【速報】OHBM2019

OHBM2019にて発表しました。

学会参加報告書

報告者氏名 杉野梨緒
発表論文タイトル Behavioral and functional connectivity analysis of Kanizsa illusory contour perception
著者 Rio Sugino, Satoru Hiwa, Keisuke Hachisuka, Fumihiko Murase, Tomoyuki Hiroyasu
主催 Organization for Human Brain Mapping
講演会名 25th Annual Meeting of the Organization for Human Brain Mapping
会場 Auditorium Parco Della Musica
開催日程 2019/06/9-2019/06/14

 

 

  1. 講演会の詳細

2019/06/9から2019/06/14にかけて,Auditorium Parco Della Musicaにて開催されました25th Annual Meeting of the Organization of Human Brain Mappingに参加いたしました.この25th Annual Meeting of the Organization of Human Brain Mappingは,Organization for Human Brain Mappingによって主催された国際会議で,ヒトの脳組織および脳機能のマッピングに関する研究に携わる様々な背景を持つ研究者を集め,これらの科学者のコミュニケーション,および教育を促進することを目的に開催されています1).

私は10~14日に参加いたしました.本研究室からは他に廣安先生,日和先生,古家,大塚,奥村,山本,吉田,風呂谷,丹が参加しました.

 

  1. 研究発表
    • 発表概要

私は11日の午後のセッション「Poster session」に参加いたしました.発表の形式はポスター発表で,発表時間は1時間となっておりました.

今回の発表は,Behavioral and functional connectivity analysis of Kanizsa illusory contour perceptionでした.以下に抄録を記載致します.

Background: Illusory contour (IC) is one of the common illusions encountered in our daily lives. The neural basis involved in IC perception has been studied so far (Ritzl Afra et al 2003), but the relationship between behavioral response and brain activity has remained unexplored. In this study, we considered IC perception speed as a behavioral measure, and assumed a functional connectivity (FC) to be correlated with it. Kanizsa figures were used to induce IC perception, and a dot localization task was used to measure reaction time (RT) to the IC. Brain activity during IC perception was measured and functional connections correlated with RT to IC were extracted by FC analysis.

Methods: Eighteen healthy adults (23.1±1.2 y/o, 4F/14M) were instructed to perform a dot localization task in an fMRI scanner (Chen Siyi et al 2018) . In the task, they judged whether the dots were inside or outside the contour, and pressed a button to answer. Fig.1 shows the experimental design. The dots were presented in a pseudo-random position with the same inside and outside probability. RT from the instance of target presentation to that of response was used as a behavioral metric reflecting the contour perception difference between the participants. The difference in average RT between IC and real contour (RC) tasks was used as an indicator of IC perception speed, and on the basis of the median value the participants were divided into FAST and SLOW groups. These two groups were compared to investigate how the difference in RT was reflected on FC network. The whole brain was parcellated into 116 regions based on the AAL atlas. A correlation coefficient matrix was calculated from region-of-interest-wise BOLD signal of each task using CONN toolbox. FC matrices for each group were compared between two tasks; and FC which was higher in the IC task than the RC task, was extracted and compared among the two groups. Furthermore, a correlation analysis was performed between FC of these connections and the difference in RTs between the two tasks.

Results: Mean values of RT differences between IC and RC tasks of FAST and SLOW groups were 131.2±28.0 ms and 218.5±69.0 ms, respectively, and there was a significant difference between the two groups (p<0.05). Fig.2a shows functional-connection differences between IC and RC tasks, which significantly differed between the two groups (p<0.05, FDR). The red line indicates the connection whose difference between IC and RC tasks is higher in the FAST group than that in the SLOW group, while the blue line shows those with a higher difference in the SLOW group. In addition, Fig.2b shows a significant correlation between the functional connection differences and average RT differences (p<0.05). The functional connections between the right supplementary motor area (SMA.R) and the orbital parts of left/right superior frontal gyri (ORBsup.L/R) were the highest among the extracted connections. SMA is the region belonging to the salient network and is related to awareness (Power Jonathan D. et al. 2011), while ORBsup is related to top-down attention (Aboitiz Francisco et al 2014). Since FC is higher in IC task than RC task, it is conceivable that these connections are related to IC perception. Furthermore, it was suggested that higher connections among these regions in the FAST group than in the SLOW group could be associated with an increase in IC perception speed.

Conclusions: In this study, FC correlated with IC perception speed was investigated using Kanizsa figures. Participants were divided into FAST and SLOW groups according to the IC perception speed, and FC was found to be higher in IC task when compared between the groups. Thus, it was shown that six functional connections in the FAST group had higher connectivity in the IC task than in the RC task. Among these connections, FC between the regions related to awareness and attention was high. These results suggest that a higher temporal synchronization is involved between these regions in IC perception.

 

  • 質疑応答

今回の講演発表では,以下のような質疑を受けました.

 

・質問内容1

正答率はどのタスクに対して算出しているのかについて質問を受けました.この質問に対して,ICタスクでの正答率を算出していると答えました.

・質問内容2

なぜ5本の結合のみが抽出されたのかについて質問を受けました.この質問に対して有意水準0.1%で無相関検定を行ったため,p値が0.001より小さい結合を抽出したためと答えました.

・質問内容3

FC解析は全脳で行われているのか,結合はいくつあるのかについて質問を受けました.この質問に対して,全脳は116領域に分割され,その全ての領域間でFCは算出されたと回答しました.

・質問内容4

RCタスクを基準として用いることについて質問を受けました.この質問に対してRCはICに対するコントロールタスクであるため,基準として用いたと回答しました.

・質問内容5

sharpnessが高い群と低い群の2つ群があるのかについて質問を受けました.この質問に対して被験者22名の中に高い人もいれば低い人もいると回答しました.

・質問内容6

考察の解釈について質問を受けました.この質問に対してSharpnessが低い人は正答率が低く,タスクを行うためによりエネルギーを使っているためFCが高くなると考えていると答えました.

・質問内容6

実験設計は事象関連デザインかについて質問を受けました.この質問に対してブロックデザインを用いていると回答しました.

・質問内容7

扁桃体が結果に含まれていることについて質問を受けました.この質問に対して視覚システムは扁桃体との構造的結合を持っており,扁桃体は情動に関わる領域であるため,情動の変化が感覚の知覚に関わるのではないかと解釈していると回答しました.

 

2.3.        感想

2回目の国際学会の参加だったため前回よりも落ち着いて発表することができた.今回は方法が比較的シンプルであったため,前回よりも正確に伝えることができたと感じている.良かった点は,学会を通して顔見知りになった方にポスターを聞きにきて欲しいと伝えたことにより,親身に発表を聞いてくれたことで,説明と質問を繰り返して研究の隅々まで伝えることができたことが挙げられる.反省点は名刺を要求されたが持っていなかったことが挙げられる.去年同様に英語を聞き取るのは苦手ではあったが,諦めずに聞き直し,自分で言い直し合っているかを確認しながら相手の発言を聞くことが出来たことができた.

 

 

  1. 聴講

今回の講演会では,下記の4件の発表を聴講しました.

 

発表タイトル       :Task-dependent functional organizations of the visual ventral stream

著者                  : Han-Gue Jo, Thilo Kellermann, Junji Ito, Sonja Grün, Ute Habel

セッション名       : Poster session

Abstruct            :

Background: The visual ventral stream is a series of hierarchical processing stages from the primary visual cortex V1 to inferior temporal cortex IT, in which neural interactions along this hierarchy enable us to recognize visual objects. However, its complex and diverse connectivity make it difficult to illustrate the functional organization, particularly when top-down cognition is involved. Depending on task-goal, the ventral stream may require different functional structure of the hierarchy to incorporate visual features of interest into object recognition [1,2]. Here we identified context-dependent functional structures of the ventral stream.

Methods: Twenty-eight participants performed three types of visual cognition task during fMRI measurement. The three task conditions that required distinct cognitive processes for object recognition were used in order to drive the visual ventral stream: searching for a target object, memorizing objects in natural scenes, or free viewing of the same natural scenes. We identified a task-dependent connectivity network of the ventral stream, utilizing a hierarchical seed-based connectivity approach that explicitly compared task-specific BOLD time-series. Seed-based analysis was performed within the ventral stream, and the first cortical processing stage V1 was subjected as a seed region. Voxel clusters that revealed significant task effect were identified as regions of interest (ROIs) and these ROIs were further subjected as seeds for subsequent seed-based analyses. On the basis of the identified ROIs, we demonstrated task-dependent connectivity to which extent the connectivity increases or decreases during each of the visual search, memory, and free viewing conditions.

Results: The hierarchical seed-based connectivity approach identified five ROIs in the visual ventral stream (Figure 1), representing a task-dependent functional network. The connections across the identified ROIs were organized into correlated and anti-correlated structures according to the context of visual cognition. Searching for a target object separated the visual area V1 and V4 from the high-order visual area PIT (the posterior part of the IT), while memorizing objects strengthened the coupling of V4 with PIT. Furthermore, task-dependent activation was found in V1 and V4, while the PIT showed deactivation.

Conclusions: The present study demonstrated context-dependent functional structures of the visual ventral stream. In particular, while the ventral stream was organized into correlated and anti-correlated structures during searching for a target object, memorizing objects manifested a correlated structure. Our results further suggest a putative boundary between V4 and PIT, which divides the visual hierarchy into two subdivisions that interact competitively or cooperatively depending on task demand. These results highlight the context-dependent nature of the ventral stream and shed light on how the visual hierarchy is selectively mediated to bias object recognition toward features of interest.

この発表は腹側皮質視覚路のコンテキスト依存機能構造を識別に関する研究でした. 3 種類の視覚認識課題(目標対象物の探索,自然シーンにおける対象物の記憶,または同じ自然シーンの自由視聴)を用いることにより,腹側皮質視覚路の機能である物体特定や物体認識の働きを見ていました.この3種類のタスクが非常に興味深かったです.またこの視覚路は神経相互作用によって視覚的対象を認識することが可能であると言われており,先日調査したばかりだったので,また新たな知見を得ることができ非常に勉強になりました.解析においては,腹側皮質視覚路の処理段階の階層において1番初めの領域であるV1をSeed領域としてSeed-based analysisを行い,有意なタスク効果を持つことがわかった領域をROIとして同定し,さらにそのROIをSeed領域としてSeed-based analysisを行うという方法でした.この解析方法は真似てみることが出来そうだったので,今後の研究にも活かしたいと思っています.

発表タイトル       :10,000 Social Brains: Charting sexual dimorphism in the UK Biobank

著者                  : Hannah Kiesow

セッション名       : Oral session: Population Neuroscience

Abstruct            : Reliance on one’s social network provides many advantages. The social brain hypothesis (Byrne & Whiten, 1988; Humphrey, 1976) argues that neocortex volume in primates co-evolved with the cognitive costs required to maintain complex social environments. Various complex social indices have structural implications in the brain. For example, larger social network size was associated with increases in gray matter volume in regions engaged in social processing in the human (Lewis, Rezaie, Brown, Roberts, & Dunbar, 2011) and nonhuman (Sallet et al., 2011) primate brain. Individual variation in social brain volumes may be expressed according to sex. Sex has been argued to be the phenotypical distinction that explains most behavioral variability in most species. The different behavioral profiles of males and females presumably rely on distinct topographical brain circuits that are anatomically or functionally dimorphic. Thus, the aim of our study was to investigate the neural manifestations of sexual dimorphism in different indices of social behavior.

この発表は10000人の分の脳構造データを用いた性差研究でした.性別はほとんどの種において,もっとも行動の多様性を説明する表現型の違いであると主張されており,男性と女性の異なる行動のプロファイルは解剖学的または機能的に異なる脳回路に依存していると考えられている.そのため社会的行動の異なる指標(社会的内輪指標,社会的アウトレット指標,社会的経済指標,社会文化的移行指標)を用いて性的二形性の神経基盤について研究がされていた.解析として社会的指標の脳容積の分布を明示的にモデル化する確率的階層モデリングを用いていた.このモデルは予想される社会人口統計学的変動を表すために年齢と性別に条件づけられており,長期可塑性効果の結果を反映している.その結果,社会的な脳の特定の領域の体積と関連していること,機能的結合ネットワークを通して違いが検出されたこと,類似した生活習慣因子の社会的指標の中で識別できる複雑な社会変数における性関連の影響が示唆されたと発表していた.私たちの研究室でもテーマとして用いられていることから性差に関する研究は身近であるものの,これほどのビッグデータに対して研究が行われていることに驚きました.しかし最近調査を行ったサンプルサイズ設計を考慮すると,サンプルサイズが大きいことのデメリットが存在するのではと感じました.普段は脳機能研究の発表を中心に聴講しているので,脳構造研究の話は非常に新鮮で興味深いと感じました.

 

 

 

発表タイトル       :Changes in pRFs during perceptual filling-in of an artificial scotoma in humans

著者                  : Joana Carvalho, Remco Renken, Frans cornelissen

セッション名       : Poster session

Abstruct            :

Background: When the information extracted from a visual scene is incomplete, the visual system attempts to predict what is missing by extrapolating from nearby information. This is filling-in. Despite its clinical and scientific relevance, the neuronal mechanisms underlying filling-in are still ill-understood. Here, we used fMRI in combination with population receptive field (pRF) mapping to determine how and where in the visual hierarchy filling-in takes place. In our experiment, we measured pRF properties during and in the absence of perceptual filling-in, while observers viewed band-pass filtered textures on which artificial scotomas could be superimposed.

Methods: Seven observers (3 females; age-range: 26–32) with normal or corrected to normal vision were scanned using a Siemens Prisma 3T scanner. Retinotopic mapping was performed using:1) spatial frequency retinotopy (SFR) – the contrast between the carrier and the bar was only perceived on the basis of spatial frequency; and 2) SFR with four artificial scotomas superimposed (SFR_scot). The scotomas were centred at each quarter field at 5 deg eccentricity, the diameter of the scotomas was 3 deg, as depicted in figure 1A. High contrast localiser scans were used to obtain the locations of the artificial Scotoma Projection Zones (aSPZ). During scanning, participants were asked to perform a fixation task: they had to press a button each time the fixation point changed from red to green. For both SFR and SFR_scot, a single run consisted of 136 functional images (204 s). The pRF estimation was performed using the mrVista (VISTASOFT) Matlab toolbox and using a custom implementation of Bayesian pRF. Data was thresholded by retaining the pRF models that explained at least 15% of the variance.

 

The interaction between the presence of scotomas and the pRFs was modelled via a gain field (GF) model, Klein et al, 2014. A GF shifts the position and size of a pRF. The GF was centred at the edge of the scotoma. Its size was estimated by minimising the error between predicted and measured position shifts (SFR_scot vs SFR). Data was split in a training (50% of the data) and test set.

Results: By comparing the pRFs estimated using SFR and SFR_scot we observed a change in position towards the scotoma, figure 1A. This effect was present throughout the six visual areas tested and it scales with visual hierarchy, figure 1B. The change in position is minimum near the edge of the scotoma and gradually increases with the distance from the edge, figure 1D. pRFs originally within the aSPZ shift radially towards the edge of the scotoma, see figure 1E. Regarding the pRF size, no significant changes were measured between SFR and SFR_scot, see figure 1C.

 

The common GF explained on average 65 % of the measured position changes. GF sizes tend to increase with visual hierarchy.

Conclusions:

 

The presence of artificial scotomas resulted in pRFs shifts towards the scotoma’s edge throughout the visual cortex. We interpret this as an evidence of perceptual filling-in. The pRF shifts of neurons within the aSPZ resulted from an extrapolation process- it enables the stimulation by spared portions of the visual field. Surprisingly, the pRFs outside the aSPZ were also attracted towards the scotoma’s edge. This process was modeled using a GF. This suggests that attention directed to the edge of the scotomas modulates the pRFs position. Furthermore our results are in agreement with previous studies which suggested that filling-in depends on local processes generated at the edge of the scotoma in early visual areas, Komatsu, H. (2006). However in contrast with previous findings, we did not find evidence for expansion of the receptive fields. We conclude that, in response to an artificial scotoma – and most likely filling-in – there is a short-term reorganization not only in the aSPZ but throughout the visual cortex.

この発表は, フィリングインと呼ばれる面の形成に関する研究であり,私が用いているKanizsa figureでもフィリングインの要素が存在するため,非常に近い研究でした。また去年のOHBMで知ったpRFを用いており視覚的階層のどの領域でどこの補間を行っているのかを検討していました.このpRFは脳領域と視野領域の関連を見ることができる解析方法であることは理解していたが,其のために必要な設計やツールは理解できないままであった.しかし,MATLAB上で使用可能なツールボックスを教えていただくことができ,実験設計として注視点の色が変化することへの反応を含んでいたことから,実験設計に必要な要素を知ることができた.非常に興味深い解析方法なので調査し自身の研究にも使うことができるのであれば挑戦してみたいと思っている.

 

発表タイトル       : Neural substrates of human facial emotion processing: evidence from an ALE meta-analysis

著者                  : shaoling peng, Xinyu Liang, Chenxi Zhao, Gaolang Gong

セッション名       : Poster session

Abstruct : Background: There are six basic emotions: anger, fear, sad, happy, disgust and surprise[1]. To date, fMRI results regarding the human facial emotion processing for each of the basic emotions are inconsistent, possibly due to differences in subject group, stimulus materials, and experimental paradigms across studies. To address this, we here applied a coordinate-based activation likelihood estimation (ALE) meta-analysis [2, 3] to investigate neural substrates underlying human emotional face processing.

Methods: Candidate articles were from 3 sources: 1) PubMed dataset; 2) studies listed by other related meta-analysis studies[4-6] and 3)references of studies retrieved by 1 and 2. Eligible studies were selected using following inclusion criteria: (1) fMRI or PET studies; (2) healthy subjects with age older than 18; (3) whole brain analysis; (4) emotional facial stimuli as experimental condition, with neutral face as control condition; (5) includes activating, rather than deactivating coordinates.

Once the eligible studies were obtained, coordinates were extracted and analyzed using the ALE meta-analytic tools, where a cluster-level FWE threshold of p < 0.05 and a cluster-forming threshold of p < 0.001 were applied as the significant level. We first located brain areas that are activated under each basic emotion by analyzing studies with neutral faces as control stimuli. Next, studies of all basic emotions are combined to investigate emotional face processing in general.

Results: 125 studies with a total of 2675 subjects were selected. The “surprise” condition was excluded, because of the very small number of eligible studies (i.e., 4).

The ALE results for each basic emotion are shown in Figure 1. All basic emotions except “disgust” showed activation in the amygdala. Both “sad” and “happy” groups have only one significant cluster in the left amygdala, while “angry” and “fear” groups activated both the left and right amygdala. In addition to activation in the amygadala, watching “angry” faces also triggered activation in the right fusiform gyrus, while “fear” face processing triggered activation in the bilateral fusiform gyrus, right occipital lobe and left insula. In contrast, “Disgust” facial processing activated bilateral middle and inferior occipital gyrus.

Comparing all emotional faces with neutral face, which putatively involves only the general emotional cognitive processing component, showed activation in the bilateral amygdala, bilateral fusiform gyrus, bilateral insula, bilateral thalamus, and bilateral middle and inferior occipital gyrus.

Conclusions: Our results show shared and distinct patterns of activation when processing human faces with different basic emotions. As expected, the amygdala is pivotal to human emotional processing. Processing human emotional faces not only recruits brain regions involved in emotion processing, but also areas that are known to be engaged in face processing, e.g., the fusiform gyrus [7].

この発表は, メタアナリシスを用いた情動の研究でした.PubMedのデータセットを用いてメタアナリシスの1つであるALEを用いて情動に関わる脳賦活領域を抽出していました.125個の研究分,計2675人分のデータを用いてhappy,sad,disgust,angry,fearの各情動について検討を行っていました.また情動そのものに関連する脳領域の特定も行なっていました.参考文献を選択する基準として,fMRIまたはPET研究であること,18歳以上の健常人であること,全脳分析であること,実験条件としての感情的顔面刺激、対照条件として中立面を用いていること,座標が有効であることと設定していた.その結果,異なる基本的な感情を持つ人間の顔を認識する処理を行うときの活性化は異なるパターンを示しており,扁桃体が人間の感情処理にとって非常に重要であることがわかったと発表していました.メタアナリシスを調査していたときに,PICOという選択基準の存在を知ったが,実際にメタアナリシスを用いた研究がどのように論文を選択しているのかについてはあまり調査できていなかったので,今回この聴講を受けて理解が深まったと思います.

参考文献

1) OHBM2018 Annual meeting,

https://www.humanbrainmapping.org/i4a/pages/index.cfm?pageID=3821

 

カテゴリー: 国際会議   パーマリンク

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