【助成 40 - 10】

ウェブゲームと計算論的モデリングを通して、人の汎化及び弁別能力を測定し、統合失調症との関係を評価する研究者 東京大学ニューロインテリジェンス国際研究機構 講師

Ｃａｉ Ｍｉｎｇｂｏ〔研究の概要〕この研究では、強化学習における一般化と識別プロセスを測定できる新しい実験パラダイムを開発しました。私たちは、3 歳から 50 歳以上までの広範な年齢層の人々が課題を実行した際の行動を説明するための計算モデルを開発することで、これらの二つのプロセスがどのように発展し、それに対する年齢の影響を見つけました。また、観察された変化の基になるさまざまな認知プロセスの変化するパラメーターを特定しました。さらに、この課題の変種をオンラインで大規模な参加者グループに実施することで、これら二つのプロセスのバランスと統合失調症に関連する症状との潜在的な関連性を見つけました。
〔研究経過および成果〕

causedSchizophrenia (統合失調症) is a mental disordermisattributingthat creates a huge burden to the society.

people to have a disorganized view of the world,

Although with intensive research, its cause

developing into delusion (妄想). However, thisremains unclear. The major medicines to treat

hypothesis has not been tested. Importantly, toschizophrenia target a type of receptors for the

eventually transform biological findings into

neurotransmitter dopamine, named D2 receptors

the understanding of schizophrenia, behavioral(ドーパミン D2 受容体). Recently, myexperiments on human participants have to becolleagues found that this receptor is criticalconducted to confirm that people who havefor animals to learn to discriminate thetendency to develop schizophrenia indeed over-difference between similar situations ingeneralize

their predictability of future outcome (Iino,situations. Towards this goal, my lab has

et al., Nature 2020). In other words, when

designed a web-based game to measure the degree

there is deficit in D2 receptors, animals

by which people can generalize and discriminate

over-generalize (過度の汎化) what

have

when they learn to gain rewards.

inDevelopmental

different situation fromdiscrimination

learned.
aArguably,

similarbut

theyover-generalizing

andcausepeople

orover-generalization
causesmay

eventually

under-discriminatechangeofandleaddifferent

generalizationandWe have previously collected data of 1007 participants

past experiences can lead to wrong
prediction,

bywith ages starting from 3 years old to higher than 50

toyears old, playing the game we developed. In this game,misattribute the surprising outcome to the wrong
cause. It is possible that frequent confusion

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participants need to learn which of the 18 different

variables underlie the observed performance change inobjects lead to more reward and which lead to more

the graph above.

punishment, and to choose only those leading toFurthermore, we have examined the relationshipreward.

between generalization/discrimination in our task and

The expected amounts of rewardorthe degree of severity ofpsychotic symptoms from agroupofparticipants

recruited online. Contrary
to our original hypothesis,
wepunishment by choosing each stimulus is organized ina hierarchical way according to the semantic

found

apositivecorrelation

betweenperformanceofdiscrimination of the severity of psychotic symptoms(r=0.31, p=0.004, N=89), indicating that people withcategories (as in the figure above).
We quantified generalization by the difference in thefrequencies of choosing stimuli of the same values but
belong to different categories, and discrimination by
the difference in the frequencies of choosing stimuli inthe same categories but with higher or lower values.
We found that performance of generalization increases
with age and peaks at 30~34 years old and declines
afterwards, while the discrimination peaks at 14~15
years old and remains stable afterwards.

By modeling the behavior in more details, we foundthat age-related change of multiple learning-related

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higher risk of schizophrenia may rely less on priorknowledge of semantical categories when learning
values of stimuli.
〔発表論文〕We are in the process of completing the manuscripts
summarizing the findings and will submit the papers
soon.