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Snir A, Cieśla K, Ozdemir G, Vekslar R, Amedi A. Localizing 3D motion through the fingertips: Following in the footsteps of elephants. iScience 2024; 27:109820. [PMID: 38799571 PMCID: PMC11126990 DOI: 10.1016/j.isci.2024.109820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/07/2024] [Accepted: 04/24/2024] [Indexed: 05/29/2024] Open
Abstract
Each sense serves a different specific function in spatial perception, and they all form a joint multisensory spatial representation. For instance, hearing enables localization in the entire 3D external space, while touch traditionally only allows localization of objects on the body (i.e., within the peripersonal space alone). We use an in-house touch-motion algorithm (TMA) to evaluate individuals' capability to understand externalized 3D information through touch, a skill that was not acquired during an individual's development or in evolution. Four experiments demonstrate quick learning and high accuracy in localization of motion using vibrotactile inputs on fingertips and successful audio-tactile integration in background noise. Subjective responses in some participants imply spatial experiences through visualization and perception of tactile "moving" sources beyond reach. We discuss our findings with respect to developing new skills in an adult brain, including combining a newly acquired "sense" with an existing one and computation-based brain organization.
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Affiliation(s)
- Adi Snir
- The Baruch Ivcher Institute for Brain, Cognition, and Technology, The Baruch Ivcher School of Psychology, Reichman University, HaUniversita 8, Herzliya 461010, Israel
| | - Katarzyna Cieśla
- The Baruch Ivcher Institute for Brain, Cognition, and Technology, The Baruch Ivcher School of Psychology, Reichman University, HaUniversita 8, Herzliya 461010, Israel
- World Hearing Centre, Institute of Physiology and Pathology of Hearing, Mokra 17, 05-830 Kajetany, Nadarzyn, Poland
| | - Gizem Ozdemir
- The Baruch Ivcher Institute for Brain, Cognition, and Technology, The Baruch Ivcher School of Psychology, Reichman University, HaUniversita 8, Herzliya 461010, Israel
| | - Rotem Vekslar
- The Baruch Ivcher Institute for Brain, Cognition, and Technology, The Baruch Ivcher School of Psychology, Reichman University, HaUniversita 8, Herzliya 461010, Israel
| | - Amir Amedi
- The Baruch Ivcher Institute for Brain, Cognition, and Technology, The Baruch Ivcher School of Psychology, Reichman University, HaUniversita 8, Herzliya 461010, Israel
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2
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Ng KKW, Lafee O, Bouchatta O, Makdani AD, Marshall AG, Olausson H, McIntyre S, Nagi SS. Human Foot Outperforms the Hand in Mechanical Pain Discrimination. eNeuro 2024; 11:ENEURO.0412-23.2024. [PMID: 38272674 PMCID: PMC10875634 DOI: 10.1523/eneuro.0412-23.2024] [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: 09/25/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/27/2024] Open
Abstract
Tactile discrimination has been extensively studied, but mechanical pain discrimination remains poorly characterized. Here, we measured the capacity for mechanical pain discrimination using a two-alternative forced choice paradigm, with force-calibrated indentation stimuli (Semmes-Weinstein monofilaments) applied to the hand and foot dorsa of healthy human volunteers. In order to characterize the relationship between peripheral nociceptor activity and pain perception, we recorded single-unit activity from myelinated (A) and unmyelinated (C) mechanosensitive nociceptors in the skin using microneurography. At the perceptual level, we found that the foot was better at discriminating noxious forces than the hand, which stands in contrast to that for innocuous force discrimination, where the hand performed better than the foot. This observation of superior mechanical pain discrimination on the foot compared to the hand could not be explained by the responsiveness of individual nociceptors. We found no significant difference in the discrimination performance of either the myelinated or unmyelinated class of nociceptors between skin regions. This suggests the possibility that other factors such as skin biophysics, receptor density or central mechanisms may underlie these regional differences.
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Affiliation(s)
- Kevin K W Ng
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Odai Lafee
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Otmane Bouchatta
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Adarsh D Makdani
- Research Centre for Brain and Behaviour, School of Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Andrew G Marshall
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Håkan Olausson
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Sarah McIntyre
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Saad S Nagi
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
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3
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Mohamadi M, Meftahi N, Javidi-Alsaadi P. Comparison of tactile acuity between patients with chronic patellofemoral pain with central sensitization and healthy persons: A cross-sectional study. Physiother Theory Pract 2024:1-7. [PMID: 38165123 DOI: 10.1080/09593985.2023.2300040] [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: 06/26/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND Patellofemoral pain (PFP) is a common multifactorial condition in young and physically active people. OBJECTIVE The occurrence of central sensitization may play an important role in sensory disturbance. This study was designed to investigate, in patients with chronic PFP, the presence of disturbances in tactile acuity with central sensitization. METHODS Thirty patients with chronic PFP and 30 matched healthy controls entered this cross-sectional study. Graphesthesia (numerical score), two-point discrimination (mm), and point-to-point sensation (mm) were assessed in all participants. RESULTS The results of between-group comparisons showed that there were significant differences between the involved knee in patients with chronic PFP and healthy participants in graphesthesia (median = 13 [case], 19 [control]; p < .001), two-point discrimination (median = 25.8 [case], 20.3 [control]; p < .001), and point-to-point sensation (median = 14.5 [case], 6.2 [control]; p < .001). There was also a significant difference in graphesthesia between the non-involved knee in patients with chronic PFP and healthy participants (median = 17 [case], 19 [control]; p = .003). The results of within-group comparisons revealed a significant difference in graphesthesia, two-point discrimination, and point-to-point sensation between the involved and non-involved knee in patients with chronic PFP (p < .001). Moreover, there was a positive correlation between two-point discrimination and pain in patients with chronic PFP (r = 0.446, p = .014). CONCLUSION The findings of this study reveal that there is a sensory deficit in patients with chronic PFP. Because sensory information is necessary for motor control and pain perception, we can assume that clinical symptoms in these patients are related to sensory deficits.
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Affiliation(s)
- Marzieh Mohamadi
- Rehabilitation Research Center, Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
| | - Narges Meftahi
- Rehabilitation Research Center, Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
| | - Pouria Javidi-Alsaadi
- Rehabilitation Research Center, Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
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4
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Brewer AA, Barton B. Cortical field maps across human sensory cortex. Front Comput Neurosci 2023; 17:1232005. [PMID: 38164408 PMCID: PMC10758003 DOI: 10.3389/fncom.2023.1232005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 11/07/2023] [Indexed: 01/03/2024] Open
Abstract
Cortical processing pathways for sensory information in the mammalian brain tend to be organized into topographical representations that encode various fundamental sensory dimensions. Numerous laboratories have now shown how these representations are organized into numerous cortical field maps (CMFs) across visual and auditory cortex, with each CFM supporting a specialized computation or set of computations that underlie the associated perceptual behaviors. An individual CFM is defined by two orthogonal topographical gradients that reflect two essential aspects of feature space for that sense. Multiple adjacent CFMs are then organized across visual and auditory cortex into macrostructural patterns termed cloverleaf clusters. CFMs within cloverleaf clusters are thought to share properties such as receptive field distribution, cortical magnification, and processing specialization. Recent measurements point to the likely existence of CFMs in the other senses, as well, with topographical representations of at least one sensory dimension demonstrated in somatosensory, gustatory, and possibly olfactory cortical pathways. Here we discuss the evidence for CFM and cloverleaf cluster organization across human sensory cortex as well as approaches used to identify such organizational patterns. Knowledge of how these topographical representations are organized across cortex provides us with insight into how our conscious perceptions are created from our basic sensory inputs. In addition, studying how these representations change during development, trauma, and disease serves as an important tool for developing improvements in clinical therapies and rehabilitation for sensory deficits.
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Affiliation(s)
- Alyssa A. Brewer
- mindSPACE Laboratory, Departments of Cognitive Sciences and Language Science (by Courtesy), Center for Hearing Research, University of California, Irvine, Irvine, CA, United States
| | - Brian Barton
- mindSPACE Laboratory, Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, United States
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5
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Asghar M, Sanchez-Panchuelo R, Schluppeck D, Francis S. Two-Dimensional Population Receptive Field Mapping of Human Primary Somatosensory Cortex. Brain Topogr 2023; 36:816-834. [PMID: 37634160 PMCID: PMC10522535 DOI: 10.1007/s10548-023-01000-8] [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: 05/10/2023] [Accepted: 08/09/2023] [Indexed: 08/29/2023]
Abstract
Functional magnetic resonance imaging can provide detailed maps of how sensory space is mapped in the human brain. Here, we use a novel 16 stimulator setup (a 4 × 4 grid) to measure two-dimensional sensory maps of between and within-digit (D2-D4) space using high spatial-resolution (1.25 mm isotropic) imaging at 7 Tesla together with population receptive field (pRF) mapping in 10 participants. Using a 2D Gaussian pRF model, we capture maps of the coverage of digits D2-D5 across Brodmann areas and estimate pRF size and shape. In addition, we compare results to previous studies that used fewer stimulators by constraining pRF models to a 1D Gaussian Between Digit or 1D Gaussian Within Digit model. We show that pRFs across somatosensory areas tend to have a strong preference to cover the within-digit axis. We show an increase in pRF size moving from D2-D5. We quantify pRF shapes in Brodmann area (BA) 3b, 3a, 1, 2 and show differences in pRF size in Brodmann areas 3a-2, with larger estimates for BA2. Generally, the 2D Gaussian pRF model better represents pRF coverage maps generated by our data, which itself is produced from a 2D stimulation grid.
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Affiliation(s)
- Michael Asghar
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK.
| | - Rosa Sanchez-Panchuelo
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- University Hospitals Birmingham NHS Foundation Trust, Nottingham, UK
| | | | - Susan Francis
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
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6
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Paredes Sanchez J, Titmus M, Lawson-Smith H, Di Pietro F. Tactile acuity improves during acute experimental pain of the limb. Pain Rep 2023; 8:e1091. [PMID: 38225958 PMCID: PMC10789456 DOI: 10.1097/pr9.0000000000001091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 05/18/2023] [Accepted: 05/26/2023] [Indexed: 01/17/2024] Open
Abstract
Introduction Chronic pain is associated with poor tactile acuity, commonly measured with the 2-point discrimination (TPD) test. Although poor tactile acuity across chronic pain conditions is well established, less is known in acute pain. Objective Recent conflicting findings in experimentally induced neck and back pain led us to conduct a TPD investigation in experimentally induced limb pain. We hypothesised altered TPD during experimental upper limb pain, but we did not speculate on the direction of the change. Methods Thirty healthy subjects immersed their dominant hand in a circulating cold-water bath at 7°C (cold pressor test [CPT]). Two-point discrimination was measured at baseline (pre-CPT), during pain (during-CPT), and after withdrawal from the water (post-CPT) in 3 different sites: (1) the dominant forearm, (2) dominant arm and (3) contralateral forearm. Results Repeated-measures analysis of variance revealed a significant main effect of time (F(2,56) = 4.45, P = 0.02, η p 2 = 0.14) on TPD; in all 3 sites, TPD values decreased (ie, tactile acuity improved) during pain. Interestingly, the contralateral forearm followed a similar pattern to the dominant (ie, painful) forearm, and furthermore was the only site that exhibited any correlation with pain, albeit in an intriguing direction (r = 0.57, P = 0.001), ie, the greater the pain the worse the tactile acuity. Conclusion The improvements in tactile acuity during experimentally induced limb pain may reflect a protective response. The changes in the corresponding site in the contralateral limb may reflect a protective spinal cross talk. Such a response, together with the interesting relationship between tactile acuity and pain, warrant further inquiry.
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Affiliation(s)
| | - Morgan Titmus
- Curtin Medical School, Curtin University, Western Australia, Australia
| | | | - Flavia Di Pietro
- Curtin Medical School, Curtin University, Western Australia, Australia
- Curtin Health and Innovation Research Institute (CHIRI), Curtin University, Western Australia, Australia
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7
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Kromer JA, Tass PA. Synaptic reshaping of plastic neuronal networks by periodic multichannel stimulation with single-pulse and burst stimuli. PLoS Comput Biol 2022; 18:e1010568. [PMID: 36327232 PMCID: PMC9632832 DOI: 10.1371/journal.pcbi.1010568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/14/2022] [Indexed: 11/06/2022] Open
Abstract
Synaptic dysfunction is associated with several brain disorders, including Alzheimer's disease, Parkinson's disease (PD) and obsessive compulsive disorder (OCD). Utilizing synaptic plasticity, brain stimulation is capable of reshaping synaptic connectivity. This may pave the way for novel therapies that specifically counteract pathological synaptic connectivity. For instance, in PD, novel multichannel coordinated reset stimulation (CRS) was designed to counteract neuronal synchrony and down-regulate pathological synaptic connectivity. CRS was shown to entail long-lasting therapeutic aftereffects in PD patients and related animal models. This is in marked contrast to conventional deep brain stimulation (DBS) therapy, where PD symptoms return shortly after stimulation ceases. In the present paper, we study synaptic reshaping by periodic multichannel stimulation (PMCS) in networks of leaky integrate-and-fire (LIF) neurons with spike-timing-dependent plasticity (STDP). During PMCS, phase-shifted periodic stimulus trains are delivered to segregated neuronal subpopulations. Harnessing STDP, PMCS leads to changes of the synaptic network structure. We found that the PMCS-induced changes of the network structure depend on both the phase lags between stimuli and the shape of individual stimuli. Single-pulse stimuli and burst stimuli with low intraburst frequency down-regulate synapses between neurons receiving stimuli simultaneously. In contrast, burst stimuli with high intraburst frequency up-regulate these synapses. We derive theoretical approximations of the stimulation-induced network structure. This enables us to formulate stimulation strategies for inducing a variety of network structures. Our results provide testable hypotheses for future pre-clinical and clinical studies and suggest that periodic multichannel stimulation may be suitable for reshaping plastic neuronal networks to counteract pathological synaptic connectivity. Furthermore, we provide novel insight on how the stimulus type may affect the long-lasting outcome of conventional DBS. This may strongly impact parameter adjustment procedures for clinical DBS, which, so far, primarily focused on acute effects of stimulation.
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Affiliation(s)
- Justus A Kromer
- Department of Neurosurgery, Stanford University, Stanford, California, United States of America
| | - Peter A Tass
- Department of Neurosurgery, Stanford University, Stanford, California, United States of America
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8
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Edmondson LR, Jiménez Rodríguez A, Saal HP. Expansion and contraction of resource allocation in sensory bottlenecks. eLife 2022; 11:70777. [PMID: 35924884 PMCID: PMC9391039 DOI: 10.7554/elife.70777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/29/2022] [Indexed: 11/22/2022] Open
Abstract
Topographic sensory representations often do not scale proportionally to the size of their input regions, with some expanded and others contracted. In vision, the foveal representation is magnified cortically, as are the fingertips in touch. What principles drive this allocation, and how should receptor density, for example, the high innervation of the fovea or the fingertips, and stimulus statistics, for example, the higher contact frequencies on the fingertips, contribute? Building on work in efficient coding, we address this problem using linear models that optimally decorrelate the sensory signals. We introduce a sensory bottleneck to impose constraints on resource allocation and derive the optimal neural allocation. We find that bottleneck width is a crucial factor in resource allocation, inducing either expansion or contraction. Both receptor density and stimulus statistics affect allocation and jointly determine convergence for wider bottlenecks. Furthermore, we show a close match between the predicted and empirical cortical allocations in a well-studied model system, the star-nosed mole. Overall, our results suggest that the strength of cortical magnification depends on resource limits.
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Affiliation(s)
- Laura R Edmondson
- Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | | | - Hannes P Saal
- Department of Psychology, University of Sheffield, Sheffield, United Kingdom
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9
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Vittersø AD, Halicka M, Buckingham G, Proulx MJ, Bultitude JH. The sensorimotor theory of pathological pain revisited. Neurosci Biobehav Rev 2022; 139:104735. [PMID: 35705110 DOI: 10.1016/j.neubiorev.2022.104735] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/13/2022] [Accepted: 06/07/2022] [Indexed: 01/31/2023]
Abstract
Harris (1999) proposed that pain can arise in the absence of tissue damage because changes in the cortical representation of the painful body part lead to incongruences between motor intention and sensory feedback. This idea, subsequently termed the sensorimotor theory of pain, has formed the basis for novel treatments for pathological pain. Here we review the evidence that people with pathological pain have changes to processes contributing to sensorimotor function: motor function, sensory feedback, cognitive representations of the body and its surrounding space, multisensory processing, and sensorimotor integration. Changes to sensorimotor processing are most evident in the form of motor deficits, sensory changes, and body representations distortions, and for Complex Regional Pain Syndrome (CRPS), fibromyalgia, and low back pain. Many sensorimotor changes are related to cortical processing, pain, and other clinical characteristics. However, there is very limited evidence that changes in sensorimotor processing actually lead to pain. We therefore propose that the theory is more appropriate for understanding why pain persists rather than how it arises.
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Affiliation(s)
- Axel D Vittersø
- Centre for Pain Research, University of Bath, Bath, Somerset, United Kingdom; Department of Psychology, University of Bath, Bath, Somerset, United Kingdom; Department of Sport & Health Sciences, University of Exeter, Exeter, Devon, United Kingdom; Department of Psychology, Oslo New University College, Oslo, Norway.
| | - Monika Halicka
- Centre for Pain Research, University of Bath, Bath, Somerset, United Kingdom; Department of Psychology, University of Bath, Bath, Somerset, United Kingdom
| | - Gavin Buckingham
- Department of Sport & Health Sciences, University of Exeter, Exeter, Devon, United Kingdom
| | - Michael J Proulx
- Department of Psychology, University of Bath, Bath, Somerset, United Kingdom; Centre for Real and Virtual Environments Augmentation Labs, Department of Computer Science, University of Bath, Bath, Somerset, United Kingdom
| | - Janet H Bultitude
- Centre for Pain Research, University of Bath, Bath, Somerset, United Kingdom; Department of Psychology, University of Bath, Bath, Somerset, United Kingdom
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10
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Longo MR. Distortion of mental body representations. Trends Cogn Sci 2022; 26:241-254. [PMID: 34952785 DOI: 10.1016/j.tics.2021.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 11/18/2021] [Accepted: 11/21/2021] [Indexed: 01/07/2023]
Abstract
Our body is central to our sense of self, and distorted body representations are found in several serious medical conditions. This paper reviews evidence that distortions of body representations are also common in healthy individuals, and occur in domains including tactile spatial perception, proprioception, and the conscious body image. Across domains, there is a general tendency for body width to be overestimated compared to body length. Intriguingly, distortions in both eating disorders and chronic pain appear to be exaggerations of this baseline pattern of distortions, suggesting that these conditions may relate to dysfunction of mechanisms for body perception. Distortions of body representations provide a revealing window into basic aspects of self-perception.
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Affiliation(s)
- Matthew R Longo
- Department of Psychological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK.
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11
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Metzger A, Toscani M, Valsecchi M, Drewing K. Target Search and Inspection Strategies in Haptic Search. IEEE TRANSACTIONS ON HAPTICS 2021; 14:804-815. [PMID: 33929965 DOI: 10.1109/toh.2021.3076847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Haptic search is a common everyday task, usually consisting of two processes: target search and target analysis. During target search we need to know where our fingers are in space, remember the already completed path and the outline of the remaining space. During target analysis we need to understand whether the detected potential target is the desired one. Here we characterized dynamics of exploratory movements in these two processes. In our experiments participants searched for a particular configuration of symbols on a rectangular tactile display. We observed that participants preferentially moved the hand parallel to the edges of the tactile display during target search, which possibly eased orientation within the search space. After a potential target was detected by any of the fingers, there was higher probability that subsequent exploration was performed by the index or the middle finger. At the same time, these fingers dramatically slowed down. Being in contact with the potential target, the index and the middle finger moved within a smaller area than the other fingers, which rather seemed to move away to leave them space. These results suggest that the middle and the index finger are specialized for fine analysis in haptic search.
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12
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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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13
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Lu F, Wang M, Xu S, Chen H, Yuan Z, Luo L, Wang X, Zhang J, Dai J, Wang X, Chen H, Zhou J. Decreased interhemispheric resting-state functional connectivity in male adolescents with conduct disorder. Brain Imaging Behav 2021; 15:1201-1210. [PMID: 32623563 DOI: 10.1007/s11682-020-00320-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Conduct disorder (CD) is a common psychiatric disorder defined by a repetitive and persistent pattern of aggressive and antisocial behaviors. Although numerous task-based and resting-state functional magnetic resonance imaging (rsfMRI) studies have emphasized the disrupted functional connectivity in CD, the CD-related alterations in functional interactions between the bilateral cerebral hemispheres are rarely investigated directly. In this study, a voxel-mirrored homotopic connectivity (VMHC) method based on rsfMRI was employed for the first time to examine the abnormalities of interhemispheric functional connectivity in patients with CD. The VMHC was compared between eighteen pure CD patients and eighteen typically developing (TD) healthy controls. In CD patients, reduced homotopic connectivity was observed relative to TDs in the middle occipital gyrus (MOG), pre- and postcentral gyrus, rolandic operculum and paracentral lobe (PCL) which were the components of visual and motor networks. Furthermore, the VMHC of the MOG and PCL was found to be negatively correlated with clinical scores in the CD group. Moreover, the regions with altered VMHC exhibited a relative good and robust ability to discriminate CD patients from TDs. This study provided a novel angle to identify the important role of interhemispheric coordination in the pathophysiology underlying CD and further indicated that the aberrant homotopic connectivity could be a potential clinical neural marker for CD diagnosis.
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Affiliation(s)
- Fengmei Lu
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China.,MOE Key Lab for Neuroinformation, High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Mengyun Wang
- Faculty of Health Sciences, University of Macau, Macau, China
| | - Shiyang Xu
- Faculty of Health Sciences, University of Macau, Macau, China.,Centre for Cognitive and Brain Sciences, University of Macau, Macau, China
| | - Heng Chen
- School of Medicine, Guizhou University, Guizhou, China
| | - Zhen Yuan
- Faculty of Health Sciences, University of Macau, Macau, China.,Centre for Cognitive and Brain Sciences, University of Macau, Macau, China
| | - Lizhu Luo
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiuli Wang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
| | - Jiang Zhang
- Department of Medical Information Engineering, Sichuan University, Chengdu, 610065, China
| | - Jing Dai
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiaoping Wang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, China.,National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China
| | - Huafu Chen
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China.,MOE Key Lab for Neuroinformation, High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Jiansong Zhou
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, China. .,National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China.
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Computational approach to understand temporal and spatial tactile transmission processes from mechanical stimuli of the index fingertip to the primary somatosensory cortex. J Neurosci Methods 2021; 359:109215. [PMID: 33957157 DOI: 10.1016/j.jneumeth.2021.109215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 04/15/2021] [Accepted: 04/29/2021] [Indexed: 11/23/2022]
Abstract
Mechanisms of information transmission using tactile sense are one of major concerns in producing simulated experience in virtual or augmented reality as well as in compensating elderly or impaired people with diminished tactile sensory function. However, important mechanism of the difference of peak latency in the primary somatosensory cortex (SI) between electrical and mechanical stimulations of finger skin is not fully understood. We propose a computational approach to fuse a computational model to simulate temporal and spatial transmission processes from mechanical stimuli to the SI and experimental method using a magnetoencephalograph (MEG). In our model, a tactile model that combined a three-dimensional mechanical model of fingertip skin and a neurophysiological model of a slowly adapting type 1 (SA1) mechanoreceptor was integrated with a somatosensory evoked field (SEF) response model. Electrical and mechanical stimulations were applied to the same locations of the right or left index fingertips of three subjects using a MEG. By identifying parameters of the SEF response model using the electrical stimulation test data, predicted first peak latency due to a mechanical stimulus was identical to its average value obtained from the mechanical stimulation test data, while the spatial map predicted at the multiple SA1 receptors qualitatively corresponded to the MEG image map in the timings of peak latency. This suggests that mechanical change in the skin and neurophysiological responses generate the difference of peak latency in SI between electrical and mechanical stimulations. The computational approach has the potential for detailed investigation of mechanisms of tactile information transmission.
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Lu F, Zhao Y, He Z, Ma X, Yao X, Liu P, Wang X, Yang G, Zhou J. Altered dynamic regional homogeneity in patients with conduct disorder. Neuropsychologia 2021; 157:107865. [PMID: 33894243 DOI: 10.1016/j.neuropsychologia.2021.107865] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/23/2021] [Accepted: 04/18/2021] [Indexed: 10/21/2022]
Abstract
Conduct disorder (CD) is a psychiatric condition characterized by severe aggressive and antisocial behaviors. Prior neuroimaging work reported that CD is associated with abnormal resting-state local intrinsic brain activity (IBA). However, few studies detected the time-varying brain activity patterns in CD. In this study, eighteen adolescent patients with CD and 18 typically developing controls underwent resting-state functional magnetic resonance imaging scans. We then compared the dynamic characteristics of IBA by calculating the dynamic regional homogeneity (dReHo) through a sliding-window approach between the two groups, and the correlations between the dReHo variability and clinical symptoms in CD were further examined. Moreover, the statistical between-group differences in dReHo were selected as classification features to help distinguish CD patients from controls by adopting a linear support vector machine (SVM) classifier. CD patients showed increased dReHo variability in the left precuneus, right postcentral gyrus, right precentral gyrus, left middle cingulate gyrus, and left paracentral lobule compared to controls, and dReHo variability in the left precuneus was significantly positively associated with impulsiveness scores in CD patients. Importantly, SVM combined with the leave-one-out cross-validation method results demonstrated that 75% (p < 0.001) subjects were correctly classified with sensitivity of 61% and specificity of 89%. Our results provided the initial evidence that CD is characterized by abnormal dynamic IBA patterns, giving novel insights into the neuropathological mechanisms of CD. Further, our findings exhibited that the dReHo variability may distinguish CD patients from controls with high accuracy.
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Affiliation(s)
- Fengmei Lu
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Yi Zhao
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Zongling He
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xujing Ma
- Department of Medical Technology, Cangzhou Medical College, Cangzhou, 061001, PR China
| | - Xudong Yao
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Peiqu Liu
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China
| | - Xiaoping Wang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China
| | - Guocheng Yang
- Department of Information Science and Technology, Chengdu University of Technology, China.
| | - Jiansong Zhou
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China.
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Härtner J, Strauss S, Pfannmöller J, Lotze M. Tactile acuity of fingertips and hand representation size in human Area 3b and Area 1 of the primary somatosensory cortex. Neuroimage 2021; 232:117912. [PMID: 33652142 DOI: 10.1016/j.neuroimage.2021.117912] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 02/20/2021] [Accepted: 02/21/2021] [Indexed: 11/26/2022] Open
Abstract
Intracortical mapping in monkeys revealed a full body map in all four cytoarchitectonic subdivisions of the contralateral primary somatosensory cortex (S1), as well as positive associations between spatio-tactile acuity performance of the fingers and their representation field size especially within cytoarchitectonic Area 3b and Area 1. Previous non-invasive investigations on these associations in humans assumed a monotonous decrease of representation field size from index finger to little finger although the field sizes are known to change in response to training or in disease. Recent developments improved noninvasive functional mapping of S1 by a) adding a cognitive task during repetitive stimulation to decrease habituation to the stimuli, b) smaller voxel size of fMRI-sequences, c) surface-based analysis accounting for cortical curvature, and d) increase of spatial specificity for fMRI data analysis by avoidance of smoothing, partial volume effects, and pial vein signals. We here applied repetitive pneumatic stimulation of digit 1 (D1; thumb) and digit 5 (D5; little finger) on both hands to investigate finger/hand representation maps in the complete S1, but also in cytoarchitectonic Areas 1, 2, 3a, and 3b separately, in 21 healthy volunteers using 3T fMRI. The distances between activation maxima of D1 and D5 were evaluated by two independent raters, blinded for performance parameters. The fingertip representations showed a somatotopy and were localized in the transition region between the crown and the anterior wall of the post central gyrus agreeing with Area 1 and 3b. Participants were comprehensively tested for tactile performance using von Freyhair filaments to determine cutaneous sensory thresholds (CST) as well as grating orientation thresholds (GOT) and two-point resolution (TPD) for spatio-tactile acuity testing. Motor performance was evaluated with pinch grip performance (Roeder test). We found bilateral associations of D1-D5 distance for GOT thresholds and partially also for TPD in Area 3b and in Area 1, but not if using the complete S1 mask. In conclusion, we here demonstrate that 3T fMRI is capable to map associations between spatio-tactile acuity and the fingertip representation in Area 3b and Area 1 in healthy participants.
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Affiliation(s)
- J Härtner
- Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine of Greifswald, Walther-Rathenau-Str.46, D-17475 Greifswald, Germany
| | - S Strauss
- Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine of Greifswald, Walther-Rathenau-Str.46, D-17475 Greifswald, Germany; Neurology, University Medicine of Greifswald, Germany
| | - J Pfannmöller
- Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine of Greifswald, Walther-Rathenau-Str.46, D-17475 Greifswald, Germany; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, USA
| | - M Lotze
- Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine of Greifswald, Walther-Rathenau-Str.46, D-17475 Greifswald, Germany.
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Schaefer M, Joch M, Rother N. Feeling Touched: Empathy Is Associated With Performance in a Tactile Acuity Task. Front Hum Neurosci 2021; 15:593425. [PMID: 33633552 PMCID: PMC7900490 DOI: 10.3389/fnhum.2021.593425] [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: 08/10/2020] [Accepted: 01/12/2021] [Indexed: 12/30/2022] Open
Abstract
The concept of empathy describes our capacity to understand the emotions and intentions of others and to relate to our conspecifics. Numerous studies investigated empathy as a state as well as a stable personality trait. For example, recent studies in neuroscience suggest, among other brain areas such as the insula or the ACC, a role of the somatosensory cortices for empathy (e.g., when observing someone else being touched). Since the classic understanding of the primary somatosensory cortex is to represent touch on the body surface, we here aimed to test whether tactile performance is linked to the personality trait empathy. To test this, we examined the tactile acuity of 95 healthy participants (mean age 31 years) by using a two-point discrimination threshold task at the index fingers. Trait empathy was assessed by employing the interpersonal reactivity index (IRI), which measures self-reported empathy with four scales (empathic concern, perspective taking, fantasy, and personal distress). Results of regression analyses suggested the subscale empathic concern to be positively associated with performance in the tactile acuity task. We discuss this finding in the light of recent studies on empathy and consider possible implications of tactile training to enhance empathy.
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Affiliation(s)
- Michael Schaefer
- Department Naturwissenschaften, Medical School Berlin, Berlin, Germany
| | - Marcel Joch
- Department Naturwissenschaften, Medical School Berlin, Berlin, Germany
| | - Nikolas Rother
- Department Naturwissenschaften, Medical School Berlin, Berlin, Germany
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18
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A Systematic Comparison of Perceptual Performance in Softness Discrimination with Different Fingers. Atten Percept Psychophys 2020; 82:3696-3709. [PMID: 32686066 PMCID: PMC7536162 DOI: 10.3758/s13414-020-02100-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In studies investigating haptic softness perception, participants are typically instructed to explore soft objects by indenting them with their index finger. In contrast, performance with other fingers has rarely been investigated. We wondered which fingers are used in spontaneous exploration and if performance differences between fingers can explain spontaneous usage. In Experiment 1 participants discriminated the softness of two rubber stimuli with hardly any constraints on finger movements. Results indicate that humans use successive phases of different fingers and finger combinations during an exploration, preferring index, middle, and (to a lesser extent) ring finger. In Experiment 2 we compared discrimination thresholds between conditions, with participants using one of the four fingers of the dominant hand. Participants compared the softness of rubber stimuli in a two-interval forced choice discrimination task. Performance with index and middle finger was better as compared to ring and little finger, the little finger was the worst. In Experiment 3 we again compared discrimination thresholds, but participants were told to use constant peak force. Performance with the little finger was worst, whereas performance for the other fingers did not differ. We conclude that in spontaneous exploration the preference of combinations of index, middle, and partly ring finger seems to be well chosen, as indicated by improved performance with the spontaneously used fingers. Better performance seems to be based on both different motor abilities to produce force, mainly linked to using index and middle finger, and different sensory sensitivities, mainly linked to avoiding the little finger.
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Lu F, Liu P, Chen H, Wang M, Xu S, Yuan Z, Wang X, Wang S, Zhou J. More than just statics: Abnormal dynamic amplitude of low-frequency fluctuation in adolescent patients with pure conduct disorder. J Psychiatr Res 2020; 131:60-68. [PMID: 32937251 DOI: 10.1016/j.jpsychires.2020.08.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/28/2020] [Accepted: 08/22/2020] [Indexed: 02/05/2023]
Abstract
BACKGROUND The human brain activity is inherently dynamic over time. Conventional neuroimaging studies have reported abnormalities of static intrinsic brain activity or connectivity in adolescent patients with conduct disorder (CD). Little is known, however, regarding the temporal dynamics alterations of brain activity in CD. METHODS In this study, resting-state functional magnetic resonance imaging examinations were performed on adolescent patients with pure CD and age-matched typically developing (TD) controls. The dynamic amplitude of low-frequency fluctuation (dALFF) was first measured using a sliding-window method. The temporal variability (TV) was then quantified as the variance of dALFF over time and compared between the two groups. Further, the relationships between aberrant TV of dALFF and clinical features were evaluated. RESULTS CD patients showed reduced brain dynamics (less temporal variability) in the default-mode network, frontal-limbic cortices, sensorimotor areas, and visual regions which are involved in cognitive, emotional and perceptional processes. Importantly, receiver operating characteristic curve analysis revealed that regions with altered TV of dALFF exhibited a better ability to distinguish CD patients than the results from static ALFF in the current data set. CONCLUSIONS Our findings extended previous work by providing a novel perspective on the neural mechanisms underlying adolescent patients with CD and demonstrated that the altered dynamic local brain activity may be a potential biomarker for CD diagnosis.
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Affiliation(s)
- Fengmei Lu
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Peiqu Liu
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China
| | - Heng Chen
- School of Medicine, Guizhou University, Guizhou, 550025, China
| | - Mengyun Wang
- Faculty of Health Sciences, University of Macau, Taipa, SAR, Macau, China; Centre for Cognitive and Brain Sciences, University of Macau, Taipa, SAR, Macau, China
| | - Shiyang Xu
- Faculty of Health Sciences, University of Macau, Taipa, SAR, Macau, China; Centre for Cognitive and Brain Sciences, University of Macau, Taipa, SAR, Macau, China
| | - Zhen Yuan
- Faculty of Health Sciences, University of Macau, Taipa, SAR, Macau, China; Centre for Cognitive and Brain Sciences, University of Macau, Taipa, SAR, Macau, China
| | - Xiaoping Wang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China
| | - Song Wang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China; Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, No. 37 Guo Xue Xiang, Chengdu, 610041, China.
| | - Jiansong Zhou
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center on Mental Disorders, Changsha, 410011, Hunan, China.
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20
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Van der Looven R, Deschrijver M, Hermans L, De Muynck M, Vingerhoets G. Hand size representation in healthy children and young adults. J Exp Child Psychol 2020; 203:105016. [PMID: 33246254 DOI: 10.1016/j.jecp.2020.105016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 10/22/2022]
Abstract
Whereas we experience our body as a coherent volumetric object, the brain appears to maintain highly fragmented representations of individual body parts. Little is known about how body representations of hand size and shape are built and evolve during infancy and young adulthood. This study aimed to investigate the effect of hand side, handedness, and age on the development of central hand size representation. The observational study with comparison groups was conducted with 90 typically developing Belgian school children and young adults (48 male and 42 female; age range = 5.0-23.0 years; 49 left-handed and 41 right-handed). Participants estimated their hand size and shape using two different tasks. In the localization task, participants were verbally cued to judge the locations of 10 anatomical landmarks of an occluded hand. An implicit hand size map was constructed and compared with actual hand dimensions. In the template selection task, the explicit hand shape was measured with a depictive method. Hand shape indexes were calculated and compared for the actual, implicit, and explicit conditions. Participants were divided into four age groups (5-8 years, 9-10 years, 11-16 years, and 17-23 years). Implicit hand maps featured underestimation of finger length and overestimation of hand width, which is already present in the youngest children. Linear mixed modeling revealed no influence of hand side on finger length underestimation; nonetheless, a significant main effect of age (p = .001) was exposed. Sinistrals aged 11 to 16 years showed significantly less underestimation (p = .03) than dextrals of the same age. As for the hand shape, the implicit condition differed significantly with the actual and explicit conditions (p < .001). Again, the implicit shape index was subjected to handedness and age effects, with significant differences being found between sinistrals and dextrals in the age groups of 9 and 10 years (p = .029) and 11 to 16 years (p < .001). In conclusion, the implicit metric component of the hand representation in children and young adults is misperceived, featuring shortened fingers and broadened hands since a very young age. Crucially, the finger length underestimation increases with age and shows a different developmental trajectory for sinistrals and dextrals. In contrast, the explicit hand shape is approximately veridical and seems immune from age and handedness effects. This study confirms the dual character of somatoperception and establishes a point of reference for children and young adults.
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Affiliation(s)
- Ruth Van der Looven
- Child Rehabilitation Centre, Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium.
| | - Miguel Deschrijver
- Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium
| | - Linda Hermans
- Child Rehabilitation Centre, Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium
| | - Martine De Muynck
- Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium
| | - Guy Vingerhoets
- Department of Experimental Psychology, Faculty of Psychology and Educational Sciences, Ghent University, 9000 Ghent, Belgium
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Intra- and Inter-Rater Reliability of Three Measurements for Assessing Tactile Acuity in Individuals with Chronic Low Back Pain. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:8367095. [PMID: 33299457 PMCID: PMC7707974 DOI: 10.1155/2020/8367095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 10/30/2020] [Accepted: 11/06/2020] [Indexed: 12/02/2022]
Abstract
Objective To investigate the intra- and inter-rater reliability of three measurements on painful and pain-free sides in participants with chronic low back pain (CLBP) at different ages. Methods We recruited 60 participants with CLBP and divided them equally into a group of younger participants with chronic low back pain (18 ≤ age ≤ 35, Y-CLBP) and a group of older participants with chronic low back pain (36 ≤ age ≤ 65, O-CLBP). Participants were assessed by two testers within the same day (10 min interval), and one of the testers repeated the assessment program 24 h later. The intraclass correlation coefficient (ICC) was used to assess reliability. The Pearson correlation coefficient was used to analyze the correlation between tactile acuity and age, waistline, and pain-related variables. Results In the Y-CLBP group, the intra-rater reliability of two-point discrimination (TPD), point-to-point test (PTP), and two-point estimation (TPE) on the painful and pain-free sides was good (ICC range: 0.74–0.85), whereas the inter-rater reliability of TPD, PTP, and TPE on the painful and pain-free sides was moderate to good (ICC range: 0.65–0.76). In the O-CLBP group, the intra-rater reliability of TPD, PTP, and TPE on the painful and pain-free sides was good (ICC range: 0.75–0.85), whereas the inter-rater reliability of TPD, PTP, and TPE on the painful and pain-free sides was moderate to good (ICC range: 0.70–0.85). Age, waistline, duration of pain, maximum pain, general pain, and unpleasant score caused by pain were positively correlated with tactile acuity thresholds (D-TPD, A-TPD, PTP, and TPE) (r > 0.365, p < 0.05). When BMI was controlled, age, waistline, and pain-related variables were positively correlated with tactile acuity thresholds (r > 0.388; p < 0.05). Conclusion In the participants of Y-CLBP and O-CLBP groups, TPD, PTP, and TPE have moderate-to-good intra- and inter-rater reliability on the painful and pain-free sides of the fifth lumbar vertebrae.
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A Distorted Body Schema and Susceptibility to Experiencing Anomalous Somatosensory Sensations in Fibromyalgia Syndrome. Clin J Pain 2020; 35:887-893. [PMID: 31433318 DOI: 10.1097/ajp.0000000000000754] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Evidence suggests that there is an association between chronic pain and disruption of the body schema. We tested the hypothesis in fibromyalgia syndrome (FMS). MATERIALS AND METHODS We investigated distinct perceptual aspects of the body schema both in a sample of patients with FMS and in pain-free controls. Performances on the left/right judgment task were measured; tactile acuity was assessed by using the 2-point discrimination test. Furthermore, we evaluated sensations evoked by tactile stimulation with von Frey filaments to body parts that were experiencing pain. Anomalous sensations elicited by sensory-motor conflict (SMC) were also investigated. RESULTS Patients with FMS showed inferior performance on the right/left judgment task, both in terms of correct matches (75.38% vs. 89.67%, respectively; P<0.05) and response time (2.58 s vs. 1.89 s, respectively; P<0.05). Effect sizes were large and very large, respectively. Two-point discrimination thresholds were significantly higher (P<0.05) in participants from the FMS sample (mean of 49.71 mm, SD: 12.09 mm) relative to controls (mean of 37.36 mm, SD: 7.81 mm). Nine of 14 participants with FMS, but no control participants, reported referred sensations upon tactile stimulation, including tingling, pins and needles, weight, and cramps. Referral sites included regions both adjacent and remote to stimulated sites. Patients with FMS scored across all items within the administered questionnaire addressing anomalous sensations on the mirror setup (Cohen d=1.04 to 2.42 across all items), and FMS patients perceived pain during the SMC (the required statistical power for it to be statistically significant was 96% and for it to be recognized as a difference of means in pain item). CONCLUSION Our present findings suggest a disrupted body schema and propensity to experiencing anomalous somatosensory sensations during SMC in people with FMS.
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Peviani V, Bottini G. Proprioceptive errors in the localization of hand landmarks: What can be learnt about the hand metric representation? PLoS One 2020; 15:e0236416. [PMID: 32735572 PMCID: PMC7394425 DOI: 10.1371/journal.pone.0236416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 07/06/2020] [Indexed: 01/13/2023] Open
Abstract
Proprioception acquires a crucial role in estimating the configuration of our body segments in space when visual information is not available. Proprioceptive accuracy is assessed by asking participants to match the perceived position of an unseen body landmark through reaching movements. This task was also adopted to study the perceived hand structure by computing the relative distances between averaged proprioceptive judgments (hand Localization Task). However, the pattern of proprioceptive errors leading to the misperceived hand structure is unexplored. Here, we aimed to characterize this pattern across different hand landmarks, having different anatomo-physiological properties and cortical representations. Furthermore, we sought to describe the error consistency and its stability over time. To this purpose, we analyzed the proprioceptive errors of 43 healthy participants during the hand Localization Task. We found larger but more consistent errors for the fingertips compared to the knuckles, possibly due to poorer proprioceptive signal, compensated by other sources of spatial information. Furthermore, we found a shift (overlap effect) and a temporal drift of the hand perceived position towards the shoulder of origin, which was consistent within and between subjects. The overlap effect had a greater influence on lateral compared to medial landmarks, leading to the hand width overestimation. Our results are compatible with domain-general and body-specific spatial biases affecting the proprioceptive localization of the hand landmarks, thus the apparent hand structure misperception.
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Affiliation(s)
- Valeria Peviani
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Frankfurt am Main, Germany
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Gabriella Bottini
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Frankfurt am Main, Germany
- Cognitive Neuropsychology Center, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy
- NeuroMI, Milan Center for Neuroscience, Milan, Italy
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Bayesian population receptive field modeling in human somatosensory cortex. Neuroimage 2020; 208:116465. [DOI: 10.1016/j.neuroimage.2019.116465] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 12/09/2019] [Accepted: 12/12/2019] [Indexed: 11/17/2022] Open
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Manser-Smith K, Tamè L, Longo MR. A common representation of fingers and toes. Acta Psychol (Amst) 2019; 199:102900. [PMID: 31400650 DOI: 10.1016/j.actpsy.2019.102900] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/10/2019] [Accepted: 07/29/2019] [Indexed: 12/23/2022] Open
Abstract
There are many similarities and differences between the human hands and feet. On a psychological level, there is some evidence from clinical disorders and studies of tactile localisation in healthy adults for deep functional connections between the hands and feet. One form these connections may take is in common high-level mental representations of the hands and feet. Previous studies have shown that there are systematic, but distinct patterns of confusion found between both the fingers and toes. Further, there are clear individual differences between people in the exact patterns of mislocalisations. Here, we investigated whether these idiosyncratic differences in tactile localisation are shared between the fingers and toes, which may indicate a shared high-level representation. We obtained confusion matrices showing the pattern of mislocalisation on the hairy skin surfaces of both the fingers and toes. Using a decoding approach, we show that idiosyncratic differences in individuals' pattern of confusions are shared across the fingers and toes, despite different overall patterns of confusions. These results suggest that there is a common representation of the fingers and toes.
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26
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Shah VA, Casadio M, Scheidt RA, Mrotek LA. Spatial and temporal influences on discrimination of vibrotactile stimuli on the arm. Exp Brain Res 2019; 237:2075-2086. [PMID: 31175382 PMCID: PMC6640119 DOI: 10.1007/s00221-019-05564-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/18/2019] [Indexed: 11/29/2022]
Abstract
Body-machine interfaces (BMIs) provide a non-invasive way to control devices. Vibrotactile stimulation has been used by BMIs to provide performance feedback to the user, thereby reducing visual demands. To advance the goal of developing a compact, multivariate vibrotactile display for BMIs, we performed two psychophysical experiments to determine the acuity of vibrotactile perception across the arm. The first experiment assessed vibration intensity discrimination of sequentially presented stimuli within four dermatomes of the arm (C5, C7, C8, and T1) and on the ulnar head. The second experiment compared vibration intensity discrimination when pairs of vibrotactile stimuli were presented simultaneously vs. sequentially within and across dermatomes. The first experiment found a small but statistically significant difference between dermatomes C7 and T1, but discrimination thresholds at the other three locations did not differ. Thus, while all tested dermatomes of the arm and hand could serve as viable sites of vibrotactile stimulation for a practical BMI, ideal implementations should account for small differences in perceptual acuity across dermatomes. The second experiment found that sequential delivery of vibrotactile stimuli resulted in better intensity discrimination than simultaneous delivery, independent of whether the pairs were located within the same dermatome or across dermatomes. Taken together, our results suggest that the arm may be a viable site to transfer multivariate information via vibrotactile feedback for body-machine interfaces. However, user training may be needed to overcome the perceptual disadvantage of simultaneous vs. sequentially presented stimuli.
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Affiliation(s)
- Valay A Shah
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA.
| | - Maura Casadio
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA
- DIBRIS, University of Genova, Genova, Italy
| | - Robert A Scheidt
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Division of Civil, Mechanical and Manufacturing Innovation, National Science Foundation, Alexandria, VA, USA
| | - Leigh A Mrotek
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA
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Abstract
Our body is a volumetric, three-dimensional (3-D) object in the world, and we experience it as such. Existing methods for measuring the perceptual body image, however, have been based on judgments of one-dimensional (1-D) length or two-dimensional images. We developed a new approach to the 3-D perceptual body image of the fingers by asking people to judge whether each finger would fit through rings of varying diameter. This task requires participants to conceptualize their finger as a volumetric object entering the ring. In two experiments, we used an adaptive staircase procedure to estimate the perceived size of each finger. There were systematic distortions of perceived 3-D finger size, with the size of index finger and (to a lesser extent) the middle finger underestimated. These distortions were unaffected by changes in hand posture. Notably, the pattern of distortions is qualitatively different from that found in previous research investigating 1-D finger length, suggesting that 3-D judgments of the body may differ in fundamental ways from 1-D judgments of individual body dimensions.
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Affiliation(s)
- Ebru Ecem Tavacioglu
- Department of Psychological Sciences, Birkbeck, University of London, UK; Department of Psychology, Ludwig-Maximilians-Universität Munchen, Munich, Germany; Psychology Department, Istanbul Sehir University, Turkey
| | - Elena Azañón
- Department of Psychological Sciences, Birkbeck, University of London, UK; Institute of Psychology, Otto von Guericke University Magdeburg, Germany; Center for Behavioral Brain Sciences, Otto von Guericke University Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Matthew R Longo
- Department of Psychological Sciences, Birkbeck, University of London, UK
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Marasco PD, Bourbeau DJ, Shell CE, Granja-Vazquez R, Ina JG. The neural response properties and cortical organization of a rapidly adapting muscle sensory group response that overlaps with the frequencies that elicit the kinesthetic illusion. PLoS One 2017; 12:e0188559. [PMID: 29182648 PMCID: PMC5705069 DOI: 10.1371/journal.pone.0188559] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/09/2017] [Indexed: 11/18/2022] Open
Abstract
Kinesthesia is the sense of limb movement. It is fundamental to efficient motor control, yet its neurophysiological components remain poorly understood. The contributions of primary muscle spindles and cutaneous afferents to the kinesthetic sense have been well studied; however, potential contributions from muscle sensory group responses that are different than the muscle spindles have not been ruled out. Electrophysiological recordings in peripheral nerves and brains of male Sprague Dawley rats with a degloved forelimb preparation provide evidence of a rapidly adapting muscle sensory group response that overlaps with vibratory inputs known to generate illusionary perceptions of limb movement in humans (kinesthetic illusion). This group was characteristically distinct from type Ia muscle spindle fibers, the receptor historically attributed to limb movement sensation, suggesting that type Ia muscle spindle fibers may not be the sole carrier of kinesthetic information. The sensory-neural structure of muscles is complex and there are a number of possible sources for this response group; with Golgi tendon organs being the most likely candidate. The rapidly adapting muscle sensory group response projected to proprioceptive brain regions, the rodent homolog of cortical area 3a and the second somatosensory area (S2), with similar adaption and frequency response profiles between the brain and peripheral nerves. Their representational organization was muscle-specific (myocentric) and magnified for proximal and multi-articulate limb joints. Projection to proprioceptive brain areas, myocentric representational magnification of muscles prone to movement error, overlap with illusionary vibrational input, and resonant frequencies of volitional motor unit contraction suggest that this group response may be involved with limb movement processing.
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Affiliation(s)
- Paul D. Marasco
- Advanced Platform Technology Center of Excellence, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
- Laboratory for Bionic Integration, Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail:
| | - Dennis J. Bourbeau
- Functional Electrical Stimulation Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
- Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, Ohio, United States of America
| | - Courtney E. Shell
- Laboratory for Bionic Integration, Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Rafael Granja-Vazquez
- Laboratory for Bionic Integration, Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Jason G. Ina
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
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Tass PA. Vibrotactile Coordinated Reset Stimulation for the Treatment of Neurological Diseases: Concepts and Device Specifications. Cureus 2017; 9:e1535. [PMID: 28983444 PMCID: PMC5624565 DOI: 10.7759/cureus.1535] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Coordinated reset stimulation (CRS) consists of spatiotemporal sequences of stimuli delivered to different sites in the brain. Computationally, it was shown that by achieving an unlearning of abnormal synaptic connectivity, CRS can cause a long-lasting reduction of pathological synchronization, a hallmark feature of Parkinson’s disease and other brain disorders. Pre-clinical and proof of concept clinical studies in parkinsonian monkeys and patients showed that CRS applied through deep brain stimulation electrodes implanted in the subthalamic nucleus resulted in cumulative and long-lasting therapeutic effects along with a reduction of beta band oscillations. To apply CRS noninvasively by vibrotactile stimulation delivered to different fingertips, we present three different possible stimulation concepts. These different CRS approaches target different mechanoreceptors and related stimulus mechanisms. The different approaches are based on the diverse physiology of mechanoreceptors and dynamic CRS principles. Required stimulation parameters and specifications provide a guideline for technically implementing vibrotactile CRS during clinical tests.
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Longo MR. Expansion of Perceptual Body Maps Near - But Not Across - The Wrist. Front Hum Neurosci 2017; 11:111. [PMID: 28326030 PMCID: PMC5339231 DOI: 10.3389/fnhum.2017.00111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/22/2017] [Indexed: 11/13/2022] Open
Abstract
Perceiving the external spatial location of touch requires that tactile information about the stimulus location on the skin be integrated with proprioceptive information about the location of the body in external space, a process called tactile spatial remapping. Recent results have suggested that this process relies on a distorted representation of the hand. Here, I investigated whether similar distortions are also found on the forearm and how they are affected by the presence of the wrist joint, which forms a categorical, segmental boundary between the hand and the arm. Participants used a baton to judge the perceived location of touches applied to their left hand or forearm. Similar distortions were apparent on both body parts, with overestimation of distances in the medio-lateral axis compared to the proximo-distal axis. There was no perceptual expansion of distances that crossed the wrist boundary. However, there was increased overestimation of distances near the wrist in the medio-lateral orientation. These results replicate recent findings of a distorted representation of the hand underlying tactile spatial remapping, and show that this effect is not idiosyncratic to the hand, but also affects the forearm. These distortions may be a general characteristic of the mental representation of the arms.
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Affiliation(s)
- Matthew R Longo
- Department of Psychological Sciences, Birkbeck, University of London London, UK
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High-resolution fMRI investigations of the fingertip somatotopy and variability in BA3b and BA1 of the primary somatosensory cortex. Neuroscience 2016; 339:667-677. [DOI: 10.1016/j.neuroscience.2016.10.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 09/23/2016] [Accepted: 10/12/2016] [Indexed: 11/17/2022]
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Disrupted Tactile Acuity in People With Achilles Tendinopathy: A Preliminary Case-Control Investigation. J Orthop Sports Phys Ther 2016; 46:1061-1064. [PMID: 27796191 DOI: 10.2519/jospt.2016.6514] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Study Design Controlled laboratory study, preliminary case-control design. Background The mechanisms that contribute to Achilles tendinopathy remain poorly understood. The disparity between pain experience and peripheral pathology demonstrated in patients with Achilles tendinopathy suggests that changes in central nervous system function may be involved. Objectives To investigate whether lower-limb tactile acuity is impaired in people with nonacute Achilles tendinopathy. Methods Thirteen consecutive participants with nonacute midportion Achilles tendinopathy and 13 healthy controls were enrolled. Two-point discrimination thresholds over the affected Achilles tendon, unaffected tendon, and tendon of healthy controls were evaluated. Independent and dependent t tests were used to compare group means. Results Two-point discrimination distance over the affected limb in participants with Achilles tendinopathy was significantly increased when compared to the unaffected limb (mean difference, 11.7 mm; 95% confidence interval [CI]: 1.9, 21.5; P = .02) and to healthy controls (mean difference, 13.1 mm; 95% CI: 1.6, 24.6; P = .03). There was no significant difference between the healthy controls and the unaffected side in people with Achilles tendinopathy (mean difference, 1.4 mm; 95% CI: -7.9, 5.1; P = .66). Conclusion These data provide the first evidence of reduced 2-point discrimination over the affected tendon in patients with Achilles tendinopathy. Further research is needed to determine the cause for the change in tactile acuity. J Orthop Sports Phys Ther 2016;46(12):1061-1064. Epub 30 Oct 2016. doi:10.2519/jospt.2016.6514.
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Ferrè ER, Sahani M, Haggard P. Subliminal stimulation and somatosensory signal detection. Acta Psychol (Amst) 2016; 170:103-11. [PMID: 27387873 DOI: 10.1016/j.actpsy.2016.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 06/17/2016] [Accepted: 06/21/2016] [Indexed: 11/19/2022] Open
Abstract
Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals.
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Affiliation(s)
- Elisa Raffaella Ferrè
- Institute of Cognitive Neuroscience, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK; Department of Psychology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
| | - Maneesh Sahani
- Gatsby Computational Neuroscience Unit, University College London, 25 Howland Street, London, W1T4JG, UK
| | - Patrick Haggard
- Institute of Cognitive Neuroscience, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK.
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Abstract
Delusions and misperceptions about the body are a conspicuous feature of numerous neurological and psychiatric conditions. In stark contrast to such pathological cases, the immediacy and familiarity of our ordinary experience of our body can make it seem as if our representation of our body is highly accurate, even infallible. Recent research has begun to demonstrate, however, that large and systematic distortions of body representation are a normal part of healthy cognition. Here, I describe this research, focusing on distortions of body representations underlying tactile distance perception and position sense. I also discuss evidence for distortions of higher-order body representations, such as the conscious body image. Finally, I will end with a discussion of the potential relations among different body representations and their distortions.
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Affiliation(s)
- Matthew R Longo
- a Department of Psychological Sciences , Birkbeck, University of London , London , UK
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Miller LE, Longo MR, Saygin AP. Mental body representations retain homuncular shape distortions: Evidence from Weber's illusion. Conscious Cogn 2015; 40:17-25. [PMID: 26741857 DOI: 10.1016/j.concog.2015.12.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 10/22/2022]
Abstract
Mental body representations underlying tactile perception do not accurately reflect the body's true morphology. For example, perceived tactile distance is dependent on both the body part being touched and the stimulus orientation, a phenomenon called Weber's illusion. These findings suggest the presence of size and shape distortions, respectively. However, whereas each morphological feature is typically measured in isolation, a complete morphological characterization requires the concurrent measurement of both size and shape. We did so in three experiments, manipulating both the stimulated body parts (hand; forearm) and stimulus orientation while requiring participants to make tactile distance judgments. We found that the forearm was significantly more distorted than the hand lengthwise but not widthwise. Effects of stimulus orientation are thought to reflect receptive field anisotropies in primary somatosensory cortex. The results of the present study therefore suggest that mental body representations retain homuncular shape distortions that characterize early stages of somatosensory processing.
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Affiliation(s)
- Luke E Miller
- Department of Cognitive Science, University of California, San Diego, USA; Kavli Institute for Brain and Mind, University of California, San Diego, USA.
| | - Matthew R Longo
- Department of Psychological Sciences, Birkbeck, University of London, United Kingdom
| | - Ayse P Saygin
- Department of Cognitive Science, University of California, San Diego, USA; Kavli Institute for Brain and Mind, University of California, San Diego, USA
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Longo MR, Mattioni S, Ganea N. Perceptual and Conceptual Distortions of Implicit Hand Maps. Front Hum Neurosci 2015; 9:656. [PMID: 26733842 PMCID: PMC4679851 DOI: 10.3389/fnhum.2015.00656] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/18/2015] [Indexed: 01/15/2023] Open
Abstract
Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of landmarks on an occluded hand, Longo and Haggard (2010) constructed implicit perceptual maps of represented hand structure, showing large underestimation of finger length and overestimation of hand width. Here, we investigated the contribution of two potential sources of distortions to such effects: perceptual distortions reflecting spatial warping of the representation of bodily tissue itself, perhaps reflecting distortions of somatotopic cortical maps, and conceptual distortions reflecting mistaken beliefs about the locations of different landmarks within the body. In Experiment 1 we compared distorted hand maps to a task in which participants explicitly judged the location of their knuckles in a hand silhouette. The results revealed the conceptual distortions are responsible for at least part of the underestimation of finger length, but cannot explain overestimation of hand width. Experiment 2 compared distortions of the participant’s own hand based on position sense with a prosthetic hand based on visual memory. Underestimation of finger length was found for both hands, providing further evidence that it reflects a conceptual distortion. In contrast, overestimation of hand width was specific to representation of the participant’s own hand, confirming it reflects a perceptual distortion. Together, these results suggest that distorted body representations do not reflect a single underlying cause. Rather, both perceptual and conceptual distortions contribute to the overall configuration of the hand representation.
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Affiliation(s)
- Matthew R Longo
- Department of Psychological Sciences, Birkbeck University of London London, UK
| | - Stefania Mattioni
- Department of Psychological Sciences, Birkbeck University of LondonLondon, UK; Centre for Mind/Brain Sciences, University of TrentoTrento, Italy
| | - Nataşa Ganea
- Department of Psychological Sciences, Birkbeck University of London London, UK
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Dempsey-Jones H, Harrar V, Oliver J, Johansen-Berg H, Spence C, Makin TR. Transfer of tactile perceptual learning to untrained neighboring fingers reflects natural use relationships. J Neurophysiol 2015; 115:1088-97. [PMID: 26631145 PMCID: PMC4808091 DOI: 10.1152/jn.00181.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 12/01/2015] [Indexed: 12/31/2022] Open
Abstract
Tactile learning transfers from trained to untrained fingers in a pattern that reflects overlap between the representations of fingers in the somatosensory system (e.g., neurons with multifinger receptive fields). While physical proximity on the body is known to determine the topography of somatosensory representations, tactile coactivation is also an established organizing principle of somatosensory topography. In this study we investigated whether tactile coactivation, induced by habitual inter-finger cooperative use (use pattern), shapes inter-finger overlap. To this end, we used psychophysics to compare the transfer of tactile learning from the middle finger to its adjacent fingers. This allowed us to compare transfer to two fingers that are both physically and cortically adjacent to the middle finger but have differing use patterns. Specifically, the middle finger is used more frequently with the ring than with the index finger. We predicted this should lead to greater representational overlap between the former than the latter pair. Furthermore, this difference in overlap should be reflected in differential learning transfer from the middle to index vs. ring fingers. Subsequently, we predicted temporary learning-related changes in the middle finger's representation (e.g., cortical magnification) would cause transient interference in perceptual thresholds of the ring, but not the index, finger. Supporting this, longitudinal analysis revealed a divergence where learning transfer was fast to the index finger but relatively delayed to the ring finger. Our results support the theory that tactile coactivation patterns between digits affect their topographic relationships. Our findings emphasize how action shapes perception and somatosensory organization.
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Affiliation(s)
- Harriet Dempsey-Jones
- FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; School of Psychology, University of Queensland, Brisbane, Australia
| | - Vanessa Harrar
- School of Optometry, University of Montreal, Montreal, Quebec, Canada; and Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Jonathan Oliver
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Heidi Johansen-Berg
- FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Charles Spence
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Tamar R Makin
- FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom;
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Abstract
Bodily training typically evokes behavioral and perceptual gains, enforcing neuroplastic processes and affecting neural representations. We investigated the effect on somatosensory perception of a three-day Zen meditation exercise, a purely mental intervention. Tactile spatial discrimination of the right index finger was persistently improved by only 6 hours of mental–sensory focusing on this finger, suggesting that intrinsic brain activity created by mental states can alter perception and behavior similarly to external stimulation.
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Poor judgment of distance between nociceptive stimuli. Cognition 2015; 143:41-7. [PMID: 26113448 PMCID: PMC4534310 DOI: 10.1016/j.cognition.2015.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/20/2015] [Accepted: 06/10/2015] [Indexed: 11/21/2022]
Abstract
Judgments of absolute distance between nociceptive stimuli are much worse than judgments of distance between tactile stimuli. Judgments of distance between two nociceptive stimuli are poor even on body regions where nociceptive spatial acuity is higher than tactile spatial acuity. Control experiments ruled out explanations based on inaccurate localization of double nociceptive stimuli.
Although pain is traditionally assumed to be poorly localized, recent work indicates that spatial acuity for nociception is surprisingly high. Here we investigated whether the nervous system can also accurately estimate the distance between two nociceptive stimuli. Estimating distance implies a metric representation of spatial relations, a property that underlies abilities such as perceiving the size of external objects. We presented pairs of simultaneous nociceptive or non-nociceptive somatosensory stimuli, and asked participants to judge the distance between them. Judgments of distance between nociceptive stimuli were much worse than judgments of distance between non-nociceptive tactile stimuli, even on skin regions where spatial acuity for nociception exceeded spatial acuity for touch. Control experiments ruled out explanations based on inaccurate localization of double nociceptive stimuli. Thus, the nervous system poorly represents the distance between two nociceptive stimuli. The dissociation between high spatial acuity and poor distance judgment in the nociceptive system may reflect a specialization for computing accurate spatial representations useful to protect the body, rather than to perceive the size of external objects.
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Abstract
Several forms of perception require that sensory information be referenced to representations of the size and shape of the body. This requirement is especially acute in somatosensation in which the main receptor surface (i.e., the skin) is itself coextensive with the body. This paper reviews recent research investigating the body representations underlying somatosensory information processing, including abilities such as tactile localization, tactile size perception, and position sense. These representations show remarkably large and stereotyped distortions of represented body size and shape. Intriguingly, these distortions appear to mirror distortions characteristic of somatosensory maps, though in attenuated form. In contrast, when asked to make overt judgments about perceived body form, participants are generally quite accurate. This pattern of results suggests that higher-level somatosensory processing relies on a class of implicit body representation, distinct from the conscious body image. I discuss the implications of these results for understanding the nature of body representation and the factors that influence it.
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Affiliation(s)
- Matthew R. Longo
- Department of Psychological Sciences, Birkbeck, University of London, UK
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42
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Haag LM, Heba S, Lenz M, Glaubitz B, Höffken O, Kalisch T, Puts NA, Edden RAE, Tegenthoff M, Dinse H, Schmidt-Wilcke T. Resting BOLD fluctuations in the primary somatosensory cortex correlate with tactile acuity. Cortex 2014; 64:20-8. [PMID: 25461704 DOI: 10.1016/j.cortex.2014.09.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 08/08/2014] [Accepted: 09/26/2014] [Indexed: 01/21/2023]
Abstract
Sensory perception, including 2-point discrimination (2 ptD), is tightly linked to cortical processing of tactile stimuli in primary somatosensory cortices. While the role of cortical activity in response to a tactile stimulus has been widely investigated, the role of baseline cortical activity is largely unknown. Using resting state fMRI we investigated the relationship between local BOLD fluctuations in the primary somatosensory cortex (the representational field of the hand) and 2 ptD of the corresponding index finger (right and left). Cortical activity was measured using fractional amplitudes of the low frequency BOLD fluctuations (fALFF) and synchronicity using regional homogeneity (ReHo) of the S1 hand region during rest. 2 ptD correlated with higher ReHo values in the representational areas of the contralateral S1 cortex (left hand: p = .028; right hand: p = .049). 2 ptD additionally correlated with higher fALFF in the representational area of the left hand (p = .007) and showed a trend for a significant correlation in the representational area of the right hand (p = .051). Thus, higher BOLD amplitudes and synchronicity at rest, as measures of cortical activity and synchronicity, respectively, are related to better tactile discrimination abilities of the contralateral hand. Our findings extend the relationship seen between spontaneous BOLD fluctuations and sensory perception.
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Affiliation(s)
- Lauren M Haag
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Stefanie Heba
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Melanie Lenz
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Benjamin Glaubitz
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Oliver Höffken
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Tobias Kalisch
- Institute of Neuroinformatics, Ruhr University Bochum, Bochum, Germany.
| | - Nicholaas A Puts
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Richard A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Martin Tegenthoff
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
| | - Hubert Dinse
- Institute of Neuroinformatics, Ruhr University Bochum, Bochum, Germany.
| | - Tobias Schmidt-Wilcke
- Department of Neurology, BG-University Clinic Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
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Catley MJ, O'Connell NE, Berryman C, Ayhan FF, Moseley GL. Is Tactile Acuity Altered in People With Chronic Pain? A Systematic Review and Meta-analysis. THE JOURNAL OF PAIN 2014; 15:985-1000. [DOI: 10.1016/j.jpain.2014.06.009] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 06/10/2014] [Accepted: 06/17/2014] [Indexed: 01/28/2023]
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Schweisfurth MA, Schweizer R, Treue S. Feature-based attentional modulation of orientation perception in somatosensation. Front Hum Neurosci 2014; 8:519. [PMID: 25071535 PMCID: PMC4095560 DOI: 10.3389/fnhum.2014.00519] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/27/2014] [Indexed: 11/21/2022] Open
Abstract
In a reaction time study of human tactile orientation detection the effects of spatial attention and feature-based attention were investigated. Subjects had to give speeded responses to target orientations (parallel and orthogonal to the finger axis) in a random stream of oblique tactile distractor orientations presented to their index and ring fingers. Before each block of trials, subjects received a tactile cue at one finger. By manipulating the validity of this cue with respect to its location and orientation (feature), we provided an incentive to subjects to attend spatially to the cued location and only there to the cued orientation. Subjects showed quicker responses to parallel compared to orthogonal targets, pointing to an orientation anisotropy in sensory processing. Also, faster reaction times (RTs) were observed in location-matched trials, i.e., when targets appeared on the cued finger, representing a perceptual benefit of spatial attention. Most importantly, RTs were shorter to orientations matching the cue, both at the cued and at the uncued location, documenting a global enhancement of tactile sensation by feature-based attention. This is the first report of a perceptual benefit of feature-based attention outside the spatial focus of attention in somatosensory perception. The similarity to effects of feature-based attention in visual perception supports the notion of matching attentional mechanisms across sensory domains.
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Affiliation(s)
- Meike A Schweisfurth
- Cognitive Neuroscience Laboratory, German Primate Center Goettingen, Germany ; Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie Goettingen, Germany
| | - Renate Schweizer
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie Goettingen, Germany
| | - Stefan Treue
- Cognitive Neuroscience Laboratory, German Primate Center Goettingen, Germany ; Faculty for Biology and Psychology, Goettingen University Goettingen, Germany ; Bernstein Center for Computational Neuroscience Goettingen, Germany
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Mancini F, Bauleo A, Cole J, Lui F, Porro CA, Haggard P, Iannetti GD. Whole-body mapping of spatial acuity for pain and touch. Ann Neurol 2014; 75:917-24. [PMID: 24816757 PMCID: PMC4143958 DOI: 10.1002/ana.24179] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 05/08/2014] [Accepted: 05/08/2014] [Indexed: 12/30/2022]
Abstract
Objective Tactile spatial acuity is routinely tested in neurology to assess the state of the dorsal column system. In contrast, spatial acuity for pain is not assessed, having never been systematically characterized. More than a century after the initial description of tactile acuity across the body, we provide the first systematic whole-body mapping of spatial acuity for pain. Methods We evaluated the 2-point discrimination thresholds for both nociceptive-selective and tactile stimuli across several skin regions. Thresholds were estimated using pairs of simultaneous stimuli, and also using successive stimuli. Results and interpretation These two approaches produced convergent results. The fingertip was the area of highest spatial acuity, for both pain and touch. On the glabrous skin of the hand, the gradient of spatial acuity for pain followed that observed for touch. On the hairy skin of the upper limb, spatial acuity for pain and touch followed opposite proximal–distal gradients, consistent with the known innervation density of this body territory. Finally, by testing spatial acuity for pain in a rare participant completely lacking Aβ fibers, we demonstrate that spatial acuity for pain does not rely on a functioning system of tactile primary afferents. This study represents the first systematic characterization of spatial acuity for pain across multiple regions of the body surface. Ann Neurol 2014;75:917–924
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Affiliation(s)
- Flavia Mancini
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom; Institute of Cognitive Neuroscience, University College London, London, United Kingdom
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Abstract
Previous behavioral research suggests enhanced local visual processing in individuals with autism spectrum disorders (ASDs). Here we used functional MRI and population receptive field (pRF) analysis to test whether the response selectivity of human visual cortex is atypical in individuals with high-functioning ASDs compared with neurotypical, demographically matched controls. For each voxel, we fitted a pRF model to fMRI signals measured while participants viewed flickering bar stimuli traversing the visual field. In most extrastriate regions, perifoveal pRFs were larger in the ASD group than in controls. We observed no differences in V1 or V3A. Differences in the hemodynamic response function, eye movements, or increased measurement noise could not account for these results; individuals with ASDs showed stronger, more reliable responses to visual stimulation. Interestingly, pRF sizes also correlated with individual differences in autistic traits but there were no correlations with behavioral measures of visual processing. Our findings thus suggest that visual cortex in ASDs is not characterized by sharper spatial selectivity. Instead, we speculate that visual cortical function in ASDs may be characterized by extrastriate cortical hyperexcitability or differential attentional deployment.
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Bolton DAE, Staines WR. Attention-based modulation of tactile stimuli: a comparison between prefrontal lesion patients and healthy age-matched controls. Neuropsychologia 2014; 57:101-11. [PMID: 24650526 DOI: 10.1016/j.neuropsychologia.2014.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 03/05/2014] [Accepted: 03/10/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To investigate the role of the prefrontal cortex in attention-based modulation of cortical somatosensory processing. METHODS Six prefrontal stroke patients were compared with eleven neurologically intact older adults during a vibrotactile discrimination task. All subjects attended to stimuli on one digit while ignoring distracter stimuli on a separate digit of the same hand. Subjects were required to report infrequent targets on the attended digit only. Throughout testing electroencephalography was used to measure event-related potentials for both task-relevant and irrelevant stimuli. RESULTS Prefrontal patients demonstrated significant changes in cortical somatosensory processing based on attention compared to age-matched controls. This was evident both in early unimodal somatosensory processing (i.e. P100) and in later cortical processing stages (i.e. long-latency positivity). Moreover, there was a tendency towards a tonic loss of inhibition over early somatosensory cortical processing (i.e. P50). CONCLUSIONS The attention-based modulation noted for neurologically intact older adults was absent in prefrontal lesion patients. SIGNIFICANCE The present study highlights the important role of prefrontal regions in sustaining inhibition over early sensory cortical processing stages and in modifying somatosensory transmission based on task-relevance. Notably these deficits extend beyond those previously shown to occur as a function of age.
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Affiliation(s)
- David A E Bolton
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; Heart and Stroke Foundation Centre for Stroke Recovery, ON, Canada.
| | - W Richard Staines
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; Heart and Stroke Foundation Centre for Stroke Recovery, ON, Canada
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Lee KG, Jacobs MF, Asmussen MJ, Zapallow CM, Tommerdahl M, Nelson AJ. Continuous theta-burst stimulation modulates tactile synchronization. BMC Neurosci 2013; 14:89. [PMID: 23968301 PMCID: PMC3844444 DOI: 10.1186/1471-2202-14-89] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 08/21/2013] [Indexed: 11/22/2022] Open
Abstract
Background Temporal order judgement (TOJ) is the ability to detect the order of occurrence of two sequentially delivered stimuli. Previous research has shown that TOJ in the presence of synchronized periodic conditioning stimuli impairs TOJ performance, and this phenomenon is suggested to be mediated by GABAergic interneurons that cause perceptual binding across the two skin sites. Application of continuous theta-burst repetitive TMS (cTBS) over primary somatosensory cortex (SI) alters temporal and spatial tactile perception. The purpose of this study was to examine TOJ perception in the presence and absence of synchronized periodic conditioning stimuli before and after cTBS applied over left-hemisphere SI. A TOJ task was administered on the right index and middle finger (D2 and D3) in two separate sessions in the presence and absence of conditioning stimuli (a background low amplitude sinusoidal vibration). Results CTBS reduced the impact of the conditioning stimuli on TOJ performance for up to 18 minutes following stimulation while sham cTBS did not affect TOJ performance. In contrast, the TOJ task performed in the absence of synchronized conditioning stimulation was unaltered following cTBS. Conclusion We conclude that cTBS suppresses inhibitory networks in SI that mediate perceptual binding during TOJ synchronization. CTBS offers one method to suppress cortical excitability in the cortex and potentially benefit clinical populations with altered inhibitory cortical circuits. Additionally, TOJ measures with conditioning stimuli may provide an avenue to assess sensory processing in neurologically impaired patient populations.
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Affiliation(s)
- Kevin Gh Lee
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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Ferrè ER, Vagnoni E, Haggard P. Vestibular contributions to bodily awareness. Neuropsychologia 2013; 51:1445-52. [DOI: 10.1016/j.neuropsychologia.2013.04.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 10/26/2022]
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Neural changes with tactile learning reflect decision-level reweighting of perceptual readout. J Neurosci 2013; 33:5387-98. [PMID: 23516304 DOI: 10.1523/jneurosci.3482-12.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite considerable work, the neural basis of perceptual learning remains uncertain. For visual learning, although some studies suggested that changes in early sensory representations are responsible, other studies point to decision-level reweighting of perceptual readout. These competing possibilities have not been examined in other sensory systems, investigating which could help resolve the issue. Here we report a study of human tactile microspatial learning in which participants achieved >six-fold decline in acuity threshold after multiple training sessions. Functional magnetic resonance imaging was performed during performance of the tactile microspatial task and a control, tactile temporal task. Effective connectivity between relevant brain regions was estimated using multivariate, autoregressive models of hidden neuronal variables obtained by deconvolution of the hemodynamic response. Training-specific increases in task-selective activation assessed using the task × session interaction and associated changes in effective connectivity primarily involved subcortical and anterior neocortical regions implicated in motor and/or decision processes, rather than somatosensory cortical regions. A control group of participants tested twice, without intervening training, exhibited neither threshold improvement nor increases in task-selective activation. Our observations argue that neuroplasticity mediating perceptual learning occurs at the stage of perceptual readout by decision networks. This is consonant with the growing shift away from strictly modular conceptualization of the brain toward the idea that complex network interactions underlie even simple tasks. The convergence of our findings on tactile learning with recent studies of visual learning reconciles earlier discrepancies in the literature on perceptual learning.
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