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Dalrymple AN, Fisher LE, Weber DJ. A preliminary study exploring the effects of transcutaneous spinal cord stimulation on spinal excitability and phantom limb pain in people with a transtibial amputation. J Neural Eng 2024; 21:046058. [PMID: 39094627 DOI: 10.1088/1741-2552/ad6a8d] [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: 10/21/2023] [Accepted: 08/02/2024] [Indexed: 08/04/2024]
Abstract
Objective. Phantom limb pain (PLP) is debilitating and affects over 70% of people with lower-limb amputation. Other neuropathic pain conditions correspond with increased spinal excitability, which can be measured using reflexes andF-waves. Spinal cord neuromodulation can be used to reduce neuropathic pain in a variety of conditions and may affect spinal excitability, but has not been extensively used for treating PLP. Here, we propose using a non-invasive neuromodulation method, transcutaneous spinal cord stimulation (tSCS), to reduce PLP and modulate spinal excitability after transtibial amputation.Approach. We recruited three participants, two males (5- and 9-years post-amputation, traumatic and alcohol-induced neuropathy) and one female (3 months post-amputation, diabetic neuropathy) for this 5 d study. We measured pain using the McGill Pain Questionnaire (MPQ), visual analog scale (VAS), and pain pressure threshold (PPT) test. We measured spinal reflex and motoneuron excitability using posterior root-muscle (PRM) reflexes andF-waves, respectively. We delivered tSCS for 30 min d-1for 5 d.Main Results. After 5 d of tSCS, MPQ scores decreased by clinically-meaningful amounts for all participants from 34.0 ± 7.0-18.3 ± 6.8; however, there were no clinically-significant decreases in VAS scores. Two participants had increased PPTs across the residual limb (Day 1: 5.4 ± 1.6 lbf; Day 5: 11.4 ± 1.0 lbf).F-waves had normal latencies but small amplitudes. PRM reflexes had high thresholds (59.5 ± 6.1μC) and low amplitudes, suggesting that in PLP, the spinal cord is hypoexcitable. After 5 d of tSCS, reflex thresholds decreased significantly (38.6 ± 12.2μC;p< 0.001).Significance. These preliminary results in this non-placebo-controlled study suggest that, overall, limb amputation and PLP may be associated with reduced spinal excitability and tSCS can increase spinal excitability and reduce PLP.
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Affiliation(s)
- Ashley N Dalrymple
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
- NeuroMechatronics Lab, Carnegie Mellon University, Pittsburgh, PA, United States of America
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America
- Department of Physical Medicine & Rehabilitation, University of Utah, Salt Lake City, UT, United States of America
- NERVES Lab, University of Utah, Salt Lake City, UT, United States of America
| | - Lee E Fisher
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- Center for Neural Basis of Cognition, Pittsburgh, PA, United States of America
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Douglas J Weber
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
- NeuroMechatronics Lab, Carnegie Mellon University, Pittsburgh, PA, United States of America
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, United States of America
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2
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Tolmacheva A, Agranovich O, Blagovechtchenski E. The importance of brain mapping for rehabilitation in birth nonprogressive neuromuscular diseases. FRONTIERS IN NEUROIMAGING 2024; 3:1359491. [PMID: 39077762 PMCID: PMC11284525 DOI: 10.3389/fnimg.2024.1359491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 05/30/2024] [Indexed: 07/31/2024]
Abstract
While motor mapping has been extensively studied in acquired motor conditions, a lack has been observed in terms of research on neurological disorders present since birth, with damage to the spinal cord and peripheral nerves (hence, defined in this study as nonprogressive neuromuscular diseases). Despite an injury at the level below the brain, the subsequent changes in the motor system involve cortical reorganization. In the scientific community, the need for a comprehensive approach targeting the brain is increasingly recognized for greater motor recovery in these patients. Transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) are the most utilized techniques for motor mapping. The knowledge obtained through motor mapping may be used to develop effective individual neuromodulation therapy that helps in functional motor recovery. This brief review compares the results of the brain mapping of a few existing studies in individuals with nonprogressive motor disorders of nonbrain origin present at birth to the brain mapping of individuals with similar acquired motor conditions. The review reveals some particular features in terms of central adaptation in individuals with birth conditions compared to their acquired counterparts, such as the nonsomatotopic presentation of involved muscles in the sensorimotor cortex and nonadjacent cortical areas. This topic is undoubtedly intriguing, justifying further research in the field. This review also discusses the benefits these patients can obtain from neuromodulation therapy addressed to the central nervous system and the importance of individual neurophysiological assessment in designing rehabilitation therapy for children with birth motor disorders.
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Affiliation(s)
- Aleksandra Tolmacheva
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
| | - Olga Agranovich
- G.I. Turner Scientific Research Institute for Children's Orthopaedics, Ministry of Health of Russia, Saint Petersburg, Russia
| | - Evgeny Blagovechtchenski
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
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3
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Ambron E, Garcea FE, Cason S, Medina J, Detre JA, Coslett HB. The influence of hand posture on tactile processing: Evidence from a 7T functional magnetic resonance imaging study. Cortex 2024; 173:138-149. [PMID: 38394974 DOI: 10.1016/j.cortex.2023.12.019] [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: 05/26/2023] [Revised: 09/19/2023] [Accepted: 12/13/2023] [Indexed: 02/25/2024]
Abstract
Although behavioral evidence has shown that postural changes influence the ability to localize or detect tactile stimuli, little is known regarding the brain areas that modulate these effects. This 7T functional magnetic resonance imaging (fMRI) study explores the effects of touch of the hand as a function of hand location (right or left side of the body) and hand configuration (open or closed). We predicted that changes in hand configuration would be represented in contralateral primary somatosensory cortex (S1) and the anterior intraparietal area (aIPS), whereas change in position of the hand would be associated with alterations in activation in the superior parietal lobule. Multivoxel pattern analysis and a region of interest approach partially supported our predictions. Decoding accuracy for hand location was above chance level in superior parietal lobule (SPL) and in the anterior intraparietal (aIPS) area; above chance classification of hand configuration was observed in SPL and S1. This evidence confirmed the role of the parietal cortex in postural effects on touch and the possible role of S1 in coding the body form representation of the hand.
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Affiliation(s)
- Elisabetta Ambron
- Laboratory for Cognition and Neural Stimulation, Perelman School of Medicine at the University of Pennsylvania, USA; Department Neurology, University of Pennsylvania, USA.
| | - Frank E Garcea
- Department of Neurosurgery, University of Rochester Medical Center, NY, USA; Department of Neuroscience, University of Rochester Medical Center, NY, USA; Del Monte Institute for Neuroscience, University of Rochester Medical Center, NY, USA.
| | - Samuel Cason
- Laboratory for Cognition and Neural Stimulation, Perelman School of Medicine at the University of Pennsylvania, USA; Department Neurology, University of Pennsylvania, USA
| | - Jared Medina
- Department of Psychological and Brain Sciences, University of Delaware, USA
| | - John A Detre
- Department Neurology, University of Pennsylvania, USA
| | - H Branch Coslett
- Laboratory for Cognition and Neural Stimulation, Perelman School of Medicine at the University of Pennsylvania, USA; Department Neurology, University of Pennsylvania, USA
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4
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Saccone EJ, Tian M, Bedny M. Developing cortex is functionally pluripotent: Evidence from blindness. Dev Cogn Neurosci 2024; 66:101360. [PMID: 38394708 PMCID: PMC10899073 DOI: 10.1016/j.dcn.2024.101360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 01/25/2024] [Accepted: 02/19/2024] [Indexed: 02/25/2024] Open
Abstract
How rigidly does innate architecture constrain function of developing cortex? What is the contribution of early experience? We review insights into these questions from visual cortex function in people born blind. In blindness, occipital cortices are active during auditory and tactile tasks. What 'cross-modal' plasticity tells us about cortical flexibility is debated. On the one hand, visual networks of blind people respond to higher cognitive information, such as sentence grammar, suggesting drastic repurposing. On the other, in line with 'metamodal' accounts, sighted and blind populations show shared domain preferences in ventral occipito-temporal cortex (vOTC), suggesting visual areas switch input modality but perform the same or similar perceptual functions (e.g., face recognition) in blindness. Here we bring these disparate literatures together, reviewing and synthesizing evidence that speaks to whether visual cortices have similar or different functions in blind and sighted people. Together, the evidence suggests that in blindness, visual cortices are incorporated into higher-cognitive (e.g., fronto-parietal) networks, which are a major source long-range input to the visual system. We propose the connectivity-constrained experience-dependent account. Functional development is constrained by innate anatomical connectivity, experience and behavioral needs. Infant cortex is pluripotent, the same anatomical constraints develop into different functional outcomes.
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Affiliation(s)
- Elizabeth J Saccone
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
| | - Mengyu Tian
- Center for Educational Science and Technology, Beijing Normal University at Zhuhai, China
| | - Marina Bedny
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
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5
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Fitzgerald JJ, Battraw MA, James MA, Bagley AM, Schofield JS, Joiner WM. Moving a missing hand: children born with below elbow deficiency can enact hand grasp patterns with their residual muscles. J Neuroeng Rehabil 2024; 21:13. [PMID: 38263225 PMCID: PMC10804465 DOI: 10.1186/s12984-024-01306-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/12/2024] [Indexed: 01/25/2024] Open
Abstract
Children with a unilateral congenital below elbow deficiency (UCBED) have one typical upper limb and one that lacks a hand, ending below the elbow at the proximal/mid forearm. UCBED is an isolated condition, and affected children otherwise develop normal sensorimotor control. Unlike adults with upper limb absence, the majority of whom have an acquired loss, children with UCBED never developed a hand, so their residual muscles have never actuated an intact limb. Their ability to purposefully modulate affected muscle activity is often assumed to be limited, and this assumption has influenced prosthetic design and prescription practices for this population as many modern devices derive control signals from affected muscle activity. To better understand the motor capabilities of the affected muscles, we used ultrasound imaging to study 6 children with UCBED. We examined the extent to which subjects activate their affected muscles when performing mirrored movements with their typical and missing hands. We demonstrate that all subjects could intentionally and consistently enact at least five distinct muscle patterns when attempting different missing hand movements (e.g., power grasp) and found similar performance across affected and typically developed limbs. These results suggest that although participants had never actuated the missing hand they could distinctively and consistently activate the residual muscle patterns associated with actions on the unaffected side. These findings indicate that motor control still develops in the absence of the normal effector, and can serve as a guide for developing prostheses that leverage the full extent of these children's motor control capabilities.
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Affiliation(s)
- Justin J Fitzgerald
- Department of Biomedical Engineering, University of California, Davis, CA, USA
- Department of Neurobiology, Physiology and Behavior, University of California, 1 Shields Avenue, Davis, CA, 95616, USA
- Clinical and Translational Science Center, University of California Davis Health, Sacramento, CA, USA
| | - Marcus A Battraw
- Department of Mechanical and Aerospace Engineering, University of California, Davis, CA, USA
| | - Michelle A James
- Shriners Children's Northern California, Sacramento, CA, USA
- Department of Orthopaedic Surgery, University of California Davis Health, Sacramento, CA, USA
| | - Anita M Bagley
- Shriners Children's Northern California, Sacramento, CA, USA
- Department of Orthopaedic Surgery, University of California Davis Health, Sacramento, CA, USA
| | - Jonathon S Schofield
- Department of Mechanical and Aerospace Engineering, University of California, Davis, CA, USA
| | - Wilsaan M Joiner
- Department of Neurobiology, Physiology and Behavior, University of California, 1 Shields Avenue, Davis, CA, 95616, USA.
- Department of Neurology, University of California Davis Health, Sacramento, CA, USA.
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6
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Schone HR, Maimon Mor RO, Kollamkulam M, Gerrand C, Woollard A, Kang NV, Baker CI, Makin TR. Stable Cortical Body Maps Before and After Arm Amputation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571314. [PMID: 38168448 PMCID: PMC10760201 DOI: 10.1101/2023.12.13.571314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Neuroscientists have long debated the adult brain's capacity to reorganize itself in response to injury. A driving model for studying plasticity has been limb amputation. For decades, it was believed that amputation triggers large-scale reorganization of cortical body resources. However, these studies have relied on cross-sectional observations post-amputation, without directly tracking neural changes. Here, we longitudinally followed adult patients with planned arm amputations and measured hand and face representations, before and after amputation. By interrogating the representational structure elicited from movements of the hand (pre-amputation) and phantom hand (post-amputation), we demonstrate that hand representation is unaltered. Further, we observed no evidence for lower face (lip) reorganization into the deprived hand region. Collectively, our findings provide direct and decisive evidence that amputation does not trigger large-scale cortical reorganization.
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Affiliation(s)
- Hunter R. Schone
- Institute of Cognitive Neuroscience, University College London, London, UK
- Laboratory of Brain & Cognition, National Institutes of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA, USA
| | - Roni O. Maimon Mor
- Institute of Cognitive Neuroscience, University College London, London, UK
- Department of Experimental Psychology, University College London, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Mathew Kollamkulam
- Institute of Cognitive Neuroscience, University College London, London, UK
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Craig Gerrand
- Department of Orthopaedic Oncology, Royal National Orthopaedic Hospital NHS Trust, Stanmore, Middlesex, UK
| | | | - Norbert V. Kang
- Plastic Surgery Department, Royal Free Hospital NHS Trust, London, UK
| | - Chris I. Baker
- Laboratory of Brain & Cognition, National Institutes of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Tamar R. Makin
- Institute of Cognitive Neuroscience, University College London, London, UK
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, UK
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
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7
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Abstract
Neurological insults, such as congenital blindness, deafness, amputation, and stroke, often result in surprising and impressive behavioural changes. Cortical reorganisation, which refers to preserved brain tissue taking on a new functional role, is often invoked to account for these behavioural changes. Here, we revisit many of the classical animal and patient cortical remapping studies that spawned this notion of reorganisation. We highlight empirical, methodological, and conceptual problems that call this notion into doubt. We argue that appeal to the idea of reorganisation is attributable in part to the way that cortical maps are empirically derived. Specifically, cortical maps are often defined based on oversimplified assumptions of 'winner-takes-all', which in turn leads to an erroneous interpretation of what it means when these maps appear to change. Conceptually, remapping is interpreted as a circuit receiving novel input and processing it in a way unrelated to its original function. This implies that neurons are either pluripotent enough to change what they are tuned to or that a circuit can change what it computes. Instead of reorganisation, we argue that remapping is more likely to occur due to potentiation of pre-existing architecture that already has the requisite representational and computational capacity pre-injury. This architecture can be facilitated via Hebbian and homeostatic plasticity mechanisms. Crucially, our revised framework proposes that opportunities for functional change are constrained throughout the lifespan by the underlying structural 'blueprint'. At no period, including early in development, does the cortex offer structural opportunities for functional pluripotency. We conclude that reorganisation as a distinct form of cortical plasticity, ubiquitously evoked with words such as 'take-over'' and 'rewiring', does not exist.
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Affiliation(s)
- Tamar R Makin
- MRC Cognition and Brain Sciences Unit, University of CambridgeCambridgeUnited Kingdom
| | - John W Krakauer
- Department of Neuroscience, Johns Hopkins University School of MedicineBaltimoreUnited States
- Department of Neurology, Johns Hopkins University School of MedicineBaltimoreUnited States
- The Santa Fe InstituteSanta FeUnited States
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8
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Marneweck M, Gardner C, Dundon NM, Smith J, Frey SH. Reorganization of sensorimotor representations of the intact limb after upper but not lower limb traumatic amputation. Neuroimage Clin 2023; 39:103499. [PMID: 37634375 PMCID: PMC10470418 DOI: 10.1016/j.nicl.2023.103499] [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] [Received: 07/14/2023] [Accepted: 08/16/2023] [Indexed: 08/29/2023]
Abstract
It is becoming increasingly clear that limb loss induces wider spread reorganization of representations of the body that are nonadjacent to the affected cortical territory. Data from upper extremity amputees reveal intrusion of the representation of the ipsilateral intact limb into the former hand territory. Here we test for the first time whether this reorganization of the intact limb into the deprived cortex is specific to the neurological organization of the upper limbs or reflects large scale adaptation that is triggered by any unilateral amputation. BOLD activity was measured as human subjects with upper limb and lower limb traumatic amputation and their controls moved the toes on each foot, open and closed each hand and pursed their lips. Subjects with amputation were asked to imagine moving the missing limb while remaining still. Bayesian pattern component modeling of fMRI data showed that intact ipsilateral movements and contralateral movements of the hand and foot were distinctly represented in the deprived sensorimotor cortex years after upper limb amputation. In contrast, there was evidence reminiscent of contralateral specificity for hand and foot movements following lower limb amputation, like that seen in controls. We propose the cortical reorganization of the intact limb to be a function of use-dependent plasticity that is more specific to the consequence of upper limb loss of forcing an asymmetric reliance on the intact hand and arm. The contribution of this reorganization to phantom pain or a heightened risk of overuse and resultant maladaptive plasticity needs investigating before targeting such reorganization in intervention.
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Affiliation(s)
| | - Cooper Gardner
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Neil M Dundon
- Department of Brain and Psychological Sciences, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Child and Adolescent Psychiatry, Psychotherapy and Psychosomatics, University of Freiburg, 79104 Freiburg, Germany
| | - Jolinda Smith
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Scott H Frey
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA
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Sanders Z, Dempsey‐Jones H, Wesselink DB, Edmondson LR, Puckett AM, Saal HP, Makin TR. Similar somatotopy for active and passive digit representation in primary somatosensory cortex. Hum Brain Mapp 2023; 44:3568-3585. [PMID: 37145934 PMCID: PMC10203813 DOI: 10.1002/hbm.26298] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 12/11/2022] [Accepted: 03/13/2023] [Indexed: 05/07/2023] Open
Abstract
Scientists traditionally use passive stimulation to examine the organisation of primary somatosensory cortex (SI). However, given the close, bidirectional relationship between the somatosensory and motor systems, active paradigms involving free movement may uncover alternative SI representational motifs. Here, we used 7 Tesla functional magnetic resonance imaging to compare hallmark features of SI digit representation between active and passive tasks which were unmatched on task or stimulus properties. The spatial location of digit maps, somatotopic organisation, and inter-digit representational structure were largely consistent between tasks, indicating representational consistency. We also observed some task differences. The active task produced higher univariate activity and multivariate representational information content (inter-digit distances). The passive task showed a trend towards greater selectivity for digits versus their neighbours. Our findings highlight that, while the gross features of SI functional organisation are task invariant, it is important to also consider motor contributions to digit representation.
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Affiliation(s)
- Zeena‐Britt Sanders
- Wellcome Centre of Integrative NeuroimagingFMRIB, John Radcliffe HospitalOxfordUK
| | - Harriet Dempsey‐Jones
- Institute of Cognitive NeuroscienceUniversity College LondonLondonUK
- School of PsychologyThe University of QueenslandBrisbaneAustralia
| | - Daan B. Wesselink
- Wellcome Centre of Integrative NeuroimagingFMRIB, John Radcliffe HospitalOxfordUK
- Institute of Cognitive NeuroscienceUniversity College LondonLondonUK
| | | | - Alexander M. Puckett
- School of PsychologyThe University of QueenslandBrisbaneAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneAustralia
| | - Hannes P. Saal
- Queensland Brain InstituteThe University of QueenslandBrisbaneAustralia
| | - Tamar R. Makin
- Wellcome Centre of Integrative NeuroimagingFMRIB, John Radcliffe HospitalOxfordUK
- Institute of Cognitive NeuroscienceUniversity College LondonLondonUK
- MRC Cognition and Brain Sciences UnitUniversity of CambridgeCambridgeUK
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10
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Kikkert S, Sonar HA, Freund P, Paik J, Wenderoth N. Hand and face somatotopy shown using MRI-safe vibrotactile stimulation with a novel soft pneumatic actuator (SPA)-skin interface. Neuroimage 2023; 269:119932. [PMID: 36750151 DOI: 10.1016/j.neuroimage.2023.119932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 01/23/2023] [Accepted: 02/02/2023] [Indexed: 02/07/2023] Open
Abstract
The exact somatotopy of the human facial representation in the primary somatosensory cortex (S1) remains debated. One reason that progress has been hampered is due to the methodological challenge of how to apply automated vibrotactile stimuli to face areas in a manner that is: (1) reliable despite differences in the curvatures of face locations; and (2) MR-compatible and free of MR-interference artefacts when applied in the MR head-coil. Here we overcome this challenge by using soft pneumatic actuator (SPA) technology. SPAs are made of a soft silicon material and can be in- or deflated by means of airflow, have a small diameter, and are flexible in structure, enabling good skin contact even on curved body surfaces (as on the face). To validate our approach, we first mapped the well-characterised S1 finger layout using this novel device and confirmed that tactile stimulation of the fingers elicited characteristic somatotopic finger activations in S1. We then used the device to automatically and systematically deliver somatosensory stimulation to different face locations. We found that the forehead representation was least distant from the representation of the hand. Within the face representation, we found that the lip representation is most distant from the forehead representation, with the chin represented in between. Together, our results demonstrate that this novel MR compatible device produces robust and clear somatotopic representational patterns using vibrotactile stimulation through SPA-technology.
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Affiliation(s)
- Sanne Kikkert
- Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland; Spinal Cord Injury Center Balgrist, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
| | | | - Patrick Freund
- Spinal Cord Injury Center Balgrist, University Hospital Zürich, University of Zürich, Zürich, Switzerland
| | - Jamie Paik
- Reconfigurable Robotics Lab, EPFL, Lausanne, Switzerland
| | - Nicole Wenderoth
- Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
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11
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Root V, Muret D, Arribas M, Amoruso E, Thornton J, Tarall-Jozwiak A, Tracey I, Makin TR. Complex pattern of facial remapping in somatosensory cortex following congenital but not acquired hand loss. eLife 2022; 11:e76158. [PMID: 36583538 PMCID: PMC9851617 DOI: 10.7554/elife.76158] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/29/2022] [Indexed: 12/31/2022] Open
Abstract
Cortical remapping after hand loss in the primary somatosensory cortex (S1) is thought to be predominantly dictated by cortical proximity, with adjacent body parts remapping into the deprived area. Traditionally, this remapping has been characterised by changes in the lip representation, which is assumed to be the immediate neighbour of the hand based on electrophysiological research in non-human primates. However, the orientation of facial somatotopy in humans is debated, with contrasting work reporting both an inverted and upright topography. We aimed to fill this gap in the S1 homunculus by investigating the topographic organisation of the face. Using both univariate and multivariate approaches we examined the extent of face-to-hand remapping in individuals with a congenital and acquired missing hand (hereafter one-handers and amputees, respectively), relative to two-handed controls. Participants were asked to move different facial parts (forehead, nose, lips, tongue) during functional MRI (fMRI) scanning. We first confirmed an upright face organisation in all three groups, with the upper-face and not the lips bordering the hand area. We further found little evidence for remapping of both forehead and lips in amputees, with no significant relationship to the chronicity of their phantom limb pain (PLP). In contrast, we found converging evidence for a complex pattern of face remapping in congenital one-handers across multiple facial parts, where relative to controls, the location of the cortical neighbour - the forehead - is shown to shift away from the deprived hand area, which is subsequently more activated by the lips and the tongue. Together, our findings demonstrate that the face representation in humans is highly plastic, but that this plasticity is restricted by the developmental stage of input deprivation, rather than cortical proximity.
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Affiliation(s)
- Victoria Root
- WIN Centre, University of OxfordOxfordUnited Kingdom
- Institute of Cognitive Neuroscience, University College LondonLondonUnited Kingdom
- Medical Research Council Cognition and Brain Sciences Unit (CBU), University of CambridgeCambridgeUnited Kingdom
| | - Dollyane Muret
- Institute of Cognitive Neuroscience, University College LondonLondonUnited Kingdom
| | - Maite Arribas
- Institute of Cognitive Neuroscience, University College LondonLondonUnited Kingdom
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College LondonLondonUnited Kingdom
| | - Elena Amoruso
- Institute of Cognitive Neuroscience, University College LondonLondonUnited Kingdom
- Medical Research Council Cognition and Brain Sciences Unit (CBU), University of CambridgeCambridgeUnited Kingdom
| | - John Thornton
- Wellcome Trust Centre for Neuroimaging, University College LondonLondonUnited Kingdom
| | | | - Irene Tracey
- WIN Centre, University of OxfordOxfordUnited Kingdom
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College LondonLondonUnited Kingdom
- Medical Research Council Cognition and Brain Sciences Unit (CBU), University of CambridgeCambridgeUnited Kingdom
- Wellcome Trust Centre for Neuroimaging, University College LondonLondonUnited Kingdom
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12
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Philip BA, Valyear KF, Cirstea CM, Baune NA, Kaufman C, Frey SH. Changes in Primary Somatosensory Cortex Following Allogeneic Hand Transplantation or Autogenic Hand Replantation. FRONTIERS IN NEUROIMAGING 2022; 1:919694. [PMID: 36590253 PMCID: PMC9802660 DOI: 10.3389/fnimg.2022.919694] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 09/09/2022] [Indexed: 01/03/2023]
Abstract
Former amputees who undergo allogeneic hand transplantation or autogenic hand replantation (jointly, "hand restoration") present a unique opportunity to measure the range of post-deafferentation plastic changes in the nervous system, especially primary somatosensory cortex (S1). However, few such patients exist, and previous studies compared single cases to small groups of typical adults. Here, we studied 5 individuals (n = 8 sessions: a transplant with 2 sessions, a transplant with 3 sessions, and three replants with 1 session each). We used functional magnetic resonance imaging (fMRI) to measure S1 responsiveness to controlled pneumatic tactile stimulation delivered to each patient's left and right fingertips and lower face. These data were compared with responses acquired from typical adults (n = 29) and current unilateral amputees (n = 19). During stimulation of the affected hand, patients' affected S1 (contralateral to affected hand) responded to stimulation in a manner similar both to amputees and to typical adults. The presence of contralateral responses indicated grossly typical S1 function, but responses were universally at the low end of the range of typical variability. Patients' affected S1 showed substantial individual variability in responses to stimulation of the intact hand: while all patients fell within the range of typical adults, some patient sessions (4/8) had substantial ipsilateral responses similar to those exhibited by current amputees. Unlike hand restoration patients, current amputees exhibited substantial S1 reorganization compared to typical adults, including bilateral S1 responses to stimulation of the intact hand. In all three participant groups, we assessed tactile localization by measuring individuals' ability to identify the location of touch on the palm and fingers. Curiously, while transplant patients improved their tactile sensory localization over time, this was uncorrelated with changes in S1 responses to tactile stimuli. Overall, our results provide the first description of cortical responses to well-controlled tactile stimulation after hand restoration. Our case studies indicate that hand restoration patients show S1 function within the range of both typical adults and amputees, but with low-amplitude and individual-specific responses that indicate a wide range of potential cortical neurological changes following de-afferentation and re-afferentation.
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Affiliation(s)
- Benjamin A. Philip
- Department of Psychological Sciences, University of Missouri, Columbia, MO, United States
- Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, United States
| | - Kenneth F. Valyear
- Department of Psychological Sciences, University of Missouri, Columbia, MO, United States
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom
| | - Carmen M. Cirstea
- Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia, MO, United States
| | - Nathan A. Baune
- Department of Psychological Sciences, University of Missouri, Columbia, MO, United States
- Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, United States
| | - Christina Kaufman
- Department of Cardiovascular and Thoracic Surgery, University of Louisville School of Medicine, Louisville, KY, United States
| | - Scott H. Frey
- Department of Psychological Sciences, University of Missouri, Columbia, MO, United States
- Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia, MO, United States
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13
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Luke DP, Lungu L, Friday R, Terhune DB. The chemical induction of synaesthesia. Hum Psychopharmacol 2022; 37:e2832. [PMID: 35044677 DOI: 10.1002/hup.2832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/24/2021] [Accepted: 01/04/2022] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Preliminary research suggests that experiences resembling synaesthesia are frequently reported under the influence of a diverse range of chemical substances although the incidence, chemical specificity, and characteristics of these effects are poorly understood. METHODS Here we surveyed recreational drug users and self-reported developmental synaesthetes regarding their use of 28 psychoactive drugs from 12 different drug classes and whether they had experienced synaesthesia under the influence of these substances. RESULTS The drug class of tryptamines exhibited the highest incidence rates of drug-induced synaesthesia in controls and induction rates of novel forms of synaesthesia in developmental synaesthetes. Induction incidence rates in controls were strongly correlated with the corresponding induction and enhancement rates in developmental synaesthetes. In addition, the use of lysergic acid diethylamide (LSD) was the strongest predictor of drug-induced synaesthesia in both controls and developmental synaesthetes. Clear evidence was observed for a clustering of synaesthesia-induction rates as a function of drug class in both groups, denoting non-random incidence rates within drug classes. Sound-colour synaesthesia was the most commonly observed type of induced synaesthesia. Further analyses suggest the presence of synaesthesia-prone individuals, who were more likely to experience drug-induced synaesthesia with multiple drugs. CONCLUSIONS These data corroborate the hypothesized link between drug-induced synaesthesia and serotoninergic activity, but also suggest the possibility of alternative neurochemical pathways involved in the induction of synaesthesia. They further imply that the induction and modulation of synaesthesia in controls and developmental synaesthetes share overlapping mechanisms and that certain individuals may be more susceptible to experiencing induced synaesthesia with different drugs.
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Affiliation(s)
- David P Luke
- Centre for Mental Health, School of Human Sciences, University of Greenwich, London, UK
| | - Laura Lungu
- Department of Psychology, Goldsmiths, University of London, London, UK
| | - Ross Friday
- Centre for Mental Health, School of Human Sciences, University of Greenwich, London, UK
| | - Devin B Terhune
- Department of Psychology, Goldsmiths, University of London, London, UK.,Department of Experimental Psychology, University of Oxford, London, UK
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14
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Pang D, Ashkan K. Deep brain stimulation for phantom limb pain. Eur J Paediatr Neurol 2022; 39:96-102. [PMID: 35728428 DOI: 10.1016/j.ejpn.2022.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 03/25/2022] [Accepted: 05/23/2022] [Indexed: 11/29/2022]
Abstract
Phantom limb pain is a rare cause of chronic pain in children but it is associated with extremely refractory pain and disability. The reason for limb amputation is often due to treatment for cancer or trauma and it has a lower incidence compared to adults. The mechanism of why phantom pain exists remains uncertain and may be a result of cortical reorganisation as well as ectopic peripheral input. Treatment is aimed at reducing both symptoms as well as managing pain related disability and functional restoration. Neuromodulatory approaches using deep brain stimulation for phantom limb pain is reserved for only the most refractory cases. The targets for brain stimulation include the thalamic nuclei and motor cortex. Novel targets such as the anterior cingulate cortex remain experimental as cases of serious adverse effects such as seziures have limited their widespread uptake. A multidisciplinary approach is crucial to successful rehabilitation using a biopsychosocial pain management approach.
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Affiliation(s)
- David Pang
- Consultant in Pain Management, Pain Management Centre, INPUT St Thomas Hospital, London, SE1 7EH, UK.
| | - Keyoumars Ashkan
- Department of Neurosurgery, Kins's College Hospital NHS Foundation Trust, London, UK
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15
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Wesselink DB, Sanders ZB, Edmondson LR, Dempsey-Jones H, Kieliba P, Kikkert S, Themistocleous AC, Emir U, Diedrichsen J, Saal HP, Makin TR. Malleability of the cortical hand map following a finger nerve block. SCIENCE ADVANCES 2022; 8:eabk2393. [PMID: 35452294 PMCID: PMC9032959 DOI: 10.1126/sciadv.abk2393] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Electrophysiological studies in monkeys show that finger amputation triggers local remapping within the deprived primary somatosensory cortex (S1). Human neuroimaging research, however, shows persistent S1 representation of the missing hand's fingers, even decades after amputation. Here, we explore whether this apparent contradiction stems from underestimating the distributed peripheral and central representation of fingers in the hand map. Using pharmacological single-finger nerve block and 7-tesla neuroimaging, we first replicated previous accounts (electrophysiological and other) of local S1 remapping. Local blocking also triggered activity changes to nonblocked fingers across the entire hand area. Using methods exploiting interfinger representational overlap, however, we also show that the blocked finger representation remained persistent despite input loss. Computational modeling suggests that both local stability and global reorganization are driven by distributed processing underlying the topographic map, combined with homeostatic mechanisms. Our findings reveal complex interfinger representational features that play a key role in brain (re)organization, beyond (re)mapping.
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Affiliation(s)
- Daan B. Wesselink
- Institute of Cognitive Neuroscience, University College London, London, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Corresponding author.
| | - Zeena-Britt Sanders
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Laura R. Edmondson
- Active Touch Laboratory, Department of Psychology, The University of Sheffield, Sheffield, UK
| | - Harriet Dempsey-Jones
- Institute of Cognitive Neuroscience, University College London, London, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
- School of Psychology, University of Queensland, Brisbane, Australia
| | - Paulina Kieliba
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Sanne Kikkert
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Andreas C. Themistocleous
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Brain Function Research Group, University of the Witwatersrand, Johannesburg, South Africa
| | - Uzay Emir
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Jörn Diedrichsen
- Brain and Mind Institute, University of Western Ontario, London, Canada
| | - Hannes P. Saal
- Active Touch Laboratory, Department of Psychology, The University of Sheffield, Sheffield, UK
| | - Tamar R. Makin
- Institute of Cognitive Neuroscience, University College London, London, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
- Wellcome Centre for Human Neuroimaging, University College London, London, UK
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16
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Muret D, Root V, Kieliba P, Clode D, Makin TR. Beyond body maps: Information content of specific body parts is distributed across the somatosensory homunculus. Cell Rep 2022; 38:110523. [PMID: 35294887 PMCID: PMC8938902 DOI: 10.1016/j.celrep.2022.110523] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/10/2021] [Accepted: 02/21/2022] [Indexed: 11/23/2022] Open
Abstract
The homunculus in primary somatosensory cortex (S1) is famous for its body part selectivity, but this dominant feature may eclipse other representational features, e.g., information content, also relevant for S1 organization. Using multivariate fMRI analysis, we ask whether body part information content can be identified in S1 beyond its primary region. Throughout S1, we identify significant representational dissimilarities between body parts but also subparts in distant non-primary regions (e.g., between the hand and the lips in the foot region and between different face parts in the foot region). Two movements performed by one body part (e.g., the hand) could also be dissociated well beyond its primary region (e.g., in the foot and face regions), even within Brodmann area 3b. Our results demonstrate that information content is more distributed across S1 than selectivity maps suggest. This finding reveals underlying information contents in S1 that could be harnessed for rehabilitation and brain-machine interfaces.
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Affiliation(s)
- Dollyane Muret
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK.
| | - Victoria Root
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK; Wellcome Centre of Integrative Neuroimaging, University of Oxford, Oxford OX3 9DU, UK
| | - Paulina Kieliba
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK
| | - Danielle Clode
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK; Dani Clode Design, 40 Hillside Road, London SW2 3HW, UK
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK; Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3AR, UK
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17
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Raffin E. The various forms of sensorimotor plasticity following limb amputation and their link with rehabilitation strategies. Rev Neurol (Paris) 2021; 177:1112-1120. [PMID: 34657732 DOI: 10.1016/j.neurol.2021.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/06/2021] [Accepted: 09/21/2021] [Indexed: 12/31/2022]
Abstract
Limb amputation is characterized by complex and intermingled brain reorganization processes combining sensorimotor deprivation induced by the loss of the limb per se, and compensatory behaviors, such as the over-use of the intact or remaining limb. While a large body of evidence documents sensorimotor representation plasticity following arm amputation, less investigations have been performed to fully understand the use-dependent plasticity phenomenon and the role of behavioral compensation in brain reorganization. In this article, I will review the findings on sensorimotor plasticity after limb amputation, focusing on these two aspects: sensorimotor deprivation and adaptive patterns of limb usage, and describe the models that attempt to link these reorganizational processes with phantom limb pain. Two main models have been proposed: the maladaptive plasticity model which states that the reorganization of the adjacent cortical territories into the representation of the missing limb is proportional to phantom pain intensity, and the persistent representation model, which rather suggests that the intensity of residual brain activity associated with phantom hand movements scales with phantom limb pain intensity. I will finally illustrate how this fundamental research helps designing new therapeutic strategies for phantom plain relief.
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Affiliation(s)
- E Raffin
- Defitech Chair in Clinical Neuroengineering, École Polytechnique Fédérale de Lausanne, Center for Neuroprosthetics and Brain Mind Institute, EPFL, UPHUMMEL lab, Swiss Federal Institute of Technology (EPFL), Campus Biotech, Room H4.3.132.084, Chemin des Mines 9, 1202 Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Center for Neuroprosthetics and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland.
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18
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Kikkert S, Pfyffer D, Verling M, Freund P, Wenderoth N. Finger somatotopy is preserved after tetraplegia but deteriorates over time. eLife 2021; 10:e67713. [PMID: 34665133 PMCID: PMC8575460 DOI: 10.7554/elife.67713] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 10/18/2021] [Indexed: 12/12/2022] Open
Abstract
Previous studies showed reorganised and/or altered activity in the primary sensorimotor cortex after a spinal cord injury (SCI), suggested to reflect abnormal processing. However, little is known about whether somatotopically specific representations can be activated despite reduced or absent afferent hand inputs. In this observational study, we used functional MRI and a (attempted) finger movement task in tetraplegic patients to characterise the somatotopic hand layout in primary somatosensory cortex. We further used structural MRI to assess spared spinal tissue bridges. We found that somatotopic hand representations can be activated through attempted finger movements in the absence of sensory and motor hand functioning, and no spared spinal tissue bridges. Such preserved hand somatotopy could be exploited by rehabilitation approaches that aim to establish new hand-brain functional connections after SCI (e.g. neuroprosthetics). However, over years since SCI the hand representation somatotopy deteriorated, suggesting that somatotopic hand representations are more easily targeted within the first years after SCI.
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Affiliation(s)
- Sanne Kikkert
- Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH ZürichZürichSwitzerland
- Spinal Cord Injury Center, Balgrist University Hospital, University of ZürichZürichSwitzerland
| | - Dario Pfyffer
- Spinal Cord Injury Center, Balgrist University Hospital, University of ZürichZürichSwitzerland
| | - Michaela Verling
- Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH ZürichZürichSwitzerland
| | - Patrick Freund
- Spinal Cord Injury Center, Balgrist University Hospital, University of ZürichZürichSwitzerland
- Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College LondonLondonUnited Kingdom
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College LondonLondonUnited Kingdom
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | - Nicole Wenderoth
- Neural Control of Movement Laboratory, Department of Health Sciences and Technology, ETH ZürichZürichSwitzerland
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19
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Dominijanni G, Shokur S, Salvietti G, Buehler S, Palmerini E, Rossi S, De Vignemont F, d’Avella A, Makin TR, Prattichizzo D, Micera S. The neural resource allocation problem when enhancing human bodies with extra robotic limbs. NAT MACH INTELL 2021. [DOI: 10.1038/s42256-021-00398-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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20
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Maimon-Mor RO, Schone HR, Henderson Slater D, Faisal AA, Makin TR. Early life experience sets hard limits on motor learning as evidenced from artificial arm use. eLife 2021; 10:66320. [PMID: 34605407 PMCID: PMC8523152 DOI: 10.7554/elife.66320] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 10/01/2021] [Indexed: 11/13/2022] Open
Abstract
The study of artificial arms provides a unique opportunity to address long-standing questions on sensorimotor plasticity and development. Learning to use an artificial arm arguably depends on fundamental building blocks of body representation and would therefore be impacted by early life experience. We tested artificial arm motor-control in two adult populations with upper-limb deficiencies: a congenital group—individuals who were born with a partial arm, and an acquired group—who lost their arm following amputation in adulthood. Brain plasticity research teaches us that the earlier we train to acquire new skills (or use a new technology) the better we benefit from this practice as adults. Instead, we found that although the congenital group started using an artificial arm as toddlers, they produced increased error noise and directional errors when reaching to visual targets, relative to the acquired group who performed similarly to controls. However, the earlier an individual with a congenital limb difference was fitted with an artificial arm, the better their motor control was. Since we found no group differences when reaching without visual feedback, we suggest that the ability to perform efficient visual-based corrective movements is highly dependent on either biological or artificial arm experience at a very young age. Subsequently, opportunities for sensorimotor plasticity become more limited.
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Affiliation(s)
- Roni O Maimon-Mor
- WIN Centre, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom.,Institute of Cognitive Neuroscience, University College London, London, United Kingdom
| | - Hunter R Schone
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,Laboratory of Brain & Cognition, NIMH, National Institutes of Health, Bethesda, United States
| | | | - A Aldo Faisal
- Departments of Bioengineering and of Computing, Imperial College London, London, United Kingdom
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom
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21
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Wang L, Zhang Z, Okada T, Li C, Chen D, Funahashi S, Wu J, Yan T. Population Receptive Field Characteristics in the between- and Within-Digit Dimensions of the Undominant Hand in the Primary Somatosensory Cortex. Cereb Cortex 2021; 31:4427-4438. [PMID: 33973012 PMCID: PMC8408438 DOI: 10.1093/cercor/bhab097] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/02/2021] [Accepted: 03/20/2021] [Indexed: 11/13/2022] Open
Abstract
Somatotopy is an important guiding principle for sensory fiber organization in the primary somatosensory cortex (S1), which reflects tactile information processing and is associated with disease-related reorganization. However, it is difficult to measure the neuronal encoding scheme in S1 in vivo in normal participants. Here, we investigated the somatotopic map of the undominant hand using a Bayesian population receptive field (pRF) model. The model was established in hand space with between- and within-digit dimensions. In the between-digit dimension, orderly representation was found, which had low variability across participants. The pRF shape tended to be elliptical for digits with high spatial acuity, for which the long axis was along the within-digit dimension. In addition, the pRF width showed different change trends in the 2 dimensions across digits. These results provide new insights into the neural mechanisms in S1, allowing for in-depth investigation of somatosensory information processing and disease-related reorganization.
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Affiliation(s)
- Luyao Wang
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China.,Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Zhilin Zhang
- Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Tomohisa Okada
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Chunlin Li
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
| | - Duanduan Chen
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Shintaro Funahashi
- Advanced research institute of multidisciplinary science, Beijing Institute of Technology, Beijing 100081, China
| | - Jinglong Wu
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Tianyi Yan
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
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22
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Neural Plasticity in a French Horn Player with Bilateral Amelia. Neural Plast 2021; 2021:4570135. [PMID: 34373687 PMCID: PMC8349270 DOI: 10.1155/2021/4570135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 07/01/2021] [Accepted: 07/19/2021] [Indexed: 11/26/2022] Open
Abstract
Precise control of movement and timing play a key role in musical performance. This motor skill requires coordination across multiple joints, muscles, and limbs, which is acquired through extensive musical training from childhood on. Thus, making music can be a strong driver for neuroplasticity. We here present the rare case of a professional french horn player with a congenital bilateral amelia of the upper limbs. We were able to show a unique cerebral and cerebellar somatotopic representation of his toe and feet, that do not follow the characteristic patterns of contralateral cortical and ipsilateral cerebellar layout. Although being a professional horn player who trained his embouchure muscles, including tongue, pharyngeal, and facial muscle usage excessively, there were no obvious signs for an expanded somatosensory representation in this part of the classic homunculus. Compared to the literature and in contrast to control subjects, the musicians' foot movement-related activations occurred in cerebellar areas that are typically more related to hand than to foot activation.
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23
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Copeland C, Mukherjee M, Wang Y, Fraser K, Zuniga JM. Changes in Sensorimotor Cortical Activation in Children Using Prostheses and Prosthetic Simulators. Brain Sci 2021; 11:991. [PMID: 34439610 PMCID: PMC8392534 DOI: 10.3390/brainsci11080991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/19/2021] [Accepted: 07/23/2021] [Indexed: 11/17/2022] Open
Abstract
This study aimed to examine the neural responses of children using prostheses and prosthetic simulators to better elucidate the emulation abilities of the simulators. We utilized functional near-infrared spectroscopy (fNIRS) to evaluate the neural response in five children with a congenital upper limb reduction (ULR) using a body-powered prosthesis to complete a 60 s gross motor dexterity task. The ULR group was matched with five typically developing children (TD) using their non-preferred hand and a prosthetic simulator on the same hand. The ULR group had lower activation within the primary motor cortex (M1) and supplementary motor area (SMA) compared to the TD group, but nonsignificant differences in the primary somatosensory area (S1). Compared to using their non-preferred hand, the TD group exhibited significantly higher action in S1 when using the simulator, but nonsignificant differences in M1 and SMA. The non-significant differences in S1 activation between groups and the increased activation evoked by the simulator's use may suggest rapid changes in feedback prioritization during tool use. We suggest that prosthetic simulators may elicit increased reliance on proprioceptive and tactile feedback during motor tasks. This knowledge may help to develop future prosthesis rehabilitative training or the improvement of tool-based skills.
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Affiliation(s)
- Christopher Copeland
- Department of Biomechanics, University of Nebraska-Omaha, Omaha, NE 68182, USA; (C.C.); (M.M.); (K.F.)
| | - Mukul Mukherjee
- Department of Biomechanics, University of Nebraska-Omaha, Omaha, NE 68182, USA; (C.C.); (M.M.); (K.F.)
| | - Yingying Wang
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE 68583, USA;
| | - Kaitlin Fraser
- Department of Biomechanics, University of Nebraska-Omaha, Omaha, NE 68182, USA; (C.C.); (M.M.); (K.F.)
| | - Jorge M. Zuniga
- Department of Biomechanics, University of Nebraska-Omaha, Omaha, NE 68182, USA; (C.C.); (M.M.); (K.F.)
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24
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van den Boom M, Miller KJ, Gregg NM, Ojeda Valencia G, Lee KH, Richner TJ, Ramsey NF, Worrell GA, Hermes D. Typical somatomotor physiology of the hand is preserved in a patient with an amputated arm: An ECoG case study. Neuroimage Clin 2021; 31:102728. [PMID: 34182408 PMCID: PMC8253998 DOI: 10.1016/j.nicl.2021.102728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/17/2021] [Accepted: 05/10/2021] [Indexed: 12/03/2022]
Abstract
Electrophysiological signals in the human motor system may change in different ways after deafferentation, with some studies emphasizing reorganization while others propose retained physiology. Understanding whether motor electrophysiology is retained over longer periods of time can be invaluable for patients with paralysis (e.g. ALS or brainstem stroke) when signals from sensorimotor areas may be used for communication or control over neural prosthetic devices. In addition, a maintained electrophysiology can potentially benefit the treatment of phantom limb pains through prolonged use of these signals in a brain-machine interface (BCI). Here, we were presented with the unique opportunity to investigate the physiology of the sensorimotor cortex in a patient with an amputated arm using electrocorticographic (ECoG) measurements. While implanted with an ECoG grid for clinical evaluation of electrical stimulation for phantom limb pain, the patient performed attempted finger movements with the contralateral (lost) hand and executed finger movements with the ipsilateral (healthy) hand. The electrophysiology of the sensorimotor cortex contralateral to the amputated hand remained very similar to that of hand movement in healthy people, with a spatially focused increase of high-frequency band (65-175 Hz; HFB) power over the hand region and a distributed decrease in low-frequency band (15-28 Hz; LFB) power. The representation of the three different fingers (thumb, index and little) remained intact and HFB patterns could be decoded using support vector learning at single-trial classification accuracies of >90%, based on the first 1-3 s of the HFB response. These results indicate that hand representations are largely retained in the motor cortex. The intact physiological response of the amputated hand, the high distinguishability of the fingers and fast temporal peak are encouraging for neural prosthetic devices that target the sensorimotor cortex.
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Affiliation(s)
- Max van den Boom
- Department of Physiology and Biomedical Engineering, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Department of Neurology & Neurosurgery, UMC Utrecht Brain Center, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - Kai J Miller
- Department of Neurosurgery, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Nicholas M Gregg
- Department of Neurology, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Gabriela Ojeda Valencia
- Department of Physiology and Biomedical Engineering, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Kendall H Lee
- Department of Neurosurgery, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Thomas J Richner
- Department of Neurosurgery, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Nick F Ramsey
- Department of Neurology & Neurosurgery, UMC Utrecht Brain Center, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Greg A Worrell
- Department of Neurology, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Dora Hermes
- Department of Physiology and Biomedical Engineering, Mayo Clinic Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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Kieliba P, Clode D, Maimon-Mor RO, Makin TR. Robotic hand augmentation drives changes in neural body representation. Sci Robot 2021; 6:eabd7935. [PMID: 34043536 PMCID: PMC7612043 DOI: 10.1126/scirobotics.abd7935] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 04/23/2021] [Indexed: 01/11/2023]
Abstract
Humans have long been fascinated by the opportunities afforded through augmentation. This vision not only depends on technological innovations but also critically relies on our brain's ability to learn, adapt, and interface with augmentation devices. Here, we investigated whether successful motor augmentation with an extra robotic thumb can be achieved and what its implications are on the neural representation and function of the biological hand. Able-bodied participants were trained to use an extra robotic thumb (called the Third Thumb) over 5 days, including both lab-based and unstructured daily use. We challenged participants to complete normally bimanual tasks using only the augmented hand and examined their ability to develop hand-robot interactions. Participants were tested on a variety of behavioral and brain imaging tests, designed to interrogate the augmented hand's representation before and after the training. Training improved Third Thumb motor control, dexterity, and hand-robot coordination, even when cognitive load was increased or when vision was occluded. It also resulted in increased sense of embodiment over the Third Thumb. Consequently, augmentation influenced key aspects of hand representation and motor control. Third Thumb usage weakened natural kinematic synergies of the biological hand. Furthermore, brain decoding revealed a mild collapse of the augmented hand's motor representation after training, even while the Third Thumb was not worn. Together, our findings demonstrate that motor augmentation can be readily achieved, with potential for flexible use, reduced cognitive reliance, and increased sense of embodiment. Yet, augmentation may incur changes to the biological hand representation. Such neurocognitive consequences are crucial for successful implementation of future augmentation technologies.
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Affiliation(s)
- Paulina Kieliba
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK
| | - Danielle Clode
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK
- Dani Clode design, 40 Hillside Road, London SW2 3HW, UK
| | - Roni O Maimon-Mor
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK
- WIN Centre, University of Oxford, Oxford OX3 9DU, UK
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK.
- Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3AR, UK
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Wang L, Tomson SN, Lu G, Yau JM. Cortical representations of phantom movements in lower limb amputees. Eur J Neurosci 2021; 53:3160-3174. [PMID: 33662143 DOI: 10.1111/ejn.15170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 11/28/2022]
Abstract
Understanding how sensorimotor cortex (SMC) organization relates to limb loss has major clinical implications, as cortical activity associated with phantom hand movements has been shown to predict phantom pain reports. Critically, earlier studies have largely focused on upper limb amputees; far less is known regarding SMC activity in lower limb amputees, despite the fact that this population comprises the majority of major limb loss cases. We aimed to characterize BOLD fMRI responses associated with phantom and sound limb movements to test the hypothesis that SMC organization is preserved in individuals with lower limb loss. Individuals with unilateral or bilateral lower limb loss underwent fMRI scans as they performed simple movements of their sound or phantom limbs. We observed that voluntary movements of the sound and phantom ankles were associated with BOLD signal changes in medial and superior portions of the precentral and postcentral gyri. In both hemispheres, contralateral limb movements were associated with greater signal changes compared to ipsilateral limb movements. Hand and mouth movements were associated with distinct activation patterns localized to more lateral SMC regions. We additionally tested whether activations associated with phantom movements related to self-report assessments indexing phantom pain experiences, nonpainful phantom sensations and phantom movement capabilities. We found that responses during phantom ankle movements did not correlate with any of the composite phantom limb indices in our sample. Our collective results reveal that SMC representations of the amputated limb persist and that traditional somatotopic organization is generally preserved in individuals suffering from lower limb loss.
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Affiliation(s)
- Lingyan Wang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Steffie N Tomson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Grace Lu
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Jeffrey M Yau
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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27
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Dempsey-Jones H, Steudte-Schmiedgen S, Browning M, Makin TR, Woud ML, Harmer CJ, Margraf J, Reinecke A. Human perceptual learning is delayed by the N-methyl-D-aspartate receptor partial agonist D-cycloserine. J Psychopharmacol 2021; 35:253-264. [PMID: 33570017 PMCID: PMC7924109 DOI: 10.1177/0269881120986349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND The optimisation of learning has long been a focus of scientific research, particularly in relation to improving psychological treatment and recovery of brain function. Previously, partial N-methyl-D-aspartate agonists have been shown to augment reward learning, procedural learning and psychological therapy, but many studies also report no impact of these compounds on the same processes. AIMS Here we investigate whether administration of an N-methyl-D-aspartate partial agonist (D-cycloserine) modulates a previously unexplored process - tactile perceptual learning. Further, we use a longitudinal design to investigate whether N-methyl-D-aspartate-related learning effects vary with time, thereby providing a potentially simple explanation for apparent mixed effects in previous research. METHODS Thirty-four volunteers were randomised to receive one dose of 250 mg D-cycloserine or placebo 2 h before tactile sensitivity training. Tactile perception was measured using psychophysical methods before and after training, and 24/48 h later. RESULTS The placebo group showed immediate within-day tactile perception gains, but no further improvements between-days. In contrast, tactile perception remained at baseline on day one in the D-cycloserine group (no within-day learning), but showed significant overnight gains on day two. Both groups were equivalent in tactile perception by the final testing - indicating N-methyl-D-aspartate effects changed the timing, but not the overall amount of tactile learning. CONCLUSIONS In sum, we provide first evidence for modulation of perceptual learning by administration of a partial N-methyl-D-aspartate agonist. Resolving how the effects of such compounds become apparent over time will assist the optimisation of testing schedules, and may help resolve discrepancies across the learning and cognition domains.
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Affiliation(s)
- Harriet Dempsey-Jones
- Wellcome Centre for Integrated Neuroimaging, University of Oxford, Oxford, UK
- School of Psychology, University of Queensland, Brisbane, Australia
| | - Susann Steudte-Schmiedgen
- Department of Psychotherapy and Psychosomatic Medicine, Technische Universität Dresden, Dresden, Germany
| | - Michael Browning
- Department of Psychiatry, University of Oxford, Oxford, UK
- Oxford Health NHS Foundation Trust, Oxford, UK
| | - Tamar R Makin
- Wellcome Centre for Integrated Neuroimaging, University of Oxford, Oxford, UK
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Marcella L Woud
- Department of Clinical Psychology and Psychotherapy, Ruhr-University Bochum, Bochum, Germany
| | - Catherine J Harmer
- Department of Psychiatry, University of Oxford, Oxford, UK
- Oxford Health NHS Foundation Trust, Oxford, UK
| | - Juergen Margraf
- Department of Clinical Psychology and Psychotherapy, Ruhr-University Bochum, Bochum, Germany
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28
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Balakhanlou E, Webster J, Borgia M, Resnik L. Frequency and Severity of Phantom Limb Pain in Veterans with Major Upper Limb Amputation: Results of a National Survey. PM R 2020; 13:827-835. [DOI: 10.1002/pmrj.12485] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 08/20/2020] [Accepted: 08/31/2020] [Indexed: 12/26/2022]
Affiliation(s)
- Ellie Balakhanlou
- School of Medicine at Virginia Commonwealth University Richmond VA USA
| | - Joseph Webster
- School of Medicine at Virginia Commonwealth University Richmond VA USA
- Hunter Homes McGuire Veterans Affairs Medical Center Richmond VA USA
| | - Matthew Borgia
- Research Department Providence VA Medical Center Providence RI USA
| | - Linda Resnik
- Research Department Providence VA Medical Center Providence RI USA
- Health Services, Policy and Practice Brown University Providence RI USA
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Jafari M, Aflalo T, Chivukula S, Kellis SS, Salas MA, Norman SL, Pejsa K, Liu CY, Andersen RA. The human primary somatosensory cortex encodes imagined movement in the absence of sensory information. Commun Biol 2020; 3:757. [PMID: 33311578 PMCID: PMC7732821 DOI: 10.1038/s42003-020-01484-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 11/15/2020] [Indexed: 02/07/2023] Open
Abstract
Classical systems neuroscience positions primary sensory areas as early feed-forward processing stations for refining incoming sensory information. This view may oversimplify their role given extensive bi-directional connectivity with multimodal cortical and subcortical regions. Here we show that single units in human primary somatosensory cortex encode imagined reaches in a cognitive motor task, but not other sensory–motor variables such as movement plans or imagined arm position. A population reference-frame analysis demonstrates coding relative to the cued starting hand location suggesting that imagined reaching movements are encoded relative to imagined limb position. These results imply a potential role for primary somatosensory cortex in cognitive imagery, engagement during motor production in the absence of sensation or expected sensation, and suggest that somatosensory cortex can provide control signals for future neural prosthetic systems. Matiar Jafari, Tyson Aflalo et al. show that the human primary somatosensory cortex is activated when subjects imagine reaches in a cognitive motor task, but not when they plan movement or imagine a static limb position. These results highlight a role for this region in cognitive imagery and motor control in the absence of sensory information.
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Affiliation(s)
- Matiar Jafari
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA.,UCLA-Caltech Medical Scientist Training Program, Los Angeles, CA, USA
| | - Tyson Aflalo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA. .,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA.
| | - Srinivas Chivukula
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Department of Neurological Surgery, Los Angeles Medical Center, University of California, Los Angeles, Los Angeles, CA, USA
| | - Spencer Sterling Kellis
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA.,USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, USA.,Department of Neurological Surgery, Keck School of Medicine of USC, Los Angeles, CA, USA
| | | | - Sumner Lee Norman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA
| | - Kelsie Pejsa
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA
| | - Charles Yu Liu
- USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, USA.,Department of Neurological Surgery, Keck School of Medicine of USC, Los Angeles, CA, USA.,Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA
| | - Richard Alan Andersen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Tianqiao and Chrissy Chen Brain-Machine Interface Center, Chen Institute for Neuroscience, California Institute of Technology, Pasadena, CA, USA
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Muret D, Makin TR. The homeostatic homunculus: rethinking deprivation-triggered reorganisation. Curr Opin Neurobiol 2020; 67:115-122. [PMID: 33248404 DOI: 10.1016/j.conb.2020.08.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/15/2020] [Accepted: 08/16/2020] [Indexed: 12/16/2022]
Abstract
While amputation was considered a prominent model for cortical reorganisation, recent evidence highlights persistent representation of the missing hand. We offer a new perspective on the literature of amputation-triggered sensorimotor plasticity, by emphasising the need for homeostasis and emerging evidence of latent activity distributed across the homunculus. We argue that deprivation uncovers pre-existing latent activity, which can manifest as remapping, but that since this activity was already there, remapping could in some instances correspond to functional stability of the system rather than reorganisation. Adaptive behaviour and Hebbian-like plasticity may also play crucial roles in maintaining the functional organisation of the homunculus when deprivation occurs in adulthood or in early development. Collectively, we suggest that the brain's need for stability may underlie several key phenotypes for brain remapping, previously interpreted as consequential to reorganisation. Nevertheless, reorganisation may still be possible, especially when cortical changes contribute to the stability of the system.
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Affiliation(s)
- Dollyane Muret
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom.
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Makin TR, de Vignemont F, Micera S. Soft Embodiment for Engineering Artificial Limbs. Trends Cogn Sci 2020; 24:965-968. [PMID: 33129721 DOI: 10.1016/j.tics.2020.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/17/2020] [Accepted: 09/21/2020] [Indexed: 11/28/2022]
Abstract
We highlight two alternative, yet complementary, solutions for harnessing available neural resources for improving integration of artificial limbs (ALs) through embodiment. 'Hard' embodiment exploits neural and cognitive body mechanisms by closely mimicking their original biological functions. 'Soft' embodiment exploits these same mechanisms by recycling them to support a different function altogether.
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Affiliation(s)
- Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AZ, UK.
| | - Frederique de Vignemont
- Institut Jean Nicod, Département d'études cognitives, École normale supérieure (ENS), École des Hautes Études en Sciences Sociales (EHLESS), Centre national de la recherche scientifique (CNRS), Paris Sciences et Lettres (PSL) University, UMR 8129, 29 rue d'Ulm, 75005 Paris, France
| | - Silvestro Micera
- BioRobotics Institute and Department of Excellence in Robotics and Artificial Intelligence, Scuola Superiore Sant'Anna, viale Rinaldo Piaggio 34, 56025, Pontedera, Italy; Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
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32
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Dempsey-Jones H, Wesselink DB, Friedman J, Makin TR. Organized Toe Maps in Extreme Foot Users. Cell Rep 2020; 28:2748-2756.e4. [PMID: 31509738 PMCID: PMC6899508 DOI: 10.1016/j.celrep.2019.08.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 03/28/2019] [Accepted: 08/05/2019] [Indexed: 12/11/2022] Open
Abstract
Although the fine-grained features of topographic maps in the somatosensory cortex can be shaped by everyday experience, it is unknown whether behavior can support the expression of somatotopic maps where they do not typically occur. Unlike the fingers, represented in all primates, individuated toe maps have only been found in non-human primates. Using 1-mm resolution fMRI, we identify organized toe maps in two individuals born without either upper limb who use their feet to substitute missing hand function and even support their profession as foot artists. We demonstrate that the ordering and structure of the artists’ toe representation mimics typical hand representation. We further reveal “hand-like” features of activity patterns, not only in the foot area but also similarly in the missing hand area. We suggest humans may have an innate capacity for forming additional topographic maps that can be expressed with appropriate experience. We ask if extreme behavior can cause the (re)emergence of somatotopic maps We investigated two foot artists, born without arms 7T fMRI shows individuated maps of up to 5 toes in the artists but not controls Activity in artists’ foot and hand areas was more “hand-like” than in controls
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Affiliation(s)
| | - Daan B Wesselink
- Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford OX3 9DU, UK.
| | - Jason Friedman
- Physical Therapy Department, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 699 7801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 699 7801, Israel
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK
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Makin TR, Flor H. Brain (re)organisation following amputation: Implications for phantom limb pain. Neuroimage 2020; 218:116943. [PMID: 32428706 PMCID: PMC7422832 DOI: 10.1016/j.neuroimage.2020.116943] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 12/11/2022] Open
Abstract
Following arm amputation the region that represented the missing hand in primary somatosensory cortex (S1) becomes deprived of its primary input, resulting in changed boundaries of the S1 body map. This remapping process has been termed 'reorganisation' and has been attributed to multiple mechanisms, including increased expression of previously masked inputs. In a maladaptive plasticity model, such reorganisation has been associated with phantom limb pain (PLP). Brain activity associated with phantom hand movements is also correlated with PLP, suggesting that preserved limb functional representation may serve as a complementary process. Here we review some of the most recent evidence for the potential drivers and consequences of brain (re)organisation following amputation, based on human neuroimaging. We emphasise other perceptual and behavioural factors consequential to arm amputation, such as non-painful phantom sensations, perceived limb ownership, intact hand compensatory behaviour or prosthesis use, which have also been related to both cortical changes and PLP. We also discuss new findings based on interventions designed to alter the brain representation of the phantom limb, including augmented/virtual reality applications and brain computer interfaces. These studies point to a close interaction of sensory changes and alterations in brain regions involved in body representation, pain processing and motor control. Finally, we review recent evidence based on methodological advances such as high field neuroimaging and multivariate techniques that provide new opportunities to interrogate somatosensory representations in the missing hand cortical territory. Collectively, this research highlights the need to consider potential contributions of additional brain mechanisms, beyond S1 remapping, and the dynamic interplay of contextual factors with brain changes for understanding and alleviating PLP.
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Affiliation(s)
- Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom; Wellcome Centre for Human Neuroimaging, University College London, London, UK.
| | - Herta Flor
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Department of Psychology, School of Social Sciences, University of Mannheim, Germany; Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Assessment of cortical reorganization and preserved function in phantom limb pain: a methodological perspective. Sci Rep 2020; 10:11504. [PMID: 32661345 PMCID: PMC7359300 DOI: 10.1038/s41598-020-68206-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 06/19/2020] [Indexed: 02/07/2023] Open
Abstract
Phantom limb pain (PLP) has been associated with reorganization in primary somatosensory cortex (S1) and preserved S1 function. Here we examined if methodological differences in the assessment of cortical representations might explain these findings. We used functional magnetic resonance imaging during a virtual reality movement task, analogous to the classical mirror box task, in twenty amputees with and without PLP and twenty matched healthy controls. We assessed the relationship between task-related activation maxima and PLP intensity in S1 and motor cortex (M1) in individually-defined or group-conjoint regions of interest (ROI) (overlap of task-related activation between the groups). We also measured cortical distances between both locations and correlated them with PLP intensity. Amputees compared to controls showed significantly increased activation in M1, S1 and S1M1 unrelated to PLP. Neural activity in M1 was positively related to PLP intensity in amputees with PLP when a group-conjoint ROI was chosen. The location of activation maxima differed between groups in S1 and M1. Cortical distance measures were unrelated to PLP. These findings suggest that sensory and motor maps differentially relate to PLP and that methodological differences might explain discrepant findings in the literature.
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35
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Kristoffersen MB, Franzke AW, van der Sluis CK, Bongers RM, Murgia A. Should Hands Be Restricted When Measuring Able-Bodied Participants to Evaluate Machine Learning Controlled Prosthetic Hands? IEEE Trans Neural Syst Rehabil Eng 2020; 28:1977-1983. [PMID: 32746317 DOI: 10.1109/tnsre.2020.3007803] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE When evaluating methods for machine-learning controlled prosthetic hands, able-bodied participants are often recruited, for practical reasons, instead of participants with upper limb absence (ULA). However, able-bodied participants have been shown to often perform myoelectric control tasks better than participants with ULA. It has been suggested that this performance difference can be reduced by restricting the wrist and hand movements of able-bodied participants. However, the effect of such restrictions on the consistency and separability of the electromyogram's (EMG) features remains unknown. The present work investigates whether the EMG separability and consistency between unaffected and affected arms differ and whether they change after restricting the unaffected limb in persons with ULA. METHODS Both arms of participants with unilateral ULA were compared in two conditions: with the unaffected hand and wrist restricted or not. Furthermore, it was tested if the effect of arm and restriction is influenced by arm posture (arm down, arm in front, or arm up). RESULTS Fourteen participants (two women, age = 53.4±4.05) with acquired transradial limb loss were recruited. We found that the unaffected limb generated more separated EMG than the affected limb. Furthermore, restricting the unaffected hand and wrist lowered the separability of the EMG when the arm was held down. CONCLUSION Limb restriction is a viable method to make the EMG of able-bodied participants more similar to that of participants with ULA. SIGNIFICANCE Future research that evaluates methods for machine learning controlled hands in able-bodied participants should restrict the participants' hand and wrist.
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Maimon-Mor RO, Makin TR. Is an artificial limb embodied as a hand? Brain decoding in prosthetic limb users. PLoS Biol 2020; 18:e3000729. [PMID: 32511238 PMCID: PMC7302856 DOI: 10.1371/journal.pbio.3000729] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 06/18/2020] [Accepted: 05/20/2020] [Indexed: 02/07/2023] Open
Abstract
The potential ability of the human brain to represent an artificial limb as a body part (embodiment) has been inspiring engineers, clinicians, and scientists as a means to optimise human-machine interfaces. Using functional MRI (fMRI), we studied whether neural embodiment actually occurs in prosthesis users' occipitotemporal cortex (OTC). Compared with controls, different prostheses types were visually represented more similarly to each other, relative to hands and tools, indicating the emergence of a dissociated prosthesis categorisation. Greater daily life prosthesis usage correlated positively with greater prosthesis categorisation. Moreover, when comparing prosthesis users' representation of their own prosthesis to controls' representation of a similar looking prosthesis, prosthesis users represented their own prosthesis more dissimilarly to hands, challenging current views of visual prosthesis embodiment. Our results reveal a use-dependent neural correlate for wearable technology adoption, demonstrating adaptive use-related plasticity within the OTC. Because these neural correlates were independent of the prostheses' appearance and control, our findings offer new opportunities for prosthesis design by lifting restrictions imposed by the embodiment theory for artificial limbs.
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Affiliation(s)
- Roni O. Maimon-Mor
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom
- WIN Centre, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - Tamar R. Makin
- Institute of Cognitive Neuroscience, University College London, London, United Kingdom
- WIN Centre, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom
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Maimon-Mor RO, Schone HR, Moran R, Brugger P, Makin TR. Motor control drives visual bodily judgements. Cognition 2020; 196:104120. [PMID: 31945591 PMCID: PMC7033558 DOI: 10.1016/j.cognition.2019.104120] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 11/17/2022]
Abstract
The 'embodied cognition' framework proposes that our motor repertoire shapes visual perception and cognition. But recent studies showing normal visual body representation in individuals born without hands challenges the contribution of motor control on visual body representation. Here, we studied hand laterality judgements in three groups with fundamentally different visual and motor hand experiences: two-handed controls, one-handers born without a hand (congenital one-handers) and one-handers with an acquired amputation (amputees). Congenital one-handers, lacking both motor and first-person visual information of their missing hand, diverged in their performance from the other groups, exhibiting more errors for their intact hand and slower reaction-times for challenging hand postures. Amputees, who have lingering non-visual motor control of their missing (phantom) hand, performed the task similarly to controls. Amputees' reaction-times for visual laterality judgements correlated positively with their phantom hand's motor control, such that deteriorated motor control associated with slower visual laterality judgements. Finally, we have implemented a computational simulation to describe how a mechanism that utilises a single hand representation in congenital one-handers as opposed to two in controls, could replicate our empirical results. Together, our findings demonstrate that motor control is a driver in making visual bodily judgments.
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Affiliation(s)
- Roni O Maimon-Mor
- Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK; WIN Centre, Nuffield Department of Clinical Neuroscience, University of Oxford, Headington, Oxford OX3 9DU, UK.
| | - Hunter R Schone
- Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK
| | - Rani Moran
- Max Planck University College London Centre for Computational Psychiatry and Ageing Research, University College London, London WC1B 5EH, UK
| | - Peter Brugger
- Department of Neurology, Neuropsychology Unit, University Hospital Zurich, Switzerland
| | - Tamar R Makin
- Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK; WIN Centre, Nuffield Department of Clinical Neuroscience, University of Oxford, Headington, Oxford OX3 9DU, UK
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Stavisky SD, Willett FR, Wilson GH, Murphy BA, Rezaii P, Avansino DT, Memberg WD, Miller JP, Kirsch RF, Hochberg LR, Ajiboye AB, Druckmann S, Shenoy KV, Henderson JM. Neural ensemble dynamics in dorsal motor cortex during speech in people with paralysis. eLife 2019; 8:e46015. [PMID: 31820736 PMCID: PMC6954053 DOI: 10.7554/elife.46015] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 11/14/2019] [Indexed: 01/20/2023] Open
Abstract
Speaking is a sensorimotor behavior whose neural basis is difficult to study with single neuron resolution due to the scarcity of human intracortical measurements. We used electrode arrays to record from the motor cortex 'hand knob' in two people with tetraplegia, an area not previously implicated in speech. Neurons modulated during speaking and during non-speaking movements of the tongue, lips, and jaw. This challenges whether the conventional model of a 'motor homunculus' division by major body regions extends to the single-neuron scale. Spoken words and syllables could be decoded from single trials, demonstrating the potential of intracortical recordings for brain-computer interfaces to restore speech. Two neural population dynamics features previously reported for arm movements were also present during speaking: a component that was mostly invariant across initiating different words, followed by rotatory dynamics during speaking. This suggests that common neural dynamical motifs may underlie movement of arm and speech articulators.
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Affiliation(s)
- Sergey D Stavisky
- Department of NeurosurgeryStanford UniversityStanfordUnited States
- Department of Electrical EngineeringStanford UniversityStanfordUnited States
| | - Francis R Willett
- Department of NeurosurgeryStanford UniversityStanfordUnited States
- Department of Electrical EngineeringStanford UniversityStanfordUnited States
| | - Guy H Wilson
- Neurosciences ProgramStanford UniversityStanfordUnited States
| | - Brian A Murphy
- Department of Biomedical EngineeringCase Western Reserve UniversityClevelandUnited States
- FES Center, Rehab R&D ServiceLouis Stokes Cleveland Department of Veterans Affairs Medical CenterClevelandUnited States
| | - Paymon Rezaii
- Department of NeurosurgeryStanford UniversityStanfordUnited States
| | | | - William D Memberg
- Department of Biomedical EngineeringCase Western Reserve UniversityClevelandUnited States
- FES Center, Rehab R&D ServiceLouis Stokes Cleveland Department of Veterans Affairs Medical CenterClevelandUnited States
| | - Jonathan P Miller
- FES Center, Rehab R&D ServiceLouis Stokes Cleveland Department of Veterans Affairs Medical CenterClevelandUnited States
- Department of NeurosurgeryUniversity Hospitals Cleveland Medical CenterClevelandUnited States
| | - Robert F Kirsch
- Department of Biomedical EngineeringCase Western Reserve UniversityClevelandUnited States
- FES Center, Rehab R&D ServiceLouis Stokes Cleveland Department of Veterans Affairs Medical CenterClevelandUnited States
| | - Leigh R Hochberg
- VA RR&D Center for Neurorestoration and Neurotechnology, Rehabilitation R&D ServiceProvidence VA Medical CenterProvidenceUnited States
- Center for Neurotechnology and Neurorecovery, Department of NeurologyMassachusetts General Hospital, Harvard Medical SchoolBostonUnited States
- School of Engineering and Robert J. & Nandy D. Carney Institute for Brain ScienceBrown UniversityProvidenceUnited States
| | - A Bolu Ajiboye
- Department of Biomedical EngineeringCase Western Reserve UniversityClevelandUnited States
- FES Center, Rehab R&D ServiceLouis Stokes Cleveland Department of Veterans Affairs Medical CenterClevelandUnited States
| | - Shaul Druckmann
- Department of NeurobiologyStanford UniversityStanfordUnited States
| | - Krishna V Shenoy
- Department of Electrical EngineeringStanford UniversityStanfordUnited States
- Department of NeurobiologyStanford UniversityStanfordUnited States
- Department of BioengineeringStanford UniversityStanfordUnited States
- Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Wu Tsai Neurosciences InstituteStanford UniversityStanfordUnited States
- Bio-X ProgramStanford UniversityStanfordUnited States
| | - Jaimie M Henderson
- Department of NeurosurgeryStanford UniversityStanfordUnited States
- Wu Tsai Neurosciences InstituteStanford UniversityStanfordUnited States
- Bio-X ProgramStanford UniversityStanfordUnited States
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Valyear KF, Philip BA, Cirstea CM, Chen PW, Baune NA, Marchal N, Frey SH. Interhemispheric transfer of post-amputation cortical plasticity within the human somatosensory cortex. Neuroimage 2019; 206:116291. [PMID: 31639508 DOI: 10.1016/j.neuroimage.2019.116291] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/27/2019] [Accepted: 10/16/2019] [Indexed: 11/15/2022] Open
Abstract
Animal models reveal that deafferenting forelimb injuries precipitate reorganization in both contralateral and ipsilateral somatosensory cortices. The functional significance and duration of these effects are unknown, and it is unclear whether they also occur in injured humans. We delivered cutaneous stimulation during functional magnetic resonance imaging (fMRI) to map the sensory cortical representation of the intact hand and lower face in a group of chronic, unilateral, upper extremity amputees (N = 19) and healthy matched controls (N = 29). Amputees exhibited greater activity than controls within the deafferented former sensory hand territory (S1f) during stimulation of the intact hand, but not of the lower face. Despite this cortical reorganization, amputees did not differ from controls in tactile acuity on their intact hands. S1f responses during hand stimulation were unrelated to tactile acuity, pain, prosthesis usage, or time since amputation. These effects appeared specific to the deafferented somatosensory modality, as fMRI visual mapping paradigm failed to detect any differences between groups. We conclude that S1f becomes responsive to cutaneous stimulation of the intact hand of amputees, and that this modality-specific reorganizational change persists for many years, if not indefinitely. The functional relevance of these changes, if any, remains unknown.
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Affiliation(s)
- Kenneth F Valyear
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; School of Psychology, Bangor University, Bangor, UK
| | - Benjamin A Philip
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
| | - Carmen M Cirstea
- Department of Physical Medicine and Rehabilitation, University of Missouri School of Medicine, Columbia, MO, USA
| | - Pin-Wei Chen
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
| | - Nathan A Baune
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
| | - Noah Marchal
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; College of Engineering, University of Missouri, Columbia, MO, USA
| | - Scott H Frey
- Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Department of Physical Medicine and Rehabilitation, University of Missouri School of Medicine, Columbia, MO, USA.
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40
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Christie BP, Charkhkar H, Shell CE, Marasco PD, Tyler DJ, Triolo RJ. Visual inputs and postural manipulations affect the location of somatosensory percepts elicited by electrical stimulation. Sci Rep 2019; 9:11699. [PMID: 31406122 PMCID: PMC6690924 DOI: 10.1038/s41598-019-47867-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/25/2019] [Indexed: 12/02/2022] Open
Abstract
The perception of somatosensation requires the integration of multimodal information, yet the effects of vision and posture on somatosensory percepts elicited by neural stimulation are not well established. In this study, we applied electrical stimulation directly to the residual nerves of trans-tibial amputees to elicit sensations referred to their missing feet. We evaluated the influence of congruent and incongruent visual inputs and postural manipulations on the perceived size and location of stimulation-evoked somatosensory percepts. We found that although standing upright may cause percept size to change, congruent visual inputs and/or body posture resulted in better localization. We also observed visual capture: the location of a somatosensory percept shifted toward a visual input when vision was incongruent with stimulation-induced sensation. Visual capture did not occur when an adopted posture was incongruent with somatosensation. Our results suggest that internal model predictions based on postural manipulations reinforce perceived sensations, but do not alter them. These characterizations of multisensory integration are important for the development of somatosensory-enabled prostheses because current neural stimulation paradigms cannot replicate the afferent signals of natural tactile stimuli. Nevertheless, multisensory inputs can improve perceptual precision and highlight regions of the foot important for balance and locomotion.
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Affiliation(s)
- Breanne P Christie
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA. .,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA.
| | - Hamid Charkhkar
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
| | - Courtney E Shell
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Paul D Marasco
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Dustin J Tyler
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
| | - Ronald J Triolo
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
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Friston KJ, Diedrichsen J, Holmes E, Zeidman P. Variational representational similarity analysis. Neuroimage 2019; 201:115986. [PMID: 31255808 PMCID: PMC6892264 DOI: 10.1016/j.neuroimage.2019.06.064] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 06/24/2019] [Accepted: 06/27/2019] [Indexed: 01/09/2023] Open
Abstract
This technical note describes a variational or Bayesian implementation of representational similarity analysis (RSA) and pattern component modelling (PCM). It considers RSA and PCM as Bayesian model comparison procedures that assess the evidence for stimulus or condition-specific patterns of responses distributed over voxels or channels. On this view, one can use standard variational inference procedures to quantify the contributions of particular patterns to the data, by evaluating second-order parameters or hyperparameters. Crucially, this allows one to use parametric empirical Bayes (PEB) to infer which patterns are consistent among subjects. At the between-subject level, one can then assess the evidence for different (combinations of) hypotheses about condition-specific effects using Bayesian model comparison. Alternatively, one can select a single hypothesis that best explains the pattern of responses using Bayesian model selection. This note rehearses the technical aspects of within and between-subject RSA using a worked example, as implemented in the Statistical Parametric Mapping (SPM) software. En route, we highlight the connection between univariate and multivariate analyses of neuroimaging data and the sorts of analyses that are possible using component modelling and representational similarity analysis. We introduce variational RSA, a method for multivariate analysis in neuroimaging. This treats RSA a standard covariance component estimation problem. An efficient estimation scheme, variational Laplace, is used to estimate parameters. Bayesian model comparison is used to optimally test for mixtures of effects. We illustrate the approach using simulated and empirical fMRI data.
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Affiliation(s)
- Karl J Friston
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, UCL, WC1N 3AR, UK.
| | - Jörn Diedrichsen
- Brain and Mind Institute, Department for Statistical and Actuarial Sciences, Department for Computer Science, University of Western Ontario, Canada.
| | - Emma Holmes
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, UCL, WC1N 3AR, UK.
| | - Peter Zeidman
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, UCL, WC1N 3AR, UK.
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