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Gong X, He T, Wang Q, Lu J, Fang F. Time Course of Orientation Ensemble Representation in the Human Brain. J Neurosci 2025; 45:e1688232024. [PMID: 39746825 PMCID: PMC11823330 DOI: 10.1523/jneurosci.1688-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/02/2024] [Accepted: 12/10/2024] [Indexed: 01/04/2025] Open
Abstract
Natural scenes are filled with groups of similar items. Humans employ ensemble coding to extract the summary statistical information of the environment, thereby enhancing the efficiency of information processing, something particularly useful when observing natural scenes. However, the neural mechanisms underlying the representation of ensemble information in the brain remain elusive. In particular, whether ensemble representation results from the mere summation of individual item representations or it engages other specific processes remains unclear. In this study, we utilized a set of orientation ensembles wherein none of the individual item orientations were the same as the ensemble orientation. We recorded magnetoencephalography (MEG) signals from human participants (both sexes) when they performed an ensemble orientation discrimination task. Time-resolved multivariate pattern analysis (MVPA) and the inverted encoding model (IEM) were employed to unravel the neural mechanisms of the ensemble orientation representation and track its time course. First, we achieved successful decoding of the ensemble orientation, with a high correlation between the decoding and behavioral accuracies. Second, the IEM analysis demonstrated that the representation of the ensemble orientation differed from the sum of the representations of individual item orientations, suggesting that ensemble coding could further modulate orientation representation in the brain. Moreover, using source reconstruction, we showed that the representation of ensemble orientation manifested in early visual areas. Taken together, our findings reveal the emergence of the ensemble representation in the human visual cortex and advance the understanding of how the brain captures and represents ensemble information.
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Affiliation(s)
- Xizi Gong
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, People's Republic of China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, People's Republic of China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, People's Republic of China
- Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing 100871, People's Republic of China
| | - Tao He
- Center for the Cognitive Science of Language, Beijing Language and Culture University, Beijing 100083, People's Republic of China
| | - Qian Wang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, People's Republic of China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, People's Republic of China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, People's Republic of China
- Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing 100871, People's Republic of China
| | - Junshi Lu
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, People's Republic of China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, People's Republic of China
| | - Fang Fang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, People's Republic of China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, People's Republic of China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, People's Republic of China
- Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing 100871, People's Republic of China
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Virtanen LS, Saarela TP, Olkkonen M. Ensemble percepts of colored targets among distractors are influenced by hue similarity, not categorical identity. J Vis 2024; 24:12. [PMID: 39412766 PMCID: PMC11498646 DOI: 10.1167/jov.24.11.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 08/26/2024] [Indexed: 10/25/2024] Open
Abstract
Color can be used to group similar elements, and ensemble percepts of color can be formed for such groups. In real-life settings, however, elements of similar color are often spatially interspersed among other elements and seen against a background. Forming an ensemble percept of these elements would require the segmentation of the correct color signals for integration. Can the human visual system do this? We examined whether observers can extract the ensemble mean hue from a target hue distribution among distractors and whether a color category boundary between target and distractor hues facilitates ensemble hue formation. Observers were able to selectively judge the target ensemble mean hue, but the presence of distractor hues added noise to the ensemble estimates and caused perceptual biases. The more similar the distractor hues were to the target hues, the noisier the estimates became, possibly reflecting incomplete or inaccurate segmentation of the two hue ensembles. Asymmetries between nominally equidistant distractors and substantial individual variability, however, point to additional factors beyond simple mixing of target and distractor distributions. Finally, we found no evidence for categorical facilitation in selective ensemble hue formation.
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Affiliation(s)
- Lari S Virtanen
- Department of Psychology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Toni P Saarela
- Department of Psychology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Maria Olkkonen
- Department of Psychology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Yashiro R, Sawayama M, Amano K. Decoding time-resolved neural representations of orientation ensemble perception. Front Neurosci 2024; 18:1387393. [PMID: 39148524 PMCID: PMC11325722 DOI: 10.3389/fnins.2024.1387393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 07/15/2024] [Indexed: 08/17/2024] Open
Abstract
The visual system can compute summary statistics of several visual elements at a glance. Numerous studies have shown that an ensemble of different visual features can be perceived over 50-200 ms; however, the time point at which the visual system forms an accurate ensemble representation associated with an individual's perception remains unclear. This is mainly because most previous studies have not fully addressed time-resolved neural representations that occur during ensemble perception, particularly lacking quantification of the representational strength of ensembles and their correlation with behavior. Here, we conducted orientation ensemble discrimination tasks and electroencephalogram (EEG) recordings to decode orientation representations over time while human observers discriminated an average of multiple orientations. We modeled EEG signals as a linear sum of hypothetical orientation channel responses and inverted this model to quantify the representational strength of orientation ensemble. Our analysis using this inverted encoding model revealed stronger representations of the average orientation over 400-700 ms. We also correlated the orientation representation estimated from EEG signals with the perceived average orientation reported in the ensemble discrimination task with adjustment methods. We found that the estimated orientation at approximately 600-700 ms significantly correlated with the individual differences in perceived average orientation. These results suggest that although ensembles can be quickly and roughly computed, the visual system may gradually compute an orientation ensemble over several hundred milliseconds to achieve a more accurate ensemble representation.
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Affiliation(s)
- Ryuto Yashiro
- Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Masataka Sawayama
- Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Kaoru Amano
- Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan
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Zhao Y, Zeng T, Wang T, Fang F, Pan Y, Jia J. Subcortical encoding of summary statistics in humans. Cognition 2023; 234:105384. [PMID: 36736077 DOI: 10.1016/j.cognition.2023.105384] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 02/04/2023]
Abstract
Statistical encoding compresses redundant information from multiple items into a single summary metric (e.g., mean). Such statistical representation has been suggested to be automatic, but at which stage it is extracted is unknown. Here, we examined the involvement of the subcortex in the processing of summary statistics. We presented an array of circles dichoptically or monocularly while matching the number of perceived circles after binocular fusion. Experiments 1 and 2 showed that interocularly suppressed, invisible circles were automatically involved in the summary statistical representation, but only when they were presented to the same eye as the visible circles. This same-eye effect was further observed for consciously processed circles in Experiment 3, in which the estimated mean size of the circles was biased toward the information transmitted by monocular channels. Together, we provide converging evidence that the processing of summary statistics, an assumed high-level cognitive process, is mediated by subcortical structures.
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Affiliation(s)
- Yuqing Zhao
- Department of Psychology, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China; Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou 310015, Zhejiang, China
| | - Ting Zeng
- Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou 310015, Zhejiang, China; School of Psychology, Jiangxi Normal University, Nanchang 330022, Jiangxi, China
| | - Tongyu Wang
- Department of Psychology, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China; Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou 310015, Zhejiang, China
| | - Fang Fang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100871, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Yi Pan
- Department of Psychology, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
| | - Jianrong Jia
- Department of Psychology, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China; Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou 310015, Zhejiang, China.
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Jia J, Wang T, Chen S, Ding N, Fang F. Ensemble size perception: Its neural signature and the role of global interaction over individual items. Neuropsychologia 2022; 173:108290. [PMID: 35697088 DOI: 10.1016/j.neuropsychologia.2022.108290] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 06/02/2022] [Accepted: 06/07/2022] [Indexed: 10/18/2022]
Abstract
To efficiently process complex visual scenes, the visual system often summarizes statistical information across individual items and represents them as an ensemble. However, due to the lack of techniques to disentangle the representation of the ensemble from that of the individual items constituting the ensemble, whether there exists a specialized neural mechanism for ensemble processing and how ensemble perception is computed in the brain remain unknown. To address these issues, we used a frequency-tagging EEG approach to track brain responses to periodically updated ensemble sizes. Neural responses tracking the ensemble size were detected in parieto-occipital electrodes, revealing a global and specialized neural mechanism of ensemble size perception. We then used the temporal response function to isolate neural responses to the individual sizes and their interactions. Notably, while the individual sizes and their local and global interactions were encoded in the EEG signals, only the global interaction contributed directly to the ensemble size perception. Finally, distributed attention to the global stimulus pattern enhanced the neural signature of the ensemble size, mainly by modulating the neural representation of the global interaction between all individual sizes. These findings advocate a specialized, global neural mechanism of ensemble size perception and suggest that global interaction between individual items contributes to ensemble perception.
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Affiliation(s)
- Jianrong Jia
- Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou, 311121, China; Institute of Psychological Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Tongyu Wang
- Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou, 311121, China; Institute of Psychological Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Siqi Chen
- Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou, 311121, China; Institute of Psychological Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Nai Ding
- Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Sciences, Zhejiang University, Hangzhou, 311121, China; Research Center for Advanced Artificial Intelligence Theory, Zhejiang Lab, Hangzhou, 311121, China
| | - Fang Fang
- School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100871, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China; Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing, 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
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