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Norata D, Musumeci G, Todisco A, Cruciani A, Motolese F, Capone F, Lattanzi S, Ranieri F, Di Lazzaro V, Pilato F. Bilateral median nerve stimulation and High-Frequency Oscillations unveil interhemispheric inhibition of primary sensory cortex. Clin Neurophysiol 2024; 165:154-165. [PMID: 39033697 DOI: 10.1016/j.clinph.2024.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 06/04/2024] [Accepted: 06/19/2024] [Indexed: 07/23/2024]
Abstract
OBJECTIVE This study aimed at investigating the effect of median nerve stimulation on ipsilateral cortical potentials evoked by contralateral median nerve electrical stimulation. METHODS We recorded somatosensory-evoked potentials (SEPs) from the left parietal cortex in 15 right-handed, healthy subjects. We administered bilateral median nerve stimulation, with the ipsilateral stimulation preceding the stimulation on the contralateral by intervals of 5, 10, 20, or 40 ms. We adjusted these intervals based on each individual's N20 latency. As a measure of S1 excitability, the amplitude of the N20 and the area of the High Frequency Oscillation (HFO) burst were analyzed for each condition. RESULTS The results revealed significant inhibition of N20 amplitude by ipsilateral median nerve stimulation at interstimulus intervals (ISIs) between 5 and 40 ms. Late HFO burst was suppressed at short ISIs of 5 and 10 ms, pointing to a transcallosal inhibitory effect on S1 intracortical circuits. CONCLUSIONS Findings suggest interhemispheric interaction between the primary somatosensory areas, supporting the existence of transcallosal transfer of tactile information. SIGNIFICANCE This study provides valuable insights into the interhemispheric connections between primary sensory areas and underscore the potential role of interhemispheric interactions in somatosensory processing.
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Affiliation(s)
- Davide Norata
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy; Neurological Clinic and Stroke Unit, Department of Experimental and Clinical Medicine (DiMSC), Marche Polytechnic University, Via Conca 71, 60020 Ancona, Italy.
| | - Gabriella Musumeci
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy
| | - Antonio Todisco
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy
| | - Alessandro Cruciani
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy
| | - Francesco Motolese
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy; Fondazione Policlinico Universitario Campus Bio-Medico, Via Alvaro del Portillo, 200, 00128 Roma, Italy
| | - Fioravante Capone
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy; Fondazione Policlinico Universitario Campus Bio-Medico, Via Alvaro del Portillo, 200, 00128 Roma, Italy
| | - Simona Lattanzi
- Neurological Clinic and Stroke Unit, Department of Experimental and Clinical Medicine (DiMSC), Marche Polytechnic University, Via Conca 71, 60020 Ancona, Italy
| | - Federico Ranieri
- Neurology Unit, Department of Neuroscience, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Vincenzo Di Lazzaro
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy; Fondazione Policlinico Universitario Campus Bio-Medico, Via Alvaro del Portillo, 200, 00128 Roma, Italy
| | - Fabio Pilato
- Department of Medicine and Surgery, Unit of Neurology, Neurophysiology, Neurobiology and Psichiatry, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo, 21, 00128 Roma, Italy; Fondazione Policlinico Universitario Campus Bio-Medico, Via Alvaro del Portillo, 200, 00128 Roma, Italy
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2
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Hewitt D, Byrne A, Henderson J, Wilford K, Chawla R, Sharma ML, Frank B, Fallon N, Brown C, Stancak A. Pulse Intensity Effects of Burst and Tonic Spinal Cord Stimulation on Neural Responses to Brushing in Patients With Neuropathic Pain. Neuromodulation 2022:S1094-7159(22)01349-6. [DOI: 10.1016/j.neurom.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 10/21/2022] [Accepted: 11/01/2022] [Indexed: 12/04/2022]
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3
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Darki F, Ferrario A, Rankin J. Hierarchical processing underpins competition in tactile perceptual bistability. J Comput Neurosci 2022; 51:343-360. [PMID: 37204542 PMCID: PMC10404575 DOI: 10.1007/s10827-023-00852-0] [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: 11/07/2022] [Revised: 04/25/2023] [Accepted: 04/28/2023] [Indexed: 05/20/2023]
Abstract
Ambiguous sensory information can lead to spontaneous alternations between perceptual states, recently shown to extend to tactile perception. The authors recently proposed a simplified form of tactile rivalry which evokes two competing percepts for a fixed difference in input amplitudes across antiphase, pulsatile stimulation of the left and right fingers. This study addresses the need for a tactile rivalry model that captures the dynamics of perceptual alternations and that incorporates the structure of the somatosensory system. The model features hierarchical processing with two stages. The first and the second stages of model could be located at the secondary somatosensory cortex (area S2), or in higher areas driven by S2. The model captures dynamical features specific to the tactile rivalry percepts and produces general characteristics of perceptual rivalry: input strength dependence of dominance times (Levelt's proposition II), short-tailed skewness of dominance time distributions and the ratio of distribution moments. The presented modelling work leads to experimentally testable predictions. The same hierarchical model could generalise to account for percept formation, competition and alternations for bistable stimuli that involve pulsatile inputs from the visual and auditory domains.
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Affiliation(s)
- Farzaneh Darki
- Department of Mathematics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Andrea Ferrario
- Biorobotics Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - James Rankin
- Department of Mathematics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
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4
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Ahmed Mahmutoglu M, Rupp A, Naumgärtner U. Simultaneous EEG/MEG yields complementary information of nociceptive evoked responses. Clin Neurophysiol 2022; 143:21-35. [DOI: 10.1016/j.clinph.2022.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 07/31/2022] [Accepted: 08/04/2022] [Indexed: 11/03/2022]
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5
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Alhassani G, Liston MB, Clothier PJ, Schabrun SM. Interhemispheric Inhibition Between Primary Sensory Cortices is not Influenced by Acute Muscle Pain. THE JOURNAL OF PAIN 2022; 23:1177-1186. [PMID: 35131448 DOI: 10.1016/j.jpain.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 12/19/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Bilateral deficits in sensorimotor function have been observed in unilateral musculoskeletal pain conditions. Altered interhemispheric inhibition (IHI) between primary sensory cortices (S1s) is one mechanism that could explain this phenomenon. However, IHI between S1s in response to acute muscle pain, and the relationship between IHI and pressure pain sensitivity in the unaffected limb have not been examined. In 21 healthy individuals, IHI was assessed using somatosensory evoked potentials in response to paired median nerve electrical stimulation at: 1) baseline; 2) immediately following pain resolution; and 3) at 30-minutes follow-up. Acute muscle pain was induced by injection of hypertonic saline into the right abductor pollicis brevis (APB) muscle. Pressure pain thresholds were assessed at the right and left APB muscles before and 30-minutes after pain resolution. Compared to baseline, IHI from the affected to unaffected S1 was unaltered in response to acute muscle pain immediately following pain resolution, or at 30-minutes follow-up. Pressure pain thresholds were reduced over the right (P = .001) and left (P = .001) APB muscles at 30-minutes follow-up. These findings suggest IHI between S1s is unaffected by acute, short-lasting muscle pain, despite the development of increased sensitivity to pressure in the unaffected APB muscle. PERSPECTIVE: IHI from the affected S1 (contralateral to the side of pain) to unaffected S1 is unaltered following the resolution of acute muscle pain. This finding suggests that IHI between S1s may not be relevant in the development of bilateral sensorimotor symptoms in unilateral pain conditions.
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Affiliation(s)
- Ghufran Alhassani
- School of Health Sciences, Western Sydney University, Penrith, NSW, Australia
| | - Matthew B Liston
- Centre for Human and Applied Physiological Sciences, Kings College, London, UK
| | - Peter J Clothier
- School of Health Sciences, Western Sydney University, Penrith, NSW, Australia
| | - Siobhan M Schabrun
- School of Health Sciences, Western Sydney University, Penrith, NSW, Australia; Centre for Pain IMPACT, Neuroscience Research Australia, Sydney, NSW, Australia.
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6
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Hewitt D, Newton-Fenner A, Henderson J, Fallon NB, Brown C, Stancak A. Intensity-dependent modulation of cortical somatosensory processing during external, low-frequency peripheral nerve stimulation in humans. J Neurophysiol 2022; 127:1629-1641. [PMID: 35611988 PMCID: PMC9190739 DOI: 10.1152/jn.00511.2021] [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] [Indexed: 01/20/2023] Open
Abstract
External low-frequency peripheral nerve stimulation (LFS) has been proposed as a novel method for neuropathic pain relief. Previous studies have reported that LFS elicits long-term depression-like effects on human pain perception when delivered at noxious intensities, whereas lower intensities are ineffective. To shed light on cortical regions mediating the effects of LFS, we investigated changes in somatosensory-evoked potentials (SEPs) during four LFS intensities. LFS was applied to the radial nerve (600 pulses, 1 Hz) of 24 healthy participants at perception (1 times), low (5 times), medium (10 times), and high intensities (15 times detection threshold). SEPs were recorded during LFS, and averaged SEPs in 10 consecutive 1-min epochs of LFS were analyzed using source dipole modeling. Changes in resting electroencephalography (EEG) were investigated after each LFS block. Source activity in the midcingulate cortex (MCC) decreased linearly during LFS, with greater attenuation at stronger LFS intensities, and in the ipsilateral operculo-insular cortex during the two lowest LFS stimulus intensities. Increased LFS intensities resulted in greater augmentation of contralateral primary sensorimotor cortex (SI/MI) activity. Stronger LFS intensities were followed by increased α (alpha, 9-11 Hz) band power in SI/MI and decreased θ (theta, 3-5 Hz) band power in MCC. Intensity-dependent attenuation of MCC activity with LFS is consistent with a state of long-term depression. Sustained increases in contralateral SI/MI activity suggests that effects of LFS on somatosensory processing may also be dependent on satiation of SI/MI. Further research could clarify if the activation of SI/MI during LFS competes with nociceptive processing in neuropathic pain.NEW & NOTEWORTHY Somatosensory-evoked potentials during low-frequency stimulation of peripheral nerves were examined at graded stimulus intensities. Low-frequency stimulation was associated with decreased responsiveness in the midcingulate cortex and increased responsiveness in primary sensorimotor cortex. Greater intensities were associated with increased midcingulate cortex θ band power and decreased sensorimotor cortex α band power. Results further previous evidence of an inhibition of somatosensory processing during and after low-frequency stimulation and point toward a potential augmentation of activity in somatosensory processing regions.
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Affiliation(s)
- Danielle Hewitt
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom
| | - Alice Newton-Fenner
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom,2Institute for Risk and Uncertainty, University of Liverpool, Liverpool, United Kingdom
| | - Jessica Henderson
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom
| | - Nicholas B. Fallon
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom
| | - Christopher Brown
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom
| | - Andrej Stancak
- 1Department of Psychological Sciences, grid.10025.36University of Liverpool, Liverpool, United Kingdom,2Institute for Risk and Uncertainty, University of Liverpool, Liverpool, United Kingdom
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7
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Wang Y, Oh H, Barlow SM. Dynamic causal modeling of sensorimotor networks elicited by saltatory pneumotactile velocity in the glabrous hand. J Neuroimaging 2022; 32:752-764. [PMID: 35044016 DOI: 10.1111/jon.12968] [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: 11/08/2021] [Revised: 12/12/2021] [Accepted: 01/04/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The effective connectivity of neuronal networks during passive saltatory pneumotactile velocity stimulation to the glabrous hand with different velocities is still unknown. The present study investigated the effectivity connectivity elicited by saltatory pneumotactile velocity arrays placed on the glabrous hand at three velocities (5, 25, and 65 cm/second). METHODS Dynamic causal modeling (DCM) was used on functional MRI data sampled from 20 neurotypical adults. Five brain regions, including the left primary somatosensory (SI) and motor (M1) cortices, bilateral secondary somatosensory (SII) cortices, and right cerebellar lobule VI, were used to build model space. RESULTS Three velocities (5, 25, and 65 cm/second) of saltatory pneumotactile stimuli were processed in both serial and parallel modes within the sensorimotor networks. The medium velocity of 25 cm/second modulated forward interhemispheric connection from the contralateral SII to the ipsilateral SII. Pneumotactile stimulation at the medium velocity of 25 cm/second also influenced contralateral M1 through contralateral SI. Finally, the right cerebellar lobule VI was involved in the sensorimotor networks. CONCLUSIONS Our DCM results suggest the coexistence of both serial and parallel processing for saltatory pneumotactile velocity stimulation. Significant contralateral M1 modulation promotes the prospect that the passive saltatory pneumotactile velocity arrays can be used to design sensorimotor rehabilitation protocols to activate M1. The effective connectivity from the right cerebellar lobule VI to other cortical regions demonstrates the cerebellum's role in the sensorimotor networks through feedforward and feedback neuronal pathways.
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Affiliation(s)
- Yingying Wang
- Neuroimaging for Language, Literacy and Learning Laboratory, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Center for Brain, Biology and Behavior, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Nebraska Center for Research on Children, Youth, Families and Schools, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Hyuntaek Oh
- Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Communication Neuroscience Laboratory, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Steven M Barlow
- Center for Brain, Biology and Behavior, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.,Communication Neuroscience Laboratory, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
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8
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Lindenbaum L, Zehe S, Anlauff J, Hermann T, Kissler JM. Different Patterns of Attention Modulation in Early N140 and Late P300 sERPs Following Ipsilateral vs. Contralateral Stimulation at the Fingers and Cheeks. Front Hum Neurosci 2021; 15:781778. [PMID: 34938169 PMCID: PMC8685294 DOI: 10.3389/fnhum.2021.781778] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/16/2021] [Indexed: 11/13/2022] Open
Abstract
Intra-hemispheric interference has been often observed when body parts with neighboring representations within the same hemisphere are stimulated. However, patterns of interference in early and late somatosensory processing stages due to the stimulation of different body parts have not been explored. Here, we explore functional similarities and differences between attention modulation of the somatosensory N140 and P300 elicited at the fingers vs. cheeks. In an active oddball paradigm, 22 participants received vibrotactile intensity deviant stimulation either ipsilateral (within-hemisphere) or contralateral (between-hemisphere) at the fingers or cheeks. The ipsilateral deviant always covered a larger area of skin than the contralateral deviant. Overall, both N140 and P300 amplitudes were higher following stimulation at the cheek and N140 topographies differed between fingers and cheek stimulation. For the N140, results showed higher deviant ERP amplitudes following contralateral than ipsilateral stimulation, regardless of the stimulated body part. N140 peak latency differed between stimulated body parts with shorter latencies for the stimulation at the fingers. Regarding P300 amplitudes, contralateral deviant stimulation at the fingers replicated the N140 pattern, showing higher responses and shorter latencies than ipsilateral stimulation at the fingers. For the stimulation at the cheeks, ipsilateral deviants elicited higher P300 amplitudes and longer latencies than contralateral ones. These findings indicate that at the fingers ipsilateral deviant stimulation leads to intra-hemispheric interference, with significantly smaller ERP amplitudes than in contralateral stimulation, both at early and late processing stages. By contrast, at the cheeks, intra-hemispheric interference is selective for early processing stages. Therefore, the mechanisms of intra-hemispheric processing differ from inter-hemispheric ones and the pattern of intra-hemispheric interference in early and late processing stages is body-part specific.
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Affiliation(s)
- Laura Lindenbaum
- Department of Psychology, Bielefeld University, Bielefeld, Germany.,Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
| | - Sebastian Zehe
- Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany.,Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - Jan Anlauff
- Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany.,Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - Thomas Hermann
- Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany.,Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - Johanna Maria Kissler
- Department of Psychology, Bielefeld University, Bielefeld, Germany.,Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
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9
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Cortical interaction of bilateral inputs is similar for noxious and innocuous stimuli but leads to different perceptual effects. Exp Brain Res 2021; 239:2803-2819. [PMID: 34279670 DOI: 10.1007/s00221-021-06175-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/10/2021] [Indexed: 12/20/2022]
Abstract
The cerebral integration of somatosensory inputs from multiple sources is essential to produce adapted behaviors. Previous studies suggest that bilateral somatosensory inputs interact differently depending on stimulus characteristics, including their noxious nature. The aim of this study was to clarify how bilateral inputs evoked by noxious laser stimuli, noxious shocks, and innocuous shocks interact in terms of perception and brain responses. The experiment comprised two conditions (right-hand stimulation and concurrent stimulation of both hands) in which painful laser stimuli, painful shocks and non-painful shocks were delivered. Perception, somatosensory-evoked potentials (P45, N100, P260), laser-evoked potentials (N1, N2 and P2) and event-related spectral perturbations (delta to gamma oscillation power) were compared between conditions and stimulus modalities. The amplitude of negative vertex potentials (N2 or N100) and the power of delta/theta oscillations were increased in the bilateral compared with unilateral condition, regardless of the stimulus type (P < 0.01). However, gamma oscillation power increased for painful and non-painful shocks (P < 0.01), but not for painful laser stimuli (P = 0.08). Despite the similarities in terms of brain activity, bilateral inputs interacted differently for painful stimuli, for which perception remained unchanged, and non-painful stimuli, for which perception increased. This may reflect a ceiling effect for the attentional capture by noxious stimuli and warrants further investigations to examine the regulation of such interactions by bottom-up and top-down processes.
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10
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Makin ADJ, Tyson-Carr J, Derpsch Y, Rampone G, Bertamini M. Electrophysiological priming effects demonstrate independence and overlap of visual regularity representations in the extrastriate cortex. PLoS One 2021; 16:e0254361. [PMID: 34242360 PMCID: PMC8270198 DOI: 10.1371/journal.pone.0254361] [Citation(s) in RCA: 4] [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: 11/03/2020] [Accepted: 06/24/2021] [Indexed: 11/18/2022] Open
Abstract
An Event Related Potential (ERP) component called the Sustained Posterior Negativity (SPN) is generated by regular visual patterns (e.g. vertical reflectional symmetry, horizontal reflectional symmetry or rotational symmetry). Behavioural studies suggest symmetry becomes increasingly salient when the exemplars update rapidly. In line with this, Experiment 1 (N = 48) found that SPN amplitude increased when three different reflectional symmetry patterns were presented sequentially. We call this effect ‘SPN priming’. We then exploited SPN priming to investigate independence of different symmetry representations. SPN priming did not survive changes in retinal location (Experiment 2, N = 48) or non-orthogonal changes in axis orientation (Experiment 3, N = 48). However, SPN priming transferred between vertical and horizontal axis orientations (Experiment 4, N = 48) and between reflectional and rotational symmetry (Experiment 5, N = 48). SPN priming is interesting in itself, and a useful new method for identifying functional boundaries of the symmetry response. We conclude that visual regularities at different retinal locations are coded independently. However, there is some overlap between different regularities presented at the same retinal location.
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Affiliation(s)
- Alexis D. J. Makin
- Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - John Tyson-Carr
- Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Yiovanna Derpsch
- Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Giulia Rampone
- Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Marco Bertamini
- Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom
- Department of General Psychology, University of Padova, Padova, Italy
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11
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Hewitt D, Byrne A, Henderson J, Newton-Fenner A, Tyson-Carr J, Fallon N, Brown C, Stancak A. Inhibition of cortical somatosensory processing during and after low frequency peripheral nerve stimulation in humans. Clin Neurophysiol 2021; 132:1481-1495. [PMID: 34023628 DOI: 10.1016/j.clinph.2021.03.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/25/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Transcutaneous low-frequency stimulation (LFS) elicits long-term depression-like effects on human pain perception. However, the neural mechanisms underlying LFS are poorly understood. We investigated cortical activation changes occurring during LFS and if changes were associated with reduced nociceptive processing and increased amplitude of spontaneous cortical oscillations post-treatment. METHODS LFS was applied to the radial nerve of 25 healthy volunteers over two sessions using active (1 Hz) or sham (0.02 Hz) frequencies. Changes in resting electroencephalography (EEG) and laser-evoked potentials (LEPs) were investigated before and after LFS. Somatosensory-evoked potentials were recorded during LFS and source analysis was carried out. RESULTS Ipsilateral midcingulate and operculo-insular cortex source activity declined linearly during LFS. Active LFS was associated with attenuated long-latency LEP amplitude in ipsilateral frontocentral electrodes and increased resting alpha (8-12 Hz) and beta (16-24 Hz) band power in electrodes overlying operculo-insular, sensorimotor and frontal cortical regions. Reduced ipsilateral operculo-insular cortex source activity during LFS correlated with a smaller post-treatment alpha-band power increase. CONCLUSIONS LFS attenuated somatosensory processing both during and after stimulation. SIGNIFICANCE Results further our understanding of the attenuation of somatosensory processing both during and after LFS.
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Affiliation(s)
- Danielle Hewitt
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK.
| | - Adam Byrne
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK
| | - Jessica Henderson
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Alice Newton-Fenner
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK
| | - John Tyson-Carr
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Nicholas Fallon
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Christopher Brown
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Andrej Stancak
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK
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12
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Source dipole analysis reveals a new brain response to visual symmetry. Sci Rep 2021; 11:285. [PMID: 33431986 PMCID: PMC7801689 DOI: 10.1038/s41598-020-79457-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 12/02/2020] [Indexed: 11/28/2022] Open
Abstract
Visual regularity activates a network of brain regions in the extrastriate cortex. Previous EEG studies have found that this response scales parametrically with proportion of symmetry in symmetry + noise displays. The parametric symmetry response happens in many tasks, but it is enhanced during active regularity discrimination. However, the origins and time course of this selective enhancement are unclear. Here we answered remaining questions with new source dipole analysis. As assumed, the parametric symmetry response found at the sensor level was generated by a pair of dipoles in the left and right extrastriate cortex. This bilateral activity was itself enhanced during regularity discrimination. However, we identified a third, and later, symmetry response in the posterior cingulate during regularity discrimination. Unlike the extrastriate response, this previously unknown activation only indexes strong, task relevant regularity signals. This clarifies the neural circuits which mediate the perceptual and cognitive aspects of symmetry discrimination.
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13
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Kim MY, Kwon H, Yang TH, Kim K. Vibration Alert to the Brain: Evoked and Induced MEG Responses to High-Frequency Vibrotactile Stimuli on the Index Finger of Dominant and Non-dominant Hand. Front Hum Neurosci 2020; 14:576082. [PMID: 33250728 PMCID: PMC7674801 DOI: 10.3389/fnhum.2020.576082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/12/2020] [Indexed: 11/13/2022] Open
Abstract
Background: In recent years, vibrotactile haptic feedback technology has been widely used for user interfaces in the mobile devices. Although functional neuroimaging studies have investigated human brain responses to different types of tactile inputs, the neural mechanisms underlying high-frequency vibrotactile perception are still relatively unknown. Our aim was to investigate neuromagnetic brain responses to high-frequency vibrotactile stimulation, using magnetoencephalography (MEG). Methods: We measured 152-channel whole-head MEG in 30 healthy, right-handed volunteers (aged 20–28 years, 15 females). A total of 300 vibrotactile stimuli were presented at the tip of either the left index finger or the right index finger in two separate sessions. Sinusoidal vibrations at 150 Hz for 200 ms were generated with random inter-stimulus intervals between 1.6 and 2.4 s. Both time-locked analysis and time-frequency analysis were performed to identify peak responses and oscillatory modulations elicited by high-frequency vibrations. The significance of the evoked and induced responses for dominant and non-dominant hand stimulation conditions was statistically tested, respectively. The difference in responses between stimulation conditions was also statistically evaluated. Results: Prominent peak responses were observed at 56 ms (M50) and at 100 ms (M100) for both stimulation conditions. The M50 response revealed clear dipolar field patterns in the contralateral side with significant cortical activations in the contralateral primary sensorimotor area, whereas the M100 response was not as prominent as the M50. Vibrotactile stimulation induced significant suppression of both alpha (8–12 Hz) and beta (20–30 Hz) band activity during the mid-latency period (0.2–0.4 s), primarily in sensorimotor areas contralateral to the stimulation side. In addition, a significant alpha enhancement effect in posterior regions was accompanied with alpha suppressions in sensorimotor regions. The alpha suppression was observed in a broader distribution of cortical areas for the non-dominant hand stimulation. Conclusion: Our data demonstrate that high-frequency tactile vibrations, which is known to primarily activate Pacinian corpuscles, elicit somatosensory M50 and M100 responses in the evoked fields and induce modulations of alpha and beta band oscillations during mid-latency periods. Our study is also consistent with that the primary sensorimotor area is significantly involved in the processing of high-frequency vibrotactile information with contralateral dominance.
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Affiliation(s)
- Min-Young Kim
- Quantum Technology Institute, Korea Research Institute of Standards and Science, Daejeon, South Korea
| | - Hyukchan Kwon
- Quantum Technology Institute, Korea Research Institute of Standards and Science, Daejeon, South Korea
| | - Tae-Heon Yang
- Department of Electronic Engineering, Korea National University of Transportation, Chungju-si, South Korea
| | - Kiwoong Kim
- Quantum Technology Institute, Korea Research Institute of Standards and Science, Daejeon, South Korea.,Department of Medical Physics, University of Science and Technology, Daejeon, South Korea
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14
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Artoni F, Tanguenza A, D'Anna E, Micera S. Somatosensory Evoked Potentials following upper limb noninvasive electrical stimulation: a case study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2881-2884. [PMID: 33018608 DOI: 10.1109/embc44109.2020.9176722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Lack of sensory feedback is one of the main issues contributing to lack of control and embodiment for upper-limb prostheses. Noninvasive nerve stimulation may help amputees overcome such limitations by providing a degree of somatotopic feedback, however its neural correlates have been only partly characterized so far. While the effects of median nerve stimulation have been studied, little attention has been given to ulnar nerve and bipolar stimulation, which might provide a finer modulation of the somatotopic sensation. Here, monopolar and bipolar transcutaneous electrical nerve stimulation (TENS) is repeatedly applied to the ulnar and median nerves and elicited Somatosensory Evoked Potentials (SEPs) are characterized by means of electroencephalography (EEG). Clear P50, P150 and P270 SEPs were outlined, with significantly different amplitudes between configurations. In each case scalp topographies showed a strong contralateral activation in the early phase after the stimulus onset (40-100 ms), compatible with generators in the somatosensory cortex and in accordance to previous literature on actual tactile stimuli, which gives way to a frontal-central distribution at long latencies (130-190 ms). These findings, although needing further validation with a larger pool of subjects, show that bipolar TENS could have potential applications in improving prosthesis control with tactile feedback.
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15
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Whitehead K, Papadelis C, Laudiano-Dray MP, Meek J, Fabrizi L. The Emergence of Hierarchical Somatosensory Processing in Late Prematurity. Cereb Cortex 2020; 29:2245-2260. [PMID: 30843584 PMCID: PMC6458926 DOI: 10.1093/cercor/bhz030] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/30/2019] [Accepted: 02/11/2019] [Indexed: 12/21/2022] Open
Abstract
The somatosensory system has a hierarchical organization. Information processing increases in complexity from the contralateral primary sensory cortex to bilateral association cortices and this is represented by a sequence of somatosensory-evoked potentials recorded with scalp electroencephalographies. The mammalian somatosensory system matures over the early postnatal period in a rostro-caudal progression, but little is known about the development of hierarchical information processing in the human infant brain. To investigate the normal human development of the somatosensory hierarchy, we recorded potentials evoked by mechanical stimulation of hands and feet in 34 infants between 34 and 42 weeks corrected gestational age, with median postnatal age of 3 days. We show that the shortest latency potential was evoked for both hands and feet at all ages with a contralateral somatotopic source in the primary somatosensory cortex (SI). However, the longer latency responses, localized in SI and beyond, matured with age. They gradually emerged for the foot and, although always present for the hand, showed a shift from purely contralateral to bilateral hemispheric activation. These results demonstrate the rostro-caudal development of human somatosensory hierarchy and suggest that the development of its higher tiers is complete only just before the time of normal birth.
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Affiliation(s)
- K Whitehead
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - C Papadelis
- Laboratory of Children's Brain Dynamics, Fetal-Neonatal Neuroimaging and Developmental Science Center, Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - M P Laudiano-Dray
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - J Meek
- Neonatal Unit, Elizabeth Garrett Anderson Wing, University College London Hospitals, London, UK
| | - L Fabrizi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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16
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Heid C, Mouraux A, Treede RD, Schuh-Hofer S, Rupp A, Baumgärtner U. Early gamma-oscillations as correlate of localized nociceptive processing in primary sensorimotor cortex. J Neurophysiol 2020; 123:1711-1726. [PMID: 32208893 DOI: 10.1152/jn.00444.2019] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Recent studies put forward the idea that stimulus-evoked gamma-band oscillations (GBOs; 30-100 Hz) play a specific role in nociception. So far, evidence for the specificity of GBOs for nociception, their possible involvement in nociceptive sensory discriminatory abilities, and knowledge regarding their cortical sources is just starting to grow. To address these questions, we used electroencephalography (EEG) to record brain activity evoked by phasic nociceptive laser stimuli and tactile stimuli applied at different intensities to the right hand and foot of 12 healthy volunteers. The EEG was analyzed in the time domain to extract phase-locked event-related brain potentials (ERPs) and in three regions of interest in the time-frequency domain (delta/theta, 40-Hz gamma, 70-Hz gamma) to extract stimulus-evoked changes in the magnitude of non-phase-locked brain oscillations. Both nociceptive and tactile stimuli, matched with respect to subjective intensity, elicited phase locked ERPs of increasing amplitude with increasing stimulus intensity. In contrast, only nociceptive stimuli elicited a significant enhancement of GBOs (65-85 Hz, 150-230 ms after stimulus onset), whose magnitude encoded stimulus intensity, whereas tactile stimuli led to a GBO decrease. Following nociceptive hand stimulation, the topographical distribution of GBOs was maximal at contralateral electrode C3, whereas maximum activity following foot stimulation was recorded at the midline electrode Cz, compatible with generation of GBOs in the representations of the hand and foot of the primary sensorimotor cortex, respectively. The differential behavior of high-frequency GBOs and low-frequency 40-Hz GBOs is indicating different functional roles and regions in sensory processing.NEW & NOTEWORTHY Gamma-band oscillations show hand-foot somatotopy compatible with generation in primary sensorimotor cortex and are present following nociceptive but not tactile stimulation of the hand and foot in humans.
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Affiliation(s)
- C Heid
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), University of Heidelberg, Mannheim, Germany
| | - A Mouraux
- Institute of Neuroscience (IONS), Université catholique de Louvain, Brussels B-1200, Belgium
| | - R-D Treede
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), University of Heidelberg, Mannheim, Germany
| | - S Schuh-Hofer
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), University of Heidelberg, Mannheim, Germany
| | - A Rupp
- Department of Neurology, Section of Biomagnetism, University of Heidelberg, Heidelberg, Germany
| | - U Baumgärtner
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences (MCTN), University of Heidelberg, Mannheim, Germany.,Department of Human Medicine, Faculty of Life Sciences, Medical School Hamburg (MSH), Hamburg, Germany
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17
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Scherg M, Berg P, Nakasato N, Beniczky S. Taking the EEG Back Into the Brain: The Power of Multiple Discrete Sources. Front Neurol 2019; 10:855. [PMID: 31481921 PMCID: PMC6710389 DOI: 10.3389/fneur.2019.00855] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 07/23/2019] [Indexed: 11/13/2022] Open
Abstract
Background: In contrast to many neuroimaging modalities, clinical interpretation of EEG does not take advantage of post-processing and digital signal analysis. In most centers, EEG is still interpreted at sensor level, exactly as half a century ago. A major task in clinical EEG interpretation is the identification of interictal epileptiform discharges (IEDs). However, due to the overlap of background activity, IEDs can be hard to detect in the scalp EEG. Since traditional montages, like bipolar and average reference, are linear transformations of the recorded channels, the question is whether we can provide linear transformations of the digital EEG to take it back into the brain, at least on a macroscopic level. The goal is to improve visibility of epileptiform activities and to separate out most of the overlap. Methods: Multiple discrete sources provide a stable linear inverse to transform the EEG into source space with little cross-talk between source regions. The model can be based on a few dipoles or regional sources, adapted to the individual EEG and MRI data, or on selected standard sources evenly distributed throughout the brain, e.g. below the 25 EEG standard electrodes. Results: Auditory and somatosensory evoked potentials serve as teaching examples to show how various source spaces can reveal the underlying source components including their loss or alteration due to lesions. Source spaces were able to reveal the propagation of source activities in frontal IEDs and the sequential activation of the major nodes of the underlying epileptic network in myoclonic epilepsy. The power of multiple discrete sources in separating the activities of different brain regions was also evident in the ongoing EEG of cases with frontal cortical dysplasia and bitemporal lobe epilepsy. The new source space 25 made IEDs more clearly visible over the EEG background signals. The more focal nature of source vs. scalp space was quantitatively confirmed using a new measurement of focality. Conclusion: Multiple discrete sources have the power to transform the EEG back into the brain by defining new EEG traces in source space. Using standard source space 25, these can provide for improved clinical interpretation of EEG.
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Affiliation(s)
| | - Patrick Berg
- Research Department, BESA GmbH, Gräfelfing, Germany
| | | | - Sándor Beniczky
- Department of Clinical Neurophysiology, Danish Epilepsy Centre, Aarhus University Hospital, Aarhus, Denmark
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18
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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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19
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Abstract
Integration of nociceptive information is essential to produce adapted responses, to promote body integrity and survival. However, how the brain integrates nociceptive inputs from different body areas remains unknown. The aim of this study was to examine the cortical integration of bilateral nociceptive inputs evoked by laser heat stimuli. Sixteen healthy volunteers (8 F, 8 M; age: 25.5 ± 4.3) were recruited to participate in one session during which painful laser stimuli were applied to their hands with 2 Nd:YAP laser systems. Electroencephalographic activity was recorded to measure laser-evoked potentials and event-related spectral perturbations. Twenty nociceptive stimuli were applied in each of the 4 counterbalanced conditions: (1) right hand, (2) left hand, and both hands with (3) attention to the right or (4) attention to the left. Compared with unilateral conditions, N2 and P2 peak amplitude as well as gamma oscillation power were decreased in bilateral conditions (P < 0.05), but these effects were not affected by the direction of attention (P > 0.1). By contrast, pain was not significantly different in any condition (P > 0.05). These findings show that although more nociceptive inputs reach the brain with multiple nociceptive stimuli, their sensory representation is decreased while pain perception remains unchanged. These interactions between cerebral processing of nociceptive information from different body regions could support coordinated behavioral responses when pain origins from multiple sources.
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20
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Induced and Evoked Properties of Vibrotactile Adaptation in the Primary Somatosensory Cortex. Neural Plast 2019; 2019:5464096. [PMID: 30915111 PMCID: PMC6402197 DOI: 10.1155/2019/5464096] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 11/11/2018] [Indexed: 11/18/2022] Open
Abstract
Prolonged exposure to afferent stimulation (“adaptation”) can cause profound short-term changes in the responsiveness of cortical sensory neurons. While several models have been proposed that link adaptation to single-neuron dynamics, including GABAergic inhibition, the process is currently imperfectly understood at the whole-brain level in humans. Here, we used magnetoencephalography (MEG) to examine the neurophysiological correlates of adaptation within SI in humans. In one condition, a 25 Hz adapting stimulus (5 s) was followed by a 1 s 25 Hz probe (“same”), and in a second condition, the adapting stimulus was followed by a 1 s 180 Hz probe (“different”). We hypothesized that changes in the mu-beta activity band (reflecting GABAergic processing) would be modulated differently between the “same” and “different” probe stimuli. We show that the primary somatosensory (SI) mu-beta response to the “same” probe is significantly reduced (p = 0.014) compared to the adapting stimulus, whereas the mu-beta response to the “different” probe is not (p = n.s.). This reduction may reflect sharpening of the spatiotemporal pattern of activity after adaptation. The stimulus onset mu-beta response did not differ between a 25 Hz adapting stimulus and a 180 Hz probe, suggesting that the mu-beta response is independent of stimulus frequency. Furthermore, we show a sustained evoked and induced desynchronization for the duration of the adapting stimulus, consistent with invasive studies. Our findings are important in understanding the neurophysiology underlying short-term and stimulus-induced plasticity in the human brain and shows that the brain response to tactile stimulation is altered after only brief stimulation.
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21
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Sliva DD, Black CJ, Bowary P, Agrawal U, Santoyo JF, Philip NS, Greenberg BD, Moore CI, Jones SR. A Prospective Study of the Impact of Transcranial Alternating Current Stimulation on EEG Correlates of Somatosensory Perception. Front Psychol 2018; 9:2117. [PMID: 30515114 PMCID: PMC6255923 DOI: 10.3389/fpsyg.2018.02117] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/15/2018] [Indexed: 01/30/2023] Open
Abstract
The (8-12 Hz) neocortical alpha rhythm is associated with shifts in attention across sensory systems, and is thought to represent a sensory gating mechanism for the inhibitory control of cortical processing. The present preliminary study sought to explore whether alpha frequency transcranial alternating current stimulation (tACS) could modulate endogenous alpha power in the somatosensory system, and whether the hypothesized modulation would causally impact perception of tactile stimuli at perceptual threshold. We combined electroencephalography (EEG) with simultaneous brief and intermittent tACS applied over primary somatosensory cortex at individuals' endogenous alpha frequency during a tactile detection task (n = 12 for EEG, n = 20 for behavior). EEG-measured pre-stimulus alpha power was higher on non-perceived than perceived trials, and analogous perceptual correlates emerged in early components of the tactile evoked response. Further, baseline normalized tactile detection performance was significantly lower during alpha than sham tACS, but the effect did not last into the post-tACS time period. Pre- to post-tACS changes in alpha power were linearly dependent upon baseline state, such that alpha power tended to increase when pre-tACS alpha power was low, and decrease when it was high. However, these observations were comparable in both groups, and not associated with evidence of tACS-induced alpha power modulation. Nevertheless, the tactile stimulus evoked response potential (ERP) revealed a potentially lasting impact of alpha tACS on circuit dynamics. The post-tACS ERP was marked by the emergence of a prominent peak ∼70 ms post-stimulus, which was not discernible post-sham, or in either pre-stimulation condition. Computational neural modeling designed to simulate macroscale EEG signals supported the hypothesis that the emergence of this peak could reflect synaptic plasticity mechanisms induced by tACS. The primary lesson learned in this study, which commanded a small sample size, was that while our experimental paradigm provided some evidence of an influence of tACS on behavior and circuit dynamics, it was not sufficient to induce observable causal effects of tACS on EEG-measured alpha oscillations. We discuss limitations and suggest improvements that may help further delineate a causal influence of tACS on cortical dynamics and perception in future studies.
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Affiliation(s)
- Danielle D. Sliva
- Department of Neuroscience, Brown University, Providence, RI, United States
| | - Christopher J. Black
- Department of Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Paul Bowary
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | - Uday Agrawal
- Harvard Medical School, Boston, MA, United States
| | - Juan F. Santoyo
- Department of Neuroscience, Brown University, Providence, RI, United States
| | - Noah S. Philip
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | - Benjamin D. Greenberg
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | | | - Stephanie R. Jones
- Department of Neuroscience, Brown University, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
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22
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Lo CC, Lin PY, Hoe ZY, Chen JJJ. Near Infrared Spectroscopy Study of Cortical Excitability During Electrical Stimulation-Assisted Cycling for Neurorehabilitation of Stroke Patients. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1292-1300. [PMID: 29877854 DOI: 10.1109/tnsre.2018.2829804] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In addition to generating functional limb movement via electrical stimulation, other research proposed lower intensity stimulation for stroke patients from proprioceptive and neuro-biofeedback aspects. This paper investigates the effects of different intensity levels of electrical stimulation during passive cycling on cortical activation using multichannel near infrared spectroscopy (NIRS) covering premotor cortex, supplementary motor area, sensorimotor cortex (SMC), and secondary sensory cortex (S2) regions. Sixteen subjects, including nine stroke patients and seven normal subjects, were instructed to perform passive cycling driven by an ergometer at a pace of 50 rpm under conditions without electrical stimulation (NES) and with low-intensity electrical stimulation (LES) at 10 mA and high-intensity electrical stimulation (HES) at 30 mA. Changes in oxyhemoglobin in different brain regions and the derived interhemispheric correlation coefficient (IHCC) representing the symmetry in response of two hemispheres were evaluated to observe cortical activation and cerebral autoregulation. Our results showed that cortical activation of normal subjects exhibited overall deactivations in HES compared with that under LES and NES. In stroke patients, bilateral S2 activated significantly greater under LES compared with those under NES and HES. The IHCC of the normal group displayed a significant higher value in SMC compared with that of the stroke group. This paper utilized noninvasive NIRS to observe hemodynamic changes and bilateral autoregulation symmetry from IHCC suggesting that passive cycling with LES could better facilitate cortical activation compared with that obtained with NES or HES. The results of this paper could provide general guidelines to simplify the settings of electrical stimulation-assisted-passive cycling in clinical use.
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23
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Tyson-Carr J, Kokmotou K, Soto V, Cook S, Fallon N, Giesbrecht T, Stancak A. Neural correlates of economic value and valuation context: an event-related potential study. J Neurophysiol 2018; 119:1924-1933. [PMID: 29442556 DOI: 10.1152/jn.00524.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The value of environmental cues and internal states is continuously evaluated by the human brain, and it is this subjective value that largely guides decision making. The present study aimed to investigate the initial value attribution process, specifically the spatiotemporal activation patterns associated with values and valuation context, using electroencephalographic event-related potentials (ERPs). Participants completed a stimulus rating task in which everyday household items marketed up to a price of £4 were evaluated with respect to their desirability or material properties. The subjective values of items were evaluated as willingness to pay (WTP) in a Becker-DeGroot-Marschak auction. On the basis of the individual's subjective WTP values, the stimuli were divided into high- and low-value items. Source dipole modeling was applied to estimate the cortical sources underlying ERP components modulated by subjective values (high vs. low WTP) and the evaluation condition (value-relevant vs. value-irrelevant judgments). Low-WTP items and value-relevant judgments both led to a more pronounced N2 visual evoked potential at right frontal scalp electrodes. Source activity in right anterior insula and left orbitofrontal cortex was larger for low vs. high WTP at ∼200 ms. At a similar latency, source activity in right anterior insula and right parahippocampal gyrus was larger for value-relevant vs. value-irrelevant judgments. A stronger response for low- than high-value items in anterior insula and orbitofrontal cortex appears to reflect aversion to low-valued item acquisition, which in an auction experiment would be perceived as a relative loss. This initial low-value bias occurs automatically irrespective of the valuation context. NEW & NOTEWORTHY We demonstrate the spatiotemporal characteristics of the brain valuation process using event-related potentials and willingness to pay as a measure of subjective value. The N2 component resolves values of objects with a bias toward low-value items. The value-related changes of the N2 component are part of an automatic valuation process.
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Affiliation(s)
- John Tyson-Carr
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom
| | - Katerina Kokmotou
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom.,Institute for Risk and Uncertainty, University of Liverpool , Liverpool , United Kingdom
| | - Vicente Soto
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom
| | - Stephanie Cook
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom
| | - Nicholas Fallon
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom
| | - Timo Giesbrecht
- Unilever Research and Development, Port Sunlight, United Kingdom
| | - Andrej Stancak
- Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom.,Institute for Risk and Uncertainty, University of Liverpool , Liverpool , United Kingdom
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24
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Stancak A, Fallon N, Fenu A, Kokmotou K, Soto V, Cook S. Neural Mechanisms of Attentional Switching Between Pain and a Visual Illusion Task: A Laser Evoked Potential Study. Brain Topogr 2017; 31:430-446. [PMID: 29260349 PMCID: PMC5889779 DOI: 10.1007/s10548-017-0613-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 12/11/2017] [Indexed: 12/22/2022]
Abstract
Previous studies demonstrated that pain induced by a noxious stimulus during a distraction task is affected by both stimulus-driven and goal-directed processes which interact and change over time. The purpose of this exploratory study was to analyse associations of aspects of subjective pain experience and engagement with the distracting task with attention-sensitive components of noxious laser-evoked potentials (LEPs) on a single-trial basis. A laser heat stimulus was applied to the dorsum of the left hand while subjects either viewed the Rubin vase-face illusion (RVI), or focused on their pain and associated somatosensory sensations occurring on their stimulated hand. Pain-related sensations occurring with every laser stimulus were evaluated using a set of visual analogue scales. Factor analysis was used to identify the principal dimensions of pain experience. LEPs were correlated with subjective aspects of pain experience on a single-trial basis using a multiple linear regression model. A positive LEP component at the vertex electrodes in the interval 294–351 ms (P2) was smaller during focusing on RVI than during focusing on the stimulated hand. Single-trial amplitude variations of the P2 component correlated with changes in Factor 1, representing essential aspects of pain, and inversely with both Factor 2, accounting for anticipated pain, and the number of RVI figure reversals. A source dipole located in the posterior region of the cingulate cortex was the strongest contributor to the attention-related single-trial variations of the P2 component. Instantaneous amplitude variations of the P2 LEP component during switching attention towards pain in the presence of a distracting task are related to the strength of pain experience, engagement with the task, and the level of anticipated pain. Results provide neurophysiological underpinning for the use of distraction analgesia acute pain relief.
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Affiliation(s)
- Andrej Stancak
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK. .,Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK.
| | - Nicholas Fallon
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK
| | - Alessandra Fenu
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK
| | - Katerina Kokmotou
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK.,Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK
| | - Vicente Soto
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK
| | - Stephanie Cook
- Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK
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Neural Basis of Early Somatosensory Change Detection: A Magnetoencephalography Study. Brain Topogr 2017; 31:242-256. [PMID: 28913778 DOI: 10.1007/s10548-017-0591-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 09/08/2017] [Indexed: 01/05/2023]
Abstract
The mismatch negativity (MMN) reflects the early detection of changes in sensory stimuli at the cortical level. The mechanisms underlying its genesis remain debated. This magnetoencephalography study investigates the spatio-temporal dynamics and the neural mechanisms of the magnetic somatosensory MMN. Somatosensory evoked magnetic fields elicited by tactile stimulation of the right fingertip (Single), tactile stimulation of the right middle phalanx and fingertip (Double) or omissions (Omitted) of tactile stimuli were studied in different paradigms: in oddballs where Double/Omitted followed a sequence of four Single, in sequences of two stimuli where Double occurred after one Single, and in random presentation of Double only. The predictability of Double occurrence in oddballs was also manipulated. Cortical sources of evoked responses were identified using equivalent current dipole modeling. Evoked responses elicited by Double were significantly different from those elicited by Single at the contralateral secondary somatosensory (cSII) cortex. Double elicited higher cSII cortex responses than Single when preceded by a sequence of four Single, compared to when they were preceded by one Single. Double elicited higher cSII cortex response when presented alone compared to when Double were preceded by one or a sequence of Single. Omitted elicited similar cSII cortex response than Single. Double in oddballs led to higher cSII cortex responses when less predictable. These data suggest that early tactile change detection involves mainly cSII cortex. The predictive coding framework probably accounts for the SII cortex response features observed in the different tactile paradigms.
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Somatosensory lateral inhibition processes modulate motor response inhibition - an EEG source localization study. Sci Rep 2017; 7:4454. [PMID: 28667296 PMCID: PMC5493651 DOI: 10.1038/s41598-017-04887-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 05/22/2017] [Indexed: 12/31/2022] Open
Abstract
Motor inhibitory control is a central executive function, but only recently the importance of perceptual mechanisms for these processes has been focused. It is elusive whether basic mechanisms governing sensory perception affect motor inhibitory control. We examine whether sensory lateral inhibition (LI) processes modulate motor inhibitory control using a system neurophysiological approach combining EEG signal decomposition with source localization methods in a somatosensory GO/NOGO task. The results show that inter-individual variations in the strength of LI effects predominantly affect processes when information needs to be integrated between cerebral hemispheres. If information needs to be integrated between hemispheres, strong sensory suppression will lead to more impulsive errors. Importantly, the neurophysiological data suggest that not purely perceptual or motor processes are affected. Rather, LI affects the response selection level and modulates processes of stimulus categorization. This is associated with activity modulations in the posterior parietal cortex. The results suggest that when sensory suppression is high and when information needs to be integrated across hemispheres, these processes are less efficient, which likely leads to worse motor inhibitory control. The results show how basis principles modulating perceptual processes affect subsequent motor inhibitory control processes.
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Kokmotou K, Cook S, Xie Y, Wright H, Soto V, Fallon N, Giesbrecht T, Pantelous A, Stancak A. Effects of loss aversion on neural responses to loss outcomes: An event-related potential study. Biol Psychol 2017; 126:30-40. [PMID: 28396213 DOI: 10.1016/j.biopsycho.2017.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 04/04/2017] [Accepted: 04/04/2017] [Indexed: 11/19/2022]
Abstract
Loss aversion is the tendency to prefer avoiding losses over acquiring gains of the same amount. To shed light on the spatio-temporal processes underlying loss aversion, we analysed the associations between individual loss aversion and electrophysiological responses to loss and gain outcomes in a monetary gamble task. Electroencephalographic feedback-related negativity (FRN) was computed in 29 healthy participants as the difference in electrical potentials between losses and gains. Loss aversion was evaluated using non-linear parametric fitting of choices in a separate gamble task. Loss aversion correlated positively with FRN amplitude (233-263ms) at electrodes covering the lower face. Feedback related potentials were modelled by five equivalent source dipoles. From these dipoles, stronger activity in a source located in the orbitofrontal cortex was associated with loss aversion. The results suggest that loss aversion implemented during risky decision making is related to a valuation process in the orbitofrontal cortex, which manifests during learning choice outcomes.
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Affiliation(s)
- Katerina Kokmotou
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK
| | - Stephanie Cook
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Yuxin Xie
- School of Securities and Futures, Southwestern University of Finance and Economics, China
| | - Hazel Wright
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Vicente Soto
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | - Nicholas Fallon
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK
| | | | - Athanasios Pantelous
- Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK; Department of Mathematical Sciences, University of Liverpool, Liverpool, UK
| | - Andrej Stancak
- Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK.
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28
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Pang CY, Müller MM. Visual object separation resolves competitive interactions in somatosensory cortex evoked signals during concurrent vibrotactile stimulation of the left and right hand. Biol Psychol 2017; 125:154-162. [DOI: 10.1016/j.biopsycho.2017.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/29/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
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Fujimoto S, Kon N, Otaka Y, Yamaguchi T, Nakayama T, Kondo K, Ragert P, Tanaka S. Transcranial Direct Current Stimulation Over the Primary and Secondary Somatosensory Cortices Transiently Improves Tactile Spatial Discrimination in Stroke Patients. Front Neurosci 2016; 10:128. [PMID: 27064531 PMCID: PMC4814559 DOI: 10.3389/fnins.2016.00128] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/14/2016] [Indexed: 11/13/2022] Open
Abstract
In healthy subjects, dual hemisphere transcranial direct current stimulation (tDCS) over the primary (S1) and secondary somatosensory cortices (S2) has been found to transiently enhance tactile performance. However, the effect of dual hemisphere tDCS on tactile performance in stroke patients with sensory deficits remains unknown. The purpose of this study was to investigate whether dual hemisphere tDCS over S1 and S2 could enhance tactile discrimination in stroke patients. We employed a double-blind, crossover, sham-controlled experimental design. Eight chronic stroke patients with sensory deficits participated in this study. We used a grating orientation task (GOT) to measure the tactile discriminative threshold of the affected and non-affected index fingers before, during, and 10 min after four tDCS conditions. For both the S1 and S2 conditions, we placed an anodal electrode over the lesioned hemisphere and a cathodal electrode over the opposite hemisphere. We applied tDCS at an intensity of 2 mA for 15 min in both S1 and S2 conditions. We included two sham conditions in which the positions of the electrodes and the current intensity were identical to that in the S1 and S2 conditions except that current was delivered for the initial 15 s only. We found that GOT thresholds for the affected index finger during and 10 min after the S1 and S2 conditions were significantly lower compared with each sham condition. GOT thresholds were not significantly different between the S1 and S2 conditions at any time point. We concluded that dual-hemisphere tDCS over S1 and S2 can transiently enhance tactile discriminative task performance in chronic stroke patients with sensory dysfunction.
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Affiliation(s)
- Shuhei Fujimoto
- Tokyo Bay Rehabilitation HospitalChiba, Japan; Laboratory of Psychology, Hamamatsu University School of MedicineShizuoka, Japan; Department of Public Health, Kyoto University Graduate School of MedicineKyoto, Japan; Medley, Inc.Tokyo, Japan
| | - Noriko Kon
- Department of Public Health, Kyoto University Graduate School of Medicine Kyoto, Japan
| | - Yohei Otaka
- Tokyo Bay Rehabilitation HospitalChiba, Japan; Department of Rehabilitation Medicine, Keio University School of MedicineTokyo, Japan
| | - Tomofumi Yamaguchi
- Tokyo Bay Rehabilitation HospitalChiba, Japan; Department of Rehabilitation Medicine, Keio University School of MedicineTokyo, Japan
| | - Takeo Nakayama
- Department of Public Health, Kyoto University Graduate School of Medicine Kyoto, Japan
| | | | - Patrick Ragert
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain SciencesLeipzig, Germany; Faculty of Sport Science, Institute for General Kinesiology and Exercise Science, University of LeipzigLeipzig, Germany
| | - Satoshi Tanaka
- Laboratory of Psychology, Hamamatsu University School of Medicine Shizuoka, Japan
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Kashyap R, Ouyang G, Sommer W, Zhou C. Neuroanatomic localization of priming effects for famous faces with latency-corrected event-related potentials. Brain Res 2016; 1632:58-72. [DOI: 10.1016/j.brainres.2015.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/30/2015] [Accepted: 12/01/2015] [Indexed: 10/22/2022]
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31
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Pang CY, Mueller MM. Competitive interactions in somatosensory cortex for concurrent vibrotactile stimulation between and within hands. Biol Psychol 2015. [DOI: 10.1016/j.biopsycho.2015.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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32
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Brouwer GJ, Arnedo V, Offen S, Heeger DJ, Grant AC. Normalization in human somatosensory cortex. J Neurophysiol 2015; 114:2588-99. [PMID: 26311189 DOI: 10.1152/jn.00939.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 08/24/2015] [Indexed: 01/23/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) was used to measure activity in human somatosensory cortex and to test for cross-digit suppression. Subjects received stimulation (vibration of varying amplitudes) to the right thumb (target) with or without concurrent stimulation of the right middle finger (mask). Subjects were less sensitive to target stimulation (psychophysical detection thresholds were higher) when target and mask digits were stimulated concurrently compared with when the target was stimulated in isolation. fMRI voxels in a region of the left postcentral gyrus each responded when either digit was stimulated. A regression model (called a forward model) was used to separate the fMRI measurements from these voxels into two hypothetical channels, each of which responded selectively to only one of the two digits. For the channel tuned to the target digit, responses in the left postcentral gyrus increased with target stimulus amplitude but were suppressed by concurrent stimulation to the mask digit, evident as a shift in the gain of the response functions. For the channel tuned to the mask digit, a constant baseline response was evoked for all target amplitudes when the mask was absent and responses decreased with increasing target amplitude when the mask was concurrently presented. A computational model based on divisive normalization provided a good fit to the measurements for both mask-absent and target + mask stimulation. We conclude that the normalization model can explain cross-digit suppression in human somatosensory cortex, supporting the hypothesis that normalization is a canonical neural computation.
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Affiliation(s)
- Gijs Joost Brouwer
- Department of Psychology and Center for Neural Science, New York University, New York, New York; and
| | - Vanessa Arnedo
- Department of Neurology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Shani Offen
- Department of Psychology and Center for Neural Science, New York University, New York, New York; and
| | - David J Heeger
- Department of Psychology and Center for Neural Science, New York University, New York, New York; and
| | - Arthur C Grant
- Department of Neurology, State University of New York, Downstate Medical Center, Brooklyn, New York
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33
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Tamè L, Pavani F, Papadelis C, Farnè A, Braun C. Early integration of bilateral touch in the primary somatosensory cortex. Hum Brain Mapp 2014; 36:1506-23. [PMID: 25514844 DOI: 10.1002/hbm.22719] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 11/30/2014] [Accepted: 12/01/2014] [Indexed: 11/06/2022] Open
Abstract
Animal, as well as behavioural and neuroimaging studies in humans have documented integration of bilateral tactile information at the level of primary somatosensory cortex (SI). However, it is still debated whether integration in SI occurs early or late during tactile processing, and whether it is somatotopically organized. To address both the spatial and temporal aspects of bilateral tactile processing we used magnetoencephalography in a tactile repetition-suppression paradigm. We examined somatosensory evoked-responses produced by probe stimuli preceded by an adaptor, as a function of the relative position of adaptor and probe (probe always at the left index finger; adaptor at the index or middle finger of the left or right hand) and as a function of the delay between adaptor and probe (0, 25, or 125 ms). Percentage of response-amplitude suppression was computed by comparing paired (adaptor + probe) with single stimulations of adaptor and probe. Results show that response suppression varies differentially in SI and SII as a function of both spatial and temporal features of the stimuli. Remarkably, repetition suppression of SI activity emerged early in time, regardless of whether the adaptor stimulus was presented on the same and the opposite body side with respect to the probe. These novel findings support the notion of an early and somatotopically organized inter-hemispheric integration of tactile information in SI.
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Affiliation(s)
- Luigi Tamè
- Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy
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34
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Direct and crossed effects of somatosensory stimulation on neuronal excitability and motor performance in humans. Neurosci Biobehav Rev 2014; 47:22-35. [DOI: 10.1016/j.neubiorev.2014.07.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/07/2014] [Accepted: 07/14/2014] [Indexed: 12/11/2022]
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35
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Brodie SM, Villamayor A, Borich MR, Boyd LA. Exploring the specific time course of interhemispheric inhibition between the human primary sensory cortices. J Neurophysiol 2014; 112:1470-6. [DOI: 10.1152/jn.00074.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neurophysiological mechanism of interhemispheric inhibition (IHI) between the human primary sensory cortices (S1s) is poorly understood. Here we used a paired median nerve somatosensory evoked potential protocol to observe S1-S1 IHI from the dominant to the nondominant hemisphere with electroencephalography. In 10 healthy, right-handed individuals, we compared mean peak-to-peak amplitudes of five somatosensory evoked potential components (P14/N20, N20/P25, P25/N30, N30/P40, and P40/N60) recorded over the right S1 after synchronous versus asynchronous stimulation of the right and left median nerves. Asynchronous conditioning + test stimuli (CS+TS) were delivered at interstimulus intervals of 15, 20, 25, 30, and 35 ms. We found that, in relation to synchronous stimulation, when a CS to the left S1 preceded a TS to the right S1 at the short intervals (15 and 20 ms) the amplitude of the cortical N20/P25 complex was significantly depressed, whereas at the longer intervals (25, 30, and 35 ms) significant inhibition was observed for the thalamocortical P14/N20 as well as the cortical N20/P25 components. We conclude that the magnitude of S1 IHI appears to depend on the temporal asynchrony of bilateral inputs and the specific timing is likely reflective of a direct transcallosal mechanism. Employing a method that enables direct S1 IHI to be reliably quantified may provide a novel tool to assess potential IHI imbalances in individuals with neurological damage, such as stroke.
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Affiliation(s)
- Sonia M. Brodie
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Anica Villamayor
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Michael R. Borich
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Lara A. Boyd
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; and
- Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
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36
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Test–retest reliability of concurrently recorded steady-state and somatosensory evoked potentials in somatosensory sustained spatial attention. Biol Psychol 2014; 100:86-96. [DOI: 10.1016/j.biopsycho.2014.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 11/19/2022]
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Ann Stringer E, Qiao PG, Friedman RM, Holroyd L, Newton AT, Gore JC, Min Chen L. Distinct fine-scale fMRI activation patterns of contra- and ipsilateral somatosensory areas 3b and 1 in humans. Hum Brain Mapp 2014; 35:4841-57. [PMID: 24692215 DOI: 10.1002/hbm.22517] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 02/12/2014] [Accepted: 03/17/2014] [Indexed: 11/06/2022] Open
Abstract
Inter-areal and ipsilateral cortical responses to tactile stimulation have not been well described in human S1 cortex. By taking advantage of the high signal-to-noise ratio at 7 T, we quantified blood oxygenation level dependent (BOLD) response patterns and time courses to tactile stimuli on individual distal finger pads at a fine spatial scale, and examined whether there are inter-areal (area 3b versus area 1) and interhemispheric response differences to unilateral tactile stimulation in healthy human subjects. We found that 2-Hz tactile stimulation of individual fingertips evoked detectable BOLD signal changes in both contralateral and ipsilateral area 3b and area 1. Contralateral digit activations were organized in an orderly somatotopic manner, and BOLD responses in area 3b were more digit selective than those in area 1. However, the area of cortex that was responsive to stimulation of a single digit (stimulus-response field) was similar across areas. In the ipsilateral hemisphere, response magnitudes in both areas 3b and 1 were significantly weaker than those of the contralateral hemisphere. Digit activations exhibited no clear somatotopic organizational pattern in either area 3b or area 1, yet digit selectivity was retained in area 1 but not in area 3b. The observation of distinct digit-selective responses of contralateral area 3b versus area 1 supports a higher order function of contralateral area 1 in spatial integration. In contrast, ipsilateral cortices may play a less discriminative role in the perception of unilateral tactile sensation in humans.
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Onishi H, Sugawara K, Yamashiro K, Sato D, Suzuki M, Kirimoto H, Tamaki H, Murakami H, Kameyama S. Effect of the number of pins and inter-pin distance on somatosensory evoked magnetic fields following mechanical tactile stimulation. Brain Res 2013; 1535:78-88. [DOI: 10.1016/j.brainres.2013.08.048] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/23/2013] [Accepted: 08/24/2013] [Indexed: 11/26/2022]
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Besle J, Sánchez-Panchuelo RM, Bowtell R, Francis S, Schluppeck D. Event-related fMRI at 7T reveals overlapping cortical representations for adjacent fingertips in S1 of individual subjects. Hum Brain Mapp 2013; 35:2027-43. [PMID: 24014446 PMCID: PMC4216413 DOI: 10.1002/hbm.22310] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/25/2013] [Accepted: 04/02/2013] [Indexed: 11/21/2022] Open
Abstract
Recent fMRI studies of the human primary somatosensory cortex have been able to differentiate the cortical representations of different fingertips at a single‐subject level. These studies did not, however, investigate the expected overlap in cortical activation due to the stimulation of different fingers. Here, we used an event‐related design in six subjects at 7 Tesla to explore the overlap in cortical responses elicited in S1 by vibrotactile stimulation of the five fingertips. We found that all parts of S1 show some degree of spatial overlap between the cortical representations of adjacent or even nonadjacent fingertips. In S1, the posterior bank of the central sulcus showed less overlap than regions in the post‐central gyrus, which responded to up to five fingertips. The functional properties of these two areas are consistent with the known layout of cytoarchitectonically defined subareas, and we speculate that they correspond to subarea 3b (S1 proper) and subarea 1, respectively. In contrast with previous fMRI studies, however, we did not observe discrete activation clusters that could unequivocally be attributed to different subareas of S1. Venous maps based on T2*‐weighted structural images suggest that the observed overlap is not driven by extra‐vascular contributions from large veins. Hum Brain Mapp 35:2027–2043, 2014. © 2013 The Authors Human Brain Mapping published by Wiley Periodicals, Inc.
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Affiliation(s)
- Julien Besle
- Visual Neuroscience Group, School of Psychology, University of Nottingham, NG7 2RD, Nottingham, United Kingdom
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40
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Somatotopic finger mapping using MEG: toward an optimal stimulation paradigm. Clin Neurophysiol 2013; 124:1659-70. [PMID: 23518470 DOI: 10.1016/j.clinph.2013.01.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 12/19/2012] [Accepted: 01/15/2013] [Indexed: 11/21/2022]
Abstract
OBJECTIVE In non-invasive somatotopic mapping based on neuromagnetic source analysis, the recording time can be shortened and accuracy improved by applying simultaneously vibrotactile stimuli at different frequencies to multiple body sites and recording multiple steady-state responses. This study compared the reliability of sensory evoked responses, source localization performance, and reproducibility of digit maps for three different stimulation paradigms. METHODS Vibrotactile stimuli were applied to the fingertip and neuromagnetic steady-state responses were recorded. Index and middle fingers were stimulated either sequentially in separate blocks, simultaneously at different frequencies, or in alternating temporal order within a block. RESULTS Response amplitudes were largest and source localization was most accurate between 21 and 23 Hz. Separation of adjacent digits was significant for all paradigms in all participants. Suppressive interactions occurred between simultaneously applied stimuli. However, when frequently alternating between stimulus sites, the higher stimulus novelty resulted in increased amplitudes and superior localization performance. CONCLUSIONS When receptive fields are strongly overlapping, the alternating stimulation is preferable over recording multiple steady state responses. SIGNIFICANCE The new paradigm improved the measurement of the distance of somatotopic finger representation in human primary somatosensory cortex, which is an important metric for neuroplastic reorganization after learning and rehabilitation training.
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Onishi H, Sugawara K, Yamashiro K, Sato D, Suzuki M, Kirimoto H, Tamaki H, Murakami H, Kameyama S. Neuromagnetic activation following active and passive finger movements. Brain Behav 2013; 3:178-92. [PMID: 23531918 PMCID: PMC3607158 DOI: 10.1002/brb3.126] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/31/2012] [Accepted: 01/15/2013] [Indexed: 11/10/2022] Open
Abstract
The detailed time courses of cortical activities and source localizations following passive finger movement were studied using whole-head magnetoencephalography (MEG). We recorded motor-related cortical magnetic fields following voluntary movement and somatosensory-evoked magnetic fields following passive movement (PM) in 13 volunteers. The most prominent movement-evoked magnetic field (MEF1) following active movement was obtained approximately 35.3 ± 8.4 msec after movement onset, and the equivalent current dipole (ECD) was estimated to be in the primary motor cortex (Brodmann area 4). Two peaks of MEG response associated with PM were recorded from 30 to 100 msec after movement onset. The earliest component (PM1) peaked at 36.2 ± 8.2 msec, and the second component (PM2) peaked at 86.1 ± 12.1 msec after movement onset. The peak latency and ECD localization of PM1, estimated to be in area 4, were the same as those of the most prominent MEF following active movement. ECDs of PM2 were estimated to be not only in area 4 but also in the supplementary motor area (SMA) and the posterior parietal cortex (PPC) over the hemisphere contralateral to the movement, and in the secondary somatosensory cortex (S2) of both hemispheres. The peak latency of each source activity was obtained at 54-109 msec in SMA, 64-114 msec in PPC, and 84-184 msec in the S2. Our results suggest that the magnetic waveforms at middle latency (50-100 msec) after PM are different from those after active movement and that these waveforms are generated by the activities of several cortical areas, that is, area 4 and SMA, PPC, and S2. In this study, the time courses of the activities in SMA, PPC, and S2 accompanying PM in humans were successfully recorded using MEG with a multiple dipole analysis system.
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Affiliation(s)
- Hideaki Onishi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan
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42
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Kuehn E, Mueller K, Turner R, Schütz-Bosbach S. The functional architecture of S1 during touch observation described with 7 T fMRI. Brain Struct Funct 2013; 219:119-40. [PMID: 23283478 PMCID: PMC3889700 DOI: 10.1007/s00429-012-0489-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 11/20/2012] [Indexed: 12/19/2022]
Abstract
Recent studies indicate that the primary somatosensory cortex (S1) is active not only when touch is physically perceived but also when it is merely observed to be experienced by another person. This social responsivity of S1 has important implications for our understanding of S1 functioning. However, S1 activity during touch observation has not been characterized in great detail to date. We focused on two features of the S1 functional architecture during touch observation, namely the topographical arrangement of index and middle finger receptive fields (RFs), and their dynamic shrinkage during concurrent activation. Both features have important implications for human behavior. We conducted two fMRI studies at 7 T, one where touch was physically perceived, and one where touch was observed. In the two experiments, participants either had their index finger and/or middle finger stimulated using paintbrushes, or just observed similar touch events on video. Our data show that observing and physically experiencing touch elicits overlapping activity changes in S1. In addition, observing touch to the index finger or the middle finger alone evoked topographically arranged activation foci in S1. Importantly, when co-activated, the index and middle finger RFs not only shrank during physical touch perception, but also during touch observation. Our data, therefore, indicate a similarity between the functional architecture of S1 during touch observation and physical touch perception with respect to single-digit topography and RF shrinkage. These results may allow the tentative conclusion that even primary somatosensory experiences, such as physical touch perception, can be shared amongst individuals.
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Affiliation(s)
- Esther Kuehn
- Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, 04103, Leipzig, Germany,
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43
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Stancak A, Ward H, Fallon N. Modulation of pain by emotional sounds: a laser-evoked potential study. Eur J Pain 2012; 17:324-35. [PMID: 22927219 DOI: 10.1002/j.1532-2149.2012.00206.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2012] [Indexed: 11/08/2022]
Abstract
BACKGROUND Previous studies have shown increases in experimental pain during induction of a negative emotion with visual stimuli, verbal statements or unpleasant odours. The goal of the present study was to analyse the spatio-temporal activation patterns underlying pain augmentation during negative emotional sounds. METHODS Negative (e.g., crying), positive (e.g., laughter) and neutral (e.g., distant traffic) sound samples of 4 s duration were presented while noxious laser stimuli were administered to the dorsum of the right hand in 16 healthy participants. The electroencephalographic laser-evoked potentials (LEPs) were modelled using six equivalent source dipoles located in the left and right fronto-opercular/anterior-insular cortex, left parietal operculum, left primary somatosensory cortex, medial parietal cortex and left medial temporal cortex. RESULTS Negative emotional sounds were associated with stronger pain than neutral or positive sounds. The source activity in the left medial temporal cortex, purportedly involving hippocampal formation, in the epoch 294-330 ms was greater during negative than neutral or positive sounds. In the left fronto-opercular/anterior-insular cortex, negative sounds failed to show the positive potential component at around 260 ms that was observed during positive and especially during neutral sounds. CONCLUSIONS Results suggest increased input of pain-related information into the hippocampal formation when listening to negative emotional sounds, which may in turn facilitate temporal binding between representations of noxious and other behaviourally relevant stimuli, and perhaps associative learning. Absence of the positive potential component fronto-opercular/anterior-insular cortex during negative sounds points to a slow attentional disengagement from pain and increased awareness of the painful stimulus.
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Affiliation(s)
- A Stancak
- Department of Experimental Psychology, Institute of Psychology, Health, and Society, University of Liverpool, UK.
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Lim M, Kim JS, Chung CK. Modulation of somatosensory evoked magnetic fields by intensity of interfering stimuli in human somatosensory cortex: An MEG study. Neuroimage 2012; 61:660-9. [DOI: 10.1016/j.neuroimage.2012.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 03/12/2012] [Accepted: 04/02/2012] [Indexed: 10/28/2022] Open
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Spatiotemporal dynamics of bimanual integration in human somatosensory cortex and their relevance to bimanual object manipulation. J Neurosci 2012; 32:5667-77. [PMID: 22514328 DOI: 10.1523/jneurosci.5957-11.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Little is known about the spatiotemporal dynamics of cortical responses that integrate slightly asynchronous somatosensory inputs from both hands. This study aimed to clarify the timing and magnitude of interhemispheric interactions during early integration of bimanual somatosensory information in different somatosensory regions and their relevance for bimanual object manipulation and exploration. Using multi-fiber probabilistic diffusion tractography and MEG source analysis of conditioning-test (C-T) median nerve somatosensory evoked fields in healthy human subjects, we sought to extract measures of structural and effective callosal connectivity between different somatosensory cortical regions and correlated them with bimanual tactile task performance. Neuromagnetic responses were found in major somatosensory regions, i.e., primary somatosensory cortex SI, secondary somatosensory cortex SII, posterior parietal cortex, and premotor cortex. Contralateral to the test stimulus, SII activity was maximally suppressed by 51% at C-T intervals of 40 and 60 ms. This interhemispheric inhibition of the contralateral SII source activity correlated directly and topographically specifically with the fractional anisotropy of callosal fibers interconnecting SII. Thus, the putative pathway that mediated inhibitory interhemispheric interactions in SII was a transcallosal route from ipsilateral to contralateral SII. Moreover, interhemispheric inhibition of SII source activity correlated directly with bimanual tactile task performance. These findings were exclusive to SII. Our data suggest that early interhemispheric somatosensory integration primarily occurs in SII, is mediated by callosal fibers that interconnect homologous SII areas, and has behavioral importance for bimanual object manipulation and exploration.
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Maihöfner C, Jesberger F, Seifert F, Kaltenhäuser M. Cortical processing of mechanical hyperalgesia: A MEG study. Eur J Pain 2012; 14:64-70. [DOI: 10.1016/j.ejpain.2009.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 01/31/2009] [Accepted: 02/12/2009] [Indexed: 11/27/2022]
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Spatiotemporal properties of neuron response suppression in owl monkey primary somatosensory cortex when stimuli are presented to both hands. J Neurosci 2011; 31:3589-601. [PMID: 21389215 DOI: 10.1523/jneurosci.4310-10.2011] [Citation(s) in RCA: 57] [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 the lack of ipsilateral receptive fields (RFs) for neurons in the hand representation of area 3b of primary somatosensory cortex, interhemispheric interactions have been reported to varying degrees. We investigated spatiotemporal properties of these interactions to determine the following: response types, timing between stimuli to evoke the strongest bimanual interactions, topographical distribution of effects, and their dependence on similarity of stimulus locations on the two hands. We analyzed response magnitudes and latencies of single neurons and multineuron clusters recorded from 100-electrode arrays implanted in one hemisphere of each of two anesthetized owl monkeys. Skin indentations were delivered to the two hands simultaneously and asynchronously at mirror locations (matched sites on each hand) and nonmirror locations. Since multiple neurons were recorded simultaneously, stimuli on the contralateral hand could be within or outside of the classical RFs of any given neuron. For most neurons, stimulation on the ipsilateral hand suppressed responses to stimuli on the contralateral hand. Maximum suppression occurred when the ipsilateral stimulus was presented 100 ms before the contralateral stimulus onset (p < 0.0005). The longest stimulus onset delay tested (500 ms) allowed contralateral responses to recover to control levels (p = 0.428). Stimulation on mirror digits did not differ from stimulation on nonmirror locations (p = 1.000). These results indicate that interhemispheric interactions are common in area 3b, somewhat topographically diffuse, and maximal when the suppressing ipsilateral stimulus precedes the contralateral stimulus. Our findings point to a neurophysiological basis for "interference" effects found in human psychophysical studies of bimanual stimulation.
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Cortical activation changes during repeated laser stimulation: a magnetoencephalographic study. PLoS One 2011; 6:e19744. [PMID: 21572954 PMCID: PMC3091873 DOI: 10.1371/journal.pone.0019744] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 04/15/2011] [Indexed: 12/31/2022] Open
Abstract
Repeated warm laser stimuli produce a progressive increase of the sensation of warmth and heat and eventually that of a burning pain. The pain resulting from repetitive warm stimuli is mediated by summated C fibre responses. To shed more light on the cortical changes associated with pain during repeated subnoxious warm stimution, we analysed magnetoencephalographic (MEG) evoked fields in eleven subjects during application of repetitive warm laser stimuli to the dorsum of the right hand. One set of stimuli encompassed 10 laser pulses occurring at 2.5 s intervals. Parameters of laser stimulation were optimised to elicit a pleasant warm sensation upon a single stimulus with a rise of skin temperature after repeated stimulation not exceeding the threshold of C mechano-heat fibres. Subjects reported a progressive increase of the intensity of heat and burning pain during repeated laser stimulation in spite of only mild (4.8°C) increase of skin temperature from the first stimulus to the tenth stimulus. The mean reaction time, evaluated in six subjects, was 1.33 s, confirming involvement of C fibres. The neuromagnetic fields were modelled by five equivalent source dipoles located in the occipital cortex, cerebellum, posterior cingulate cortex, and left and right operculo-insular cortex. The only component showing statistically significant changes during repetitive laser stimulation was the late component of the contralateral operculo-insular source peaking at 1.05 s after stimulus onset. The amplitude increases of the late component of the contralateral operculo-insular source dipole correlated with the subjects' numerical ratings of warmth and pain. Results point to a pivotal role of the contralateral operculo-insular region in processing of C-fibre mediated pain during repeated subnoxious laser stimulation.
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Ragert P, Nierhaus T, Cohen LG, Villringer A. Interhemispheric interactions between the human primary somatosensory cortices. PLoS One 2011; 6:e16150. [PMID: 21347308 PMCID: PMC3037378 DOI: 10.1371/journal.pone.0016150] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 12/13/2010] [Indexed: 11/26/2022] Open
Abstract
In the somatosensory domain it is still unclear at which processing stage information reaches the opposite hemispheres. Due to dense transcallosal connections, the secondary somatosensory cortex (S2) has been proposed to be the key candidate for interhemispheric information transfer. However, recent animal studies showed that the primary somatosensory cortex (S1) might as well account for interhemispheric information transfer. Using paired median nerve somatosensory evoked potential recordings in humans we tested the hypothesis that interhemispheric inhibitory interactions in the somatosensory system occur already in an early cortical processing stage such as S1. Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms. No such changes were observed for later cortical components such as the N20/P25, N30, P40 and N60 amplitude. Additionally, the subcortically generated P14 response in left S1 was also not affected. These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20–25 ms after median nerve stimulation.
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Affiliation(s)
- Patrick Ragert
- Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
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Task requirements change signal strength of the primary somatosensory M50: Oddball vs. one-back tasks. Psychophysiology 2010; 48:569-77. [DOI: 10.1111/j.1469-8986.2010.01116.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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