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Pan Y, Frisson S, Federmeier KD, Jensen O. Early parafoveal semantic integration in natural reading. eLife 2024; 12:RP91327. [PMID: 38968325 PMCID: PMC11226228 DOI: 10.7554/elife.91327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2024] Open
Abstract
Humans can read and comprehend text rapidly, implying that readers might process multiple words per fixation. However, the extent to which parafoveal words are previewed and integrated into the evolving sentence context remains disputed. We investigated parafoveal processing during natural reading by recording brain activity and eye movements using MEG and an eye tracker while participants silently read one-line sentences. The sentences contained an unpredictable target word that was either congruent or incongruent with the sentence context. To measure parafoveal processing, we flickered the target words at 60 Hz and measured the resulting brain responses (i.e. Rapid Invisible Frequency Tagging, RIFT) during fixations on the pre-target words. Our results revealed a significantly weaker tagging response for target words that were incongruent with the previous context compared to congruent ones, even within 100ms of fixating the word immediately preceding the target. This reduction in the RIFT response was also found to be predictive of individual reading speed. We conclude that semantic information is not only extracted from the parafovea but can also be integrated with the previous context before the word is fixated. This early and extensive parafoveal processing supports the rapid word processing required for natural reading. Our study suggests that theoretical frameworks of natural reading should incorporate the concept of deep parafoveal processing.
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Affiliation(s)
- Yali Pan
- Centre for Human Brain Health, School of Psychology, University of BirminghamBirminghamUnited Kingdom
| | - Steven Frisson
- Centre for Human Brain Health, School of Psychology, University of BirminghamBirminghamUnited Kingdom
| | - Kara D Federmeier
- Department of Psychology, Program in Neuroscience, and the Beckman Institute for Advanced Science and Technology, University of IllinoisChampaignUnited States
| | - Ole Jensen
- Centre for Human Brain Health, School of Psychology, University of BirminghamBirminghamUnited Kingdom
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2
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Neri B, Callara AL, Vanello N, Menicucci D, Zaccaro A, Piarulli A, Laurino M, Norbu N, Kechok J, Sherab N, Gemignani A. Report from a Tibetan Monastery: EEG neural correlates of concentrative and analytical meditation. Front Psychol 2024; 15:1348317. [PMID: 38756494 PMCID: PMC11098278 DOI: 10.3389/fpsyg.2024.1348317] [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: 12/08/2023] [Accepted: 04/16/2024] [Indexed: 05/18/2024] Open
Abstract
The positive effects of meditation on human wellbeing are indisputable, ranging from emotion regulation improvement to stress reduction and present-moment awareness enhancement. Changes in brain activity regulate and support these phenomena. However, the heterogeneity of meditation practices and their cultural background, as well as their poor categorization limit the generalization of results to all types of meditation. Here, we took advantage of a collaboration with the very singular and precious community of the Monks and Geshes of the Tibetan University of Sera-Jey in India to study the neural correlates of the two main types of meditation recognized in Tibetan Buddhism, namely concentrative and analytical meditation. Twenty-three meditators with different levels of expertise underwent to an ecological (i.e., within the monastery) EEG acquisition consisting of an analytical and/or concentrative meditation session at "their best," and with the only constraint of performing a 5-min-long baseline at the beginning of the session. Time-varying power-spectral-density estimates of each session were compared against the baseline (i.e., within session) and between conditions (i.e., analytical vs. concentrative). Our results showed that concentrative meditation elicited more numerous and marked changes in the EEG power compared to analytical meditation, and mainly in the form of an increase in the theta, alpha and beta frequency ranges. Moreover, the full immersion in the Monastery life allowed to share the results and discuss their interpretation with the best scholars of the Monastic University, ensuring the identification of the most expert meditators, as well as to highlight better the differences between the different types of meditation practiced by each of them.
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Affiliation(s)
- Bruno Neri
- Dipartimento di Ingegneria dell’Informazione, University of Pisa, Pisa, Italy
| | - Alejandro Luis Callara
- Dipartimento di Ingegneria dell’Informazione, University of Pisa, Pisa, Italy
- Research Center “E. Piaggio”, University of Pisa, Pisa, Italy
| | - Nicola Vanello
- Dipartimento di Ingegneria dell’Informazione, University of Pisa, Pisa, Italy
- Research Center “E. Piaggio”, University of Pisa, Pisa, Italy
| | - Danilo Menicucci
- Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Andrea Zaccaro
- Department of Neuroscience, Imaging and Clinical Sciences, “G. d’Annunzio” University of Chieti-Pescara, Chieti, Italy
| | - Andrea Piarulli
- Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | | | - Ngawang Norbu
- Sera Jey Monastic University for Advanced Buddhist Studies & Practice, Bylakuppe, Mysore, India
| | - Jampa Kechok
- Sera Jey Monastic University for Advanced Buddhist Studies & Practice, Bylakuppe, Mysore, India
| | - Ngawang Sherab
- Sera Jey Monastic University for Advanced Buddhist Studies & Practice, Bylakuppe, Mysore, India
| | - Angelo Gemignani
- Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
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3
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Kim H, Won K, Ahn M, Jun SC. Comparison of recognition methods for an asynchronous (un-cued) BCI system: an investigation with 40-class SSVEP dataset. Biomed Eng Lett 2024; 14:617-630. [PMID: 38645586 PMCID: PMC11026332 DOI: 10.1007/s13534-024-00357-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 04/23/2024] Open
Abstract
Steady-state visual evoked potential (SSVEP)-based brain-computer Interface (BCI) has demonstrated the potential to manage multi-command targets to achieve high-speed communication. Recent studies on multi-class SSVEP-based BCI have focused on synchronous systems, which rely on predefined time and task indicators; thus, these systems that use passive approaches may be less suitable for practical applications. Asynchronous systems recognize the user's intention (whether or not the user is willing to use systems) from brain activity; then, after recognizing the user's willingness, they begin to operate by switching swiftly for real-time control. Consequently, various methodologies have been proposed to capture the user's intention. However, in-depth investigation of recognition methods in asynchronous BCI system is lacking. Thus, in this work, three recognition methods (power spectral density analysis, canonical correlation analysis (CCA), and support vector machine (SVM)) used widely in asynchronous SSVEP BCI systems were explored to compare their performance. Further, we categorized asynchronous systems into two approaches (1-stage and 2-stage) based upon the recognition process's design, and compared their performance. To do so, a 40-class SSVEP dataset collected from 40 subjects was introduced. Finally, we found that the CCA-based method in the 2-stage approach demonstrated statistically significantly higher performance with a sensitivity of 97.62 ± 02.06%, specificity of 76.50 ± 23.50%, and accuracy of 75.59 ± 10.09%. Thus, it is expected that the 2-stage approach together with CCA-based recognition and FB-CCA classification have good potential to be implemented in practical asynchronous SSVEP BCI systems.
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Affiliation(s)
- Heegyu Kim
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Bukgu, Gwangju, 61005 Korea
| | - Kyungho Won
- Hybrid Team, Inria, Univ Rennes, IRISA, CNRS, F35000 Rennes, France
| | - Minkyu Ahn
- School of Computer Science and Electrical Engineering, Handong Global University, Bukgu, Pohang, 37554 Korea
| | - Sung Chan Jun
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Bukgu, Gwangju, 61005 Korea
- School of Artificial Intelligence, Gwangju Institute of Science and Technology, Bukgu, Gwangju, 61005 Korea
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4
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Otero M, Prieur-Coloma Y, El-Deredy W, Weinstein A. A High-Resolution LED Stimulator for Steady-State Visual Stimulation: Customizable, Affordable, and Open Source. SENSORS (BASEL, SWITZERLAND) 2024; 24:678. [PMID: 38276370 PMCID: PMC10819381 DOI: 10.3390/s24020678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024]
Abstract
Visually evoked steady-state potentials (SSVEPs) are neural responses elicited by visual stimuli oscillating at specific frequencies. In this study, we introduce a novel LED stimulator system explicitly designed for steady-state visual stimulation, offering precise control over visual stimulus parameters, including frequency resolution, luminance, and the ability to control the phase at the end of the stimulation. The LED stimulator provides a personalized, modular, and affordable option for experimental setups. Based on the Teensy 3.2 board, the stimulator utilizes direct digital synthesis and pulse width modulation techniques to control the LEDs. We validated its performance through four experiments: the first two measured LED light intensities directly, while the last two assessed the stimulator's impact on EEG recordings. The results demonstrate that the stimulator can deliver a stimulus suitable for generating SSVEPs with the desired frequency and phase resolution. As an open source resource, we provide comprehensive documentation, including all necessary codes and electrical diagrams, which facilitates the system's replication and adaptation for specific experimental requirements, enhancing its potential for widespread use in the field of neuroscience setups.
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Affiliation(s)
- Mónica Otero
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago de Chile 8420000, Chile;
- Centro BASAL Ciencia & Vida, Universidad San Sebastián, Santiago de Chile 8580000, Chile
| | - Yunier Prieur-Coloma
- Brain Dynamics Laboratory, Universidad de Valparaíso, Valparaíso 2340000, Chile; (Y.P.-C.); (W.E.-D.)
- Escuela de Ingeniería Civil Biomédica, Facultad de Ingeniería, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Wael El-Deredy
- Brain Dynamics Laboratory, Universidad de Valparaíso, Valparaíso 2340000, Chile; (Y.P.-C.); (W.E.-D.)
- Escuela de Ingeniería Civil Biomédica, Facultad de Ingeniería, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Advanced Center for Electrical and Electronic Engineering, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
| | - Alejandro Weinstein
- Escuela de Ingeniería Civil Biomédica, Facultad de Ingeniería, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Advanced Center for Electrical and Electronic Engineering, Universidad Técnica Federico Santa María, Valparaíso 2340000, Chile
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Cabrera Castillos K, Ladouce S, Darmet L, Dehais F. Burst c-VEP Based BCI: Optimizing stimulus design for enhanced classification with minimal calibration data and improved user experience. Neuroimage 2023; 284:120446. [PMID: 37949256 DOI: 10.1016/j.neuroimage.2023.120446] [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: 08/18/2023] [Revised: 10/31/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023] Open
Abstract
The utilization of aperiodic flickering visual stimuli under the form of code-modulated Visual Evoked Potentials (c-VEP) represents a pivotal advancement in the field of reactive Brain-Computer Interface (rBCI). A major advantage of the c-VEP approach is that the training of the model is independent of the number and complexity of targets, which helps reduce calibration time. Nevertheless, the existing designs of c-VEP stimuli can be further improved in terms of visual user experience but also to achieve a higher signal-to-noise ratio, while shortening the selection time and calibration process. In this study, we introduce an innovative variant of code-VEP, referred to as "Burst c-VEP". This original approach involves the presentation of short bursts of aperiodic visual flashes at a deliberately slow rate, typically ranging from two to four flashes per second. The rationale behind this design is to leverage the sensitivity of the primary visual cortex to transient changes in low-level stimuli features to reliably elicit distinctive series of visual evoked potentials. In comparison to other types of faster-paced code sequences, burst c-VEP exhibit favorable properties to achieve high bitwise decoding performance using convolutional neural networks (CNN), which yields potential to attain faster selection time with the need for less calibration data. Furthermore, our investigation focuses on reducing the perceptual saliency of c-VEP through the attenuation of visual stimuli contrast and intensity to significantly improve users' visual comfort. The proposed solutions were tested through an offline 4-classes c-VEP protocol involving 12 participants. Following a factorial design, participants were instructed to focus on c-VEP targets whose pattern (burst and maximum-length sequences) and amplitude (100% or 40% amplitude depth modulations) were manipulated across experimental conditions. Firstly, the full amplitude burst c-VEP sequences exhibited higher accuracy, ranging from 90.5% (with 17.6s of calibration data) to 95.6% (with 52.8s of calibration data), compared to its m-sequence counterpart (71.4% to 85.0%). The mean selection time for both types of codes (1.5 s) compared favorably to reports from previous studies. Secondly, our findings revealed that lowering the intensity of the stimuli only slightly decreased the accuracy of the burst code sequences to 94.2% while leading to substantial improvements in terms of user experience. Taken together, these results demonstrate the high potential of the proposed burst codes to advance reactive BCI both in terms of performance and usability. The collected dataset, along with the proposed CNN architecture implementation, are shared through open-access repositories.
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Affiliation(s)
- Kalou Cabrera Castillos
- Human Factors and Neuroergonomics, Institut Supérieur de l'Aéronautique et de l'Espace, 10 Av. Edouard Belin, Toulouse, 31400, France.
| | - Simon Ladouce
- Human Factors and Neuroergonomics, Institut Supérieur de l'Aéronautique et de l'Espace, 10 Av. Edouard Belin, Toulouse, 31400, France
| | - Ludovic Darmet
- Human Factors and Neuroergonomics, Institut Supérieur de l'Aéronautique et de l'Espace, 10 Av. Edouard Belin, Toulouse, 31400, France
| | - Frédéric Dehais
- Human Factors and Neuroergonomics, Institut Supérieur de l'Aéronautique et de l'Espace, 10 Av. Edouard Belin, Toulouse, 31400, France; Biomedical Engineering, Drexel University, Philadelphia, 19104, PA, United States
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6
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Callara AL, Fontanelli L, Belcari I, Rho G, Greco A, Zelič Ž, Sebastiani L, Santarcangelo EL. Modulation of the heartbeat evoked cortical potential by hypnotizability and hypnosis. Psychophysiology 2023; 60:e14309. [PMID: 37070749 DOI: 10.1111/psyp.14309] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/07/2023] [Accepted: 03/22/2023] [Indexed: 04/19/2023]
Abstract
Hypnotizability is a psychophysiological trait measured by scales and associated with several differences, including interoceptive accuracy and the morpho-functional characteristics of interoception-related brain regions. The aim of the study was to assess whether the amplitude of the heartbeat evoked cortical potential (HEP), a correlate of interoceptive accuracy, differs in participants with low (lows) and high (highs) hypnotizability scores (assessed by the Stanford Hypnotic Susceptibility Scale, Form A) before and after the induction of hypnosis. ECG and EEG were monitored in 16 highs and 15 lows during an experimental session, including open eyes baseline (B), closed eyes relaxation (R), hypnotic induction (IND), neutral hypnosis (NH), and post session baseline (Post). No significant difference was observed between groups and conditions in autonomic variables. The HEP amplitude was lower in highs than in lows at the right parietal site, likely due to hypnotizability related differences in the functional connection between the right insula and parietal cortex. It increased in highs and decreased in lows across the session, possibly due to the highs' preeminently internally directed attention and to the lows' possible disengagement from the task. Since interoception is involved in several cognitive-emotional functions, its hypnotizability related differences may contribute to the variability of experience and behavior in daily life.
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Affiliation(s)
- Alejandro Luis Callara
- Department of Information Engineering, University of Pisa, Pisa, Italy
- Research Center "E. Piaggio", University of Pisa, Pisa, Italy
| | - Lorenzo Fontanelli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Iacopo Belcari
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Gianluca Rho
- Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Alberto Greco
- Department of Information Engineering, University of Pisa, Pisa, Italy
- Research Center "E. Piaggio", University of Pisa, Pisa, Italy
| | - Žan Zelič
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Laura Sebastiani
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Enrica L Santarcangelo
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
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Tanaka Y, Ito Y, Terasawa Y, Umeda S. Modulation of heartbeat-evoked potential and cardiac cycle effect by auditory stimuli. Biol Psychol 2023; 182:108637. [PMID: 37490801 DOI: 10.1016/j.biopsycho.2023.108637] [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: 08/22/2022] [Revised: 06/29/2023] [Accepted: 07/11/2023] [Indexed: 07/27/2023]
Abstract
Interoception has been proposed as a factor that influences various psychological processes (Khalsa et al., 2018). Afferent signals from the cardiovascular system vary across cardiac cycle phases. Heartbeat-evoked potentials (HEP) and event-related potentials (ERP) were measured to examine whether interoceptive signals differed between cardiac cycle phases. Simultaneously, participants performed an auditory oddball task in which the timing of the presenting stimulus was synchronized with the heartbeat. Pure tones were presented at 10 ms (late diastole condition), 200 ms (systole condition), or 500 ms after the R wave (diastole condition). Greater HEP amplitudes were observed when the tone was presented during diastole than during systole or late diastole. ERP showed the same tendency: a greater amplitude was observed during diastole than systole or late diastole. These results suggest that the processing of interoception reflected by HEP and exteroception reflected by ERP share attentional resources when both stimuli coincide. When the tone was presented during systole, attention to the internal state decreased compared with when the tone was presented during diastole, and attention was distributed to both exteroception and interoception. Our study suggests that HEP may be considered an indication of a relative amount of resources to process the interoception.
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Affiliation(s)
- Yuto Tanaka
- Global Research Institute, Keio University, 2-15-45 Mita, Minato-ku, Tokyo 108-8345, Japan.
| | - Yuichi Ito
- Department of Psychological Sciences, Kwansei Gakuin University, 1-155 Uegahara Ichibancho, Nishinomiya, Hyogo 662-8501, Japan
| | - Yuri Terasawa
- Department of Psychology, Keio University, 2-15-45 Mita, Minato-ku, Tokyo 108-8345, Japan
| | - Satoshi Umeda
- Department of Psychology, Keio University, 2-15-45 Mita, Minato-ku, Tokyo 108-8345, Japan
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8
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Li R, Xu M, You J, Zhou X, Meng J, Xiao X, Jung TP, Ming D. Modulation of rhythmic visual stimulation on left-right attentional asymmetry. Front Neurosci 2023; 17:1156890. [PMID: 37250403 PMCID: PMC10213214 DOI: 10.3389/fnins.2023.1156890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
The rhythmic visual stimulation (RVS)-induced oscillatory brain responses, namely steady-state visual evoked potentials (SSVEPs), have been widely used as a biomarker in studies of neural processing based on the assumption that they would not affect cognition. However, recent studies have suggested that the generation of SSVEPs might be attributed to neural entrainment and thus could impact brain functions. But their neural and behavioral effects are yet to be explored. No study has reported the SSVEP influence on functional cerebral asymmetry (FCA). We propose a novel lateralized visual discrimination paradigm to test the SSVEP effects on visuospatial selective attention by FCA analyses. Thirty-eight participants covertly shifted their attention to a target triangle appearing in either the lower-left or -right visual field (LVF or RVF), and judged its orientation. Meanwhile, participants were exposed to a series of task-independent RVSs at different frequencies, including 0 (no RVS), 10, 15, and 40-Hz. As a result, it showed that target discrimination accuracy and reaction time (RT) varied significantly across RVS frequency. Furthermore, attentional asymmetries differed for the 40-Hz condition relative to the 10-Hz condition as indexed by enhanced RT bias to the right visual field, and larger Pd EEG component for attentional suppression. Our results demonstrated that RVSs had frequency-specific effects on left-right attentional asymmetries in both behavior and neural activities. These findings provided new insights into the functional role of SSVEP on FCAs.
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Affiliation(s)
- Rong Li
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
| | - Minpeng Xu
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Jia You
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
| | - Xiaoyu Zhou
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
| | - Jiayuan Meng
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Xiaolin Xiao
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Tzyy-Ping Jung
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
- Swartz Center for Computational Neuroscience, University of California San Diego, San Diego, CA, United States
| | - Dong Ming
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
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Gjorgieva E, Geib BR, Cabeza R, Woldorff MG. The influence of imagery vividness and internally-directed attention on the neural mechanisms underlying the encoding of visual mental images into episodic memory. Cereb Cortex 2023; 33:3207-3220. [PMID: 35945684 DOI: 10.1093/cercor/bhac270] [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: 12/02/2021] [Revised: 06/10/2022] [Accepted: 06/12/2022] [Indexed: 11/13/2022] Open
Abstract
Attention can be directed externally toward sensory information or internally toward self-generated information. Using electroencephalography (EEG), we investigated the attentional processes underlying the formation and encoding of self-generated mental images into episodic memory. Participants viewed flickering words referring to common objects and were tasked with forming visual mental images of the objects and rating their vividness. Subsequent memory for the presented object words was assessed using an old-new recognition task. Internally-directed attention during image generation was indexed as a reduction in steady-state visual evoked potentials (SSVEPs), oscillatory EEG responses at the frequency of a flickering stimulus. The results yielded 3 main findings. First, SSVEP power driven by the flickering word stimuli decreased as subjects directed attention internally to form the corresponding mental image. Second, SSVEP power returned to pre-imagery baseline more slowly for low- than high-vividness later remembered items, suggesting that longer internally-directed attention is required to generate subsequently remembered low-vividness images. Finally, the event-related-potential difference due to memory was more sustained for subsequently remembered low- versus high-vividness items, suggesting that additional conceptual processing may have been needed to remember the low-vividness visual images. Taken together, the results clarify the neural mechanisms supporting the encoding of self-generated information.
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Affiliation(s)
- Eva Gjorgieva
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, United States
- Center for Cognitive Neuroscience, Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States
| | - Benjamin R Geib
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, United States
- Center for Cognitive Neuroscience, Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States
| | - Roberto Cabeza
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, United States
- Center for Cognitive Neuroscience, Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States
| | - Marty G Woldorff
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, United States
- Department of Psychiatry, Duke University, Durham, NC 27708, United States
- Center for Cognitive Neuroscience, Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States
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