1
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Guidali G, Bagattini C, De Matola M, Brignani D. Influence of frontal-to-parietal connectivity in pseudoneglect: A cortico-cortical paired associative stimulation study. Cortex 2023; 169:50-64. [PMID: 37862830 DOI: 10.1016/j.cortex.2023.08.012] [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: 06/09/2023] [Revised: 07/27/2023] [Accepted: 08/23/2023] [Indexed: 10/22/2023]
Abstract
Pseudoneglect is a set of visuospatial biases that entails a behavioral advantage for stimuli appearing in the left hemifield compared to the right one. Although right hemisphere dominance for visuospatial processing has been invoked to explain this phenomenon, its neurophysiological mechanisms are still debated, and the role of intra- and inter-hemispheric connectivity is yet to be defined. The present study explored the possibility of modulating pseudoneglect in healthy participants through a cortico-cortical paired associative stimulation protocol (ccPAS): a non-invasive brain stimulation protocol that manipulates the interplay between brain regions through the repeated, time-locked coupling of two transcranial magnetic stimulation (TMS) pulses. In the first experiment, healthy participants underwent a frontal-to-parietal (FP) and a parietal-to-frontal (PF) ccPAS. In the FP protocol, the first TMS pulse targeted the right frontal eye field (FEF), and the second pulse the right inferior parietal lobule (IPL), two critical areas for visuospatial and attentional processing. In the PF condition, the order of the pulses was reversed. In both protocols, the inter-stimulus interval (ISI) was 10 ms. Before and after stimulation, pseudoneglect was assessed with a landmark task and a manual line bisection task. A second experiment controlled for ccPAS timing dependency by testing FP-ccPAS with a longer ISI of 100 ms. Results showed that after administering the FP-ccPAS with the ISI of 10 ms, participants' leftward bias in the landmark task increased significantly, with no effects in the manual line bisection task. The other two protocols tested were ineffective. Our findings showed that ccPAS could be used to modulate pseudoneglect by exploiting frontal-to-parietal connectivity, possibly through increased top-down attentional control. FP-ccPAS could represent a promising tool to investigate connectivity properties within visuospatial and attentional networks in the healthy and as a potential rehabilitation protocol in patients suffering from severe visuospatial pathologies.
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Affiliation(s)
- Giacomo Guidali
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.
| | - Chiara Bagattini
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Matteo De Matola
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Debora Brignani
- Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.
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2
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Abstract
Cognitive enhancement is becoming progressively popular as a subject of scientific investigation and by the public, although possible adverse effects are not sufficiently understood. We call for cognitive enhancement to build on more specific, mechanistic theories given that a-theoretical approaches to cognitive enhancement are both a cause and a consequence of a strong, if not exclusive focus on the benefits of procedures suited to enhance human cognition. We focus on downsides of cognitive enhancement and suggest that every attempt to enhance human cognition needs to deal with two basic principles: the neuro-competition principle and the nonlinearity principle. We discuss the possibility of both principles in light of recent attempts to improve human cognition by means of transcranial direct current stimulation, a well-established brain stimulation method, and clinically relevant nootropic drugs. We propose that much stronger emphasis on mechanistic theorizing is necessary in guiding future research on both the upsides and the downsides of cognitive enhancement.
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Affiliation(s)
- Lorenza S Colzato
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden, Germany.,Department of Cognitive Psychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr University Bochum, Bochum, Germany.,Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
| | - Bernhard Hommel
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China.,Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, Leiden, Netherlands
| | - Christian Beste
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden, Germany.,Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
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3
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Sabel BA, Thut G, Haueisen J, Henrich-Noack P, Herrmann CS, Hunold A, Kammer T, Matteo B, Sergeeva EG, Waleszczyk W, Antal A. Vision modulation, plasticity and restoration using non-invasive brain stimulation – An IFCN-sponsored review. Clin Neurophysiol 2020; 131:887-911. [DOI: 10.1016/j.clinph.2020.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 12/18/2019] [Accepted: 01/02/2020] [Indexed: 12/11/2022]
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4
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Elkin-Frankston S, Rushmore RJ, Valero-Cabré A. Low frequency transcranial magnetic stimulation of right posterior parietal cortex reduces reaction time to perithreshold low spatial frequency visual stimuli. Sci Rep 2020; 10:3162. [PMID: 32081939 PMCID: PMC7035391 DOI: 10.1038/s41598-020-59662-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 01/14/2020] [Indexed: 11/26/2022] Open
Abstract
Research in humans and animal models suggests that visual responses in early visual cortical areas may be modulated by top-down influences from distant cortical areas, particularly in the frontal and parietal regions. The right posterior parietal cortex is part of a broad cortical network involved in aspects of visual search and attention, but its role in modulating activity in early visual cortical areas is less well understood. This study evaluated the influence of right posterior parietal cortex (PPC) on a direct measure of visual processing in humans. Contrast sensitivity (CS) and detection response times were recorded using a visual detection paradigm to two types of centrally-presented stimuli. Participants were tested on the detection task before, after, and 1 hour after low-frequency repetitive transcranial magnetic stimulation (rTMS) to the right PPC or to the scalp vertex. Low-frequency rTMS to the right PPC did not significantly change measures of contrast sensitivity, but increased the speed at which participants responded to visual stimuli of low spatial frequency. Response times returned to baseline 1-hour after rTMS. These data indicate that low frequency rTMS to the right PPC speeds up aspects of early visual processing, likely due to a disinhibition of the homotopic left posterior parietal cortex.
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Affiliation(s)
- Seth Elkin-Frankston
- Laboratory of Cerebral Dynamics, Plasticity and Rehabilitation, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, United States.,U.S. Army Combat Capabilities Development Command Soldier Center, Natick, MA, United States
| | - Richard J Rushmore
- Laboratory of Cerebral Dynamics, Plasticity and Rehabilitation, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, United States. .,Psychiatric Neuroimaging Laboratory, Brigham and Women's Hospital, Boston, MA, United States. .,Center for Morphometric Analysis, Massachusetts General Hospital, Boston, MA, United States.
| | - Antoni Valero-Cabré
- Laboratory of Cerebral Dynamics, Plasticity and Rehabilitation, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, United States. .,Cerebral Dynamics Plasticity and Rehabilitation Group, FRONTLAB Team ICM & CNRS UMR 7225, INSERM UMR 1127, Sorbone Universtité & LPNC CNRS UMR 5105-TREAT vision, Service de Neurologie, Fondation Ophtalmologique Adolphe de Rothschild, Paris, France. .,Cognitive Neuroscience and Information Technology Research Program, Open University of Catalonia (UOC), Barcelona, Spain.
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5
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Kantak S, Luchmee D. Contralesional motor cortex is causally engaged during more dexterous actions of the paretic hand after stroke-A Preliminary report. Neurosci Lett 2020; 720:134751. [PMID: 31931032 DOI: 10.1016/j.neulet.2020.134751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/21/2019] [Accepted: 01/08/2020] [Indexed: 12/27/2022]
Abstract
Bilateral activation in motor cortex is observed during paretic hand performance after stroke; however the functional significance of contralesional motor cortex (C-M1) activation is highly debated. Particularly, it is not known if task characteristics such as dexterity influence the causal engagement of C-M1 during paretic hand performance. Transcranial magnetic stimulation (TMS) was used to quantify motor corticospinal physiology of the CM1 projecting to the contralateral resting extensor carpi radialis brevis (ECRB) and first dorsal interosseous (FDI) while eleven participants with unilateral stroke performed unimanual tasks of differing dexterity with their paretic hand. The novel finding was that compared to rest and less dexterous task (LDT), more dexterous task (MDT) performance led to increased corticospinal excitability and decreased intracortical inhibition of the C-M1 projecting to the resting FDI, but not resting ECRB. Further, using trains of repetitive TMS during MDT and LDT, we tested the behavioral relevance of C-M1 for paretic hand performance. Online rTMS perturbation to C-M1, but not to the vertex or sham stimulation led to significantly more movement errors during MDT without consistently affecting LDT performance. The present results argue for a beneficial role of C-M1 for accurate performance during dexterous motor actions with the paretic hand after stroke.
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Affiliation(s)
- Shailesh Kantak
- Neuroplasticity and Motor Behavior Laboratory, Moss Rehabilitation Research Institute, Elkins Park, PA, United States; Department of Physical Therapy, Arcadia University, Glenside, PA, United States.
| | - Dustin Luchmee
- Neuroplasticity and Motor Behavior Laboratory, Moss Rehabilitation Research Institute, Elkins Park, PA, United States
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6
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Valero-Cabré A, Toba MN, Hilgetag CC, Rushmore RJ. Perturbation-driven paradoxical facilitation of visuo-spatial function: Revisiting the 'Sprague effect'. Cortex 2019; 122:10-39. [PMID: 30905382 DOI: 10.1016/j.cortex.2019.01.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 12/17/2018] [Accepted: 01/30/2019] [Indexed: 01/29/2023]
Abstract
The 'Sprague Effect' described in the seminal paper of James Sprague (Science 153:1544-1547, 1966a) is an unexpected paradoxical effect in which a second brain lesion reversed functional deficits induced by an earlier lesion. It was observed initially in the cat where severe and permanent contralateral visually guided attentional deficits generated by the ablation of large areas of the visual cortex were reversed by the subsequent removal of the superior colliculus (SC) opposite to the cortical lesion or by the splitting of the collicular commissure. Physiologically, this effect has been explained in several ways-most notably by the reduction of the functional inhibition of the ipsilateral SC by the contralateral SC, and the restoration of normal interactions between cortical and midbrain structures after ablation. In the present review, we aim at reappraising the 'Sprague Effect' by critically analyzing studies that have been conducted in the feline and human brain. Moreover, we assess applications of the 'Sprague Effect' in the rehabilitation of visually guided attentional impairments by using non-invasive therapeutic approaches such as transcranial magnetic stimulation (TMS) and transcranial direct-current stimulation (tDCS). We also review theoretical models of the effect that emphasize the inhibition and balancing between the two hemispheres and show implications for lesion inference approaches. Last, we critically review whether the resulting inter-hemispheric rivalry theories lead toward an efficient rehabilitation of stroke in humans. We conclude by emphasizing key challenges in the field of 'Sprague Effect' applications in order to design better therapies for brain-damaged patients.
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Affiliation(s)
- Antoni Valero-Cabré
- Cerebral Dynamics, Plasticity and Rehabilitation Group, Frontlab Team, Brain and Spine Institute, ICM, Paris, France; CNRS UMR 7225, Inserm UMR S 1127, Sorbonne Universités, UPMC Paris 06, F-75013, IHU-A-ICM, Paris, France; Laboratory for Cerebral Dynamics, Plasticity & Rehabilitation, Boston University School of Medicine, Boston, MA, USA.
| | - Monica N Toba
- Laboratory of Functional Neurosciences (EA 4559), University Hospital of Amiens and University of Picardy Jules Verne, Amiens, France
| | - Claus C Hilgetag
- Institute of Computational Neuroscience, University Medical Center Eppendorf, Hamburg University, Germany; Department of Health Sciences, Boston University, Boston, MA, USA
| | - R Jarrett Rushmore
- Laboratory for Cerebral Dynamics, Plasticity & Rehabilitation, Boston University School of Medicine, Boston, MA, USA.
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7
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Abstract
The lateralization of visuospatial attention has been well investigated and demonstrated to be primarily resulting from unbalanced interaction between interhemispheric fronto-parietal networks in previous studies. Many recent studies of top-down attention have reported the neural signatures of its effects within visual cortex and identified its causal basis. However, the relationship between top-down networks and asymmetric visuospatial attention has not been well studied. In the current study, we aimed to explore the relationship between top-down connectivity and asymmetric visuospatial ability by using repetitive transcranial magnetic stimulation (rTMS) and resting-state functional connectivity (RSFC) analyses. We used rTMS and RSFC to model the virtual lesion to assess the behavioral performances in visuospatial attention shifting and to identify the behavior-related top-down functional connectivities, respectively. Furthermore, we also investigated the top-down connectivity in neglect patients to validate the RSFC findings. RSFC analyses in healthy subjects and neglect patients consistently revealed that asymmetric visuospatial ability and visuospatial neglect were closely related to the bias of top-down functional connectivity between posterior superior parietal lobule (SPL) and V1. Our findings indicate that stronger top-down connectivity has stronger dominance on its corresponding visual field. We argue that an asymmetric top-down network may represent a possible neurophysiological substrate for the ongoing functional asymmetry of visuospatial attention, and its interhemispheric unbalanced interaction could contribute to the clinical manifestations of visuospatial neglect.
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8
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Selective perturbation of cognitive conflict in the human brain-A combined fMRI and rTMS study. Sci Rep 2016; 6:38700. [PMID: 27958301 PMCID: PMC5153836 DOI: 10.1038/srep38700] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 11/14/2016] [Indexed: 11/09/2022] Open
Abstract
We investigated if single and double conflicts are processed separately in different brain regions and if they are differentially vulnerable to TMS perturbation. Fifteen human volunteers performed a single (Flanker or Simon) conflict task or a double (Flanker and Simon) conflict task in a combined functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS) study. The fMRI approach aimed at localizing brain regions involved in interference resolution induced by single Flanker (stimulus-stimulus, S-S) and Simon (stimulus-response, S-R) conflicts as well as regions involved in the double conflict condition. The data revealed a distinct activation in the right intraparietal sulcus (IPS) for Flanker interference and in the right middle frontal gyrus (MFG) for the double interference condition. The causal functional role of these brain regions was then examined in the same volunteers by using offline TMS over right IPS and right MFG. TMS perturbation of the right IPS increased the Flanker effect, but had no effect in the Simon or double conflict condition. In contrast, perturbation of the right MFG had no effect on any of the conflict types. These findings suggest a causal role of the right IPS in the processing of the single conflict of Flanker (stimulus-stimulus) interference.
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9
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Vesia M, Niemeier M, Black SE, Staines WR. The time course for visual extinction after a 'virtual' lesion of right posterior parietal cortex. Brain Cogn 2015; 98:27-34. [PMID: 26051527 DOI: 10.1016/j.bandc.2015.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/30/2015] [Accepted: 05/19/2015] [Indexed: 11/30/2022]
Abstract
Our understanding of the attentional networks in the human brain largely relies on neuropsychological studies in patients with lesions to the posterior parietal cortex (PPC), particularly in the right hemisphere, that may cause severe disruptions of attentional functions. However, lesion studies only capture a point in time when the dysfunctions caused by the damage have triggered a chain of adaptive responses in the brain. To disentangle deficits and ensuing cortical plasticity, here we examined the time course for one's ability to detect objects in the visual periphery after an inhibitory continuous theta-burst stimulation (cTBS) protocol to the left or right PPC. Our results showed that cTBS of right PPC caused participants to be less sensitive to objects appearing on the left side as well as to objects appearing on both sides at the same time, consistent with an overall shift of attention to the right side of space. In addition, we found that participants missed more objects during bilateral presentations similar to patients with visual extinction. Critically, extinction evolved over time; that is, visual extinction for ipsilateral objects improved after 10 min whereas contralateral extinction peaked around 15-25 min after cTBS. Our findings suggest that lesions to the PPC impair competition between the two visual hemifields, resulting in contralateral extinction as a secondary response, arguably due to ensuing disruptions in interhemispheric balance.
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Affiliation(s)
- Michael Vesia
- Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; Department of Kinesiology and Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Matthias Niemeier
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, Canada.
| | - Sandra E Black
- Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - W Richard Staines
- Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; Department of Kinesiology and Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
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10
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Dombrowe I, Juravle G, Alavash M, Gießing C, Hilgetag CC. The effect of 10 Hz repetitive transcranial magnetic stimulation of posterior parietal cortex on visual attention. PLoS One 2015; 10:e0126802. [PMID: 25970438 PMCID: PMC4430548 DOI: 10.1371/journal.pone.0126802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 04/08/2015] [Indexed: 11/19/2022] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) of the posterior parietal cortex (PPC) at frequencies lower than 5 Hz transiently inhibits the stimulated area. In healthy participants, such a protocol can induce a transient attentional bias to the visual hemifield ipsilateral to the stimulated hemisphere. This bias might be due to a relatively less active stimulated hemisphere and a relatively more active unstimulated hemisphere. In a previous study, Jin and Hilgetag (2008) tried to switch the attention bias from the hemifield ipsilateral to the hemifield contralateral to the stimulated hemisphere by applying high frequency rTMS. High frequency rTMS has been shown to excite, rather than inhibit, the stimulated brain area. However, the bias to the ipsilateral hemifield was still present. The participants’ performance decreased when stimuli were presented in the hemifield contralateral to the stimulation site. In the present study we tested if this unexpected result was related to the fact that participants were passively resting during stimulation rather than performing a task. Using a fully crossed factorial design, we compared the effects of high frequency rTMS applied during a visual detection task and high frequency rTMS during passive rest on the subsequent offline performance in the same detection task. Our results were mixed. After sham stimulation, performance was better after rest than after task. After active 10 Hz rTMS, participants’ performance was overall better after task than after rest. However, this effect did not reach statistical significance. The comparison of performance after rTMS with task and performance after sham stimulation with task showed that 10 Hz stimulation significantly improved performance in the whole visual field. Thus, although we found a trend to better performance after rTMS with task than after rTMS during rest, we could not reject the hypothesis that high frequency rTMS with task and high frequency rTMS during rest equally affect performance.
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Affiliation(s)
- Isabel Dombrowe
- Department of Experimental Psychology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
| | - Georgiana Juravle
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mohsen Alavash
- Biological Psychology Lab, Department of Psychology, European Medical School, University of Oldenburg, Oldenburg, Germany
| | - Carsten Gießing
- Biological Psychology Lab, Department of Psychology, European Medical School, University of Oldenburg, Oldenburg, Germany
| | - Claus C. Hilgetag
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Health Sciences, Boston University, Boston, USA
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11
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Duecker F, Sack AT. The hybrid model of attentional control: New insights into hemispheric asymmetries inferred from TMS research. Neuropsychologia 2014; 74:21-9. [PMID: 25451041 DOI: 10.1016/j.neuropsychologia.2014.11.023] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/17/2014] [Accepted: 11/19/2014] [Indexed: 11/19/2022]
Abstract
Several competing theories on the mechanisms underlying attentional control have emerged over the years that, despite their substantial differences, all emphasize the importance of hemispheric asymmetries. Transcranial magnetic stimulation (TMS) has proven particularly successful in teasing them apart by selective perturbation of the dorsal and ventral fronto-parietal network. We here critically review the TMS literature and show that hemispheric asymmetries within the dorsal attention network differ between parietal and frontal cortex. Specifically, posterior parietal cortex seems to be characterized by a contralateral bias of each hemisphere and competition between them. In contrast, the right frontal eye field seems to be involved in shifting attention toward both hemifields, whereas left frontal eye field is only involved on shifting attention toward the contralateral hemifield. In the light of presented evidence, we propose to revise the functional-anatomical model originally proposed by Corbetta and Shulman (2011, 2002) and introduce a hybrid model of hemispheric asymmetries in attentional control.
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Affiliation(s)
- Felix Duecker
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center, Maastricht University, Maastricht, The Netherlands.
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Maastricht Brain Imaging Center, Maastricht University, Maastricht, The Netherlands
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12
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Brem AK, Fried PJ, Horvath JC, Robertson EM, Pascual-Leone A. Is neuroenhancement by noninvasive brain stimulation a net zero-sum proposition? Neuroimage 2014; 85 Pt 3:1058-68. [PMID: 23880500 PMCID: PMC4392930 DOI: 10.1016/j.neuroimage.2013.07.038] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/09/2013] [Accepted: 07/13/2013] [Indexed: 10/26/2022] Open
Abstract
In the past several years, the number of studies investigating enhancement of cognitive functions through noninvasive brain stimulation (NBS) has increased considerably. NBS techniques, such as transcranial magnetic stimulation and transcranial current stimulation, seem capable of enhancing cognitive functions in patients and in healthy humans, particularly when combined with other interventions, including pharmacologic, behavioral and cognitive therapies. The "net zero-sum model", based on the assumption that brain resources are subjected to the physical principle of conservation of energy, is one of the theoretical frameworks proposed to account for such enhancement of function and its potential cost. We argue that to guide future neuroenhancement studies, the net-zero sum concept is helpful, but only if its limits are tightly defined.
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Affiliation(s)
- Anna-Katharine Brem
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Peter J. Fried
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Laboratory of Cerebral Dynamics, Plasticity and Rehabilitation, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA
| | - Jared C. Horvath
- Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Edwin M. Robertson
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Institut Guttman de Neurorehabilitació, Universitat Autonoma, Barcelona, Spain
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13
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Hesse MD, Sparing R, Fink GR. Ameliorating spatial neglect with non-invasive brain stimulation: From pathophysiological concepts to novel treatment strategies. Neuropsychol Rehabil 2011; 21:676-702. [DOI: 10.1080/09602011.2011.573931] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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14
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de Graaf TA, Roebroeck A, Goebel R, Sack AT. Brain Network Dynamics Underlying Visuospatial Judgment: An fMRI Connectivity Study. J Cogn Neurosci 2010; 22:2012-26. [DOI: 10.1162/jocn.2009.21345] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
Previous functional imaging research has consistently indicated involvement of bilateral fronto-parietal networks during the execution of visuospatial tasks. Studies with TMS have suggested that the right hemispheric network, but not the left, is functionally relevant for visuospatial judgments. However, very little is still known about the interactions within these fronto-parietal networks underlying visuospatial processing. In the current study, we investigated task modulation of functional connectivity (instantaneous correlations of regional time courses), and task-specific effective connectivity (direction of influences), within the right fronto-parietal network activated during visuospatial judgments. Ten healthy volunteers performed a behaviorally controlled visuospatial judgment task (ANGLE) or a control task (COLOR) in an fMRI experiment. Visuospatial task-specific activations were found in posterior parietal cortex (PPC) and middle/inferior frontal gyrus (MFG). Functional connectivity within this network was task-modulated, with significantly higher connectivity between PPC and MFG during ANGLE than during COLOR. Effective connectivity analysis for directed influence revealed that visuospatial task-specific projections within this network were predominantly in a frontal-to-parietal direction. Moreover, ANGLE-specific influences from thalamic nuclei to PPC were identified. Exploratory effective connectivity analysis revealed that closely neighboring clusters, within visuospatial regions, were differentially involved in the network. These neighboring clusters had opposite effective connectivity patterns to other nodes of the fronto-parietal network. Our data thus reveal that visuospatial judgments are supported by massive fronto-parietal backprojections, thalamo-parietal influence, and multiple stages, or loops, of information flow within the visuospatial network. We speculate on possible functional contributions of the various network nodes and informational loops in a neurocognitive model.
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Affiliation(s)
- Tom A. de Graaf
- 1Maastricht University, The Netherlands
- 2Maastricht Brain Imaging Center, Maastricht, The Netherlands
| | - Alard Roebroeck
- 1Maastricht University, The Netherlands
- 2Maastricht Brain Imaging Center, Maastricht, The Netherlands
| | - Rainer Goebel
- 1Maastricht University, The Netherlands
- 2Maastricht Brain Imaging Center, Maastricht, The Netherlands
| | - Alexander T. Sack
- 1Maastricht University, The Netherlands
- 2Maastricht Brain Imaging Center, Maastricht, The Netherlands
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15
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Contributions of human parietal and frontal cortices to attentional control during conflict resolution: a 1-Hz offline rTMS study. Exp Brain Res 2010; 205:131-8. [DOI: 10.1007/s00221-010-2336-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 06/13/2010] [Indexed: 01/01/2023]
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16
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The use of transcranial magnetic stimulation in cognitive neuroscience: a new synthesis of methodological issues. Neurosci Biobehav Rev 2010; 35:516-36. [PMID: 20599555 DOI: 10.1016/j.neubiorev.2010.06.005] [Citation(s) in RCA: 221] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 06/15/2010] [Accepted: 06/17/2010] [Indexed: 10/19/2022]
Abstract
Transcranial magnetic stimulation (TMS) has become a mainstay of cognitive neuroscience, thus facing new challenges due to its widespread application on behaviorally silent areas. In this review we will summarize the main technical and methodological considerations that are necessary when using TMS in cognitive neuroscience, based on a corpus of studies and technical improvements that has become available in most recent years. Although TMS has been applied only relatively recently on a large scale to the study of higher functions, a range of protocols that elucidate how this technique can be used to investigate a variety of issues is already available, such as single pulse, paired pulse, dual-site, repetitive and theta burst TMS. Finally, we will touch on recent promising approaches that provide powerful new insights about causal interactions among brain regions (i.e., TMS with other neuroimaging techniques) and will enable researchers to enhance the functional resolution of TMS (i.e., state-dependent TMS). We will end by briefly summarizing and discussing the implications of the newest safety guidelines.
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Novel 'hunting' method using transcranial magnetic stimulation over parietal cortex disrupts visuospatial sensitivity in relation to motor thresholds. Neuropsychologia 2009; 47:3152-61. [PMID: 19651149 DOI: 10.1016/j.neuropsychologia.2009.07.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 07/19/2009] [Accepted: 07/24/2009] [Indexed: 11/23/2022]
Abstract
There is considerable inter-study and inter-individual variation in the scalp location of parietal sites where transcranial magnetic stimulation (TMS) may modulate visuospatial behaviours (e.g. see Ryan, Bonilha, & Jackson, 2006); and no clear consensus on methods for identifying such sites. Here we introduce a novel TMS "hunting paradigm" that allows rapid, reliable identification of a site over the right anterior intraparietal sulcus (IPS), where short trains (at 10 Hz for 0.5 s) of TMS disrupt performance of a visuospatial task. The task involves detection of a small peripheral gap (at 14 degrees eccentricity), on one or other (known) side of an extended (29 degrees ) horizontal line centred on fixation. Signal-detection analysis confirmed that TMS at the right IPS site reduced sensitivity (d') for gap targets in the left visual hemifield. A further experiment showed that the same right-parietal TMS increased sensitivity instead for gaps in the right hemifield. Comparing TMS across a grid of scalp locations around the identified 'hotspot' confirmed the spatial-specificity of the effective site. Assessment of the TMS intensity required to produce the phenomena found this was linearly related to individuals' resting motor TMS threshold over hand M1. Our approach provides a systematic new way to identify an effective site and intensity in individuals, at which TMS over right-parietal cortex reliably changes visuospatial sensitivity.
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