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Ye X, Yang PF, Liu Q, Dillenburger BD, Friedman RM, Chen LM. A thermal nociceptive patch in the S2 cortex of nonhuman primates: a combined functional magnetic resonance imaging and electrophysiology study. Pain 2021; 162:2705-2716. [PMID: 33945242 PMCID: PMC8380756 DOI: 10.1097/j.pain.0000000000002247] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/18/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Human functional magnetic resonance imaging (fMRI) and behavioral studies have established the roles of cortical areas along the Sylvian fissure in sensing subjective pain. Yet, little is known about how sensory aspects of painful information are represented and processed by neurons in these regions and how their electrophysiological activities are related to fMRI signals. The current study aims to partially address this critical knowledge gap by performing fMRI-guided microelectrode mapping and recording studies in the homologous region of the parietal operculum in squirrel monkeys under light anesthesia. In each animal studied (n = 8), we detected mesoscale mini-networks for heat nociception in cortical regions around the lateral sulcus. Within the network, we discovered a ∼1.5 × 1.5-mm2-sized cortical patch that solely contained heat nociceptive neurons that aligned with the heat fMRI activation locus. These neurons responded slowly to thermal (heat and cold) nociceptive stimuli exclusively, continued firing for several seconds after the succession of stimulation, and exhibited multidigit receptive fields and high spontaneous firing rates. Similar to the fMRI responses, increasing temperatures in the nociceptive range led to a nonlinear increase in firing rates. The finding of a clustering of heat nociceptive neurons provides novel insights into the unique functional organization of thermal nociception in the S2 subregion of the primate brain. With fMRI, it supports the existence of a modality-preferred heat nociceptive patch that is spatially separated and intermingled with touch patches containing neurons with comparable receptive fields and the presence of functionally distinct mini-networks in primate opercular cortex.
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Affiliation(s)
- Xiang Ye
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Pai-Feng Yang
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Qing Liu
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Barbara D Dillenburger
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Robert M Friedman
- Department of Psychology, Vanderbilt University, Nashville, TN 37232, USA
| | - Li Min Chen
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Psychology, Vanderbilt University, Nashville, TN 37232, USA
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Liu Y, Huang H, Su Y, Wang M, Zhang Y, Chen W, Liu G, Jiang M. The Combination of N60 with Mismatch Negativity Improves the Prediction of Awakening from Coma. Neurocrit Care 2021; 36:727-737. [PMID: 34291392 DOI: 10.1007/s12028-021-01308-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 06/18/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Our objective was to evaluate the use of event-related potentials and the middle-latency somatosensory evoked potential (MLSEP) for the prediction of awakening in coma, determine the evaluation day that evoked potentials (EPs) best predict an awakening outcome, and determine whether the mismatch negativity (MMN) combined with the MLSEP, when recorded at 7 days after coma, improved the prediction of awakening from coma. METHODS Design prospective blinded cohort study. Setting neurointensive care unit of a university hospital. Patients 113 consecutive patients who were severely comatose, whose etiologies of coma included stroke (65 patients), hypoxic-ischemic encephalopathy (28 patients), intracranial infection (6 patients), and other (14 patients). Interventions none. Measurements we gathered Glasgow Coma Scale scores and recorded EPs for all patients who were comatose at 7, 14, and 30 days after coma onset, unless the patients returned to consciousness. The EPs examined included the MLSEP, the middle-latency auditory evoked potential, the N100, and the MMN. With telephone follow-up after 3 months, the patients were classified as awakening or nonawakening according to Glasgow Outcome Scale. RESULTS When predicting an awakening outcome, at least the unilateral presence of the N60 had the highest sensitivity (82.7%), whereas the presence of the MMN showed the highest specificity (82.0%). The area under the receiver operating characteristic curve for the EPs were high at 7 days after coma onset. At 7 days after coma onset, the combination of the N60 and MMN offered good predictive performance for awakening (area under the receiver operating characteristic curve = 0.852, 95% confidence interval 0.765-0.940), with increased sensitivity (70.0%) and improved specificity (91.7%). CONCLUSIONS The N60 and MMN were the strongest prognostic factors for an awakening outcome. Furthermore, at 7 days after coma onset, the combination of the N60 and MMN improved the prediction of an awakening outcome in patients who were comatose.
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Affiliation(s)
- Yifei Liu
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Huijin Huang
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yingying Su
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China.
| | - Miao Wang
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yan Zhang
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Weibi Chen
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Gang Liu
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Mengdi Jiang
- Neurointensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China
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Rossi-Pool R, Zainos A, Alvarez M, Diaz-deLeon G, Romo R. A continuum of invariant sensory and behavioral-context perceptual coding in secondary somatosensory cortex. Nat Commun 2021; 12:2000. [PMID: 33790301 PMCID: PMC8012659 DOI: 10.1038/s41467-021-22321-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 03/08/2021] [Indexed: 11/08/2022] Open
Abstract
A crucial role of cortical networks is the conversion of sensory inputs into perception. In the cortical somatosensory network, neurons of the primary somatosensory cortex (S1) show invariant sensory responses, while frontal lobe neuronal activity correlates with the animal's perceptual behavior. Here, we report that in the secondary somatosensory cortex (S2), neurons with invariant sensory responses coexist with neurons whose responses correlate with perceptual behavior. Importantly, the vast majority of the neurons fall along a continuum of combined sensory and categorical dynamics. Furthermore, during a non-demanding control task, the sensory responses remain unaltered while the sensory information exhibits an increase. However, perceptual responses and the associated categorical information decrease, implicating a task context-dependent processing mechanism. Conclusively, S2 neurons exhibit intriguing dynamics that are intermediate between those of S1 and frontal lobe. Our results contribute relevant evidence about the role that S2 plays in the conversion of touch into perception.
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Affiliation(s)
- Román Rossi-Pool
- Instituto de Fisiología Celular─Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico.
| | - Antonio Zainos
- Instituto de Fisiología Celular─Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Manuel Alvarez
- Instituto de Fisiología Celular─Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gabriel Diaz-deLeon
- Instituto de Fisiología Celular─Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ranulfo Romo
- Instituto de Fisiología Celular─Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico.
- El Colegio Nacional, Mexico City, Mexico.
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Qi HX, Liao CC, Reed JL, Kaas JH. Reorganization of Higher-Order Somatosensory Cortex After Sensory Loss from Hand in Squirrel Monkeys. Cereb Cortex 2020; 29:4347-4365. [PMID: 30590401 DOI: 10.1093/cercor/bhy317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 10/18/2018] [Accepted: 11/20/2018] [Indexed: 12/31/2022] Open
Abstract
Unilateral dorsal column lesions (DCL) at the cervical spinal cord deprive the hand regions of somatosensory cortex of tactile activation. However, considerable cortical reactivation occurs over weeks to months of recovery. While most studies focused on the reactivation of primary somatosensory area 3b, here, for the first time, we address how the higher-order somatosensory cortex reactivates in the same monkeys after DCL that vary across cases in completeness, post-lesion recovery times, and types of treatments. We recorded neural responses to tactile stimulation in areas 3a, 3b, 1, secondary somatosensory cortex (S2), parietal ventral (PV), and occasionally areas 2/5. Our analysis emphasized comparisons of the responsiveness, somatotopy, and receptive field size between areas 3b, 1, and S2/PV across DCL conditions and recovery times. The results indicate that the extents of the reactivation in higher-order somatosensory areas 1 and S2/PV closely reflect the reactivation in primary somatosensory cortex. Responses in higher-order areas S2 and PV can be stronger than those in area 3b, thus suggesting converging or alternative sources of inputs. The results also provide evidence that both primary and higher-order fields are effectively activated after long recovery times as well as after behavioral and electrocutaneous stimulation interventions.
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Affiliation(s)
- Hui-Xin Qi
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jamie L Reed
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
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Ryun S, Kim JS, Lee H, Chung CK. Tactile Frequency-Specific High-Gamma Activities in Human Primary and Secondary Somatosensory Cortices. Sci Rep 2017; 7:15442. [PMID: 29133909 PMCID: PMC5684355 DOI: 10.1038/s41598-017-15767-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/01/2017] [Indexed: 01/29/2023] Open
Abstract
Humans can easily detect vibrotactile stimuli up to several hundred hertz, but underlying large-scale neuronal processing mechanisms in the cortex are largely unknown. Here, we investigated the macroscopic neural correlates of various vibrotactile stimuli including artificial and naturalistic ones in human primary and secondary somatosensory cortices (S1 and S2, respectively) using electrocorticography (ECoG). We found that tactile frequency-specific high-gamma (HG, 50–140 Hz) activities are seen in both S1 and S2 with different temporal dynamics during vibration (>100 Hz). Stimulus-evoked S1 HG power, which exhibited short-delayed peaks (50–100 ms), was attenuated more quickly in vibration than in flutter (<50 Hz), and their attenuation patterns were frequency-specific within vibration range. In contrast, S2 HG power, which was activated much later than that of S1 (150–250 ms), strikingly increased with increasing stimulus frequencies in vibration range, and their changes were much greater than those in S1. Furthermore, these S1-S2 HG patterns were preserved in naturalistic stimuli such as coarse/fine textures. Our results provide persuasive evidence that S2 is critically involved in neural processing for high-frequency vibrotaction. Therefore, we propose that S1-S2 neuronal co-operation is crucial for full-range, complex vibrotactile perception in human.
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Affiliation(s)
- Seokyun Ryun
- Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Sciences, Seoul, 08826, Korea
| | - June Sic Kim
- Department of Brain & Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 08826, Korea.
| | - Hyeongrae Lee
- Department of Mental Health Research, National Center for Mental Health, Seoul, 04933, Korea
| | - Chun Kee Chung
- Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Sciences, Seoul, 08826, Korea. .,Department of Brain & Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 08826, Korea. .,Department of Neurosurgery, Seoul National University College of Medicine, Seoul, 03080, Korea.
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Chien JH, Korzeniewska A, Colloca L, Campbell C, Dougherty P, Lenz F. Human Thalamic Somatosensory Nucleus (Ventral Caudal, Vc) as a Locus for Stimulation by INPUTS from Tactile, Noxious and Thermal Sensors on an Active Prosthesis. SENSORS (BASEL, SWITZERLAND) 2017; 17:E1197. [PMID: 28538681 PMCID: PMC5492124 DOI: 10.3390/s17061197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/05/2017] [Accepted: 05/16/2017] [Indexed: 12/31/2022]
Abstract
The forebrain somatic sensory locus for input from sensors on the surface of an active prosthesis is an important component of the Brain Machine Interface. We now review the neuronal responses to controlled cutaneous stimuli and the sensations produced by Threshold Stimulation at Microampere current levels (TMIS) in such a locus, the human thalamic Ventral Caudal nucleus (Vc). The responses of these neurons to tactile stimuli mirror those for the corresponding class of tactile mechanoreceptor fiber in the peripheral nerve, and TMIS can evoke sensations like those produced by the stimuli that optimally activate each class. These neuronal responses show a somatotopic arrangement from lateral to medial in the sequence: leg, arm, face and intraoral structures. TMIS evoked sensations show a much more detailed organization into anterior posteriorly oriented rods, approximately 300 microns diameter, that represent smaller parts of the body, such as parts of individual digits. Neurons responding to painful and thermal stimuli are most dense around the posterior inferior border of Vc, and TMIS evoked pain sensations occur in one of two patterns: (i) pain evoked regardless of the frequency or number of spikes in a burst of TMIS; and (ii) the description and intensity of the sensation changes with increasing frequencies and numbers. In patients with major injuries leading to loss of somatic sensory input, TMIS often evokes sensations in the representation of parts of the body with loss of sensory input, e.g., the phantom after amputation. Some patients with these injuries have ongoing pain and pain evoked by TMIS of the representation in those parts of the body. Therefore, thalamic TMIS may produce useful patterned somatotopic feedback to the CNS from sensors on an active prosthesis that is sometimes complicated by TMIS evoked pain in the representation of those parts of the body.
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Affiliation(s)
- Jui Hong Chien
- Department of Neurosurgery, Johns Hopkins University, Baltimore, MD 21287, USA.
| | - Anna Korzeniewska
- Departments of Neurology and Cognitive Science, Johns Hopkins University, Baltimore, MD 21287, USA.
| | - Luana Colloca
- Department of Pain Translational Symptom Science, School of Nursing, and Department of Anesthesiology, School of Medicine, University of Maryland, Baltimore, MD 20742, USA.
| | - Claudia Campbell
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA.
| | - Patrick Dougherty
- Department of Anesthesiology and Critical Care Medicine, M.D. Anderson Hospital, Houston, TX 77054, USA.
| | - Frederick Lenz
- Department of Neurosurgery, Johns Hopkins University, Baltimore, MD 21287, USA.
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Debowska W, Wolak T, Nowicka A, Kozak A, Szwed M, Kossut M. Functional and Structural Neuroplasticity Induced by Short-Term Tactile Training Based on Braille Reading. Front Neurosci 2016; 10:460. [PMID: 27790087 PMCID: PMC5061995 DOI: 10.3389/fnins.2016.00460] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 09/26/2016] [Indexed: 11/30/2022] Open
Abstract
Neuroplastic changes induced by sensory learning have been recognized within the cortices of specific modalities as well as within higher ordered multimodal areas. The interplay between these areas is not fully understood, particularly in the case of somatosensory learning. Here we examined functional and structural changes induced by short-term tactile training based of Braille reading, a task that requires both significant tactile expertise and mapping of tactile input onto multimodal representations. Subjects with normal vision were trained for 3 weeks to read Braille exclusively by touch and scanned before and after training, while performing a same-different discrimination task on Braille characters and meaningless characters. Functional and diffusion-weighted magnetic resonance imaging sequences were used to assess resulting changes. The strongest training-induced effect was found in the primary somatosensory cortex (SI), where we observed bilateral augmentation in activity accompanied by an increase in fractional anisotropy (FA) within the contralateral SI. Increases of white matter fractional anisotropy were also observed in the secondary somatosensory area (SII) and the thalamus. Outside of somatosensory system, changes in both structure and function were found in i.e., the fusiform gyrus, the medial frontal gyri and the inferior parietal lobule. Our results provide evidence for functional remodeling of the somatosensory pathway and higher ordered multimodal brain areas occurring as a result of short-lasting tactile learning, and add to them a novel picture of extensive white matter plasticity.
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Affiliation(s)
- Weronika Debowska
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, Polish Academy of SciencesWarsaw, Poland; CNS Lab, Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of SciencesWarsaw, Poland
| | - Tomasz Wolak
- Bioimaging Research Center, World Hearing Center, The Institute of Physiology and Pathology of Hearing Warsaw, Poland
| | - Anna Nowicka
- Laboratory of Psychophysiology, Nencki Institute of Experimental Biology Warsaw, Poland
| | - Anna Kozak
- Department of Psychology, University of Social Sciences and Humanities Warsaw, Poland
| | - Marcin Szwed
- Department of Psychology, Jagiellonian University Cracow, Poland
| | - Malgorzata Kossut
- Laboratory of Neuroplasticity, Nencki Institute of Experimental Biology, Polish Academy of SciencesWarsaw, Poland; Department of Psychology, University of Social Sciences and HumanitiesWarsaw, Poland
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8
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Schmid AC, Chien JH, Greenspan JD, Garonzik I, Weiss N, Ohara S, Lenz FA. Neuronal responses to tactile stimuli and tactile sensations evoked by microstimulation in the human thalamic principal somatic sensory nucleus (ventral caudal). J Neurophysiol 2016; 115:2421-33. [PMID: 26864759 PMCID: PMC4922463 DOI: 10.1152/jn.00611.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/04/2016] [Indexed: 11/22/2022] Open
Abstract
The normal organization and plasticity of the cutaneous core of the thalamic principal somatosensory nucleus (ventral caudal, Vc) have been studied by single-neuron recordings and microstimulation in patients undergoing awake stereotactic operations for essential tremor (ET) without apparent somatic sensory abnormality and in patients with dystonia or chronic pain secondary to major nervous system injury. In patients with ET, most Vc neurons responded to one of the four stimuli, each of which optimally activates one mechanoreceptor type. Sensations evoked by microstimulation were similar to those evoked by the optimal stimulus only among rapidly adapting neurons. In patients with ET, Vc was highly segmented somatotopically, and vibration, movement, pressure, and sharp sensations were usually evoked by microstimulation at separate sites in Vc. In patients with conditions including spinal cord transection, amputation, or dystonia, RFs were mismatched with projected fields more commonly than in patients with ET. The representation of the border of the anesthetic area (e.g., stump) or of the dystonic limb was much larger than that of the same part of the body in patients with ET. This review describes the organization and reorganization of human Vc neuronal activity in nervous system injury and dystonia and then proposes basic mechanisms.
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Affiliation(s)
- Anne-Christine Schmid
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland; Department of Neural and Pain Sciences, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland; and Brain Imaging and NeuroStimulation (BINS) Laboratory, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jui-Hong Chien
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland
| | - Joel D Greenspan
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland; Department of Neural and Pain Sciences, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland; and
| | - Ira Garonzik
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland
| | - Nirit Weiss
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland
| | - Shinji Ohara
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland
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Agarwal M, Ulmer JL, Klein AP, Mark LP. Cortical and Subcortical Substrates of Cranial Nerve Function. Semin Ultrasound CT MR 2015; 36:275-90. [PMID: 26233861 DOI: 10.1053/j.sult.2015.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pivotal role of cranial nerves in a wholesome life experience cannot be overemphasized. Research has opened new avenues to understand cranial nerve function. Classical concept of strict bilateral cortical control of cranial nerves has given way to concepts of hemispheric dominance and hemispheric lateralization. An astute Neuroradiologist should keep abreast of these concepts and help patients and referring physicians by applying this knowledge in reading images. This chapter provides an overview of cranial nerve function and latest concepts pertaining to their cortical and subcortical control.
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Affiliation(s)
- Mohit Agarwal
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI.
| | - John L Ulmer
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
| | - Andrew P Klein
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
| | - Leighton P Mark
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
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10
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Granger causal time-dependent source connectivity in the somatosensory network. Sci Rep 2015; 5:10399. [PMID: 25997414 PMCID: PMC4441010 DOI: 10.1038/srep10399] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 04/13/2015] [Indexed: 12/29/2022] Open
Abstract
Exploration of transient Granger causal interactions in neural sources of electrophysiological activities provides deeper insights into brain information processing mechanisms. However, the underlying neural patterns are confounded by time-dependent dynamics, non-stationarity and observational noise contamination. Here we investigate transient Granger causal interactions using source time-series of somatosensory evoked magnetoencephalographic (MEG) elicited by air puff stimulation of right index finger and recorded using 306-channel MEG from 21 healthy subjects. A new time-varying connectivity approach, combining renormalised partial directed coherence with state space modelling, is employed to estimate fast changing information flow among the sources. Source analysis confirmed that somatosensory evoked MEG was mainly generated from the contralateral primary somatosensory cortex (SI) and bilateral secondary somatosensory cortices (SII). Transient Granger causality shows a serial processing of somatosensory information, 1) from contralateral SI to contralateral SII, 2) from contralateral SI to ipsilateral SII, 3) from contralateral SII to contralateral SI, and 4) from contralateral SII to ipsilateral SII. These results are consistent with established anatomical connectivity between somatosensory regions and previous source modeling results, thereby providing empirical validation of the time-varying connectivity analysis. We argue that the suggested approach provides novel information regarding transient cortical dynamic connectivity, which previous approaches could not assess.
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11
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Liao CC, Gharbawie OA, Qi H, Kaas JH. Cortical connections to single digit representations in area 3b of somatosensory cortex in squirrel monkeys and prosimian galagos. J Comp Neurol 2014; 521:3768-90. [PMID: 23749740 DOI: 10.1002/cne.23377] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/30/2013] [Accepted: 05/23/2013] [Indexed: 11/06/2022]
Abstract
The ventral posterior nucleus of thalamus sends highly segregated inputs into each digit representation in area 3b of primary somatosensory cortex. However, the spatial organization of the connections that link digit representations of areas 3b with other somatosensory areas is less understood. Here we examined the cortical inputs to individual digit representations of area 3b in four squirrel monkeys and one prosimian galago. Retrograde tracers were injected into neurophysiologically defined representations of individual digits of area 3b. Cortical tissues were cut parallel to the surface in some cases and showed that feedback projections to individual digits overlapped extensively in the hand representations of areas 3b, 1, and parietal ventral (PV) and second somatosensory (S2) areas. Other regions with overlapping populations of labeled cells included area 3a and primary motor cortex (M1). The results were confirmed in other cases in which the cortical tissues were cut in the coronal plane. The same cases also showed that cells were primarily labeled in the infragranular and supragranular layers. Thus, feedback projections to individual digit representations in area 3b mainly originate from multiple digits and other portions of hand representations of areas 3b, 1, PV, and S2. This organization is in stark contrast to the segregated thalamocortical inputs, which originate in single digit representations and terminate in the matching digit representation in the cortex. The organization of feedback connections could provide a substrate for the integration of information across the representations of adjacent digits in area 3b.
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Affiliation(s)
- Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
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12
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Chung YG, Han SW, Kim HS, Chung SC, Park JY, Wallraven C, Kim SP. Intra- and inter-hemispheric effective connectivity in the human somatosensory cortex during pressure stimulation. BMC Neurosci 2014; 15:43. [PMID: 24649878 PMCID: PMC3994419 DOI: 10.1186/1471-2202-15-43] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 03/13/2014] [Indexed: 01/08/2023] Open
Abstract
Background Slow-adapting type I (SA-I) afferents deliver sensory signals to the somatosensory cortex during low-frequency (or static) mechanical stimulation. It has been reported that the somatosensory projection from SA-I afferents is effective and reliable for object grasping and manipulation. Despite a large number of neuroimaging studies on cortical activation responding to tactile stimuli mediated by SA-I afferents, how sensory information of such tactile stimuli flows over the somatosensory cortex remains poorly understood. In this study, we investigated tactile information processing of pressure stimuli between the primary (SI) and secondary (SII) somatosensory cortices by measuring effective connectivity using dynamic causal modeling (DCM). We applied pressure stimuli for 3 s to the right index fingertip of healthy participants and acquired functional magnetic resonance imaging (fMRI) data using a 3T MRI system. Results DCM analysis revealed intra-hemispheric effective connectivity between the contralateral SI (cSI) and SII (cSII) characterized by both parallel (signal inputs to both cSI and cSII) and serial (signal transmission from cSI to cSII) pathways during pressure stimulation. DCM analysis also revealed inter-hemispheric effective connectivity among cSI, cSII, and the ipsilateral SII (iSII) characterized by serial (from cSI to cSII) and SII-level (from cSII to iSII) pathways during pressure stimulation. Conclusions Our results support a hierarchical somatosensory network that underlies processing of low-frequency tactile information. The network consists of parallel inputs to both cSI and cSII (intra-hemispheric), followed by serial pathways from cSI to cSII (intra-hemispheric) and from cSII to iSII (inter-hemispheric). Importantly, our results suggest that both serial and parallel processing take place in tactile information processing of static mechanical stimuli as well as highlighting the contribution of callosal transfer to bilateral neuronal interactions in SII.
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Affiliation(s)
| | | | | | | | | | - Christian Wallraven
- Department of Brain and Cognitive Engineering, Korea University, Seoul, Republic of Korea.
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Hagiwara K, Ogata K, Okamoto T, Uehara T, Hironaga N, Shigeto H, Kira JI, Tobimatsu S. Age-related changes across the primary and secondary somatosensory areas: an analysis of neuromagnetic oscillatory activities. Clin Neurophysiol 2013; 125:1021-9. [PMID: 24189210 DOI: 10.1016/j.clinph.2013.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Age-related changes are well documented in the primary somatosensory cortex (SI). Based on previous somatosensory evoked potential studies, the amplitude of N20 typically increases with age probably due to cortical disinhibition. However, less is known about age-related change in the secondary somatosensory cortex (SII). The current study quantified age-related changes across SI and SII mainly based on oscillatory activity indices measured with magnetoencephalography. METHODS We recorded somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation in healthy young and old subjects and assessed major SEF components. Then, we evaluated the phase-locking factor (PLF) for local field synchrony on neural oscillations and the weighted phase-lag index (wPLI) for cortico-cortical synchrony between SI and SII. RESULTS PLF was significantly increased in SI along with the increased amplitude of N20m in the old subjects. PLF was also increased in SII associated with a shortened peak latency of SEFs. wPLI analysis revealed the increased coherent activity between SI and SII. CONCLUSIONS Our results suggest that the functional coupling between SI and SII is influenced by the cortical disinhibition due to normal aging. SIGNIFICANCE We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.
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Affiliation(s)
- Koichi Hagiwara
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Katsuya Ogata
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | - Taira Uehara
- Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Naruhito Hironaga
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroshi Shigeto
- Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Jun-ichi Kira
- Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shozo Tobimatsu
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
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14
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Self-injurious behaviours are associated with alterations in the somatosensory system in children with autism spectrum disorder. Brain Struct Funct 2013; 219:1251-61. [PMID: 23644587 DOI: 10.1007/s00429-013-0562-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/19/2013] [Indexed: 10/26/2022]
Abstract
Children with autism spectrum disorder (ASD) frequently engage in self-injurious behaviours, often in the absence of reporting pain. Previous research suggests that altered pain sensitivity and repeated exposure to noxious stimuli are associated with morphological changes in somatosensory and limbic cortices. Further evidence from postmortem studies with self-injurious adults has indicated alterations in the structure and organization of the temporal lobes; however, the effect of self-injurious behaviour on cortical development in children with ASD has not yet been determined. Thirty children and adolescents (mean age = 10.6 ± 2.5 years; range 7-15 years; 29 males) with a clinical diagnosis of ASD and 30 typically developing children (N = 30, mean age = 10.7 ± 2.5 years; range 7-15 years, 26 males) underwent T1-weighted magnetic resonance and diffusion tensor imaging. No between-group differences were seen in cerebral volume, surface area or cortical thickness. Within the ASD group, self-injury scores negatively correlated with thickness in the right superior parietal lobule t = 6.3, p < 0.0001, bilateral primary somatosensory cortices (SI) (right: t = 4.4, p = 0.02; left: t = 4.48, p = 0.004) and the volume of the left ventroposterior (VP) nucleus of the thalamus (r = -0.52, p = 0.008). Based on these findings, we performed an atlas-based region-of-interest diffusion tensor imaging analysis between SI and the VP nucleus and found that children who engaged in self-injury had significantly lower fractional anisotropy (r = -0.4, p = 0.04) and higher mean diffusivity (r = 0.5, p = 0.03) values in the territory of the left posterior limb of the internal capsule. Additionally, greater incidence of self-injury was associated with increased radial diffusivity values in bilateral posterior limbs of the internal capsule (left: r = 0.5, p = 0.02; right: r = 0.5, p = 0.009) and corona radiata (left: r = 0.6, p = 0.005; right: r = 0.5, p = 0.009). Results indicate that self-injury is related to alterations in somatosensory cortical and subcortical regions and their supporting white-matter pathways. Findings could reflect use-dependent plasticity in the somatosensory system or disrupted brain development that could serve as a risk marker for self-injury.
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15
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Liu JV, Hirano Y, Nascimento GC, Stefanovic B, Leopold DA, Silva AC. fMRI in the awake marmoset: somatosensory-evoked responses, functional connectivity, and comparison with propofol anesthesia. Neuroimage 2013; 78:186-95. [PMID: 23571417 DOI: 10.1016/j.neuroimage.2013.03.038] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/21/2013] [Accepted: 03/14/2013] [Indexed: 01/20/2023] Open
Abstract
Functional neuroimaging in animal models is essential for understanding the principles of neurovascular coupling and the physiological basis of fMRI signals that are widely used to study sensory and cognitive processing in the human brain. While hemodynamic responses to sensory stimuli have been characterized in humans, animal studies are able to combine very high resolution imaging with invasive measurements and pharmacological manipulation. To date, most high-resolution studies of neurovascular coupling in small animals have been carried out in anesthetized rodents. Here we report fMRI experiments in conscious, awake common marmosets (Callithrix jacchus), and compare responses to animals anesthetized with propofol. In conscious marmosets, robust BOLD fMRI responses to somatosensory stimulation of the forearm were found in contralateral and ipsilateral regions of the thalamus, primary (SI) and secondary (SII) somatosensory cortex, and the caudate nucleus. These responses were markedly stronger than those in anesthetized marmosets and showed a monotonic increase in the amplitude of the BOLD response with stimulus frequency. On the other hand, anesthesia significantly attenuated responses in thalamus, SI and SII, and abolished responses in caudate and ipsilateral SI. Moreover, anesthesia influenced several other aspects of the fMRI responses, including the shape of the hemodynamic response function and the interareal (SI-SII) spontaneous functional connectivity. Together, these findings demonstrate the value of the conscious, awake marmoset model for studying physiological responses in the somatosensory pathway, in the absence of anesthesia, so that the data can be compared most directly to fMRI in conscious humans.
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Affiliation(s)
- Junjie V Liu
- Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10, Room B1D106, Bethesda, MD 20892, USA.
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16
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Yau JM, Connor CE, Hsiao SS. Representation of tactile curvature in macaque somatosensory area 2. J Neurophysiol 2013; 109:2999-3012. [PMID: 23536717 DOI: 10.1152/jn.00804.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tactile shape information is elaborated in a cortical hierarchy spanning primary (SI) and secondary somatosensory cortex (SII). Indeed, SI neurons in areas 3b and 1 encode simple contour features such as small oriented bars and edges, whereas higher order SII neurons represent large curved contour features such as angles and arcs. However, neural coding of these contour features has not been systematically characterized in area 2, the most caudal SI subdivision in the postcentral gyrus. In the present study, we analyzed area 2 neural responses to embossed oriented bars and curved contour fragments to establish whether curvature representations are generated in the postcentral gyrus. We found that many area 2 neurons (26 of 112) exhibit clear curvature tuning, preferring contours pointing in a particular direction. Fewer area 2 neurons (15 of 112) show preferences for oriented bars. Because area 2 response patterns closely resembled SII patterns, we also compared area 2 and SII response time courses to characterize the temporal dynamics of curvature synthesis in the somatosensory system. We found that curvature representations develop and peak concurrently in area 2 and SII. These results reveal that transitions from orientation tuning to curvature selectivity in the somatosensory cortical hierarchy occur within SI rather than between SI and SII.
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Affiliation(s)
- Jeffrey M Yau
- Zanvyl Krieger Mind/Brain Institute and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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17
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Aging-related decline in somatosensory inhibition of the human cerebral cortex. Exp Brain Res 2013; 226:145-52. [PMID: 23377148 DOI: 10.1007/s00221-013-3420-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/11/2013] [Indexed: 10/27/2022]
Abstract
Primary somatosensory (SI) cortical inhibition to repetitive stimuli tends to decline with increasing age. However, aging effects on the inhibition mechanism of secondary somatosensory cortex (SII) remain elusive. We aimed to study the aging-related changes of cortical inhibition in the human somatosensory system. Neuromagnetic responses to paired-pulse electrical stimulation to the median nerve were recorded in 21 young and 20 elderly male adults. Paired-pulse suppression (PPS) of SI and SII activities was estimated by the ratio of the response to Stimulus 2 to the response to Stimulus 1. Based on equivalent current dipole modeling, PPS ratios of the contralateral (SIIc) and ipsilateral (SIIi) secondary somatosensory cortices were higher in elderly than in young subjects (p < 0.001 in SIIc and p = 0.034 in SIIi). At an individual basis, a higher PPS ratio in SIIc than in SI was found in 16 (80 %) out of the 20 elderly participants; in contrast, the PPS ratios of SIIc and SI cortices were similar in young participants (p = 0.031). In conclusion, a larger PPS ratio in elderly suggests an aging-related decline in somatosensory cortical inhibition. Furthermore, compared to SI, the electrophysiological responses of SII cortex are especially vulnerable to aging in terms of cortical inhibition to repetitive stimulation.
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18
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Hu L, Zhang ZG, Hu Y. A time-varying source connectivity approach to reveal human somatosensory information processing. Neuroimage 2012; 62:217-28. [PMID: 22580382 DOI: 10.1016/j.neuroimage.2012.03.094] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 01/24/2012] [Accepted: 03/02/2012] [Indexed: 12/22/2022] Open
Abstract
Exploration of neural sources and their effective connectivity based on transient changes in electrophysiological activities to external stimuli is important for understanding brain mechanisms of sensory information processing. However, such cortical mechanisms have not yet been well characterized in electrophysiological studies since (1) it is difficult to estimate the stimulus-activated neural sources and their activities and (2) it is difficult to identify transient effective connectivity between neural sources in the order of milliseconds. To address these issues, we developed a time-varying source connectivity approach to effectively capture fast-changing information flows between neural sources from high-density Electroencephalography (EEG) recordings. This time-varying source connectivity approach was applied to somatosensory evoked potentials (SEPs), which were elicited by electrical stimulation of right hand and recorded using 64 channels from 16 subjects, to reveal human somatosensory information processing. First, SEP sources and their activities were estimated, both at single-subject and group level, using equivalent current dipolar source modeling. Then, the functional integration among SEP sources was explored using a Kalman smoother based time-varying effective connectivity inference method. The results showed that SEPs were mainly generated from the contralateral primary somatosensory cortex (SI), bilateral secondary somatosensory cortex (SII), and cingulate cortex (CC). Importantly, we observed a serial processing of somatosensory information in human somatosensory cortices (from SI to SII) at earlier latencies (<150 ms) and a reciprocal processing between SII and CC at later latencies (>200 ms).
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Affiliation(s)
- L Hu
- Key Laboratory of Cognition and Personality (Ministry of Education) and School of Psychology, Southwest University, Chongqing, China
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19
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Weiss N, Ohara S, Johnson KO, Lenz FA. The human thalamic somatic sensory nucleus [ventral caudal (Vc)] shows neuronal mechanoreceptor-like responses to optimal stimuli for peripheral mechanoreceptors. J Neurophysiol 2008; 101:1033-42. [PMID: 19004995 DOI: 10.1152/jn.90990.2008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the response of human cutaneous mechanoreceptors to controlled stimuli is well studied, it is not clear how these peripheral signals may be reflected in neuronal activity of the human CNS. We now test the hypothesis that individual neurons in the human thalamic principal somatic sensory nucleus [ventral caudal (Vc)] respond selectively to the optimal stimulus for one of the four mechanoreceptors. The optimal stimuli for particular mechanoreceptors were defined as follows: Pacinian corpuscles (PC), vibration at 128 Hz; rapidly adapting (RA), vibration at 32 or 64 Hz; slowly adapting type 1 (SA1), edge; slowly adapting type 2 (SA2), skin stretch. Nineteen neurons had a significant response to at least one optimal stimulus, and 17 had a significantly greater response to one stimulus than to the other three, including 7 PC-related, 7 RA-like, 3 SA1-like, and 2 SA2-like neurons. One of each of the SA1- and SA2-like thalamic neurons responded to vibration with firing rates that were lower than those to edge or stretch but not significantly. Except in the case of PC-related neurons, the receptive field (RF) sizes were larger for these thalamic neurons than for the corresponding mechanoreceptor. Von Frey thresholds were higher than those for the corresponding human RA and SA1 mechanoreceptors. These results suggest that there is a convergence of pathways transmitting input from multiple mechanoreceptors of one type on single thalamic neurons via the dorsal columns. They are also consistent with the presence of primate thalamic elements of modality and somatotopic isorepresentation.
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Affiliation(s)
- N Weiss
- Department of Neurosurgery, Meyer Bldg. 7-113, Johns Hopkins Hospital, 600 North Wolfe St., Baltimore, MD 21287-7713, USA
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20
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Hamaguchi T, Fukudo S, Kanazawa M, Tomiie T, Shimizu K, Oyama M, Sakurai K. Changes in salivary physiological stress markers induced by muscle stretching in patients with irritable bowel syndrome. Biopsychosoc Med 2008; 2:20. [PMID: 18983682 PMCID: PMC2588633 DOI: 10.1186/1751-0759-2-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 11/04/2008] [Indexed: 02/08/2023] Open
Abstract
Background Psychophysiological processing has been reported to play a crucial role in irritable bowel syndrome (IBS) but there has been no report on modulation of the stress marker chromogranin A (CgA) resulting from muscle stretching. We hypothesized that abdominal muscle stretching as a passive operation would have a beneficial effect on a biochemical index of the activity of the sympathetic/adrenomedullary system (salivary CgA) and anxiety. Methods Fifteen control and eighteen untreated IBS subjects underwent experimental abdominal muscle stretching for 4 min. Subjects relaxed in a supine position with their knees fully flexed while their pelvic and trunk rotation was passively and slowly moved from 0 degrees of abdominal rotation to about 90 degrees or the point where the subject reported feeling discomfort. Changes in the Gastrointestinal Symptoms Rating Scale (GSRS), State Trait Anxiety Inventory (STAI), Self-rating Depression Scale (SDS), ordinate scale and salivary CgA levels were compared between controls and IBS subjects before and after stretching. A three-factor analysis of variance (ANOVA) with period (before vs. after) as the within-subject factor and group (IBS vs. Control), and sex (men vs. female) as the between-subject factors was carried out on salivary CgA. Results CgA showed significant interactions between period and groups (F[1, 31] = 4.89, p = 0.03), and between groups and sex (F[1, 31] = 4.73, p = 0.03). Interactions between period and sex of CgA secretion were not shown (F[1, 3] = 2.60, p = 0.12). At the baseline, salivary CgA in IBS subjects (36.7 ± 5.9 pmol/mg) was significantly higher than in controls (19.9 ± 5.5 pmol/mg, p < 0.05). After the stretching, salivary CgA significantly decreased in the IBS group (25.5 ± 4.5 pmol/mg), and this value did not differ from that in controls (18.6 ± 3.9 pmol/mg). Conclusion Our results suggest the possibility of improving IBS pathophysiology by passive abdominal muscle stretching as indicated by CgA, a biochemical index of the activity of the sympathetic/adrenomedullary system.
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Affiliation(s)
- Toyohiro Hamaguchi
- Department of Occupational Therapy, School of Health and Social Services, Saitama Prefectural University, Saitama, Japan.
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21
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Reward facilitates tactile judgments and modulates hemodynamic responses in human primary somatosensory cortex. J Neurosci 2008; 28:8161-8. [PMID: 18701678 DOI: 10.1523/jneurosci.1093-08.2008] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Reinforcing effects of reward on action are well established, but possible effects on sensory function are less well explored. Here, using functional magnetic resonance imaging, we assessed whether reward can influence somatosensory judgments and modulate activity in human somatosensory cortex. Participants discriminated electrical somatosensory stimuli on an index finger with correct performance rewarded financially at trial end, at one of four different anticipated levels. Higher rewards improved tactile performance and led to increased hemodynamic signals from ventral striatum on rewarded trials. Remarkably, primary somatosensory cortex contralateral to the judged hand was reactivated at the point of reward delivery, despite the absence of concurrent somatosensory input at that time point. This side-specific reactivation of primary somatosensory cortex increased monotonically with level of reward. Moreover, the level of reward received on a particular trial influenced somatosensory performance and neural activity on the subsequent trial, with better discrimination and enhanced hemodynamic response in contralateral primary somatosensory cortex for trials that followed higher rewards. These results indicate that rewards can influence not only classical reward-related regions, but also early somatosensory cortex when a decision is required for that modality.
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22
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Liao CC, Yen CT. Functional Connectivity of the Secondary Somatosensory Cortex of the Rat. Anat Rec (Hoboken) 2008; 291:960-73. [DOI: 10.1002/ar.20696] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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23
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Raij T, Karhu J, Kicić D, Lioumis P, Julkunen P, Lin FH, Ahveninen J, Ilmoniemi RJ, Mäkelä JP, Hämäläinen M, Rosen BR, Belliveau JW. Parallel input makes the brain run faster. Neuroimage 2008; 40:1792-7. [PMID: 18353681 DOI: 10.1016/j.neuroimage.2008.01.055] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 01/14/2008] [Accepted: 01/18/2008] [Indexed: 11/29/2022] Open
Abstract
In serial sensory processing, information flows from the thalamus via primary sensory cortices to higher-order association areas. However, association cortices also receive, albeit weak, direct thalamocortical sensory inputs of unknown function. For example, while information proceeds from primary (SI) to secondary (SII) somatosensory cortex in a serial fashion, both areas are known to receive direct thalamocortical sensory input. The present study examines the potential roles of such parallel input arrangements. The subjects were presented with median nerve somatosensory stimuli with the instruction to respond with the contralateral hand. The locations and time courses of the activated brain areas were first identified with magnetoencephalography (MEG). In a subsequent session, these brain areas were modulated with single-pulse transcranial magnetic stimulation (TMS) at 15-210 ms after the somatosensory stimulus while electroencephalography (EEG) was recorded. TMS pulses at 15-40 ms post-stimulus significantly speeded up reaction times and somatosensory-evoked responses, with largest facilitatory effects when the TMS pulse was given to contralateral SII at about 20 ms. To explain the results, we propose that the early somatosensory-evoked physiological SII activation exerts an SII-->SI influence that facilitates the reciprocal SI-->SII pathway - with TMS to SII we apparently amplified this mechanism. The results suggest that the human brain may utilize parallel inputs to facilitate long-distance cortico-cortical connections, resulting in accelerated processing and speeded reaction times. This arrangement could also allow very early top-down modulation of the bottom-up stream of sensory information.
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Affiliation(s)
- Tommi Raij
- MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA 02129, USA.
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24
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Morley JW, Vickery RM, Stuart M, Turman AB. Suppression of vibrotactile discrimination by transcranial magnetic stimulation of primary somatosensory cortex. Eur J Neurosci 2007; 26:1007-10. [PMID: 17714193 DOI: 10.1111/j.1460-9568.2007.05729.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A number of human and animal studies have reported a differential representation of the frequency of vibrotactile stimuli in the somatosensory cortices: neurons in the primary somatosensory cortex (SI) are predominantly responsive to lower frequencies of tactile vibration, and those in the secondary somatosensory cortex (SII) are predominantly responsive to higher frequencies. We employed transcranial magnetic stimulation (TMS) over SI in human subjects to investigate the extent to which the inactivation of SI disrupted the discrimination of vibrotactile stimulation at frequencies that give rise to the tactile sensations of flutter (30 Hz) and vibration (200 Hz). Frequency discrimination around the 30-Hz standard following application of TMS to SI was reduced in seven of the eight subjects, and around the 200-Hz standard was reduced in all eight subjects. The average change in discrimination following TMS was about 20% for both low and high frequencies of vibrotactile stimulation. These data suggest that disruption of SI: (1) has a direct effect on the discrimination of both low and high frequencies of vibrotactile stimuli, consistent with a serial model of processing, or (2) has a direct effect on low-frequency vibrotactile stimuli and an indirect effect on the processing of high-frequency vibrotactile stimuli by SII via cortico-cortical connections between the two regions.
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Affiliation(s)
- J W Morley
- School of Medicine, University of Western Sydney, Locked Bag 1797, Penrith South DC, New South Wales 1797, Australia.
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25
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Wasaka T, Kida T, Nakata H, Akatsuka K, Kakigi R. Characteristics of sensori-motor interaction in the primary and secondary somatosensory cortices in humans: a magnetoencephalography study. Neuroscience 2007; 149:446-56. [PMID: 17869442 DOI: 10.1016/j.neuroscience.2007.07.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 07/25/2007] [Accepted: 07/26/2007] [Indexed: 11/30/2022]
Abstract
We studied sensori-motor interaction in the primary (SI) and secondary somatosensory cortex (SII) using magnetoencephalography. Since SII in both hemispheres was activated following unilateral stimulation, we analyzed SIIc (contralateral to stimulation) as well as SIIi (ipsilateral to stimulation). Four tasks were performed in human subjects in which a voluntary thumb movement of the left or right hand was combined with electrical stimulation applied to the index finger of the left or right hand: L(M)-L(S) (movement of the left thumb triggered stimulation to the left finger), L(M)-R(S) (movement of the left thumb triggered electrical stimulation to the right finger), R(M)-R(S) (movement of the right thumb triggered electrical stimulation to the right finger), and R(M)-L(S) (movement of the right thumb triggered electrical stimulation to the left finger). Stimulation to the index finger only (S condition) was also recorded. In SI, the amplitude of N20m and P35m was significantly attenuated in the R(M)-R(S) and L(M)-L(S) tasks compared with the S condition, but that for other tasks showed no change, corresponding to a conventional gating phenomenon. In SII, the R(M)-L(S) task significantly enhanced the amplitude of SIIc but reduced that of SIIi compared with the S condition. The L(M)-L(S) and R(M)-R(S) tasks caused a significant enhancement only in SIIi. The L(M)-R(S) task enhanced the amplitude only in SIIc. The laterality index showed that SII modulation with voluntary movement was more dominant in the hemisphere ipsilateral to movement but was not affected by the side of stimulation. These results provided the characteristics of activities in somatosensory cortices, a simple inhibition in SI but complicated changes in SII depending on the side of movement and stimulation, which may indicate the higher cognitive processing in SII.
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Affiliation(s)
- T Wasaka
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan.
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26
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Blatow M, Nennig E, Durst A, Sartor K, Stippich C. fMRI reflects functional connectivity of human somatosensory cortex. Neuroimage 2007; 37:927-36. [PMID: 17629500 DOI: 10.1016/j.neuroimage.2007.05.038] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 04/24/2007] [Accepted: 05/17/2007] [Indexed: 02/08/2023] Open
Abstract
Unilateral sensory stimulation reliably elicits contralateral somatotopic activation of primary (SI) and secondary (SII) somatosensory cortex. There is an ongoing debate about the occurrence and nature of concomitant ipsilateral SI and SII activation. Here we used functional magnetic resonance imaging (fMRI) in healthy human subjects with unilateral tactile stimulation of fingers and lips, to compare somatosensory activation patterns from distal and proximal body parts. We hypothesized that fMRI in humans should reflect the functional connectivity of somatosensory cortex as predicted by animal studies. We show that both unilateral finger and lip stimulations activate contra- and ipsilateral SI and SII cortices with high detection frequency. Correlations of BOLD-signals to the applied hemodynamic reference function were significantly higher in contralateral as compared to ipsilateral SI and SII cortices for both finger and lip stimulation, reflecting strong contribution of contralateral thalamocortical input. Furthermore, BOLD-signal correlations were higher in SI than in SII activations on the contralateral but not on the ipsilateral side. While these asymmetries within and across hemispheres were consistent for finger and lip stimulations, indicating analogous underlying organizing principles, they were less prominent for lip stimulation. Somatotopic organization was detected in SI but not in SII representations of fingers and lips. These results qualitatively and quantitatively support the prevalent concepts of anatomical and functional connectivity in the somatosensory system and therefore may allow interpretation of sensory evoked fMRI signals in terms of normal human brain function. Thus, the assessment of human somatosensory function with fMRI may permit in the future investigations of pathological conditions.
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Affiliation(s)
- Maria Blatow
- Division of Neuroradiology, Department of Neurology, University of Heidelberg Medical School, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
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27
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Spatiotemporal integration of tactile information in human somatosensory cortex. BMC Neurosci 2007; 8:21. [PMID: 17359544 PMCID: PMC1838913 DOI: 10.1186/1471-2202-8-21] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2006] [Accepted: 03/14/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Our goal was to examine the spatiotemporal integration of tactile information in the hand representation of human primary somatosensory cortex (anterior parietal somatosensory areas 3b and 1), secondary somatosensory cortex (S2), and the parietal ventral area (PV), using high-resolution whole-head magnetoencephalography (MEG). To examine representational overlap and adaptation in bilateral somatosensory cortices, we used an oddball paradigm to characterize the representation of the index finger (D2; deviant stimulus) as a function of the location of the standard stimulus in both right- and left-handed subjects. RESULTS We found that responses to deviant stimuli presented in the context of standard stimuli with an interstimulus interval (ISI) of 0.33 s were significantly and bilaterally attenuated compared to deviant stimulation alone in S2/PV, but not in anterior parietal cortex. This attenuation was dependent upon the distance between the deviant and standard stimuli: greater attenuation was found when the standard was immediately adjacent to the deviant (D3 and D2 respectively), with attenuation decreasing for non-adjacent fingers (D4 and opposite D2). We also found that cutaneous mechanical stimulation consistently elicited not only a strong early contralateral cortical response but also a weak ipsilateral response in anterior parietal cortex. This ipsilateral response appeared an average of 10.7 +/- 6.1 ms later than the early contralateral response. In addition, no hemispheric differences either in response amplitude, response latencies or oddball responses were found, independent of handedness. CONCLUSION Our findings are consistent with the large receptive fields and long neuronal recovery cycles that have been described in S2/PV, and suggest that this expression of spatiotemporal integration underlies the complex functions associated with this region. The early ipsilateral response suggests that anterior parietal fields also receive tactile input from the ipsilateral hand. The lack of a hemispheric difference in responses to digit stimulation supports a lack of any functional asymmetry in human somatosensory cortex.
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Sahai V, Mahns DA, Robinson L, Perkins NM, Coleman GT, Rowe MJ. Processing of Vibrotactile Inputs From Hairy Skin by Neurons of the Dorsal Column Nuclei in the Cat. J Neurophysiol 2006; 95:1451-64. [PMID: 16319217 DOI: 10.1152/jn.00485.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The capacity of single neurons of the dorsal column nuclei (DCN) for coding vibrotactile information from the hairy skin has been investigated in anesthetized cats to permit quantitative comparison first with the capacities of DCN neurons responding to glabrous skin vibrotactile inputs and second with those of spinocervical tract neurons responding to vibrotactile inputs from hairy skin. Dynamically sensitive tactile neurons of the DCN the input of which came from hairy skin could be divided into two classes, one associated with hair follicle afferent (HFA) input, the other with Pacinian corpuscle (PC) input. The HFA-related class was most sensitive to low-frequency (<50 Hz) vibration and had a graded response output as a function of vibrotactile intensity changes. PC-related neurons had a broader vibrotactile sensitivity, extending to ≥300 Hz and appeared to derive their input from the margins of hairy skin, near the footpads, or from deeper PC sources such as the interosseous membranes or joints. HFA-related neurons had phaselocked responses to vibration frequencies up to ∼75 Hz, whereas PC neurons retained this capacity up to frequencies of ∼300 Hz with tightest phaselocking between 50 and 200 Hz. Quantitative measures of phaselocking revealed that the HFA-related neurons provide the better signal of vibrotactile frequency up to ∼50 Hz with a switch-over to the PC-related neurons above that value. In conclusion, the functional capacities of these two classes of cuneate neuron appear to account for behavioral vibrotactile frequency discriminative performance in hairy skin, in contrast to the limited capacities of vibrotactile-sensitive neurons within the spinocervical tract system.
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Affiliation(s)
- V Sahai
- Department of Physiology and Pharmacology, School of Medical Sciences, The University of New South Wales, Sydney, Australia
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Taskin B, Jungehulsing GJ, Ruben J, Brunecker P, Krause T, Blankenburg F, Villringer A. Preserved Responsiveness of Secondary Somatosensory Cortex in Patients with Thalamic Stroke. Cereb Cortex 2005; 16:1431-9. [PMID: 16357339 DOI: 10.1093/cercor/bhj080] [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: 11/13/2022] Open
Abstract
Cortical representations may change when somatosensory input is altered. Here, we investigated the functional consequences of partial "central" deafferentation of the somatosensory cortex due to a lesion of the ventroposterior lateral nucleus (VPL) in patients at a chronic stage after solitary infarction of the thalamus. Event-related functional magnetic resonance imaging during electrical index finger stimulation of the affected and nonaffected side was performed in 6 patients exhibiting contralesional sensory deficits (mainly hypesthesia). Involvement of the VPL and additional nuclei was determined by high-resolution magnetic resonance imaging (MRI) and subsequent MRI-to-atlas coregistration. For the group, statistical parametric maps showed a reduced activation of contralateral primary somatosensory cortex (SI) in response to stimulation of the affected side. However, no significant difference in the activation of contralateral secondary somatosensory cortex (SII) compared with stimulation of the nonaffected side was detected. Correspondingly, the ratio of SII-to-SI activation for the ipsilesional hemisphere was markedly elevated as compared with the contralesional hemisphere. For preserved responsiveness of SII in thalamic stroke comparable with that of the contralesional hemisphere, possible explanations are a direct thalamocortical input to SII mediating parallel information processing, nonlinear response behavior of SII in serial processing, or reorganizational processes that evolved over time.
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Affiliation(s)
- Birol Taskin
- Neurologische Klinik und Poliklinik, Charité-Universitätsmedizin Berlin, Berlin NeuroImaging Center, Germany.
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Wasaka T, Nakata H, Akatsuka K, Kida T, Inui K, Kakigi R. Differential modulation in human primary and secondary somatosensory cortices during the preparatory period of self-initiated finger movement. Eur J Neurosci 2005; 22:1239-47. [PMID: 16176367 DOI: 10.1111/j.1460-9568.2005.04289.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To elucidate the mechanisms underlying sensorimotor integration, we investigated modulation in the primary (SI) and secondary (SII) somatosensory cortices during the preparatory period of a self-initiated finger extension. Electrical stimulation of the right median nerve was applied continuously, while the subjects performed a self-initiated finger extension and were instructed not to pay attention to the stimulation. The preparatory period was divided into five sub-periods from the onset of the electromyogram to 3000 ms before movement and the magnetoencephalogram signals following stimulation in each sub-period were averaged. Multiple source analysis indicated that the equivalent current dipoles (ECDs) were located in SI and bilateral SII. Although the ECD moment for N 20 m (the upward deflection peaking at around 20 ms) was not significantly changed, that for P 30 m (the downward deflection peaking at around 30 m) was significantly smaller in the 0- to -500-ms sub-period than the -2000- to -3000-ms sub-period. As for SII, the ECD moment for the SII ipsilateral to movement showed no significant change, while that for the contralateral SII was significantly larger in the 0- to -500-ms sub-period than the -1500- to -2000-ms or -2000- to -3000-ms sub-period. The opposite effects of movement on SI and SII cortices indicated that these cortical areas play a different role in the function of the sensorimotor integration and are affected differently by the centrifugal process.
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Affiliation(s)
- Toshiaki Wasaka
- Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
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Tommerdahl M, Simons SB, Chiu JS, Favorov O, Whitsel B. Response of SI cortex to ipsilateral, contralateral and bilateral flutter stimulation in the cat. BMC Neurosci 2005; 6:29. [PMID: 15847693 PMCID: PMC1087848 DOI: 10.1186/1471-2202-6-29] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Accepted: 04/22/2005] [Indexed: 11/10/2022] Open
Abstract
Background While SII cortex is considered to be the first cortical stage of the pathway that integrates tactile information arising from both sides of the body, SI cortex is generally not considered as a region in which neuronal response is modulated by simultaneous stimulation of bilateral (and mirror-image) skin sites. Results Optical intrinsic signal imaging was used to evaluate the response of SI and SII in the same hemisphere to 25 Hz sinusoidal vertical skin displacement stimulation ("skin flutter") applied contralaterally, ipsilaterally, and bilaterally (simultaneously) to the central pads of the forepaws. A localized increase in absorbance in both SI and SII occurred in response to both contralateral and bilateral flutter stimulation. Ipsilateral flutter stimulation evoked a localized increase in absorbance in SII, but little or no change in SI absorbance. In the forepaw representational region of SI, however, bilateral stimulation of the central pads evoked a response substantially smaller (approximately 30–35% smaller) than the response to flutter stimulation of the contralateral central pad. Conclusion The finding that the response of SI cortex to bilateral central pad flutter stimulation is substantially smaller than the response evoked by a contralateral flutter stimulus, together with the recently published observation that a region located posteriorly in SII responds with a substantially larger response to a bilateral flutter stimulus than the response evoked from the contralateral central pad, lead us to propose that the SI activity evoked by contralateral skin stimulation is suppressed/inhibited (via corticocortical connections between SII and SI in the same hemisphere) by the activity a simultaneous ipsilateral skin stimulus evokes in posterior SII.
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Affiliation(s)
- Mark Tommerdahl
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Stephen B Simons
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joannellyn S Chiu
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Oleg Favorov
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Barry Whitsel
- Department of Cellular and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
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Kitada R, Hashimoto T, Kochiyama T, Kito T, Okada T, Matsumura M, Lederman SJ, Sadato N. Tactile estimation of the roughness of gratings yields a graded response in the human brain: an fMRI study. Neuroimage 2005; 25:90-100. [PMID: 15734346 DOI: 10.1016/j.neuroimage.2004.11.026] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 10/09/2004] [Accepted: 11/20/2004] [Indexed: 11/26/2022] Open
Abstract
Human subjects can tactually estimate the magnitude of surface roughness. Although many psychophysical and neurophysiological experiments have elucidated the peripheral neural mechanisms that underlie tactile roughness estimation, the associated cortical mechanisms are not well understood. To identify the brain regions responsible for the tactile estimation of surface roughness, we used functional magnetic resonance imaging (fMRI). We utilized a combination of categorical (subtraction) and parametric factorial approaches wherein roughness was varied during both the task and its control. Fourteen human subjects performed a tactile roughness-estimation task and received the identical tactile stimulation without estimation (no-estimation task). The bilateral parietal operculum (PO), insula and right lateral prefrontal cortex showed roughness-related activation. The bilateral PO and insula showed activation during the no-estimation task, and hence might represent the sensory-based processing during roughness estimation. By contrast, the right prefrontal cortex is more related to the cognitive processing, as there was activation during the estimation task compared with the no-estimation task, but little activation was observed during the no-estimation task in comparison with rest. The lateral prefrontal area might play an important cognitive role in tactile estimation of surface roughness, whereas the PO and insula might be involved in the sensory processing that is important for estimating surface roughness.
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Affiliation(s)
- Ryo Kitada
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
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Coq JO, Qi H, Collins CE, Kaas JH. Anatomical and functional organization of somatosensory areas of the lateral fissure of the New World titi monkey (Callicebus moloch). J Comp Neurol 2004; 476:363-87. [PMID: 15282711 DOI: 10.1002/cne.20237] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The organization of anterior and lateral somatosensory cortex was investigated in titi monkeys (Callicebus moloch). Multiunit microelectrode recordings were used to identify multiple representations of the body, and anatomical tracer injections were used to reveal connections. (1) Representations of the face were identified in areas 3a, 3b, 1, S2, and the parietal ventral area (PV). In area 3b, the face was represented from chin/lower lip to upper lip and neck/upper face in a rostrocaudal sequence. The representation of the face in area 1 mirrored that of area 3b. Another face representation was located in area 3a. Adjoining face representations in S2 and PV exhibited mirror-image patterns to those of areas 3b and 1. (2) Two representations of the body, the rostral and caudal ventral somatosensory areas (VSr and VSc), were found in the dorsal part of the insula. VSc was roughly a reversal image of the S2 body representation, and VSr was roughly a reversal of PV. (3) Neurons in the insula next to VSr and VSc responded to auditory stimuli or to both auditory and somatosensory stimuli. (4) Injections of tracers within the hand representations in areas 3b, 1, and S2 revealed reciprocal connections between these three areas. Injections in areas 3b and 1 labeled the ventroposterior nucleus, whereas injections in S2 labeled the inferior ventroposterior nucleus. The present study demonstrates features of somatosensory cortex of other monkeys in titi monkeys, while revealing additional features that likely apply to other primates.
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Affiliation(s)
- Jacques-Olivier Coq
- Vanderbilt University, Department of Psychology, Nashville, Tennessee 37203, USA
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Ohara S, Weiss N, Lenz FA. Microstimulation in the region of the human thalamic principal somatic sensory nucleus evokes sensations like those of mechanical stimulation and movement. J Neurophysiol 2003; 91:736-45. [PMID: 14573561 DOI: 10.1152/jn.00648.2003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We explored the region of human thalamic somatic sensory nucleus (ventral caudal, Vc), corresponding to monkey ventral posterior (VP), with threshold microstimulation (TMIS) during stereotactic procedures for the treatment of tremor. Of 122 sites in 116 patients (124 thalami) where mechanical (touch, pressure, and sharp) or movement [movement through the body (movement) and vibration] sensations were evoked, 72 sites were found in the core or in adjacent regions, posterior-inferior (33), inferior (4), and posterior to the core (13). Sites where TMIS evoked touch were less frequently found in the core than those where movement or pressure sensations were evoked. Pressure was more commonly (P < 0.05) evoked than vibration at sites where cells had intraoral receptive fields (RFs). Touch and vibration were more commonly (P < 0.05) evoked than pressure at sites where cells had facial RFs, consistent with the relative density of rapidly adapting (RA) receptors in the mouth and face. Sites described as deep and movement were found superior and anterior in the core, consistent with the location of cells responding to stimulation of muscle afferents. At 72 of 122 sites, TMIS evoked the same sensation at two or more sites in the same plane. Of these sites, 58 are adjacent to each other, in a cluster, consistent with studies of the localization of cells responding to different modalities. These results demonstrate that mechanical and movement sensations can be evoked by stimulation in the region of Vc. The characteristics of these sites suggest that the sensations are evoked by stimulation of pathways specific to cutaneous and deep mechanoreceptors.
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Affiliation(s)
- Shinji Ohara
- Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, Maryland 21278-7713, USA
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Romo R, Hernández A, Zainos A, Salinas E. Correlated neuronal discharges that increase coding efficiency during perceptual discrimination. Neuron 2003; 38:649-57. [PMID: 12765615 DOI: 10.1016/s0896-6273(03)00287-3] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
During a sensory discrimination task, the responses of multiple sensory neurons must be combined to generate a choice. The optimal combination of responses is determined both by their dependence on the sensory stimulus and by their cofluctuations across trials-that is, the noise correlations. Positively correlated noise is considered deleterious, because it limits the coding accuracy of populations of similarly tuned neurons. However, positively correlated fluctuations between differently tuned neurons actually increase coding accuracy, because they allow the common noise to be subtracted without signal loss. This is demonstrated with data recorded from the secondary somatosensory cortex of monkeys performing a vibrotactile discrimination task. The results indicate that positive correlations are not always harmful and may be exploited by cortical networks to enhance the neural representation of features to be discriminated.
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Affiliation(s)
- Ranulfo Romo
- Instituto de Fisiologi;a Celular, Universidad Nacional Autónoma de México, 04510 México City, D.F., Mexico.
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Romo R, Salinas E. Flutter discrimination: neural codes, perception, memory and decision making. Nat Rev Neurosci 2003; 4:203-18. [PMID: 12612633 DOI: 10.1038/nrn1058] [Citation(s) in RCA: 415] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent studies combining psychophysical and neurophysiological experiments in behaving monkeys have provided new insights into how several cortical areas integrate efforts to solve a vibrotactile discrimination task. In particular, these studies have addressed how neural codes are related to perception, working memory and decision making in this model. The primary somatosensory cortex drives higher cortical areas where past and current sensory information are combined, such that a comparison of the two evolves into a behavioural decision. These and other observations in visual tasks indicate that decisions emerge from highly-distributed processes in which the details of a scheduled motor plan are gradually specified by sensory information.
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Affiliation(s)
- Ranulfo Romo
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México Distrito Federal, Mexico.
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Barba C, Frot M, Mauguière F. Early secondary somatosensory area (SII) SEPs. Data from intracerebral recordings in humans. Clin Neurophysiol 2002; 113:1778-86. [PMID: 12417231 DOI: 10.1016/s1388-2457(02)00261-4] [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: 11/29/2022]
Abstract
OBJECTIVE To record somatosensory evoked potentials (SEPs) to median nerve stimulation by chronically implanted electrodes in the parieto-rolandic opercular area of 9 epileptic patients, in order to evaluate whether somatosensory evoked responses could be generated in the second somatosensory area (SII) earlier than 40 ms after stimulus. METHODS Nine patients (4 males, 5 females) with drug-resistant partial epileptic seizures were investigated using stereotactically implanted electrodes in the parietal cortex, posterior to vertical anterior commissure plane and in the frontal opercular region rostral to vertical anterior commissure (VAC). RESULTS The main finding of this study is the recording of an early somatosensory evoked potential, (N30op), by chronically implanted electrodes in the SII area of 8 epileptic patients. In 3 patients where SEPs were performed after ipsilateral median nerve (MN) stimulation, a N30op was recorded 5.8+/-2 ms later than contralateral one. CONCLUSIONS This is the first report of early SEPs recorded by electrodes implanted in SII area. The N30op potential, even if less consistent than later potentials, confirmed the important role of the SII area in the early processing of somatosensory inputs.
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Affiliation(s)
- Carmen Barba
- Department of Neurology, Catholic University, Largo A. Gemelli 8, 00168 Rome, Italy.
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Zhang HQ, Al-Chaer ED, Willis WD. Effect of tactile inputs on thalamic responses to noxious colorectal distension in rat. J Neurophysiol 2002; 88:1185-96. [PMID: 12205140 DOI: 10.1152/jn.2002.88.3.1185] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent discoveries of visceral nociceptive inputs sharing the classical tactile pathway in the dorsal-column medial lemniscus system have opened a new venue for the investigation of somatovisceral interactions. The current study was designed to determine whether somatic innocuous inputs modulate visceral nociceptive transmission at the thalamic level. The investigation was carried out by means of extracellular single-unit recordings in the ventroposterior lateral nucleus of the thalamus in rats anesthetized with pentobarbital. Noxious visceral stimulation was achieved by reproducible colorectal distension (CRD, 20-80 mmHg) with a balloon catheter. Tactile stimulation was delivered by means of a feedback-controlled mechanical stimulator. The response of the neurons to CRD was compared before and after the conditioning procedure by giving tactile stimulation either immediately before CRD or overlapping it. Twenty-five ventroposterior lateral (VPL) thalamic neurons were found among numerous tactile-only neurons to have convergent inputs from both tactile and visceral sources. Their responses to CRD were excitatory (19), inhibitory (4), or bimodal. When cutaneous tactile stimuli were delivered before CRD, the responses were reduced in 18 cases. The reduction, however, was usually short-lasting, immediately following tactile stimulation and could not be enhanced by a prolonged conditioning procedure. It was unlikely to be attributable to neuronal habituation as the inverted procedure, CRD stimulation before tactile, often produced the opposite effect, that is, an enhanced response to skin stimulation. Repeated CRD could bring about sensitization of the responses of thalamic neurons as manifested by increased spontaneous discharge, lowered response threshold, and increased response level. Under such circumstances, the original effect of tactile stimulation on CRD responses could be weakened. In conclusion, tactile stimulation may in most circumstances inhibit thalamic neuronal responses to visceral nociceptive input produced by CRD. However, the effect appears to be mild and short-lasting at the individual neuronal level in the VPL thalamus.
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Affiliation(s)
- Hong-Qi Zhang
- School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
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Coleman GT, Bahramali H, Zhang HQ, Rowe MJ. Characterization of tactile afferent fibers in the hand of the marmoset monkey. J Neurophysiol 2001; 85:1793-804. [PMID: 11352997 DOI: 10.1152/jn.2001.85.5.1793] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The marmoset monkey, Callithrix jacchus, has increasingly been the subject of experiments for the analysis of somatosensory system function in simian primates. However, as response properties of the mechanoreceptive afferent fibers supplying the skin have not been characterized for this primate, the present study was undertaken to classify fibers innervating the glabrous skin of the marmoset hand and determine whether they resembled those described for other mammalian species, including cat, macaque monkey, and human subjects. Forty-seven tactile afferent fibers with receptive fields (RFs) on the glabrous skin of the hand were isolated in fine median and ulnar nerve strands. Controlled tactile stimuli, including static indentation and skin vibration, were used to classify fibers. Twenty-six (55%) responded to static indentation in a sustained manner and were designated slowly adapting (SA) fibers, while 21 (45%) were selectively sensitive to the dynamic components of the stimulus. The SA fibers had well-defined boundaries to their RFs, lacked spontaneous activity in most cases (23/26 fibers), had an irregular pattern of discharge to static skin indentation, and displayed graded response levels as a function of indentation amplitude, attributes that were consistent with the properties of slowly adapting type I (SAI) fibers described in other species. The dynamically sensitive afferent fibers could be subdivided into two distinct functional classes, based on their responses to vibrotactile stimulation. The majority (15/21) responded best to lower frequency vibration (~10-50 Hz) and had small RFs, whereas the second class responded preferentially to higher frequency vibration (50-700 Hz) with maximal sensitivity at ~200-300 Hz. These two classes resembled, respectively, the rapidly adapting (RA) and Pacinian corpuscle-related (PC) fiber classes found in other species, and like them, responded to vibration with tightly phase-locked patterns of response over a wide range of frequencies. The results demonstrate that the functional classes of tactile afferent fibers that supply the glabrous skin in the marmoset monkey appear to correspond with those described previously for the cat and macaque monkey, and are similar to those supplying the human hand and fingers, although the SA fibers in the human hand appear to fall into two classes, the SAI and SAII fibers. With the increasing use of the marmoset monkey as a primate model for somatosensory system studies, these data now allow tactile neurons identified at central locations, such as the cerebral cortex and thalamus, to be classified in relation to inputs from the peripheral classes identified in the present study.
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Affiliation(s)
- G T Coleman
- School of Physiology and Pharmacology, The University of New South Wales, Sydney, NSW 2052, Australia
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Zhang HQ, Zachariah MK, Coleman GT, Rowe MJ. Hierarchical Equivalence of Somatosensory Areas I and II for Tactile Processing in the Cerebral Cortex of the Marmoset Monkey. J Neurophysiol 2001; 85:1823-35. [PMID: 11352999 DOI: 10.1152/jn.2001.85.5.1823] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Responsiveness of the first somatosensory area (SI) of the cerebral cortex was investigated in the marmoset monkey ( Callithrix jacchus) in association with cooling-induced, reversible inactivation of the second somatosensory area, SII. The aim was to determine whether SI responsiveness to peripheral tactile stimulation depends on SII and therefore whether SI and SII in the marmoset occupy hierarchically equivalent positions in a parallel organizational scheme for thalamocortical tactile processing as appears to be the case in nonprimate mammals. Inactivation of SII was achieved when the temperature over SII was lowered to ≤12°C, as indicated by abolition of the SII-evoked potentials generated by brief tap stimuli to the hand or foot, and by abolition of tactile responses in single SII neurons located at the margin beneath the block. The effect of SII inactivation on SI-evoked potentials was examined in 16 experiments by simultaneous recording of the SI- and SII-evoked potentials. SI-evoked potentials were never abolished and remained unaffected in 11 cases. In three experiments there was a small reduction in amplitude and inconsistent effects in the remaining two. Responsiveness to controlled tactile stimuli was examined quantitatively in 31 individual SI neurons of different functional classes before, during, and after the inactivation of SII. Tactile responsiveness in individual SI neurons was never abolished by SII inactivation, remaining unchanged in 20 neurons (65%) while undergoing some reduction in the remaining 11 SI neurons (35%). This reduction of tactile responsiveness in one-third of SI neurons is most likely attributable to a removal of a facilitatory influence emanating from SII, based on the observation that background activity of the affected neurons was also reduced. Furthermore, phase locking of SI responses to vibrotactile stimulation was unchanged when SII was inactivated. The retention of responsiveness in SI neurons when SII was inactivated by cooling in the marmoset demonstrates that tactile inputs can reach SI without traversing an indirect, serially organized path through SII. The present results, together with our previous observations that responsiveness in the majority of SII neurons survived SI inactivation, demonstrate that there is a parallel organization of the SI and SII areas for tactile processing in the marmoset monkey and that SI and SII occupy hierarchically equivalent positions in a parallel processing network. There is therefore no longer justification for the view that there are fundamental differences in the organization of thalamocortical tactile processing for SI and SII between simian primates, in general, and other mammals.
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Affiliation(s)
- H Q Zhang
- School of Physiology and Pharmacology, The University of New South Wales, Sydney, NSW 2052, Australia
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