turner, and Sergey Gavrilets
PNAS October 8, 2013 vol. 110 no. 41 16384-16389


How did human societies evolve from small groups, integrated by face-to-face cooperation, to huge anonymous societies of today, typically organized as states? Why is there so much variation in the ability of different human populations to construct viable states? Existing theories are usually formulated as verbal models and, as a result, do not yield sharply defined, quantitative predictions that could be unambiguously tested with data. Here we develop a cultural evolutionary model that predicts where and when the largest-scale complex societies arose in human history. The central premise of the model, which we test, is that costly institutions that enabled large human groups to function without splitting up evolved as a result of intense competition between societies—primarily warfare. Warfare intensity, in turn, depended on the spread of historically attested military technologies (e.g., chariots and cavalry) and on geographic factors (e.g., rugged landscape). The model was simulated within a realistic landscape of the Afroeurasian landmass and its predictions were tested against a large dataset documenting the spatiotemporal distribution of historical large-scale societies in Afroeurasia between 1,500 BCE and 1,500 CE. The model-predicted pattern of spread of large-scale societies was very similar to the observed one. Overall, the model explained 65% of variance in the data. An alternative model, omitting the effect of diffusing military technologies, explained only 16% of variance. Our results support theories that emphasize the role of institutions in state-building and suggest a possible explanation why a long history of statehood is positively correlated with political stability, institutional quality, and income per capita.


Neural Estimates of Imagined Outcomes in the Orbitofrontal Cortex Drive Behavior and Learning

Yuji K. Takahashi, Chun Yun Chang, Federica Lucantonio, Richard Z. Haney, Benjamin A. Berg, Hau-Jie Yau, Antonello Bonci, Geoffrey Schoenbaum
Neuron, Volume 80, Issue 2, 507-518, 16 October 2013

眼窩前島皮質(OFC)のニューロンは「想像した報酬(Imagined Outcomes)」をコード。

Imagination, defined as the ability to interpret reality in ways that diverge from past experience, is fundamental to adaptive behavior. This can be seen at a simple level in our capacity to predict novel outcomes in new situations. The ability to anticipate outcomes never before received can also influence learning if those imagined outcomes are not received. The orbitofrontal cortex is a key candidate for where the process of imagining likely outcomes occurs; however, its precise role in generating these estimates and applying them to learning remain open questions. Here we address these questions by showing that single-unit activity in the orbitofrontal cortex reflects novel outcome estimates. The strength of these neural correlates predicted both behavior and learning, learning that was abolished by temporally specific inhibition of orbitofrontal neurons. These results are consistent with the proposal that the orbitofrontal cortex is critical for integrating information to imagine future outcomes.


A Critical Role for the Hippocampus in the Valuation of Imagined Outcomes

Maël Lebreton, Maxime Bertoux, Claire Boutet, Stéphane Lehericy, Bruno Dubois, Philippe Fossati, Mathias Pessiglione
PLoS Biol 11(10): e1001684. doi:10.1371/journal.pbio.1001684


Many choice situations require imagining potential outcomes, a capacity that was shown to involve memory brain regions such as the hippocampus. We reasoned that the quality of hippocampus-mediated simulation might therefore condition the subjective value assigned to imagined outcomes. We developed a novel paradigm to assess the impact of hippocampus structure and function on the propensity to favor imagined outcomes in the context of intertemporal choices. The ecological condition opposed immediate options presented as pictures (hence directly observable) to delayed options presented as texts (hence requiring mental stimulation). To avoid confounding simulation process with delay discounting, we compared this ecological condition to control conditions using the same temporal labels while keeping constant the presentation mode. Behavioral data showed that participants who imagined future options with greater details rated them as more likeable. Functional MRI data confirmed that hippocampus activity could account for subjects assigning higher values to simulated options. Structural MRI data suggested that grey matter density was a significant predictor of hippocampus activation, and therefore of the propensity to favor simulated options. Conversely, patients with hippocampus atrophy due to Alzheimer's disease, but not patients with Fronto-Temporal Dementia, were less inclined to favor options that required mental simulation. We conclude that hippocampus-mediated simulation plays a critical role in providing the motivation to pursue goals that are not present to our senses.