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Phylactou P, Shimi A, Konstantinou N. Causal evidence for the role of the sensory visual cortex in visual short-term memory maintenance. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230321. [PMID: 37090966 PMCID: PMC10113812 DOI: 10.1098/rsos.230321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 03/27/2023] [Indexed: 05/03/2023]
Abstract
The role of the sensory visual cortex during visual short-term memory (VSTM) remains controversial. This controversy is possibly due to methodological issues in previous attempts to investigate the effects of transcranial magnetic stimulation (TMS) on VSTM. The aim of this study was to use TMS, while covering previous methodological deficits. Sixty-four young adults were recruited to participate in two experiments (Experiment 1: n = 36; Experiment 2: n = 28) using a VSTM orientation change-detection task under TMS. Monocular vision was ensured using red-blue goggles combined with red-blue stimuli. Double-pulse TMS was delivered at different times (Experiment 1: 0, 200 or 1000 ms; Experiment 2: 200, 1000 ms) during a 2 s maintenance phase, on one side of the occipital hemisphere. In Experiment 2, a sham TMS condition was introduced. Decreased detection sensitivity (d') in the ipsilateral occipital hemisphere to visual hemifield, and in the real TMS (compared with sham TMS) condition indicated inhibitory TMS effects, and thus, a causal involvement of the sensory visual cortex during early (200 ms) and late (1000 ms) maintenance in VSTM. These findings are aligned with sensory recruitment, which proposes that both perceptual and memory processes rely upon the same neural substrates in the sensory visual cortex. The methods used in this study were preregistered and had received in-principle acceptance on 6 June 2022 (Stage 1 protocol can be found in: https://doi.org/10.17605/OSF.IO/EMPDT).
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Affiliation(s)
- Phivos Phylactou
- Department of Rehabilitation Sciences, Faculty of Health Sciences, Cyprus University of Technology, Limassol 3041, Cyprus
| | - Andria Shimi
- Department of Psychology, Faculty of Social Sciences and Education, University of Cyprus, CY-1678 Nicosia, Cyprus
| | - Nikos Konstantinou
- Department of Rehabilitation Sciences, Faculty of Health Sciences, Cyprus University of Technology, Limassol 3041, Cyprus
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Paradoxical facilitation alongside interhemispheric inhibition. Exp Brain Res 2021; 239:3303-3313. [PMID: 34476535 PMCID: PMC8541949 DOI: 10.1007/s00221-021-06183-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 07/20/2021] [Indexed: 11/03/2022]
Abstract
Neurophysiological experiments using transcranial magnetic stimulation (TMS) have sought to probe the function of the motor division of the corpus callosum. Primary motor cortex sends projections via the corpus callosum with a net inhibitory influence on the homologous region of the opposite hemisphere. Interhemispheric inhibition (IHI) experiments probe this inhibitory pathway. A test stimulus (TS) delivered to the motor cortex in one hemisphere elicits motor evoked potentials (MEPs) in a target muscle, while a conditioning stimulus (CS) applied to the homologous region of the opposite hemisphere modulates the effect of the TS. We predicted that large CS MEPs would be associated with increased IHI since they should be a reliable index of how effectively contralateral motor cortex was stimulated and therefore of the magnitude of interhemispheric inhibition. However, we observed a strong tendency for larger CS MEPs to be associated with reduced interhemispheric inhibition which in the extreme lead to a net effect of facilitation. This surprising effect was large, systematic, and observed in nearly all participants. We outline several hypotheses for mechanisms which may underlie this phenomenon to guide future research.
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Varone G, Hussain Z, Sheikh Z, Howard A, Boulila W, Mahmud M, Howard N, Morabito FC, Hussain A. Real-Time Artifacts Reduction during TMS-EEG Co-Registration: A Comprehensive Review on Technologies and Procedures. SENSORS 2021; 21:s21020637. [PMID: 33477526 PMCID: PMC7831109 DOI: 10.3390/s21020637] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 01/24/2023]
Abstract
Transcranial magnetic stimulation (TMS) excites neurons in the cortex, and neural activity can be simultaneously recorded using electroencephalography (EEG). However, TMS-evoked EEG potentials (TEPs) do not only reflect transcranial neural stimulation as they can be contaminated by artifacts. Over the last two decades, significant developments in EEG amplifiers, TMS-compatible technology, customized hardware and open source software have enabled researchers to develop approaches which can substantially reduce TMS-induced artifacts. In TMS-EEG experiments, various physiological and external occurrences have been identified and attempts have been made to minimize or remove them using online techniques. Despite these advances, technological issues and methodological constraints prevent straightforward recordings of early TEPs components. To the best of our knowledge, there is no review on both TMS-EEG artifacts and EEG technologies in the literature to-date. Our survey aims to provide an overview of research studies in this field over the last 40 years. We review TMS-EEG artifacts, their sources and their waveforms and present the state-of-the-art in EEG technologies and front-end characteristics. We also propose a synchronization toolbox for TMS-EEG laboratories. We then review subject preparation frameworks and online artifacts reduction maneuvers for improving data acquisition and conclude by outlining open challenges and future research directions in the field.
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Affiliation(s)
- Giuseppe Varone
- Department of Medical and Surgical Sciences, Magna Greacia University of Catanzaro, 88100 Catanzaro, Italy;
| | - Zain Hussain
- College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH16 4TJ, UK; (Z.H.); (Z.S.)
- Howard Brain Sciences Foundation, Providence, RI 02906, USA;
| | - Zakariya Sheikh
- College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH16 4TJ, UK; (Z.H.); (Z.S.)
| | - Adam Howard
- Howard Brain Sciences Foundation, Providence, RI 02906, USA;
| | - Wadii Boulila
- RIADI Laboratory, National School of Computer Sciences, University of Manouba, Manouba 2010, Tunisia;
- IS Department, College of Computer Science and Engineering, Taibah University, Medina 42353, Saudi Arabia
| | - Mufti Mahmud
- Department of Computer Science and Medical Technology Innovation Facility, Nottingham Trent University, Clifton, Nottingham NG11 8NS, UK;
| | - Newton Howard
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford OX3 9DU, UK;
| | | | - Amir Hussain
- School of Computing, Edinburgh Napier University, Edinburgh EH11 4BN, UK;
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Tran DMD, McNair NA, Harris JA, Livesey EJ. Expected TMS excites the motor system less effectively than unexpected stimulation. Neuroimage 2020; 226:117541. [PMID: 33186721 DOI: 10.1016/j.neuroimage.2020.117541] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/26/2020] [Accepted: 10/29/2020] [Indexed: 11/30/2022] Open
Abstract
The brain's response to sensory input is modulated by prediction. For example, sounds that are produced by one's own actions, or those that are strongly predicted by environmental cues, elicit an attenuated N1 component in the auditory evoked potential. It has been suggested that this form of sensory attenuation to stimulation produced by one's own actions is the reason we are unable to tickle ourselves. Here we examined whether the neural response to direct stimulation of the brain is attenuated by prediction in a similar manner. Transcranial magnetic stimulation (TMS) applied over primary motor cortex can be used to gauge the excitability of the motor system. Motor-evoked potentials (MEPs), elicited by TMS and measured in peripheral muscles, are larger when actions are being prepared and smaller when actions are voluntarily suppressed. We tested whether the amplitude of MEPs was attenuated under circumstances where the TMS pulse can be reliably predicted, even though control of the relevant motor effector was never required. Self-initiation of the TMS pulse and reliable cuing of the TMS pulse both produced attenuated MEP amplitudes, compared to those generated programmatically in an unpredictable manner. These results suggest that predictive coding may be governed by domain-general mechanisms responsible for all forms predictive learning. The findings also have important methodological implications for designing TMS experiments that control for the predictability of TMS pulses.
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Affiliation(s)
| | | | | | - Evan J Livesey
- School of Psychology, The University of Sydney, Australia
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Accessory to dissipate heat from transcranial magnetic stimulation coils. J Neurosci Methods 2019; 314:28-30. [PMID: 30659845 DOI: 10.1016/j.jneumeth.2019.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/02/2019] [Accepted: 01/15/2019] [Indexed: 11/20/2022]
Abstract
BACKGROUND Transcranial magnetic stimulation (TMS) produces magnetic pulses by passing a strong electrical current through coils of wire. Repeated stimulation accumulates heat, which places practical constraints on experimental design. New method: We designed a condensation-free pre-chilled heat sink to extend the operational duration of transcranial magnetic stimulation coils. RESULTS The application of a pre-chilled heat sink reduced the rate of heating across all tests and extended the duration of stimulation before coil overheating, particularly in conditions where heat management was problematic. Comparison with existing method: Applying an external heat sink had the practical effect of extending the operational time of TMS coils by 5.8-19.3 minutes compared to standard operating procedures. CONCLUSION Applying an external heat sink increases the quantity of data that can be collected within a single experimental session.
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Habibollahi Saatlou F, Rogasch NC, McNair NA, Biabani M, Pillen SD, Marshall TR, Bergmann TO. MAGIC: An open-source MATLAB toolbox for external control of transcranial magnetic stimulation devices. Brain Stimul 2018; 11:1189-1191. [DOI: 10.1016/j.brs.2018.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 12/29/2022] Open
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Souza VH, Matsuda RH, Peres ASC, Amorim PHJ, Moraes TF, Silva JVL, Baffa O. Development and characterization of the InVesalius Navigator software for navigated transcranial magnetic stimulation. J Neurosci Methods 2018; 309:109-120. [PMID: 30149047 DOI: 10.1016/j.jneumeth.2018.08.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 08/07/2018] [Accepted: 08/20/2018] [Indexed: 11/25/2022]
Abstract
BACKGROUND Neuronavigation provides visual guidance of an instrument during procedures of neurological interventions, and has been shown to be a valuable tool for accurately positioning transcranial magnetic stimulation (TMS) coils relative to an individual's anatomy. Despite the importance of neuronavigation, its high cost, low portability, and low availability of magnetic resonance imaging facilities limit its insertion in research and clinical environments. NEW METHOD We have developed and validated the InVesalius Navigator as the first free, open-source software for image-guided navigated TMS, compatible with multiple tracking devices. A point-based, co-registration algorithm and a guiding interface were designed for tracking any instrument (e.g. TMS coils) relative to an individual's anatomy. RESULTS Localization, precision errors, and repeatability were measured for two tracking devices during navigation in a phantom and in a simulated TMS study. Errors were measured in two commercial navigated TMS systems for comparison. Localization error was about 1.5 mm, and repeatability was about 1 mm for translation and 1° for rotation angles, both within limits established in the literature. COMPARISON WITH EXISTING METHODS Existing TMS neuronavigation software programs are not compatible with multiple tracking devices, and do not provide an easy to implement platform for custom tools. Moreover, commercial alternatives are expensive with limited portability. CONCLUSIONS InVesalius Navigator might contribute to improving spatial accuracy and the reliability of techniques for brain interventions by means of an intuitive graphical interface. Furthermore, the software can be easily integrated into existing neuroimaging tools, and customized for novel applications such as multi-locus and/or controllable-pulse TMS.
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Affiliation(s)
- Victor Hugo Souza
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil.
| | - Renan H Matsuda
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil.
| | - André S C Peres
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil; Instituto Internacional de Neurociência de Natal Edmond e Lily Safra, Instituto Santos Dumont, Rodovia RN 160 Km 03, 3003, 59280-000, Macaíba, RN, Brazil.
| | - Paulo Henrique J Amorim
- Núcleo de Tecnologias Tridimensionais, Centro de Tecnologia da Informação Renato Archer, Rodovia Dom Pedro I Km 143, 13069-901, Campinas, SP, Brazil.
| | - Thiago F Moraes
- Núcleo de Tecnologias Tridimensionais, Centro de Tecnologia da Informação Renato Archer, Rodovia Dom Pedro I Km 143, 13069-901, Campinas, SP, Brazil.
| | - Jorge Vicente L Silva
- Núcleo de Tecnologias Tridimensionais, Centro de Tecnologia da Informação Renato Archer, Rodovia Dom Pedro I Km 143, 13069-901, Campinas, SP, Brazil.
| | - Oswaldo Baffa
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil.
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