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Shimada E, Kanetaka H, Hihara H, Kanno A, Kawashima R, Nakasato N, Igarashi K. Effects of pain associated with orthodontic tooth movement on tactile sensation of periodontal ligaments. Clin Oral Investig 2023; 28:36. [PMID: 38147159 PMCID: PMC10751255 DOI: 10.1007/s00784-023-05469-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/19/2023] [Indexed: 12/27/2023]
Abstract
OBJECTIVES Pain associated with orthodontic tooth movement reportedly reduces periodontal ligament tactile sensation. However, the mechanism associated with the central nervous system remains unclear. This study was conducted by measuring somatosensory evoked magnetic fields (SEFs) during mechanical stimulation of teeth as they were being moved by separator elastics. Findings clarified the effects of pain on periodontal ligament tactile sensation during orthodontic tooth movement. MATERIALS AND METHODS Using magnetoencephalography, SEFs were measured during the application of mechanical stimuli to the mandibular right first molars of 23 right-handed healthy participants (0 h). Separator elastics were subsequently inserted into the mesial and distal interdental portions of the mandibular right first molars. The same mechanical stimuli were applied again 24 h later while the SEFs were measured (24 h). After each SEF measurements, pain was also evaluated using the Visual Analog Scale (VAS). RESULTS The VAS values were significantly higher at 24 h than at 0 h (p < 0.05). No significant difference in the peak latencies was found between those obtained at 0 h and 24 h, but the intensities around 40.0 ms in the contralateral hemisphere were significantly lower at 24 h than at 0 h (p < 0.01). CONCLUSIONS Pain associated with orthodontic tooth movement might suppress periodontal ligament tactile sensation in the primary somatosensory cortex. CLINICAL RELEVANCE Pain associated with orthodontic tooth movement might affect periodontal ligament sensation, consequently causing discomfort during occlusion.
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Affiliation(s)
- Eriya Shimada
- Division of Craniofacial Anomalies, Tohoku University Graduate School of Dentistry, Sendai, Japan.
- Department of Orthodontics and Speech Therapy for Craniofacial Anomalies, Tohoku University Hospital, Sendai, Japan.
| | - Hiroyasu Kanetaka
- Department of Orthodontics and Speech Therapy for Craniofacial Anomalies, Tohoku University Hospital, Sendai, Japan
- Division of Interdisciplinary Integration, Liaison Center for Innovative Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Hiroki Hihara
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Akitake Kanno
- Department of Advanced Spintronics Medical Engineering, Tohoku University Graduate School of Engineering, Sendai, Japan
| | - Ryuta Kawashima
- Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Nobukazu Nakasato
- Department of Advanced Spintronics Medical Engineering, Tohoku University Graduate School of Engineering, Sendai, Japan
- Department of Epileptology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kaoru Igarashi
- Division of Craniofacial Anomalies, Tohoku University Graduate School of Dentistry, Sendai, Japan
- Department of Orthodontics and Speech Therapy for Craniofacial Anomalies, Tohoku University Hospital, Sendai, Japan
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Tsujinaka R, Oda H, Fukuda S, Hamada N, Matsuoka M, Hiraoka K. Afferent volley from the digital nerve induces short-latency facilitation of perceptual sensitivity and primary sensory cortex excitability. Exp Brain Res 2023; 241:1339-1351. [PMID: 37012374 DOI: 10.1007/s00221-023-06611-y] [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: 12/23/2022] [Accepted: 03/27/2023] [Indexed: 04/05/2023]
Abstract
The present study examined whether the perceptual sensitivity and excitability of the primary sensory cortex are modulated by the afferent volley from the digital nerve of a conditioned finger within a short period of time. The perceptual threshold of an electrical stimulus to the index finger (test stimulus) was decreased by a conditioning stimulus to the index finger 4 or 6 ms before the test stimulus, or by a stimulus to the middle or ring finger 2 ms before that. This is explained by the view that the afferent volleys from the digital nerves of the fingers converge in the somatosensory areas, causing spatial summation of the afferent inputs through a small number of synaptic relays, leading to the facilitation of perceptual sensitivity. The N20 component of the somatosensory-evoked potential was facilitated by a conditioning stimulus to the middle finger 4 ms before a test stimulus or to the thumb 2 ms before the test stimulus. This is explained by the view that the afferent volley from the digital nerve of the finger adjacent to the tested finger induces lateral facilitation of the representation of the tested finger in the primary sensory cortex through a small number of synaptic relays.
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Affiliation(s)
- Ryo Tsujinaka
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino City, Japan
| | - Hitoshi Oda
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino City, Japan
| | - Shiho Fukuda
- Department of Rehabilitation Science, School of Medicine, Osaka Metropolitan University, Habikino City, Japan
| | - Naoki Hamada
- Department of Rehabilitation Science, School of Medicine, Osaka Metropolitan University, Habikino City, Japan
| | - Masakazu Matsuoka
- Department of Rehabilitation Science, School of Medicine, Osaka Metropolitan University, Habikino City, Japan
| | - Koichi Hiraoka
- Department of Rehabilitation Science, School of Medicine, Osaka Metropolitan University, Habikino City, Japan.
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3
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Arslanova I, Takamuku S, Gomi H, Haggard P. Multi-digit tactile perception I: motion integration benefits for tactile trajectories presented bimanually. J Neurophysiol 2022; 128:418-433. [PMID: 35822710 PMCID: PMC9359661 DOI: 10.1152/jn.00022.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interactions with objects involve simultaneous contact with multiple, not necessarily adjacent, skin regions. While advances have been made in understanding the capacity to selectively attend to a single tactile element among distracting stimulations, here, we examine how multiple stimulus elements are explicitly integrated into an overall tactile percept. Across four experiments, participants averaged the direction of two simultaneous tactile motion trajectories of varying discrepancy delivered to different fingerpads. Averaging performance differed between within- and between-hands conditions in terms of sensitivity and precision but was unaffected by somatotopic proximity between stimulated fingers. First, precision was greater in between-hand compared to within-hand conditions, demonstrating a bimanual perceptual advantage in multi-touch integration. Second, sensitivity to the average direction was influenced by the discrepancy between individual motion signals, but only for within-hand conditions. Overall, our experiments identify key factors that influence perception of simultaneous tactile events. In particular, we show that multi-touch integration is constrained by hand-specific rather than digit-specific mechanisms.
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Affiliation(s)
- Irena Arslanova
- Institute of Cognitive Neuroscience, grid.83440.3bUniversity College London, London, United Kingdom
| | - Shinya Takamuku
- NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japan
| | - Hiroaki Gomi
- NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japan
| | - Patrick Haggard
- Institute of Cognitive Neuroscience, grid.83440.3bUniversity College London, London, United Kingdom
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Arslanova I, Wang K, Gomi H, Haggard P. Somatosensory evoked potentials that index lateral inhibition are modulated according to the mode of perceptual processing: comparing or combining multi-digit tactile motion. Cogn Neurosci 2020; 13:47-59. [PMID: 33307992 DOI: 10.1080/17588928.2020.1839403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Many perceptual studies focus on the brain's capacity to discriminate between stimuli. However, our normal experience of the world also involves integrating multiple stimuli into a single perceptual event. Neural mechanisms such as lateral inhibition are believed to enhance local differences between sensory inputs from nearby regions of the receptor surface. However, this mechanism would seem dysfunctional when sensory inputs need to be combined rather than contrasted. Here, we investigated whether the brain can strategically regulate the strength of suppressive interactions that underlie lateral inhibition between finger representations in human somatosensory processing. To do this, we compared sensory processing between conditions that required either comparing or combining information. We delivered two simultaneous tactile motion trajectories to index and middle fingertips of the right hand. Participants had to either compare the directions of the two stimuli, or to combine them to form their average direction. To reveal preparatory tuning of somatosensory cortex, we used an established event-related potential design to measure the interaction between cortical representations evoked by digital nerve shocks immediately before each tactile stimulus. Consistent with previous studies, we found a clear suppression between cortical activations when participants were instructed to compare the tactile motion directions. Importantly, this suppression was significantly reduced when participants had to combine the same stimuli. These findings suggest that the brain can strategically switch between a comparative and a combinative mode of somatosensory processing, according to the perceptual goal, by preparatorily adjusting the strength of a process akin to lateral inhibition.
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Affiliation(s)
- Irena Arslanova
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Keying Wang
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Hiroaki Gomi
- NTT Communication Science Laboratories, NTT Corporation, Atsugishi, Japan
| | - Patrick Haggard
- Institute of Cognitive Neuroscience, University College London, London, UK
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5
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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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Yoshinaga K, Matsuhashi M, Mima T, Fukuyama H, Takahashi R, Hanakawa T, Ikeda A. Comparison of Phase Synchronization Measures for Identifying Stimulus-Induced Functional Connectivity in Human Magnetoencephalographic and Simulated Data. Front Neurosci 2020; 14:648. [PMID: 32636735 PMCID: PMC7318889 DOI: 10.3389/fnins.2020.00648] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 05/25/2020] [Indexed: 12/11/2022] Open
Abstract
Phase synchronization measures are widely used for investigating inter-regional functional connectivity (FC) of brain oscillations, but which phase synchronization measure should be chosen for a given experiment remains unclear. Using neuromagnetic brain signals recorded from healthy participants during somatosensory stimuli, we compared the performance of four phase synchronization measures, imaginary part of phase-locking value, imaginary part of coherency (ImCoh), phase lag index and weighted phase lag index (wPLI), for detecting stimulus-induced FCs between the contralateral primary and ipsilateral secondary somatosensory cortices. The analyses revealed that ImCoh exhibited the best performance for detecting stimulus-induced FCs, followed by the wPLI. We found that amplitude weighting, which is related to computing both ImCoh and wPLI, effectively attenuated the influence of noise contamination. A simulation study modeling noise-contaminated periodograms replicated these findings. The present results suggest that the amplitude-dependent measures, ImCoh followed by wPLI, may have the advantage in detecting stimulus-induced FCs.
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Affiliation(s)
- Kenji Yoshinaga
- Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Masao Matsuhashi
- Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tatsuya Mima
- Graduate School of Core Ethics and Frontier Sciences, Ritsumeikan University, Kyoto, Japan
| | - Hidenao Fukuyama
- Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Ryosuke Takahashi
- Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takashi Hanakawa
- Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Integrated Neuroanatomy and Neuroimaging, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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7
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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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8
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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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9
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Ferrè ER, Sahani M, Haggard P. Subliminal stimulation and somatosensory signal detection. Acta Psychol (Amst) 2016; 170:103-11. [PMID: 27387873 DOI: 10.1016/j.actpsy.2016.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 06/17/2016] [Accepted: 06/21/2016] [Indexed: 11/19/2022] Open
Abstract
Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals.
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Affiliation(s)
- Elisa Raffaella Ferrè
- Institute of Cognitive Neuroscience, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK; Department of Psychology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
| | - Maneesh Sahani
- Gatsby Computational Neuroscience Unit, University College London, 25 Howland Street, London, W1T4JG, UK
| | - Patrick Haggard
- Institute of Cognitive Neuroscience, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK.
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10
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Effect of muscle contraction strength on gating of somatosensory magnetic fields. Exp Brain Res 2016; 234:3389-3398. [PMID: 27435203 DOI: 10.1007/s00221-016-4736-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 07/15/2016] [Indexed: 10/21/2022]
Abstract
Afferent somatosensory information is modulated before the afferent input arrives at the primary somatosensory cortex during voluntary movement. The aim of the present study was to clarify the effect of muscular contraction strength on somatosensory evoked fields (SEFs) during voluntary movement. In addition, we examined the differences in gating between innervated and non-innervated muscle during contraction. We investigated the changes in gating effect by muscular contraction strength and innervated and non-innervated muscles in human using 306-channel magnetoencephalography. SEFs were recorded following the right median nerve stimulation in a resting condition and during isometric muscular contractions from 10 % electromyographic activity (EMG), 20 and 30 % EMG of the right extensor indicis muscle and abductor pollicis brevis muscle. Our results showed that the equivalent current dipole (ECD) strength for P35m decreased with increasing strength of muscular contraction of the right abductor pollicis brevis muscle. However, changes were observed only at 30 % EMG contraction level of the right extensor indicis muscle, which was not innervated by the median nerve. There were no significant changes in the peak latencies and ECD locations of each component in all conditions. The ECD strength did not differ significantly for N20m and P60m regardless of the strength of muscular contraction and innervation. Therefore, we suggest that the gating of SEF waveforms following peripheral nerve stimulation was affected by the strength of muscular contraction and innervation of the contracting muscle.
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11
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Cardini F, Longo MR. Congruency of body-related information induces somatosensory reorganization. Neuropsychologia 2016; 84:213-21. [DOI: 10.1016/j.neuropsychologia.2016.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 01/16/2016] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
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Hayamizu M, Hagiwara K, Hironaga N, Ogata K, Hoka S, Tobimatsu S. A spatiotemporal signature of cortical pain relief by tactile stimulation: An MEG study. Neuroimage 2016; 130:175-183. [PMID: 26854558 DOI: 10.1016/j.neuroimage.2016.01.065] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/29/2016] [Accepted: 01/31/2016] [Indexed: 12/19/2022] Open
Abstract
Recently, the cortical mechanisms of tactile-induced analgesia have been investigated; however, spatiotemporal characteristics have not been fully elucidated. The insular-opercular region integrates multiple sensory inputs, and nociceptive modulation by other sensory inputs occurs in this area. In this study, we focused on the insular-opercular region to characterize the spatiotemporal signature of tactile-induced analgesia using magnetoencephalography in 11 healthy subjects. Aδ (intra-epidermal electrical stimulation) inputs were modified by Aβ (mechanical tactile stimulation) selective stimulation, either independently or concurrently, to the right forearm. The optimal inter-stimulus interval (ISI) for cortical level modulation was determined after comparing the 40-, 60-, and 80-ms ISI conditions, and the calculated cortical arrival time difference between Aδ and Aβ inputs. Subsequently, we adopted a 60-ms ISI for cortical modulation and a 0-ms ISI for spinal level modulation. Source localization using minimum norm estimates demonstrated that pain-related activity was located in the posterior insula, whereas tactile-related activity was estimated in the parietal operculum. We also found significant inhibition of pain-related activity in the posterior insula due to cortical modulation. In contrast, spinal modulation was observed both in the posterior insula and parietal operculum. Subjective pain, as evaluated by the visual analog scale, also showed significant reduction in both conditions. Therefore, our results demonstrated that the multisensory integration within the posterior insula plays a key role in tactile-induced analgesia.
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Affiliation(s)
- Mariko Hayamizu
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Koichi Hagiwara
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Naruhito Hironaga
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Katsuya Ogata
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Sumio Hoka
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shozo Tobimatsu
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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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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14
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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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15
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The effect of anodal transcranial direct current stimulation over the primary motor or somatosensory cortices on somatosensory evoked magnetic fields. Clin Neurophysiol 2014; 126:60-7. [PMID: 24856461 DOI: 10.1016/j.clinph.2014.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 04/18/2014] [Accepted: 04/24/2014] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate the effect of anodal transcranial direct-current stimulation (tDCS) applied over the primary motor (M1) or the primary somatosensory (S1) cortices on somatosensory evoked magnetic fields (SEFs) following median nerve stimulation. METHODS Anodal tDCS was applied for 15min on the left motor or somatosensory cortices at 1mA. SEFs were recorded following right median nerve stimulation using a magnetoencephalography (MEG) system before and after the application of tDCS. SEFs was measured and compared before and after tDCS was applied over M1 or S1. RESULTS The source strengths for the P35m and P60m increased after tDCS was applied over M1 and that for the P60m increased after tDCS was applied over S1. The mean equivalent current dipole (ECD) location for the P35m was located significantly anterior to that of the N20m, but only during post 1 (10-20min after tDCS was applied over M1). CONCLUSION Our results indicated that the anodal tDCS applied over M1 affected the P35m and P60m sources on SEF components, while that applied over S1 influenced the P60m source. SIGNIFICANCE We demonstrated anodal tDCS applied over M1 or S1 can modulate somatosensory processing and components of SEFs, confirming the hypothesis for locally distinct generators of the P35m and P60m sources.
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Niimi M, Ohira T, Akiyama T, Hiraga K, Kaneko Y, Ochiai M, Fukunaga A, Kobayashi M, Kawase T. Source analysis of the magnetic field evoked during self-paced finger movements. Neurol Res 2013; 30:239-43. [PMID: 17848207 DOI: 10.1179/016164107x230801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVE The aim of this study is to investigate a source of cortical magnetic fields evoked by index finger movements. METHODS We analysed both movement-related cortical fields (MRCFs) and somatosensory-evoked fields (SEFs) by single equivalent current dipole (ECD) method in six healthy subjects. Dipole locations were superimposed on MR images of each individual subject. RESULTS The first component after finger movement (movement-evoked field I, MEFI) was observed in all subjects. The dipole of MEFI was oriented posteriorly, and was located on the posterior wall of the central sulcus of the hemisphere contralateral to the movement. The SEFs showed three major components: N20m, P30m and P60m. The dipoles of P30m and P60m were orientated posteriorly, similarly to the MEFI dipole, while that of N20m was orientated anteriorly. The dipole location of MEFI was closely located to P60m, not to N20m and P30m. The mean location of the MEFI dipole was significantly (p<0.05) superior to N20m. CONCLUSION These findings suggest that MEFI would be generated in the sensory area (area 3b) affected by multiple afferents and activities, and that the source of the MEFI is not identical to that of the N20m component.
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Affiliation(s)
- Maki Niimi
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan.
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Yao L, Meng J, Zhang D, Sheng X, Zhu X. Selective sensation based brain-computer interface via mechanical vibrotactile stimulation. PLoS One 2013; 8:e64784. [PMID: 23762253 PMCID: PMC3675213 DOI: 10.1371/journal.pone.0064784] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 04/18/2013] [Indexed: 11/19/2022] Open
Abstract
In this work, mechanical vibrotactile stimulation was applied to subjects' left and right wrist skins with equal intensity, and a selective sensation perception task was performed to achieve two types of selections similar to motor imagery Brain-Computer Interface. The proposed system was based on event-related desynchronization/synchronization (ERD/ERS), which had a correlation with processing of afferent inflow in human somatosensory system, and attentional effect which modulated the ERD/ERS. The experiments were carried out on nine subjects (without experience in selective sensation), and six of them showed a discrimination accuracy above 80%, three of them above 95%. Comparative experiments with motor imagery (with and without presence of stimulation) were also carried out, which further showed the feasibility of selective sensation as an alternative BCI task complementary to motor imagery. Specifically there was significant improvement ([Formula: see text]) from near 65% in motor imagery (with and without presence of stimulation) to above 80% in selective sensation on some subjects. The proposed BCI modality might well cooperate with existing BCI modalities in the literature in enlarging the widespread usage of BCI system.
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Affiliation(s)
- Lin Yao
- State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China
| | - Jianjun Meng
- State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China
| | - Dingguo Zhang
- State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China
| | - Xinjun Sheng
- State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China
| | - Xiangyang Zhu
- State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China
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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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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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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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Rapid enhancement of touch from non-informative vision of the hand. Neuropsychologia 2012; 50:1954-60. [PMID: 22579968 PMCID: PMC3396851 DOI: 10.1016/j.neuropsychologia.2012.04.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/15/2012] [Accepted: 04/24/2012] [Indexed: 12/28/2022]
Abstract
Processing in one sensory modality may modulate processing in another. Here we investigate how simply viewing the hand can influence the sense of touch. Previous studies showed that non-informative vision of the hand enhances tactile acuity, relative to viewing an object at the same location. However, it remains unclear whether this Visual Enhancement of Touch (VET) involves a phasic enhancement of tactile processing circuits triggered by the visual event of seeing the hand, or more prolonged, tonic neuroplastic changes, such as recruitment of additional cortical areas for tactile processing. We recorded somatosensory evoked potentials (SEPs) evoked by electrical stimulation of the right middle finger, both before and shortly after viewing either the right hand, or a neutral object presented via a mirror. Crucially, and unlike prior studies, our visual exposures were unpredictable and brief, in addition to being non-informative about touch. Viewing the hand, as opposed to viewing an object, enhanced tactile spatial discrimination measured using grating orientation judgements, and also the P50 SEP component, which has been linked to early somatosensory cortical processing. This was a trial-specific, phasic effect, occurring within a few seconds of each visual onset, rather than an accumulating, tonic effect. Thus, somatosensory cortical modulation can be triggered even by a brief, non-informative glimpse of one's hand. Such rapid multisensory modulation reveals novel aspects of the specialised brain systems for functionally representing the body.
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Cardini F, Longo MR, Haggard P. Vision of the body modulates somatosensory intracortical inhibition. Cereb Cortex 2011; 21:2014-22. [PMID: 21285259 DOI: 10.1093/cercor/bhq267] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The magnitude of somatosensory evoked potentials (SEPs) elicited by simultaneous electrical stimulation of adjacent digits is generally less than the sum of potentials evoked by stimulation of each digit individually. This under-additivity suggests suppression between representations of adjacent skin regions and may reflect a process of lateral inhibition by interneurons in somatosensory cortex. Given that simply viewing the body enhances tactile acuity and that tactile acuity depends on cortical lateral inhibition, we investigated how viewing the body modulates suppressive interactions between simultaneous afferent volleys from adjacent fingers. We recorded SEPs evoked by electrical stimulation of the right index and middle fingers, either individually or simultaneously, while participants viewed either their own hand or an object. In between trains of electrical stimuli, participants discriminated the orientation of tactile gratings applied to either finger. Consistent with previous findings, viewing the hand enhanced tactile acuity. Furthermore, viewing the hand increased the suppression of the P50 potential due to simultaneous electrical stimulation of both fingers. Moreover, the visual enhancement of tactile performance correlated across participants with the visual modulation of suppression. These results demonstrate that vision enhances somatosensation by modulating activity of inhibitory interneuronal circuits in the somatosensory cortex.
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Affiliation(s)
- Flavia Cardini
- Centro Studi e Ricerche in Neuroscienze Cognitive, University of Bologna, Cesena 47023, Italy
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23
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Severens M, Farquhar J, Desain P, Duysens J, Gielen C. Transient and steady-state responses to mechanical stimulation of different fingers reveal interactions based on lateral inhibition. Clin Neurophysiol 2010; 121:2090-6. [PMID: 21035742 DOI: 10.1016/j.clinph.2010.05.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 05/07/2010] [Accepted: 05/17/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Simultaneous tactile finger stimulation evokes transient ERP responses that are smaller than the linear summation of ERP responses to individual stimulation. Occlusion and lateral inhibition are two possible mechanisms responsible for this effect. The present study disentangles these two effects using steady-state somatosensory evoked potentials (SSSEP). Simultaneous stimulation on adjacent and distant finger pairs with the same and different stimulation frequencies are compared. METHODS The index finger (IF), middle finger (MF) and little finger (LF) were mechanically stimulated with a frequency of 18, 22 or 26Hz, respectively. Stimulation was applied for each finger separately, and for the IF (18Hz) in combination with either the MF or LF for 22 and 26Hz, respectively. A measure for interaction (IR) was calculated for the P60 component and the SSSEP amplitude. RESULTS Significant interactions were found in both the P60 response and in the SSSEP response. Stimulation of adjacent finger combinations caused more interaction than distant finger combinations. No difference was found between stimulation of two fingers with the same or a different frequency. CONCLUSIONS Our results indicate that lateral inhibition is mainly responsible for the interaction effect. SIGNIFICANCE These observations provide further insight in the mechanisms behind interaction between somatosensory inputs.
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Affiliation(s)
- M Severens
- Sint Maartenskliniek, RD&E, Hengstdal 3, The Netherlands.
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25
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Jouanin JC, Pérès M, Ducorps A, Renault B. A dynamic network involving M1-S1, SII-insular, medial insular, and cingulate cortices controls muscular activity during an isometric contraction reaction time task. Hum Brain Mapp 2009; 30:675-88. [PMID: 18266218 DOI: 10.1002/hbm.20534] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Magnetoencephalographic, electromyographic (EMG), work, and reaction time (RT) were recorded from nine subjects during visually triggered intermittent isometric contractions of the middle finger under two conditions: unloaded and loaded (30% of maximal voluntary contraction). The effect of muscle fatigue was studied over three consecutive periods under both conditions. In the loaded condition, the motor evoked field triggered by the EMG onset decreased with fatigue, whereas movement-evoked fields (MEFs) increased (P < 0.01). Fatigue was demonstrated in the loaded condition, since (i) RT increased due to an increase in the electromechanical delay (P < 0.002); (ii) work decreased from Periods 1 to 3 (P < 0.005), while (iii) the myoelectric RMS amplitude of both flexor digitorum superficialis and extensor muscles increased (P < 0.003) and (iv) during Period 3, the spectral deflection of the EMG median frequency of the FDS muscle decreased (P < 0.001). In the unloaded condition and at the beginning of the loaded condition, a parallel network including M1-S1, posterior SII-insular, and posterior cingulate cortices accounted for the MEF activities. However, under the effect of fatigue, medial insular and posterior cingulate cortices drove this network. Moreover, changes in the location of insular and M1-S1 activations were significantly correlated with muscle fatigue (increase of RMS-EMG; P < 0.03 and P < 0.01, respectively). These results demonstrate that a plastic network controls the strength of the motor command as fatigue occurs: sensory information, pain, and exhaustion act through activation of the medial insular and posterior cingulate cortices to decrease the motor command in order to preserve muscle efficiency and integrity.
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Affiliation(s)
- Jean-Claude Jouanin
- Department of Integrated Physiology, Aerospace Medical Institute of Health, Brétigny-sur-Orge, France.
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Torquati K, Franciotti R, Della Penna S, Babiloni C, Rossini PM, Romani GL, Pizzella V. Conditioning transcutaneous electrical nerve stimulation induces delayed gating effects on cortical response: A magnetoencephalographic study. Neuroimage 2007; 35:1578-85. [PMID: 17382562 DOI: 10.1016/j.neuroimage.2006.12.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 12/15/2006] [Accepted: 12/21/2006] [Indexed: 11/29/2022] Open
Abstract
The present study was undertaken to investigate after-effects of 7 Hz non-painful prolonged stimulation of the median nerve on somatosensory-evoked fields (SEFs). The working hypothesis that conditioning peripheral stimulations might produce delayed interfering ("gating") effects on the response of somatosensory cortex to test stimuli was evaluated. In the control condition, electrical thumb stimulation induced SEFs in ten subjects. In the experimental protocol, a conditioning median nerve stimulation at wrist preceded 6 electrical thumb stimulations. Equivalent current dipoles fitting SEFs modeled responses of contralateral primary area (SI) and bilateral secondary somatosensory areas (SII) following control and experimental conditions. Compared to the control condition, conditioning stimulation induced no amplitude modulation of SI response at the initial stimulus-related peak (20 ms). In contrast, later response from SI (35 ms) and response from SII were significantly weakened in amplitude. Gradual but fast recovery towards control amplitude levels was observed for the response from SI-P35, while a slightly slower cycle was featured from SII. These findings point to a delayed "gating" effect on the synchronization of somatosensory cortex after peripheral conditioning stimulations. This effect was found to be more lasting in SII area, as a possible reflection of its integrative role in sensory processing.
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Affiliation(s)
- K Torquati
- Dipartimento di Scienze Cliniche e Bioimmagini and ITAB, Istituto di Tecnologie Avanzate Biomediche, Università G. D'Annunzio, Chieti - Italy.
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Ruben J, Krause T, Taskin B, Blankenburg F, Moosmann M, Villringer A. Sub-area-specific Suppressive Interaction in the BOLD responses to simultaneous finger stimulation in human primary somatosensory cortex: evidence for increasing rostral-to-caudal convergence. ACTA ACUST UNITED AC 2005; 16:819-26. [PMID: 16162856 DOI: 10.1093/cercor/bhj025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the primary somatosensory cortex (SI) of non-human primates, receptive field properties have been shown to differ between its sub-areas with increasing convergence in areas 1 and 2 as compared with area 3b. In this study, we searched for a similar functional organization of human SI. We performed fMRI in healthy subjects during separate or simultaneous electrical stimulation of the second and third finger of the right hand. Activation patterns in response to stimulation of single fingers reflected the somatotopical arrangement within the hand area of SI. Somatotopy was more clear-cut in area 3b as compared with areas 1 and 2. The response to simultaneous stimulation was considerably smaller than the summed responses to separate stimulation of each finger alone, pointing to a suppressive interaction effect. A region-of-interest analysis in the representational areas of the second and third finger revealed sub-area-specific differential suppressive interaction with an increase along the rostral-caudal axis (areas 3b, 1 and 2: 26, 32.7 and 42.2%, respectively). These findings on differences in the topographic as well as functional organization between sub-areas of SI support the notion of increasing convergence and integration from area 3b to areas 1 and 2 in human subjects.
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Affiliation(s)
- Jan Ruben
- Charité - Universitätsmedizin Berlin, Berlin NeuroImaging Center and Department of Neurology, 10117 Berlin, Germany.
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Tamburin S, Fiaschi A, Andreoli A, Marani S, Zanette G. Sensorimotor integration to cutaneous afferents in humans: the effect of the size of the receptive field. Exp Brain Res 2005; 167:362-9. [PMID: 16078031 DOI: 10.1007/s00221-005-0041-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 04/26/2005] [Indexed: 12/19/2022]
Abstract
Transcranial magnetic stimulation (TMS) can be used to study sensorimotor integration in humans non-invasively. Motor excitability has been found to be inhibited when afferent stimuli are given to a peripheral nerve and precede TMS at interstimulus intervals (ISIs) of 20-50 ms. This phenomenon has been referred to as short-latency afferent inhibition (SAI). To better understand the functional meaning of these phenomena, we examined the effect of the size of the receptive field on SAI to cutaneous afferents in upper-limb sensorimotor areas in humans. We examined the effect of the stimulation of the isolated right first (D1), second (D2) and third finger (D3), the right second and third finger together (D23) and the right first three fingers together (D123) on the amplitude of motor evoked potentials (MEPs) to TMS in hand and forearm muscles. We examined the right abductor pollicis brevis (APB), first dorsal interosseous (FDI), extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles. Digital stimulation preceded TMS at ISIs of 20-50 ms. The effect of D2 stimulation was MEP inhibition (SAI), which was more marked and consistent in APB and FDI muscles than in ECR and FCR muscles. Similarly, D1 and D3 stimulation caused MEP reduction, while no MEP enhancement could be found to single finger stimulation. In contrast, D123 stimulation induced less effective SAI in upper-limb muscles. MEP potentiation was recorded in some muscles to D123 stimulation. A significant difference between D2 and D123 stimulation was found in APB (ISIs = 30-50 ms) and FDI (ISIs = 40-50 ms) muscles, but not in forearm muscles. The effect to D23stimulation on MEP amplitude was intermediate between those to D2 and D123 stimulation. Our data suggest that motor excitability to cutaneous afferents may be influenced by the size of the receptive fields, this effect being the result of increasing convergence between hand afferents in the somatosensory system. These phenomena appear to be topographically arranged across the representation of upper-limb muscles. These findings may help to understand the functional significance of SAI in normal physiology and pathophysiology.
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Affiliation(s)
- Stefano Tamburin
- Department of Neurological Sciences and Vision, Section of Neurological Rehabilitation, University of Verona, Verona, Italy.
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29
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Iguchi Y, Hoshi Y, Tanosaki M, Taira M, Hashimoto I. Attention induces reciprocal activity in the human somatosensory cortex enhancing relevant- and suppressing irrelevant inputs from fingers. Clin Neurophysiol 2005; 116:1077-87. [PMID: 15826848 DOI: 10.1016/j.clinph.2004.12.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Revised: 10/28/2004] [Accepted: 12/11/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVE We studied whether attention regulates information processing in the human primary somatosensory cortex (SI) by selective enhancement of relevant- and suppression of irrelevant information. METHODS Under successive and simultaneous electric stimuli to both the right index and middle fingers, tactile stimuli were randomly (20%) presented on one of the two fingers in separate two runs exchanging the finger. Subjects were requested to discriminate the tactile stimuli in an attention task to induce attention to one finger and to ignore the stimuli in a control task to avoid such an attention focus. Somatosensory evoked magnetic fields were measured only for the two-finger electric stimulation and an early component (M50) was analyzed. RESULTS In spite of the two-finger simultaneous stimulation, attention to either the index or middle finger lowered or heightened the M50-sourse location, respectively. The attention task did not increase the M50 amplitude. CONCLUSIONS Attention to a finger enhanced selectively the representation of the finger in the SI cortex. However, this SI activity did not increase the M50 amplitude, suggesting that the attention suppressed another finger region receiving the unattended inputs. SIGNIFICANCE Attention regulates the SI activity by selectively enhancing the task-relevant information and by filtering out other noise inputs.
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Affiliation(s)
- Yoshinobu Iguchi
- Department of Integrated Neuroscience, Tokyo Institute of Psychiatry, Japan.
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Tanosaki M, Iguchi Y, Kimura T, Takino R, Hashimoto I. Functional connectivity between forearm and digits representations in human somatosensory area 3b. Clin Neurophysiol 2004; 115:2638-44. [PMID: 15465453 DOI: 10.1016/j.clinph.2004.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE We compared the effects of tactile interference to the forearm on magnetic responses evoked by electric stimulation of the little finger (D5) and the thumb (D1). METHODS Electric stimulation was delivered to D5 or D1 individually. In each stimulus session, magnetic recordings were conducted with or without concurrent tactile interference to the radial side of the anterior forearm. RESULTS With forearm interference, the amplitude of the primary response (N20m) following D5 stimulation was reduced to 90.7% of the control value without interference, while that following D1 stimulation was not affected (100.7%). CONCLUSIONS In human somatosensory area 3b, the representation of the forearm is immediately adjacent to that of the D5, and distant from that of the D1. Thus, the result suggests that the tactile interference effect on N20m depends on the cortical distance between electrically and mechanically activated 3b areas. SIGNIFICANCE Intrinsic synaptic connections between the 3b hand representation and its surroundings have been hypothesized as a neural basis for plastic changes of the human brain, such as a phantom hand phenomenon. The present finding implies that these connections may play some physiological roles even in normal adult humans.
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Affiliation(s)
- Masato Tanosaki
- Third Department of Internal Medicine, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan.
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Lin YY, Shih YH, Chen JT, Hsieh JC, Yeh TC, Liao KK, Kao CD, Lin KP, Wu ZA, Ho LT. Differential effects of stimulus intensity on peripheral and neuromagnetic cortical responses to median nerve stimulation. Neuroimage 2003; 20:909-17. [PMID: 14568461 DOI: 10.1016/s1053-8119(03)00387-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2003] [Revised: 06/09/2003] [Accepted: 06/23/2003] [Indexed: 11/28/2022] Open
Abstract
To study the differential effects of tactile stimulus intensity on cortical and peripheral responses, we measured neuromagnetic cortical responses, compound muscle action potentials (CMAP), sensory nerve action potentials (SNAP), and the subjective estimation of tactile magnitude to electric median nerve stimulation at the wrist in 13 male healthy adults. The sensory perception threshold (ST) for electric pulses at wrist skin was determined and then various levels of stimulus intensity (1 approximately 6 ST) were given to each subject. At 1 ST, only the P50m components of the primary somatosensory (SI) cortical responses were recorded. The second somatosensory (SII) cortical responses were saturated at 2 ST, while the SI responses reached maximum at 3 ST equivalent to the subjective threshold intensity for "strong" tactility. The CMAP and SNAP were maximum at 4-5 ST. At 2 ST, >70% of maximum SI responses were produced, whereas only <40% of maximum CMAP or SNAP responses were obtained. We concluded that the stimulus intensities for activating or saturating somatosensory cortical responses were lower than those for CMAP and SNAP. The differential intensity effects on cortical and peripheral responses suggest a polysynaptic organization underlying the central amplification for somatosensory cortical activation. The optimal intensity levels for producing maximum SI and SII responses were 3 and 2 ST, respectively. Compared with the SII, the SI plays a crucial role in the coding of the tactile stimulus intensity.
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Affiliation(s)
- Yung-Yang Lin
- Integrated Brain Research Unit, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan.
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Torquati K, Pizzella V, Della Penna S, Franciotti R, Babiloni C, Romani GL, Rossini PM. “Gating” effects of simultaneous peripheral electrical stimulations on human secondary somatosensory cortex: a whole-head MEG study. Neuroimage 2003; 20:1704-13. [PMID: 14642480 DOI: 10.1016/s1053-8119(03)00439-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The secondary somatosensory cortex (SII) is strongly involved in the processing of somatosensory tactile and nociceptive sensations. We investigated the effect on SII responses of simultaneous painful and nonpainful electrical stimulations delivered to the thumb and little finger. According to the "bimodal" (i.e., nociceptive, tactile) organization of SII, it was expected that simultaneous painful and nonpainful stimulations would lead to modality interference with a marked reduction ("gating") of somatosensory evoked fields (SEFs) generated in SII. Eight different stimulus conditions were studied. Two conditions were simultaneous "unimodal" (thumb and little finger nonpainful; thumb and little finger painful) and two conditions were simultaneous "bimodal" (thumb nonpainful and little finger painful; thumb painful and little finger nonpainful). As a reference, four conditions included stimulations at single sites (thumb nonpainful, little finger nonpainful, thumb painful, little finger painful). The gating phenomenon was defined as the percentage of difference between the intensities of SII activation after simultaneous compared to the sum of the separate stimulations. Results showed that simultaneous stimulations induced gating effects on SEFs generated by SII. No significant gating differences were observed after the two unimodal stimulations, suggesting a negligible effect of global energy on gating. Instead, the gating effects on bilateral SII activity were stronger after simultaneous bimodal when compared to unimodal stimulations. Our findings hint that there could be a greater level of integration/convergence of painful and nonpainful stimuli in SII with respect to SI. Future studies should explore if it could have an important role in exploring pain relief.
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Affiliation(s)
- K Torquati
- Department of Clinical Sciences and Bioimaging, University of Chieti, Italy.
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Tecchio F, Babiloni C, Zappasodi F, Vecchio F, Pizzella V, Romani GL, Rossini PM. Gamma synchronization in human primary somatosensory cortex as revealed by somatosensory evoked neuromagnetic fields. Brain Res 2003; 986:63-70. [PMID: 12965230 DOI: 10.1016/s0006-8993(03)03171-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cortical sensory neurons synchronize their activity at multiple frequency bands after an external stimulation. In the somatosensory cortical areas, previous reports describe more discrete and somatotopically specific neural synchronization at the gamma band. Therefore, an efficient gamma synchronization of the neurons in primary somatosensory cortex (S1) may be expected to characterize the stimulus processing from the thumb, i.e. the hand's most skillful area. To test this hypothesis, neuromagnetic fields were evoked over human S1 by the electrical stimulation of the contralateral thumb or little finger. Neuronal synchronization was indexed by the spectral coherence of the evoked neuromagnetic fields overlying S1. The frequencies of interest were the beta (16-32 Hz) and gamma (36-46 Hz) bands. The global amount of the coherence was defined as the total event-related coherence (ERCoh) among all magnetic sensors overlying the S1. Results showed prevalent increment of beta ERCoh (20-32 Hz) after the little finger stimulation and of gamma ERCoh (36-44 Hz) after the thumb stimulation. These results suggest that the neural synchronization in S1, as revealed by the ERCoh, may vary in frequency as a function of the finger stimulated. In this framework, the neural synchronization at gamma band may characterize the cortical representation of thumb, functionally prevalent with respect to little finger in humans.
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Hamada Y, Suzuki R. Hand posture modulates neuronal interaction in the primary somatosensory cortex of humans. Clin Neurophysiol 2003; 114:1689-96. [PMID: 12948798 DOI: 10.1016/s1388-2457(03)00129-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the effects of hand posture on the modulation of neuronal interactions in the cortical finger regions of the human somatosensory cortex. METHODS Neuronal magnetic fields, evoked by electrical stimuli to the thumb and/or to the index finger of the right hand, were recorded in different hand postures ('OPEN': opened hand and 'CLOSE': both fingers in opposite position to pick up something) by using a whole head type magnetoencephalography. The equivalent current dipole (ECD) for components in the primary (SI) and secondary somatosensory cortices (SII) was calculated. The interaction ratio (IR) was calculated as a ratio of the vector sum of ECD moments evoked by respective stimulation of each finger to the ECD moment evoked by simultaneous stimulation of both fingers. RESULTS The mean IR of N20m was significantly larger in CLOSE than in OPEN (p=0.033, ANOVA). On the contrary, the IR of P40m was larger in OPEN than in CLOSE (p=0.042). The IR of SII components was not significantly different between the different hand postures (p=0.35). CONCLUSIONS Neuronal interaction between the thumb and index finger in the human SI is modulated by hand posture. Provided that forming hand posture is related to receiving sensory input, the interaction modulation may play a role in the facilitation of somatosensory processing. SIGNIFICANCE Our results suggest experimental evidence for the immediate modulation of neuronal activity in the somatosensory area.
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Affiliation(s)
- Yasukazu Hamada
- Linguistics and Philosophy, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA.
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Onitsuka T, Ninomiya H, Sato E, Yamamoto T, Tashiro N. Differential characteristics of the middle latency auditory evoked magnetic responses to interstimulus intervals. Clin Neurophysiol 2003; 114:1513-20. [PMID: 12888035 DOI: 10.1016/s1388-2457(03)00110-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE The human middle latency auditory evoked magnetic fields were recorded with different interstimulus intervals (ISI) to investigate the differential natures of P30m and the P50m, including whether the P50m source was spatially different or not from the P30m source. METHODS Twenty right-handed healthy subjects participated in the experiment. Auditory magnetic responses were recorded in the 0.5 s ISI (ISI were between 0.4 and 0.6 s) and the 1.5 s ISI conditions (ISI were between 1 and 2 s). Tone bursts were presented to the right ears 880 times consecutively for each condition. The P30m and the P50m responses were investigated, and the dipole source localization was performed. RESULTS The P50m latency was significantly prolonged, while the P30m latency did not vary in the shorter ISI. Both P50m and P30m amplitudes were significantly reduced in the shorter ISI. The P50m was located significantly more anteriorly than P30m. CONCLUSIONS These results suggest the existence of differential characteristic and spatially different magnetic responses in the middle latency range. SIGNIFICANCE This study has revealed one aspect of the different natures between P30m and P50m, and may provide a key for auditory perceptional processes in humans.
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Affiliation(s)
- Toshiaki Onitsuka
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
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Ishibashi H, Simos PG, Wheless JE, Zhang W, Baumgartner JE, Castillo EM, Papanicolaou AC. Somatosensory evoked magnetic fields in hemimegalencephaly. Neurol Res 2002; 24:459-62. [PMID: 12117314 DOI: 10.1179/016164102101200339] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Somatosensory maps were determined in three patients with hemimegalencephaly using magnetic resonance imaging (MRI) and magnetoencephalography (MEG). MRIs were characterized by thickened gray matter with clearly aberrant lamination patterns. Somatosensory Evoked Fields (SEFs), as measured by MEG, were absent from the affected hemisphere in the two patients with severe cortical lamination defects. The third patient presented with relatively preserved cortical lamination in the frontal lobe and clear cortical SEFs in this region, indicating somatotopical reorganization. These findings suggest that the presence and location of MEG-derived somatosensory maps reflect the severity of the cortical lamination defects in hemimegalencephaly.
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Affiliation(s)
- Hideaki Ishibashi
- Department of Neurosurgery, Vivian L Smith Center for Neurologic Research, The University of Texas Health Science Center at Houston, 77030, USA.
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Tanosaki M, Suzuki A, Takino R, Kimura T, Iguchi Y, Kurobe Y, Haruta Y, Hoshi Y, Hashimoto I. Neural mechanisms for generation of tactile interference effects on somatosensory evoked magnetic fields in humans. Clin Neurophysiol 2002; 113:672-80. [PMID: 11976046 DOI: 10.1016/s1388-2457(02)00052-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES We examined modification of somatosensory evoked fields following electric middle finger stimulation with interference to the same and surrounding digits in 13 subjects. METHODS During electric middle finger stimulation, concurrent tactile stimulation was applied to the middle finger, to the index and ring fingers, and to the thumb and the little finger, individually. RESULTS The amplitudes of the N20m and the P30m were significantly reduced by the interference to the middle finger, and to the index and ring fingers. The former interference induced more prominent attenuation than the latter. The amplitudes of the P60m did not show significant changes by any kind of the interference. CONCLUSIONS The N20m and the P30m were attenuated according to the cortical distance between electrically and mechanically activated 3b areas. Pyramidal neurons are interconnected by intrinsic horizontal collaterals, even if their representations are segregated. The activation of the intrinsic collaterals induces direct excitation and indirect inhibition (via inhibitory interneurons) to the target pyramidal neurons. The result indicates that the activation of the intrinsic collaterals inhibits, on balance, the postsynaptic pyramidal targets, thereby generating the attenuation of the N20m and P30m.
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Affiliation(s)
- Masato Tanosaki
- Department of Integrated Neuroscience, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya-Ku 156-8585, Japan.
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Simões C, Mertens M, Forss N, Jousmäki V, Lütkenhöner B, Hari R. Functional overlap of finger representations in human SI and SII cortices. J Neurophysiol 2001; 86:1661-5. [PMID: 11600629 DOI: 10.1152/jn.2001.86.4.1661] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We aimed to find out to what extent functional representations of different fingers of the two hands overlap at the human primary and secondary somatosensory cortices SI and SII. Somatosensory evoked fields (SEFs) were recorded with a 306-channel neuromagnetometer from 8 subjects. Tactile stimuli, produced by diaphragms driven by compressed air, were delivered to the fingertips in three different conditions. First, the right index finger was stimulated once every 2 s. Then two other stimuli were interspersed, in different sessions, to right- or left-hand fingers (thumb, middle finger, or ring finger) between the successive right index finger stimuli. Strengths of the responses to right index finger stimuli were evaluated in each condition. Responses to right index finger stimuli were modeled by three current dipoles, located at the contralateral SI and the SII cortices of both hemispheres. The earliest SI responses, peaking around 65 ms, were suppressed by 18% (P < 0.05) when the intervening stimuli were presented to the same hand; intervening stimuli to the other hand had no effect. The SII responses were bilaterally suppressed by intervening stimuli presented to either hand: in the left SII, the suppression was 39 and 42% (P < 0.01) and in the right SII 67 and 72% (P < 0.001) during left- and right-sided intervening stimuli, respectively. Left- and right-sided intervening stimuli affected similarly the SII responses and had no effect on the response latencies. The results indicate a strong and symmetric overlap of finger representations for both hands in the human SII cortices, and a weaker functional overlap for fingers of the same hand in the SI cortex.
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Affiliation(s)
- C Simões
- Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, FIN-02015 HUT Espoo, Finland.
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Hoechstetter K, Rupp A, Stancák A, Meinck HM, Stippich C, Berg P, Scherg M. Interaction of tactile input in the human primary and secondary somatosensory cortex--a magnetoencephalographic study. Neuroimage 2001; 14:759-67. [PMID: 11506548 DOI: 10.1006/nimg.2001.0855] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interaction of simultaneous tactile input at two finger sites in primary (SI) and secondary somatosensory cortex (SII) was studied by whole-head magnetoencephalography. Short pressure pulses were delivered to fingers of the right and left hand at an interstimulus interval of 1.6 s. The first phalanx of the left digit 1 and four other sites were stimulated either separately or simultaneously. We compared four sites with increasing distance: the second phalanx of left digit 1, left digit 5, and digits 1 and 5 of the right hand. The temporal evolution of source activity in the contralateral SI and bilateral SII was calculated using spatiotemporal source analysis. Interaction was assessed by comparing the source activity during simultaneous stimulation with the sum of the source activities elicited by separate stimulation. Significant suppressive interaction was observed in contralateral SI only for stimuli at the same hand, decreasing with distance. In SII, all digits of the same and the opposite hand interacted significantly with left digit 1. When stimulating bilaterally, SII source waveforms closely resembled the time course of the response to separate stimulation of the opposite hand. Thus, in bilateral simultaneous stimulation, the contralateral input arriving first in SII appeared to inhibit the later ipsilateral input. Similarly, the separate response to input at two unilateral finger sites which arrived slightly earlier in SII dominated the simultaneous response. Our results confirm previous findings of considerable overlap in the cortical hand representation in SII and illustrate hemispheric specialization to contralateral input when simultaneous stimuli occur bilaterally.
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Affiliation(s)
- K Hoechstetter
- Section of Biomagnetism, University Hospital of Heidelberg, 69120 Heidelberg, Germany
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Hoshiyama M, Kakigi R. Two evoked responses with different recovery functions in the primary somatosensory cortex in humans. Clin Neurophysiol 2001; 112:1334-42. [PMID: 11516746 DOI: 10.1016/s1388-2457(01)00564-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES We investigated the recovery function of somatosensory evoked magnetic cortical fields (SEFs) to confirm the temporal aspects of the somatosensory process in humans. METHODS SEFs were recorded following median nerve electrical stimulation in 6 healthy subjects. Double stimulation, with interstimulus intervals (ISIs) from 3 to 100 ms, was applied, and the SEF components for the second stimulation were analyzed. In a supplementary experiment, responses to single stimulations of various intensities from the sensory threshold to the motor threshold were studied. RESULTS The first SEF component (1M) diminished when the ISI was less than 10 ms, while the second component (2M) remained even when the ISI was 3 ms. The two components showed a very similar attenuation with decrease of stimulus intensity. There was no significant difference in dipole location between 1M and 2M in the primary somatosensory cortex (SI). CONCLUSIONS The results suggested that at least two independent pathways with different recovery functions exist in a similar area in the SI.
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Affiliation(s)
- M Hoshiyama
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan.
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Shafik A. Magnetic pudendal neurostimulation: a novel method for measuring pudendal nerve terminal motor latency. Clin Neurophysiol 2001; 112:1049-52. [PMID: 11377264 DOI: 10.1016/s1388-2457(00)00555-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Magnetic stimulation (MS) activates the neuromuscular tissue. This effect was used to develop a novel technique for measuring the pudendal nerve terminal motor latency (PNTML) to the external anal sphincter (EAS) in healthy volunteers and patients with fecal incontinence. METHODS The PNTML was studied in 42 healthy volunteers (mean age 44.3 years; 30 men, 12 women) and 18 patients with neurogenic fecal incontinence (mean age 42.8 years; 12 men, 6 women) using two techniques in each subject: the conventional intrarectal glove-mounted and MS. In the MS technique, the pudendal nerve was stimulated by a magnetic stimulator and a magnetic coil fixed to the perianal skin at the base of the ischiorectal fossa. Stimulation parameters were set at 70% of maximum intensity, i.e. 175 J/pulse and 40 Hz frequency. The response of EAS to MS was recorded by a surface electrode applied to the perianal skin in the vicinity of the anal orifice. RESULTS In healthy subjects, the PNTML recorded by MS from the right side (mean 2.2 ms) showed no significant difference from the left PNTML (mean 2.1 ms) and both values did not differ significantly from those recorded by the intrarectal method (right 2.2 ms; left 2.1 ms). In incontinent patients, both the right and left PNTML measured by MS exhibited a significant increase compared to the normal (P<0.05, P<0.05, respectively) but no significant difference if compared to values recorded by the intrarectal route. CONCLUSIONS The results of measuring the PNTML to the EAS by MS were as accurate as those measured by the intrarectal method. However, the MS method seems to be easier and more convenient to the patient.
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Affiliation(s)
- A Shafik
- Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt.
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Ishibashi H, Morioka T, Nishio S, Shigeto H, Yamamoto T, Fukui M. Magnetoencephalographic investigation of somatosensory homunculus in patients with peri-Rolandic tumors. Neurol Res 2001; 23:29-38. [PMID: 11210427 DOI: 10.1179/016164101101198253] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
In order to investigate functional topography of the hand somatosensory cortex in five patients with peri-Rolandic tumors (four frontal lobes and one parietal lobe), we recorded somatosensory evoked fields (SEFs) using magnetoencephalography (MEG) after stimulation of the median nerve (MN) and the five digits. The results obtained were compared with those of five normal healthy subjects. In all five patients, SEFs following MN and digit stimulation showed the previously described respective N20m and N22m components of primary sensory response. Single dipole modeling was applied to determine the three dimensional cortical representations of the N20m and N22m components. The cortical representations of the hand were identical to those of normal subjects, arranging in an orderly somatotopic way from lateral inferior to medial superior in the sequence thumb, MN, index, middle, ring, and little fingers. This sensory homunculus was confirmed by cortical recording of the somatosensory evoked potentials (SEPs) at the time of surgery. Thus, we demonstrate that SEFs, recorded on MEG in conjunction with source localization techniques, are useful to non-invasively investigate the functional topography of the human hand somatosensory cortex in pathological conditions.
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Affiliation(s)
- H Ishibashi
- Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582, Fukuoka, Japan
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