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Greenspon CM, Shelchkova ND, Hobbs TG, Bensmaia SJ, Gaunt RA. Intracortical microstimulation of human somatosensory cortex is sufficient to induce perceptual biases. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.04.19.24305901. [PMID: 38712172 PMCID: PMC11071569 DOI: 10.1101/2024.04.19.24305901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Time-order error, a psychophysical phenomenon in which the duration in between successive stimuli alters perception, has been studied for decades by neuroscientists and psychologists. To date, however, the locus of these effects is unknown. We use intracortical microstimulation of somatosensory cortex in humans as a tool to bypass initial stages of processing and restrict the possible locations that signals could be modified. We find that, using both amplitude discrimination and magnitude estimation paradigms, intracortical microstimulation reliably evoked time-order errors across all participants. Points of subjective equality were symmetrically shifted during amplitude discrimination experiments and the intensity of a successive stimulus was perceived as being more intense when compared to single stimulus trials in magnitude estimation experiments. The error was reduced for both paradigms at longer inter-stimulus intervals. These results show that direct activation of primary somatosensory cortex is sufficient to induce time-order errors.
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Affiliation(s)
- Charles M. Greenspon
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL
| | | | - Taylor G. Hobbs
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
| | - Sliman J. Bensmaia
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL
- Committee on Computational Neuroscience, University of Chicago, Chicago, IL
- Neuroscience Institute, University of Chicago, Chicago, IL
| | - Robert A. Gaunt
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA
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Hughes C, Kozai T. Dynamic amplitude modulation of microstimulation evokes biomimetic onset and offset transients and reduces depression of evoked calcium responses in sensory cortices. Brain Stimul 2023; 16:939-965. [PMID: 37244370 PMCID: PMC10330928 DOI: 10.1016/j.brs.2023.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 05/15/2023] [Accepted: 05/17/2023] [Indexed: 05/29/2023] Open
Abstract
BACKGROUND Intracortical microstimulation (ICMS) is an emerging approach to restore sensation to people with neurological injury or disease. Biomimetic microstimulation, or stimulus trains that mimic neural activity in the brain through encoding of onset and offset transients, could improve the utility of ICMS for brain-computer interface (BCI) applications, but how biomimetic microstimulation affects neural activation is not understood. Current "biomimetic" ICMS trains aim to reproduce the strong onset and offset transients evoked in the brain by sensory input through dynamic modulation of stimulus parameters. Stimulus induced depression of neural activity (decreases in evoked intensity over time) is also a potential barrier to clinical implementation of sensory feedback, and dynamic microstimulation may reduce this effect. OBJECTIVE We evaluated how bio-inspired ICMS trains with dynamic modulation of amplitude and/or frequency change the calcium response, spatial distribution, and depression of neurons in the somatosensory and visual cortices. METHODS Calcium responses of neurons were measured in Layer 2/3 of visual and somatosensory cortices of anesthetized GCaMP6s mice in response to ICMS trains with fixed amplitude and frequency (Fixed) and three dynamic ICMS trains that increased the stimulation intensity during the onset and offset of stimulation by modulating the amplitude (DynAmp), frequency (DynFreq), or amplitude and frequency (DynBoth). ICMS was provided for either 1-s with 4-s breaks (Short) or for 30-s with 15-s breaks (Long). RESULTS DynAmp and DynBoth trains evoked distinct onset and offset transients in recruited neural populations, while DynFreq trains evoked population activity similar to Fixed trains. Individual neurons had heterogeneous responses primarily based on how quickly they depressed to ICMS, where neurons farther from the electrode depressed faster and a small subpopulation (1-5%) were modulated by DynFreq trains. Neurons that depressed to Short trains were also more likely to depress to Long trains, but Long trains induced more depression overall due to the increased stimulation length. Increasing the amplitude during the hold phase resulted in an increase in recruitment and intensity which resulted in more depression and reduced offset responses. Dynamic amplitude modulation reduced stimulation induced depression by 14.6 ± 0.3% for Short and 36.1 ± 0.6% for Long trains. Ideal observers were 0.031 ± 0.009 s faster for onset detection and 1.33 ± 0.21 s faster for offset detection with dynamic amplitude encoding. CONCLUSIONS Dynamic amplitude modulation evokes distinct onset and offset transients, reduces depression of neural calcium activity, and decreases total charge injection for sensory feedback in BCIs by lowering recruitment of neurons during long maintained periods of ICMS. In contrast, dynamic frequency modulation evokes distinct onset and offset transients in a small subpopulation of neurons but also reduces depression in recruited neurons by reducing the rate of activation.
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Affiliation(s)
- Christopher Hughes
- Department of Bioengineering, University of Pittsburgh, USA; Center for the Neural Basis of Cognition, USA
| | - Takashi Kozai
- Department of Bioengineering, University of Pittsburgh, USA; Center for the Neural Basis of Cognition, USA; Department of Neuroscience, University of Pittsburgh, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA; NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA.
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3
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Effects of stimulus pulse rate on somatosensory adaptation in the human cortex. Brain Stimul 2022; 15:987-995. [DOI: 10.1016/j.brs.2022.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 05/26/2022] [Accepted: 05/31/2022] [Indexed: 01/01/2023] Open
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Pfeifer KJ, Kromer JA, Cook AJ, Hornbeck T, Lim EA, Mortimer BJP, Fogarty AS, Han SS, Dhall R, Halpern CH, Tass PA. Coordinated Reset Vibrotactile Stimulation Induces Sustained Cumulative Benefits in Parkinson's Disease. Front Physiol 2021; 12:624317. [PMID: 33889086 PMCID: PMC8055937 DOI: 10.3389/fphys.2021.624317] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/05/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Abnormal synchronization of neuronal activity in dopaminergic circuits is related to motor impairment in Parkinson's disease (PD). Vibrotactile coordinated reset (vCR) fingertip stimulation aims to counteract excessive synchronization and induce sustained unlearning of pathologic synaptic connectivity and neuronal synchrony. Here, we report two clinical feasibility studies that examine the effect of regular and noisy vCR stimulation on PD motor symptoms. Additionally, in one clinical study (study 1), we examine cortical beta band power changes in the sensorimotor cortex. Lastly, we compare these clinical results in relation to our computational findings. METHODS Study 1 examines six PD patients receiving noisy vCR stimulation and their cortical beta power changes after 3 months of daily therapy. Motor evaluations and at-rest electroencephalographic (EEG) recordings were assessed off medication pre- and post-noisy vCR. Study 2 follows three patients for 6+ months, two of whom received daily regular vCR and one patient from study 1 who received daily noisy vCR. Motor evaluations were taken at baseline, and follow-up visits were done approximately every 3 months. Computationally, in a network of leaky integrate-and-fire (LIF) neurons with spike timing-dependent plasticity, we study the differences between regular and noisy vCR by using a stimulus model that reproduces experimentally observed central neuronal phase locking. RESULTS Clinically, in both studies, we observed significantly improved motor ability. EEG recordings observed from study 1 indicated a significant decrease in off-medication cortical sensorimotor high beta power (21-30 Hz) at rest after 3 months of daily noisy vCR therapy. Computationally, vCR and noisy vCR cause comparable parameter-robust long-lasting synaptic decoupling and neuronal desynchronization. CONCLUSION In these feasibility studies of eight PD patients, regular vCR and noisy vCR were well tolerated, produced no side effects, and delivered sustained cumulative improvement of motor performance, which is congruent with our computational findings. In study 1, reduction of high beta band power over the sensorimotor cortex may suggest noisy vCR is effectively modulating the beta band at the cortical level, which may play a role in improved motor ability. These encouraging therapeutic results enable us to properly plan a proof-of-concept study.
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Affiliation(s)
- Kristina J. Pfeifer
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Justus A. Kromer
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Alexander J. Cook
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Traci Hornbeck
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Erika A. Lim
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | | | - Adam S. Fogarty
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, United States
| | - Summer S. Han
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
- Quantitative Sciences Unit, Stanford University School of Medicine, Stanford, CA, United States
| | - Rohit Dhall
- Center for Neurodegenerative Disorders, Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Casey H. Halpern
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Peter A. Tass
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
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Page DM, George JA, Wendelken SM, Davis TS, Kluger DT, Hutchinson DT, Clark GA. Discriminability of multiple cutaneous and proprioceptive hand percepts evoked by intraneural stimulation with Utah slanted electrode arrays in human amputees. J Neuroeng Rehabil 2021; 18:12. [PMID: 33478534 PMCID: PMC7819250 DOI: 10.1186/s12984-021-00808-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 01/11/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Electrical stimulation of residual afferent nerve fibers can evoke sensations from a missing limb after amputation, and bionic arms endowed with artificial sensory feedback have been shown to confer functional and psychological benefits. Here we explore the extent to which artificial sensations can be discriminated based on location, quality, and intensity. METHODS We implanted Utah Slanted Electrode Arrays (USEAs) in the arm nerves of three transradial amputees and delivered electrical stimulation via different electrodes and frequencies to produce sensations on the missing hand with various locations, qualities, and intensities. Participants performed blind discrimination trials to discriminate among these artificial sensations. RESULTS Participants successfully discriminated cutaneous and proprioceptive sensations ranging in location, quality and intensity. Performance was significantly greater than chance for all discrimination tasks, including discrimination among up to ten different cutaneous location-intensity combinations (15/30 successes, p < 0.0001) and seven different proprioceptive location-intensity combinations (21/40 successes, p < 0.0001). Variations in the site of stimulation within the nerve, via electrode selection, enabled discrimination among up to five locations and qualities (35/35 successes, p < 0.0001). Variations in the stimulation frequency enabled discrimination among four different intensities at the same location (13/20 successes, p < 0.0005). One participant also discriminated among individual stimulation of two different USEA electrodes, simultaneous stimulation on both electrodes, and interleaved stimulation on both electrodes (20/24 successes, p < 0.0001). CONCLUSION Electrode location, stimulation frequency, and stimulation pattern can be modulated to evoke functionally discriminable sensations with a range of locations, qualities, and intensities. This rich source of artificial sensory feedback may enhance functional performance and embodiment of bionic arms endowed with a sense of touch.
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Affiliation(s)
| | - Jacob A George
- Division of Physical Medicine and Rehabilitation, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Suzanne M Wendelken
- Department of Anesthesiology, Maine Medical Center, Portland, ME, 04102, USA
| | - Tyler S Davis
- Department of Neurosurgery, University of Utah, Salt Lake City, UT, 84112, USA
| | | | | | - Gregory A Clark
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
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Jamalzadeh M, Basdogan C, Guclu B. Effect of Remote Masking on Tactile Perception of Electrovibration. IEEE TRANSACTIONS ON HAPTICS 2021; 14:132-142. [PMID: 32960768 DOI: 10.1109/toh.2020.3025772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Masking has been used to study human perception of tactile stimuli, including those created by electrovibration on touch screens. Earlier studies have investigated the effect of on-site masking on tactile perception of electrovibration. In this article, we investigated whether it is possible to change the absolute detection threshold and intensity difference threshold of electrovibration at the fingertip of index finger via remote masking, i.e., by applying a (mechanical) vibrotactile stimulus on the proximal phalanx of the same finger. The masking stimuli were generated by a voice coil (the Haptuator). For 16 participants, we first measured the detection thresholds for electrovibration at the fingertip and for vibrotactile stimuli at the proximal phalanx. Then, the vibrations on the skin were measured at four different locations on the index finger of subjects to investigate how the mechanical masking stimulus propagated as the masking level was varied. Later, masked absolute thresholds of eight participants were measured. Finally, for another group of eight participants, intensity difference thresholds were measured in the presence/absence of vibrotactile masking stimuli. Our results show that vibrotactile masking stimuli generated sub-threshold vibrations around the fingertip, and hence, probably did not mechanically interfere with the electrovibration stimulus. However, there was a clear psychophysical masking effect due to central neural processes. We measured the effect of masking stimuli, up to 40 dB SL, on the difference threshold at four different intensity standards of electrovibration. We proposed two models based on hypothetical neural signals for prediction of the masking effect on intensity difference thresholds for electrovibration: amplitude and energy models. The energy model was able to predict the effect of masking more accurately, especially at high intensity masking levels.
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Rahman MS, Barnes KA, Crommett LE, Tommerdahl M, Yau JM. Auditory and tactile frequency representations are co-embedded in modality-defined cortical sensory systems. Neuroimage 2020; 215:116837. [PMID: 32289461 PMCID: PMC7292761 DOI: 10.1016/j.neuroimage.2020.116837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 03/17/2020] [Accepted: 04/06/2020] [Indexed: 11/18/2022] Open
Abstract
Sensory information is represented and elaborated in hierarchical cortical systems that are thought to be dedicated to individual sensory modalities. This traditional view of sensory cortex organization has been challenged by recent evidence of multimodal responses in primary and association sensory areas. Although it is indisputable that sensory areas respond to multiple modalities, it remains unclear whether these multimodal responses reflect selective information processing for particular stimulus features. Here, we used fMRI adaptation to identify brain regions that are sensitive to the temporal frequency information contained in auditory, tactile, and audiotactile stimulus sequences. A number of brain regions distributed over the parietal and temporal lobes exhibited frequency-selective temporal response modulation for both auditory and tactile stimulus events, as indexed by repetition suppression effects. A smaller set of regions responded to crossmodal adaptation sequences in a frequency-dependent manner. Despite an extensive overlap of multimodal frequency-selective responses across the parietal and temporal lobes, representational similarity analysis revealed a cortical "regional landscape" that clearly reflected distinct somatosensory and auditory processing systems that converged on modality-invariant areas. These structured relationships between brain regions were also evident in spontaneous signal fluctuation patterns measured at rest. Our results reveal that multimodal processing in human cortex can be feature-specific and that multimodal frequency representations are embedded in the intrinsically hierarchical organization of cortical sensory systems.
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Affiliation(s)
- Md Shoaibur Rahman
- Department of Neuroscience, Baylor College of Medicine, Houston, One Baylor Plaza, Houston, TX, 77030, USA
| | - Kelly Anne Barnes
- Department of Neuroscience, Baylor College of Medicine, Houston, One Baylor Plaza, Houston, TX, 77030, USA; Department of Behavioral and Social Sciences, San Jacinto College - South, Houston, 13735 Beamer Rd, S13.269, Houston, TX, 77089, USA
| | - Lexi E Crommett
- Department of Neuroscience, Baylor College of Medicine, Houston, One Baylor Plaza, Houston, TX, 77030, USA
| | - Mark Tommerdahl
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, CB No. 7575, Chapel Hill, NC, 27599, USA
| | - Jeffrey M Yau
- Department of Neuroscience, Baylor College of Medicine, Houston, One Baylor Plaza, Houston, TX, 77030, USA.
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Graczyk EL, Delhaye BP, Schiefer MA, Bensmaia SJ, Tyler DJ. Sensory adaptation to electrical stimulation of the somatosensory nerves. J Neural Eng 2018; 15:046002. [PMID: 29551756 DOI: 10.1088/1741-2552/aab790] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Sensory systems adapt their sensitivity to ambient stimulation levels to improve their responsiveness to changes in stimulation. The sense of touch is also subject to adaptation, as evidenced by the desensitization produced by prolonged vibratory stimulation of the skin. Electrical stimulation of nerves elicits tactile sensations that can convey feedback for bionic limbs. In this study, we investigate whether artificial touch is also subject to adaptation, despite the fact that the peripheral mechanotransducers are bypassed. APPROACH Using well-established psychophysical paradigms, we characterize the time course and magnitude of sensory adaptation caused by extended electrical stimulation of the residual somatosensory nerves in three human amputees implanted with cuff electrodes. MAIN RESULTS We find that electrical stimulation of the nerve also induces perceptual adaptation that recovers after cessation of the stimulus. The time course and magnitude of electrically-induced adaptation are equivalent to their mechanically-induced counterparts. SIGNIFICANCE We conclude that, in natural touch, the process of mechanotransduction is not required for adaptation, and artificial touch naturally experiences adaptation-induced adjustments of the dynamic range of sensations. Further, as it does for native hands, adaptation confers to bionic hands enhanced sensitivity to changes in stimulation and thus a more natural sensory experience.
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Affiliation(s)
- Emily L Graczyk
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America. Cleveland Louis Stokes Department of Veteran's Affairs Medical Center, Cleveland, OH 44106, United States of America
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Graczyk EL, Schiefer MA, Saal HP, Delhaye BP, Bensmaia SJ, Tyler DJ. The neural basis of perceived intensity in natural and artificial touch. Sci Transl Med 2017; 8:362ra142. [PMID: 27797958 DOI: 10.1126/scitranslmed.aaf5187] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 10/05/2016] [Indexed: 11/02/2022]
Abstract
Electrical stimulation of sensory nerves is a powerful tool for studying neural coding because it can activate neural populations in ways that natural stimulation cannot. Electrical stimulation of the nerve has also been used to restore sensation to patients who have suffered the loss of a limb. We have used long-term implanted electrical interfaces to elucidate the neural basis of perceived intensity in the sense of touch. To this end, we assessed the sensory correlates of neural firing rate and neuronal population recruitment independently by varying two parameters of nerve stimulation: pulse frequency and pulse width. Specifically, two amputees, chronically implanted with peripheral nerve electrodes, performed each of three psychophysical tasks-intensity discrimination, magnitude scaling, and intensity matching-in response to electrical stimulation of their somatosensory nerves. We found that stimulation pulse width and pulse frequency had systematic, cooperative effects on perceived tactile intensity and that the artificial tactile sensations could be reliably matched to skin indentations on the intact limb. We identified a quantity we termed the activation charge rate (ACR), derived from stimulation parameters, that predicted the magnitude of artificial tactile percepts across all testing conditions. On the basis of principles of nerve fiber recruitment, the ACR represents the total population spike count in the activated neural population. Our findings support the hypothesis that population spike count drives the magnitude of tactile percepts and indicate that sensory magnitude can be manipulated systematically by varying a single stimulation quantity.
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Affiliation(s)
- Emily L Graczyk
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Matthew A Schiefer
- Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Hannes P Saal
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Benoit P Delhaye
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Sliman J Bensmaia
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Dustin J Tyler
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. .,Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
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Hollins M, Corsi C, Sloan P. Pacinian Signals Determine the Direction and Magnitude of the Effect of Vibration on Pain. Perception 2017; 46:987-999. [PMID: 28715995 DOI: 10.1177/0301006617694630] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Although the ability of vibration to reduce pain has been extensively documented, an occasional participant reports that vibration increases pain. For pain patients, such reports may reflect pathophysiology, but this is unlikely in studies of experimental pain in healthy participants. In the present series of experiments on 27 pain-free individuals, we manipulated both the frequency (12, 50, and 80 Hz) and amplitude of vibration to more fully characterize vibratory pain modulation. The noxious stimulus was pressure applied to a finger, and vibration was delivered to the fleshy palmar pad at the base of the same finger. Subjects continuously reported pain on a Visual Analog Scale. Intermittent vibration was used to minimize peripheral vibratory adaptation. Pain records at 12 and 50 Hz were similar; pooling them revealed significant hypoalgesia at the highest amplitude. At 80 Hz, in contrast, the middle amplitude produced hypoalgesia, but a significant shift toward hyperalgesia occurred at the highest amplitude. The strong correlation ( r = .81) between the Pacinian-weighted power of a vibration and the absolute value of the pain modulation it produces indicates that the Pacinian system plays a key role in vibratory hypoalgesia or hyperalgesia.
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Affiliation(s)
- Mark Hollins
- University of North Carolina at Chapel Hill, NC, USA
| | | | - Page Sloan
- University of North Carolina at Chapel Hill, NC, USA
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11
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Li L, Chan A, Iqbal SM, Goldreich D. An Adaptation-Induced Repulsion Illusion in Tactile Spatial Perception. Front Hum Neurosci 2017; 11:331. [PMID: 28701936 PMCID: PMC5487416 DOI: 10.3389/fnhum.2017.00331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 06/08/2017] [Indexed: 11/23/2022] Open
Abstract
Following focal sensory adaptation, the perceived separation between visual stimuli that straddle the adapted region is often exaggerated. For instance, in the tilt aftereffect illusion, adaptation to tilted lines causes subsequently viewed lines with nearby orientations to be perceptually repelled from the adapted orientation. Repulsion illusions in the nonvisual senses have been less studied. Here, we investigated whether adaptation induces a repulsion illusion in tactile spatial perception. In a two-interval forced-choice task, participants compared the perceived separation between two point-stimuli applied on the forearms successively. Separation distance was constant on one arm (the reference) and varied on the other arm (the comparison). In Experiment 1, we took three consecutive baseline measurements, verifying that in the absence of manipulation, participants’ distance perception was unbiased across arms and stable across experimental blocks. In Experiment 2, we vibrated a region of skin on the reference arm, verifying that this focally reduced tactile sensitivity, as indicated by elevated monofilament detection thresholds. In Experiment 3, we applied vibration between the two reference points in our distance perception protocol and discovered that this caused an illusory increase in the separation between the points. We conclude that focal adaptation induces a repulsion aftereffect illusion in tactile spatial perception. The illusion provides clues as to how the tactile system represents spatial information. The analogous repulsion aftereffects caused by adaptation in different stimulus domains and sensory systems may point to fundamentally similar strategies for dynamic sensory coding.
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Affiliation(s)
- Lux Li
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Arielle Chan
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Shah M Iqbal
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Daniel Goldreich
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada.,McMaster Integrative Neuroscience Discovery and Study, McMaster UniversityHamilton, ON, Canada
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12
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Crommett LE, Pérez-Bellido A, Yau JM. Auditory adaptation improves tactile frequency perception. J Neurophysiol 2017; 117:1352-1362. [PMID: 28077668 PMCID: PMC5350269 DOI: 10.1152/jn.00783.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/06/2017] [Accepted: 01/06/2017] [Indexed: 11/22/2022] Open
Abstract
Our ability to process temporal frequency information by touch underlies our capacity to perceive and discriminate surface textures. Auditory signals, which also provide extensive temporal frequency information, can systematically alter the perception of vibrations on the hand. How auditory signals shape tactile processing is unclear; perceptual interactions between contemporaneous sounds and vibrations are consistent with multiple neural mechanisms. Here we used a crossmodal adaptation paradigm, which separated auditory and tactile stimulation in time, to test the hypothesis that tactile frequency perception depends on neural circuits that also process auditory frequency. We reasoned that auditory adaptation effects would transfer to touch only if signals from both senses converge on common representations. We found that auditory adaptation can improve tactile frequency discrimination thresholds. This occurred only when adaptor and test frequencies overlapped. In contrast, auditory adaptation did not influence tactile intensity judgments. Thus auditory adaptation enhances touch in a frequency- and feature-specific manner. A simple network model in which tactile frequency information is decoded from sensory neurons that are susceptible to auditory adaptation recapitulates these behavioral results. Our results imply that the neural circuits supporting tactile frequency perception also process auditory signals. This finding is consistent with the notion of supramodal operators performing canonical operations, like temporal frequency processing, regardless of input modality.NEW & NOTEWORTHY Auditory signals can influence the tactile perception of temporal frequency. Multiple neural mechanisms could account for the perceptual interactions between contemporaneous auditory and tactile signals. Using a crossmodal adaptation paradigm, we found that auditory adaptation causes frequency- and feature-specific improvements in tactile perception. This crossmodal transfer of aftereffects between audition and touch implies that tactile frequency perception relies on neural circuits that also process auditory frequency.
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Affiliation(s)
- Lexi E Crommett
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | | | - Jeffrey M Yau
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
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13
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Delhaye BP, Saal HP, Bensmaia SJ. Key considerations in designing a somatosensory neuroprosthesis. ACTA ACUST UNITED AC 2016; 110:402-408. [PMID: 27815182 DOI: 10.1016/j.jphysparis.2016.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 10/20/2016] [Accepted: 11/01/2016] [Indexed: 12/22/2022]
Abstract
In recent years, a consensus has emerged that somatosensory feedback needs to be provided for upper limb neuroprostheses to be useful. An increasingly promising approach to sensory restoration is to electrically stimulate neurons along the somatosensory neuraxis to convey information about the state of the prosthetic limb and about contact with objects. To date, efforts toward artificial sensory feedback have consisted mainly of demonstrating that some sensory information could be conveyed using a small number of stimulation patterns, generally delivered through single electrodes. However impressive these achievements are, results from different studies are hard to compare, as each research team implements different stimulation patterns and tests the elicited sensations differently. A critical question is whether different stimulation strategies will generalize from contrived laboratory settings to activities of daily living. Here, we lay out some key specifications that an artificial somatosensory channel should meet, discuss how different approaches should be evaluated, and caution about looming challenges that the field of sensory restoration will face.
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Affiliation(s)
- Benoit P Delhaye
- Department of Organismal Biology and Anatomy, University of Chicago, United States
| | - Hannes P Saal
- Department of Organismal Biology and Anatomy, University of Chicago, United States
| | - Sliman J Bensmaia
- Department of Organismal Biology and Anatomy, University of Chicago, United States.
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Klöcker A, Gueorguiev D, Thonnard JL, Mouraux A. Peripheral vs. central determinants of vibrotactile adaptation. J Neurophysiol 2015; 115:685-91. [PMID: 26581868 DOI: 10.1152/jn.00519.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 11/12/2015] [Indexed: 11/22/2022] Open
Abstract
Long-lasting mechanical vibrations applied to the skin induce a reversible decrease in the perception of vibration at the stimulated skin site. This phenomenon of vibrotactile adaptation has been studied extensively, yet there is still no clear consensus on the mechanisms leading to vibrotactile adaptation. In particular, the respective contributions of 1) changes affecting mechanical skin impedance, 2) peripheral processes, and 3) central processes are largely unknown. Here we used direct electrical stimulation of nerve fibers to bypass mechanical transduction processes and thereby explore the possible contribution of central vs. peripheral processes to vibrotactile adaptation. Three experiments were conducted. In the first, adaptation was induced with mechanical vibration of the fingertip (51- or 251-Hz vibration delivered for 8 min, at 40× detection threshold). In the second, we attempted to induce adaptation with transcutaneous electrical stimulation of the median nerve (51- or 251-Hz constant-current pulses delivered for 8 min, at 1.5× detection threshold). Vibrotactile detection thresholds were measured before and after adaptation. Mechanical stimulation induced a clear increase of vibrotactile detection thresholds. In contrast, thresholds were unaffected by electrical stimulation. In the third experiment, we assessed the effect of mechanical adaptation on the detection thresholds to transcutaneous electrical nerve stimuli, measured before and after adaptation. Electrical detection thresholds were unaffected by the mechanical adaptation. Taken together, our results suggest that vibrotactile adaptation is predominantly the consequence of peripheral mechanoreceptor processes and/or changes in biomechanical properties of the skin.
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Affiliation(s)
- A Klöcker
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - D Gueorguiev
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - J L Thonnard
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - A Mouraux
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
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15
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Hamilton-Fletcher G, Ward J. Representing Colour Through Hearing and Touch in Sensory Substitution Devices. Multisens Res 2013; 26:503-32. [PMID: 24800410 DOI: 10.1163/22134808-00002434] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Visual sensory substitution devices (SSDs) allow visually-deprived individuals to navigate and recognise the ‘visual world’; SSDs also provide opportunities for psychologists to study modality-independent theories of perception. At present most research has focused on encoding greyscale vision. However at the low spatial resolutions received by SSD users, colour information enhances object-ground segmentation, and provides more stable cues for scene and object recognition. Many attempts have been made to encode colour information in tactile or auditory modalities, but many of these studies exist in isolation. This review brings together a wide variety of tactile and auditory approaches to representing colour. We examine how each device constructs ‘colour’ relative to veridical human colour perception and report previous experiments using these devices. Theoretical approaches to encoding and transferring colour information through sound or touch are discussed for future devices, covering alternative stimulation approaches, perceptually distinct dimensions and intuitive cross-modal correspondences.
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Affiliation(s)
| | - Jamie Ward
- School of Psychology and Sackler Centre for Consciousness Science, University of Sussex, UK
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16
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Nguyen RH, Gillen C, Garbutt JC, Kampov-Polevoi A, Holden JK, Francisco EM, Tommerdahl M. Centrally-mediated sensory information processing is impacted with increased alcohol consumption in college-aged individuals. Brain Res 2012. [PMID: 23178333 DOI: 10.1016/j.brainres.2012.11.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alcohol consumption can have an impact on a variety of centrally-mediated functions of the nervous system, and some aspects of sensory perception can be altered as a result of long-term alcohol use. In order to assess the potential impact of alcohol intake on sensory information processing, metrics of sensory perception (simple and choice reaction time; static and dynamic threshold detection; amplitude discrimination with and without pre-exposure to conditioning stimulation) were tested in college-aged subjects (18 to 26 years of age) across a broad range of levels of alcohol consumption. The analysis indicated no detectable associations between reaction time and threshold measures with alcohol consumption. However, measures of adaptation to short duration (0.5s) conditioning stimuli were significantly associated with alcohol consumption: the impact of a confounding conditioning stimulus on amplitude discriminative capacity was comparable to values reported in previous studies on healthy controls (28.9±8.6) for light drinkers while the same adaptation metric for heavy drinkers (consuming greater than 60 drinks per month) was significantly reduced (8.9±7.1). The results suggest that while some of the sensory perceptual metrics which are normally impacted in chronic alcoholism (e.g., reaction time and threshold detection) were relatively insensitive to change with increased alcohol consumption in young non-alcoholic individuals, other metrics, which are influenced predominantly by centrally-mediated mechanisms, demonstrate a deviation from normative values with increased consumption. Results of this study suggest that higher levels of alcohol consumption may be associated with alterations in centrally-mediated neural mechanisms in this age group.
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Affiliation(s)
- Richard H Nguyen
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, NC 27599, USA
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17
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Gandhi MS, Sesek R, Tuckett R, Bamberg SJM. Progress in vibrotactile threshold evaluation techniques: a review. J Hand Ther 2011; 24:240-55; quiz 256. [PMID: 21439781 DOI: 10.1016/j.jht.2011.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 12/07/2010] [Accepted: 01/02/2011] [Indexed: 02/03/2023]
Abstract
Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.
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Affiliation(s)
- Minu Shikha Gandhi
- Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah 84112, USA
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Braun C, Eisele E, Wühle A, Stüttgen MC, Schwarz C, Demarchi G. Mislocalization of near-threshold tactile stimuli in humans: a central or peripheral phenomenon? Eur J Neurosci 2010; 33:499-508. [PMID: 21175882 DOI: 10.1111/j.1460-9568.2010.07536.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Principles of brain function can be disclosed by studying their limits during performance. Tactile stimuli with near-threshold intensities have been used to assess features of somatosensory processing. When stimulating fingers of one hand using near-threshold intensities, localization errors are observed that deviate significantly from responses obtained by guessing - incorrectly located stimuli are attributed more often to fingers neighbouring the stimulated one than to more distant fingers. Two hypotheses to explain the findings are proposed. The 'central hypothesis' posits that the degree of overlap of cortical tactile representations depends on stimulus intensity, with representations less separated for near-threshold stimuli than for suprathreshold stimuli. The 'peripheral hypothesis' assumes that systematic mislocalizations are due to activation of different sets of skin receptors with specific thresholds. The present experiments were designed to decide between the two hypotheses. Taking advantage of the frequency tuning of somatosensory receptors, their contribution to systematic misclocalizations was studied. In the first experiment, mislocalization profiles were investigated using vibratory stimuli with frequencies of 10, 20 and 100 Hz. Unambiguous mislocalization effects were only obtained for the 10-Hz stimulation, precluding the involvement of Pacinian corpuscles in systematic mislocalization. In the second experiment, Pacinian corpuscles were functionally eliminated by applying a constant 100-Hz vibratory masking stimulus together with near-threshold pulses. Despite masking, systematic mislocation patterns were observed rendering the involvement of Pacinian corpuscles unlikely. The results of both experiments are in favor of the 'central hypothesis' assuming that the extent of overlap in somatosensory representations is modulated by stimulus intensity.
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Affiliation(s)
- Christoph Braun
- CIMeC, Center for Mind/Brain Sciences, University of Trento, Via delle Regole 101, 38100 Trento, Italy.
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Venkatesan L, Barlow S, Popescu M, Popescu A, Auer ET. TAC-Cell inputs to human hand and lip induce short-term adaptation of the primary somatosensory cortex. Brain Res 2010; 1348:63-70. [PMID: 20550944 DOI: 10.1016/j.brainres.2010.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/01/2010] [Accepted: 06/05/2010] [Indexed: 11/16/2022]
Abstract
A new pneumatic tactile stimulator, called the TAC-Cell, was developed in our laboratory to non-invasively deliver patterned cutaneous stimulation to the face and hand in order to study the neuromagnetic response adaptation patterns within the primary somatosensory cortex (S1) in young adult humans. Individual TAC-Cells were positioned on the glabrous surface of the right hand, and midline of the upper and lower lip vermilion. A 151-channel magnetoencephalography (MEG) scanner was used to record the cortical response to a novel tactile stimulus which consisted of a repeating 6-pulse train delivered at three different frequencies through the active membrane surface of the TAC-Cell. The evoked activity in S1 (contralateral for hand stimulation, and bilateral for lip stimulation) was characterized from the best-fit dipoles of the earliest prominent response component. The S1 responses manifested significant modulation and adaptation as a function of the frequency of the punctate pneumatic stimulus trains and stimulus site (glabrous lip versus glabrous hand).
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Affiliation(s)
- Lalit Venkatesan
- Neuroscience, University of Kansas, 1000 Sunnyside Avenue, Lawrence, KS 66045, USA.
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20
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Zhang Z, Francisco EM, Holden JK, Dennis RG, Tommerdahl M. The impact of non-noxious heat on tactile information processing. Brain Res 2009; 1302:97-105. [PMID: 19765551 DOI: 10.1016/j.brainres.2009.09.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 09/08/2009] [Accepted: 09/10/2009] [Indexed: 11/19/2022]
Abstract
A significant number of studies that evaluated tactile-pain interactions employed heat to evoke nociceptive responses. However, relatively few studies have examined the effects of non-noxious thermal stimulation on tactile discriminative capacity. In this study, the impact that non-noxious heat had on three features of tactile information processing capacity was evaluated: vibrotactile threshold, amplitude discriminative capacity, and adaptation. It was found that warming the skin made a significant improvement on a subject's ability to detect a vibrotactile stimulus, and although the subjects' capacities for discriminating between two amplitudes of vibrotactile stimulation did not change with skin heating, the impact that adapting or conditioning stimulation normally had on amplitude discrimination capacity was significantly attenuated by the change in temperature. These results suggested that although the improvements in tactile sensitivity that were observed could have been a result of enhanced peripheral activity, the changes in measures that reflect a decrease in the sensitization to repetitive stimulation are most likely centrally mediated. The authors speculate that these centrally mediated changes could be a reflection of a change in the balance of cortical excitation and inhibition.
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Affiliation(s)
- Zheng Zhang
- Department of Biomedical Engineering, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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21
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Tommerdahl M, Favorov OV, Whitsel BL. Dynamic representations of the somatosensory cortex. Neurosci Biobehav Rev 2009; 34:160-70. [PMID: 19732790 DOI: 10.1016/j.neubiorev.2009.08.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 04/15/2009] [Accepted: 08/26/2009] [Indexed: 11/26/2022]
Abstract
Neural representation of somatosensory events undergoes major transformation in the primary somatosensory cortex (SI) from its original, more or less isomorphic, form found at the level of peripheral receptors. A large body of SI optical imaging, neural recording and psychophysical studies suggests that SI representation of stimuli encountered in everyday life is a product of dynamic processes that involve competitive interactions at multiple levels of cortical organization. Such interactions take place among neighboring neurons, among local groups of minicolumns, among neighboring macrocolumns, between SI and SII, between Pacinian and non-Pacinian channels, and bilaterally between homotopic somatosensory regions of the opposite hemispheres. Together these interactions sharpen SI response to suprathreshold and time-extended tactile stimuli by funneling the initially widespread stimulus-triggered activity in SI into the local group of macrocolumns most directly driven by the stimulus. Those macrocolumns in turn fractionate into stimulus-specific patterns of differentially active minicolumns. Thus SI dynamically shapes its representation of a tactile stimulus by selecting among all of its neurons initially activated by the stimulus a subset of neurons with receptive-field and feature-tuning properties closely matching those of the stimulus. Through this stimulus-directed dynamical selection process, which operates on a scale of hundreds of milliseconds, SI achieves a more faithful representation of stimulus properties, which is reflected in improved performance on tactile perceptual tasks.
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Affiliation(s)
- Mark Tommerdahl
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, United States.
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22
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Gescheider GA, Bolanowski SJ, Greenfield TC, Brunette KE. Perception of the tactile texture of raised-dot patterns: A multidimensional analysis. Somatosens Mot Res 2009; 22:127-40. [PMID: 16338822 DOI: 10.1080/08990220500262018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
An ALSCAL multidimensional scaling analysis in Euclidean space revealed that three orthogonal perceptual dimensions can account for the judged tactile dissimilarities of raised-dot patterns. Through magnitude estimates of various perceptual attributes, it was determined that the three dimensions consist of blur, roughness, and clarity. The only effect that selective adaptation of the Pacinian (P) channel had was to change the perceptual clarity of the raised dots against their background. Adaptation of the P channel with a 20 dB SL 250 Hz stimulus enhanced clarity. As indicated by magnitude estimates, adaptation of the P channel by the 250 Hz stimulus had no effect on the perceived roughness of the dot pattern but did cause the individual dots of the textured pattern to feel smoother. When the observer was required to estimate magnitude "overall roughness" defined as a combination of dot-pattern roughness and individual-dot roughness, adaptation of the P channel affected perceived roughness by reducing it. Taken as a whole, the results are consistent with the hypothesis that the NP channels and the P channel jointly influence the perception of textured surfaces.
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23
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Folger SE, Tannan V, Zhang Z, Holden JK, Tommerdahl M. Effects of the N-methyl-D-Aspartate receptor antagonist dextromethorphan on vibrotactile adaptation. BMC Neurosci 2008; 9:87. [PMID: 18796147 PMCID: PMC2553799 DOI: 10.1186/1471-2202-9-87] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Accepted: 09/16/2008] [Indexed: 11/29/2022] Open
Abstract
Background Previous reports have demonstrated that short durations of vibrotactile stimuli (less than or equal to 2 sec) effectively and consistently modify both the perceptual response in humans as well as the neurophysiological response in somatosensory cortex. The change in cortical response with adaptation has been well established by a number of studies, and other reports have extended those findings in determining that both GABA- and NMDAR-mediated neurotransmission play a significant role in the dynamic response of somatosensory cortical neurons. In this study, we evaluated the impact that dextromethorphan (DXM), an NMDAR antagonist, had on two distinct vibrotactile adaptation tasks. Results All subjects, both those that ingested 60 mg DXM and those that ingested placebo, were evaluated for their amplitude discriminative capacity between two simultaneously delivered vibrotactile stimuli both with and without 3 conditions of pre-exposure to adapting stimulation. The results demonstrated that the perceptual metrics of subjects who ingested 60 mg DXM were significantly altered from that of controls when the amplitude discrimination task followed one of the conditions of adapting stimulation. Without the condition of pre-exposure to an adapting stimulus (or stimuli), there was little difference between the observations obtained from the subjects that ingested DXM and controls. Peak impact on subject response occurred at 60 min post-ingestion, whereas the scores of controls who ingested placebo were not impacted. Conclusion The results – that DXM blocks vibrotactile adaptation – is consistent with the suggestion that NMDAR-mediated neurotransmission plays a significant role in the perceptual adaptive response. This finding is also consistent with neurophysiological findings that report observations of the effects of NMDAR block on the SI cortical response to repetitive vibrotactile stimulation.
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Affiliation(s)
- Stephen E Folger
- Department of Physical Therapy Education, Elon University, Elon, NC 27244, USA.
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24
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Buma DG, Buitenweg JR, Veltink PH. Intermittent stimulation delays adaptation to electrocutaneous sensory feedback. IEEE Trans Neural Syst Rehabil Eng 2007; 15:435-41. [PMID: 17894276 DOI: 10.1109/tnsre.2007.903942] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Electrotactile displays deliver information to the user by means of electrocutaneous stimulation. If such displays are used in prostheses, the functionality depends on long term stability of this information channel. The perceived sensation, however, decays within 15 min due to central adaptation if the stimulation is applied continuously and at constant strength. In this study, the effects of stimulus amplitude and intermittent stimulation on adaptation were investigated in ten healthy subjects. The perceived sensation was recorded during 15 min of constant stimulation using a visual analog scale (VAS). The sensation level with time thus measured were parameterized by the initial sensation level, the time constant of decay and the end sensation level after fitting of an exponential function through the VAS data. The time constant increased significantly when applying a high stimulation level (at 80% of the range between sensation and pain thresholds) if compared with lower levels of stimulation (20% and 50%) during continuous stimulation. Intermittent stimulation at this high stimulation level significantly increased end sensation level.
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Affiliation(s)
- Dorindo G Buma
- Biomedical Signals and Systems Group, Institute for Biomedical Technology BMTI/Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, 7500 AE Enschede, The Netherlands
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Israr A, Tan HZ, Reed CM. Frequency and amplitude discrimination along the kinestheticcutaneous continuum in the presence of masking stimuli. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2006; 120:2789-800. [PMID: 17139739 DOI: 10.1121/1.2354022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Frequency and amplitude discrimination thresholds along the kinesthetic to cutaneous continuum were evaluated on the left index fingerpad using a multifinger tactual display. Target stimuli were presented either in isolation (no-masker condition) or in the presence of masking stimuli (one- or two-masker conditions). Six reference target signals in the frequency range 2-300 Hz (two each from low-, medium-, and high-frequency regions) and at an amplitude of either 20 or 35 dB sensation levels (SL) were used. In the no-masker condition, the range of frequency Weber fraction was 0.13-0.38 and 0.14-0.28, and the range of amplitude discrimination threshold was 1.82-2.98 dB and 1.65-2.71 dB, at 20 and 35 dB SL, respectively. In the masking conditions, average frequency Weber fractions rose to 0.60 and 0.46, and average amplitude thresholds rose to 3.63 and 3.72 dB, at 20 and 35 dB SL, respectively. In general, thresholds were largest in the two-masker condition and lowest in the no-masker condition. Although the frequency and amplitude thresholds generally increased in the presence of masking stimuli, there was some indication of channel independence for low- and high-frequency target stimuli. The implications of the results for tactual communication of speech are discussed.
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Affiliation(s)
- Ali Israr
- Haptic Interface Research Laboratory, Purdue University, 465 Northwestern Avenue, West Lafayette, Indiana 47907, USA.
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26
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Hollins M, Lorenz F, Harper D. Somatosensory coding of roughness: the effect of texture adaptation in direct and indirect touch. J Neurosci 2006; 26:5582-8. [PMID: 16707809 PMCID: PMC6675297 DOI: 10.1523/jneurosci.0028-06.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To examine somatosensory mechanisms contributing to the perception of roughness, subjects examined surfaces with rigorously specified spatial textures under conditions of direct moving contact between the fingertip and the surface (direct touch) and contact through a rigid probe (indirect touch). Subjects were trained to scan the surfaces along a consistent path and with a speed of 2.7 cm/s. With each mode of touch, periods of prolonged inspection of a single adapting surface were followed by shorter periods in which the roughness of multiple test surfaces was reported. Adaptation caused a drop in perceived roughness under conditions of indirect touch, reflecting the reduced sensitivity of vibrotactile mechanisms that are the main recipients of textural information transmitted through the probe. During direct touch, adaptation had no significant effect on the perception of textures with spatial period >200 mum, which are spatially encoded. The results have an important implication for the physiological basis of the spatial code, which is believed to involve somatosensory cortical neurons with highly structured receptive fields: these cortical populations appear to be less susceptible to adaptation than otherwise similar neuronal populations in the visual system.
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Affiliation(s)
- Mark Hollins
- Department of Psychology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Abstract
In this study we investigate the haptic perception of object size. We report the results from four psychophysical experiments. In the first, we ask subjects to discriminate the size of objects that vary in surface curvature and compliance while changing contact force. We show that objects exhibit size constancy such that perception of object size using haptics does not change with changes in contact force. Based on these results, we hypothesize that size perception depends on the degree of spread between the digits at initial contact with objects. In the second experiment, we test this hypothesis by having subjects continuously contact an object that changes dynamically in size. We show that size perception takes into account the compliance of the object. In the third and fourth experiments we attempt to separate the individual contributions of proprioceptive and cutaneous input. In the third, we test the ability of subjects to perceive object size after altering the sensitivity of cutaneous receptors with adapting vibratory stimuli. The results from this experiment suggest that initial contact is signaled by the cutaneous slowly adapting type 1 afferents (SA1) and/or the rapidly adapting afferents (RA). In the last experiment, we block cutaneous input at the site of contact by anesthetizing the digital nerves and show that proprioceptive information alone provides only a rough estimate of object size. We conclude that the perception of object size depends on inputs from SA1 and possibly RA afferents, combined with inputs from proprioceptive afferents that signal the spread between digits.
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Affiliation(s)
- L. J. Berryman
- Department of Biomedical Engineering, Zanvyl Krieger Mind/Brain
Institute, Johns Hopkins University, Baltimore, Maryland
| | | | - S. S. Hsiao
- Department of Neuroscience and
- Department of Biomedical Engineering, Zanvyl Krieger Mind/Brain
Institute, Johns Hopkins University, Baltimore, Maryland
- Address for reprint requests and other correspondence: S. Hsiao,
Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, 338 Krieger Hall,
3400 N. Charles St., Baltimore, MD 21218 (E-mail:
)
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28
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Bensmaïa S, Hollins M, Yau J. Vibrotactile intensity and frequency information in the pacinian system: a psychophysical model. ACTA ACUST UNITED AC 2006; 67:828-41. [PMID: 16334055 DOI: 10.3758/bf03193536] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The objective of the study was to characterize the Pacinian representation of stimulus waveform. Subjects were presented with pairs of high-frequency vibrotactile stimuli that varied in intensity and/or frequency content and made same-different judgments under conditions of low-frequency adaptation designed to minimize the contribution of the RA system. We wished to infer the nature of the information conveyed by the Pacinian system about the stimuli from measured sensitivity (d') to stimulus differences. We first tested the hypothesis that the Pacinian system conveys only intensive information about vibratory stimuli and found that intensive cues could not account for much of the variance in the discrimination data. We then proposed a model characterizing the Pacinian-mediated representation of an arbitrary stimulus as a pattern of activation in a set of frequency-tuned minichannels. The model was shown to predict the discriminability of the stimulus pairs presented in the psychophysical experiments. Furthermore, the model parameters, optimized to fit the discrimination data, were compatible with analogous values obtained in other experimental contexts. One of the assumptions underlying the model is that information about individual spectral components is conveyed in parallel and quasi-independently. By simulating the response of a population of Pacinian afferents to a polyharmonic stimulus, we demonstrated that such a population can simultaneously convey information about multiple frequency components, despite having a homogeneous spectral profile.
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Affiliation(s)
- Sliman Bensmaïa
- University of North Carolina, Chapel Hill, North Carolina, USA.
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29
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Tommerdahl M, Hester KD, Felix ER, Hollins M, Favorov OV, Quibrera PM, Whitsel BL. Human vibrotactile frequency discriminative capacity after adaptation to 25 Hz or 200 Hz stimulation. Brain Res 2006; 1057:1-9. [PMID: 16140284 DOI: 10.1016/j.brainres.2005.04.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 04/04/2005] [Accepted: 04/13/2005] [Indexed: 10/25/2022]
Abstract
A two-interval forced-choice (2-IFC) tracking procedure was used to evaluate the effects of a 15-s pre-exposure to either 25 Hz or 200 Hz stimulation ("25 Hz or 200 Hz adaptation") on human vibrotactile frequency discrimination threshold (frequency DL/Weber fraction). Three subjects were studied. All stimuli (standard and comparison) were delivered to a central location on the thenar eminence of the hand. The frequency DL/Weber fraction was determined for each subject under the following conditions: (1) no recent prior exposure to vibrotactile stimulation ("unadapted"); (2) after 15 s adaptation to 25 Hz stimulation; and (3) after 15 s adaptation to 200 Hz stimulation. The results demonstrate that the effects of frequency of adaptation on frequency discriminative capacity when the standard stimulus is 25 Hz are not the same as when the standard stimulus is 200 Hz. The differential changes in the capacity of subjects to discriminate frequency of cutaneous flutter (10-50 Hz) or vibratory (>200 Hz) stimulation that occur subsequent to a 15-s exposure of the thenar to 25 Hz or 200 Hz stimulation are proposed to reflect frequency-specific, adaptation-induced modification of the response of contralateral primary somatosensory cortex (SI and SII) to skin mechanoreceptor afferent drive.
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Affiliation(s)
- M Tommerdahl
- Department of Biomedical Engineering, University of North Carolina School of Medicine, USA
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30
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Goodwin AW. Paradoxes in tactile adaptation. Focus on "vibratory adaptation in cutaneous mechanoreceptive afferents" and "time-course of vibratory adaptation and recovery in cutaneous mechanoreceptive afferents". J Neurophysiol 2005; 94:2995-6. [PMID: 16222069 DOI: 10.1152/jn.00766.2005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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31
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Leung YY, Bensmaïa SJ, Hsiao SS, Johnson KO. Time-course of vibratory adaptation and recovery in cutaneous mechanoreceptive afferents. J Neurophysiol 2005; 94:3037-45. [PMID: 16222071 PMCID: PMC1839047 DOI: 10.1152/jn.00001.2005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Extended suprathreshold vibratory stimulation applied to the skin results in a desensitization of cutaneous mechanoreceptive afferents. In a companion paper, we describe the dependence of the threshold shift on the parameters of the adapting stimulus and discuss neural mechanisms underlying afferent adaptation. Here we describe the time-course of afferent adaptation and recovery. We found that absolute and entrainment thresholds rise and fall exponentially during adaptation and recovery with time constants that vary with fiber type. slowly adapting type I (SA1) afferents adapt most rapidly, and pacinian (PC) afferents adapt most slowly, whereas rapidly adapting (RA) afferents exhibit intermediate rates of adaptation; SA1 fibers also recover more rapidly from adaptation than RA and PC fibers. We also showed that threshold adaptation is accompanied by a shift in the timing of the spikes within individual cycles of the adapting stimulus (i.e., a shift in the impulse phase). We invoked an integrate-and-fire model to explore possible mechanisms underlying afferent adaptation. Finally, we found that the time-course of afferent adaptation is more rapid than that of its psychophysical counterpart, as is the time-course of recovery from adaptation, suggesting that central factors play a role in the psychophysical phenomenon.
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Affiliation(s)
- Y. Y. Leung
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - S. J. Bensmaïa
- Krieger Mind/Brain Institute
- Department of Neuroscience, and
- Address for reprint requests and other correspondence: S. J. Bensmaïa, 3400 N. Charles St., Krieger 338, Baltimore, MD 21218 (E-mail: )
| | - S. S. Hsiao
- Krieger Mind/Brain Institute
- Department of Neuroscience, and
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - K. O. Johnson
- Krieger Mind/Brain Institute
- Department of Neuroscience, and
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
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Gallez A, Albanese MC, Rainville P, Duncan GH. Attenuation of Sensory and Affective Responses to Heat Pain: Evidence for Contralateral Mechanisms. J Neurophysiol 2005; 94:3509-15. [PMID: 16222074 DOI: 10.1152/jn.01006.2004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Attenuation of responses to repeated sensory events has been thoroughly studied in many modalities; however, attenuation of pain perception has not yet benefitted from such extensive investigation. Described here are two psychophysical studies that examined the effects of repeated exposure to thermal stimuli, assessing potential attenuation of the perception of pain and its possible spatial specificity. Twenty-two subjects were presented thermal stimuli to the volar surface of the right and left forearms. Twelve subjects in study 1 received the same stimuli and conditions on each of five daily experimental sessions, whereas 10 subjects in study 2 received thermal stimuli, which were restricted to one side for four daily sessions and then applied to the other side on the fifth session. Ratings of warmth intensity, pain intensity, and pain unpleasantness were recorded while the subjects performed a thermal sensory discrimination task. Results of study 1 demonstrate that repeated stimulation with noxious heat can lead to long-term attenuation of pain perception; results of study 2 extend these findings of attenuation to both pain intensity and unpleasantness and show that this effect is highly specific to the exposed body side for both aspects of the pain experience. We suggest that the functional plasticity underlying this attenuation effect lies in brain areas with a strong contralateral pattern of pain-related activation.
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Affiliation(s)
- Ariane Gallez
- Centre de Recherche en Sciences Neurologiques, Université de Montréal, Montreal, Quebec, Canada
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Bensmaïa SJ, Leung YY, Hsiao SS, Johnson KO. Vibratory adaptation of cutaneous mechanoreceptive afferents. J Neurophysiol 2005; 94:3023-36. [PMID: 16014802 PMCID: PMC1994926 DOI: 10.1152/jn.00002.2005] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of this study was to investigate the effects of extended suprathreshold vibratory stimulation on the sensitivity of slowly adapting type 1 (SA1), rapidly adapting (RA), and Pacinian (PC) afferents. To that end, an algorithm was developed to track afferent absolute (I0) and entrainment (I1) thresholds as they change over time. We recorded afferent responses to periliminal vibratory test stimuli, which were interleaved with intense vibratory conditioning stimuli during the adaptation period of each experimental run. From these measurements, the algorithm allowed us to infer changes in the afferents' sensitivity. We investigated the stimulus parameters that affect adaptation by assessing the degree to which adaptation depends on the amplitude and frequency of the adapting stimulus. For all three afferent types, I0 and I1 increased with increasing adaptation frequency and amplitude. The degree of adaptation seems to be independent of the firing rate evoked in the afferent by the conditioning stimulus. In the analysis, we distinguished between additive adaptation (in which I0 and I1 shift equally) and multiplicative effects (in which the ratio I1/I0 remains constant). RA threshold shifts are almost perfectly additive. SA1 threshold shifts are close to additive and far from multiplicative (I1 threshold shifts are twice the I0 shifts). PC shifts are more difficult to classify. We used an integrate-and-fire model to study the possible neural mechanisms. A change in transducer gain predicts a multiplicative change in I0 and I1 and is thus ruled out as a mechanism underlying SA1 and RA adaptation. A change in the resting action potential threshold predicts equal, additive change in I0 and I1 and thus accounts well for RA adaptation. A change in the degree of refractoriness during the relative refractory period predicts an additional change in I1 such as that observed for SA1 fibers. We infer that adaptation is caused by an increase in spiking thresholds produced by ion flow through transducer channels in the receptor membrane. In a companion paper, we describe the time-course of vibratory adaptation and recovery for SA1, RA, and PC fibers.
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Affiliation(s)
- S J Bensmaïa
- Krieger Mind/Brain Inst., Johns Hopkins Univ., 3400 N. Charles St, Krieger Hall 338, Baltimore, MD 21218, USA.
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Giabbiconi CM, Dancer C, Zopf R, Gruber T, Müller MM. Selective spatial attention to left or right hand flutter sensation modulates the steady-state somatosensory evoked potential. ACTA ACUST UNITED AC 2004; 20:58-66. [PMID: 15130590 DOI: 10.1016/j.cogbrainres.2004.01.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2004] [Indexed: 11/30/2022]
Abstract
Steady-state somatosensory evoked potentials (SSSEPs) were recorded from the scalp of human subjects elicited by 20 and 26 Hz mechanical vibrations applied simultaneously to the index finger of the left (20 Hz) and right hand (26 Hz). Subjects were instructed to attend to the flutter vibration at one finger while ignoring the other finger and to detect rare target events at the to-be-attended finger. The amplitude of the frequency coded SSSEP elicited by the attended vibration was significantly enlarged when attention was focused at the respective finger. This amplitude enhancement with attention was most prominent over fronto-central electrode locations contralateral to the attended finger. This is the first report to show the attentional modulation of the SSSEP amplitude in humans, suggesting an enhancement of neural responses in the sense of flutter with attention. The findings will open a new approach for studying the neural mechanisms of sustained selective attention in somatosensation.
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Affiliation(s)
- Claire Marie Giabbiconi
- Institut für Allgemeine Psychologie, Universität Leipzig, Seeburgstrasse 14-20, D-04103 Leipzig, Germany
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Abstract
The four information-processing channels of glabrous skin have distinct tuning characteristics which appear to be determined in the periphery at the level of sensory receptors and their afferent nerve fibers. The four-channel model [J Acoust Soc Am 84 (1988) 1680] has been updated to include measurement over a wider frequency range of tuning of the P and NP I channels, psychophysically determined by forward-masking and adaptation tuning curve methods. In addition to differences in their tuning, the P and NP channels differ in the following ways: (1) the P channel, but not NP channels, has been found to be capable of temporal summation, which operates by neural integration; (2) the capacity for spatial summation is also an exclusive property of the P channel; (3) sensitivity declines with age at a greater rate in the P channel than in the NP channels; (4) the masking or adaptation of a channel has no effect on the sensitivity of the other channels, although the channels interact in the summation of the perceived magnitudes of stimuli presented to separate channels.
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Affiliation(s)
- G A Gescheider
- Hamilton College, Department of Psychology, Clinton, NY 13323, USA.
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Andreatta RD, Barlow SM. Movement-related modulation of vibrotactile detection thresholds in the human orofacial system. Exp Brain Res 2003; 149:75-82. [PMID: 12592505 DOI: 10.1007/s00221-002-1336-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2002] [Accepted: 10/30/2002] [Indexed: 10/20/2022]
Abstract
By virtue of the direct coupling between circumoral skin and the underlying orofacial musculature, mechanosensation associated with precise orofacial force control may contribute significantly to processes associated with perception, proprioception, and sensorimotor control in this region. The purpose of this study was to assess lower lip (LL) vibratory detection thresholds of adult subjects during the simultaneous performance of a visually guided and continuous lip motor control task. Vibrotactile inputs were delivered to the right LL vermilion at test frequencies of 5, 10, 50, 150, 250, and 300 Hz. The psychophysical detection task was performed simultaneously with the three force control conditions: a null-force baseline condition, an active force control task performed with the right index finger, and an active force control task performed with the lip musculature. For the active tasks, subjects were instructed to use their analog force signal (lip or finger) to continuously perform a visually guided precision force task by tracking a 2 Hz sinusoidally moving target calibrated to a peak-to-peak force load of 0.2 N. Both the analog force signal and the target-tracking signal were displayed in real-time on an oscilloscope. Results showed a statistically significant elevation of LL vibrotactile detection thresholds for test frequencies below 50 Hz during the simultaneous performance of the lip force control task. Disassociating the site of motor control from the location of sensory stimulation (active control task) was effective in normalizing the elevations in LL vibrotactile thresholds, thus demonstrating that the threshold elevation during the lip force task was not solely an artifact of the added attentional load resulting from combining a perceptual task with a motor control requirement. These findings are discussed in relation to published reports of movement-related sensory gating in limb systems and the possible significance that this phenomenon may have for perception and proprioception in the orofacial system.
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Affiliation(s)
- Richard D Andreatta
- Department of Communication Sciences and Disorders, Laboratory of Speech-Orofacial Physiology, Biomedical and Health Sciences Institute, The University of Georgia, Aderhold Hall, Rm 514, Athens, GA 30602, USA.
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Kaczmarek KA. Electrotactile adaptation on the abdomen: preliminary results. IEEE TRANSACTIONS ON REHABILITATION ENGINEERING : A PUBLICATION OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY 2000; 8:499-505. [PMID: 11204041 DOI: 10.1109/86.895953] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Electrotactile (electrocutaneous) stimulation at currents greater than sensation threshold causes sensory adaptation, which temporarily raises the sensation threshold and reduces the perceived magnitude of stimulation. After 15 min of moderately intense exposure to a conditioning stimulus (10 s on, 10 s off), the sensation threshold elevation for seven observers was 60-270%, depending on the current, frequency, and number of pulses in the burst structure of the conditioning stimulus. Increases in any of these parameters increased the sensation threshold elevation. Adaptation and recovery were each complete in approximately 15 min.
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Affiliation(s)
- K A Kaczmarek
- Department of Rehabilitation Medicine, University of Wisconsin, Madison 53706, USA
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Bensmaïa SJ, Hollins M. Complex tactile waveform discrimination. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2000; 108:1236-1245. [PMID: 11008823 DOI: 10.1121/1.1288937] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Complex vibrotactile waveforms consisting of two superimposed sinusoids at varying phases were presented to the fingertip, and observers made "same-different" judgments. It was found that the low-frequency (10Hz+30Hz) waveforms were discriminable from one another while discrimination of the high-frequency (100Hz+300Hz) vibrations was poor. High-frequency adaptation did not impair discrimination of the low-frequency waveforms, suggesting that the RA channel mediated discrimination. Low-frequency adaptation impaired discrimination of the high-frequency stimuli, suggesting that the RA channel likewise mediated the modest level of performance observed in the absence of an adapting stimulus. The results indicate that this channel encodes complex waveforms temporally. A simple model for low-frequency waveform discrimination is proposed. The results obtained with the high-frequency complex waveforms are compatible with the hypothesis that the PC channel integrates stimulus energy over time.
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Affiliation(s)
- S J Bensmaïa
- Department of Psychology, University of North Carolina at Chapel Hill 27599-3270, USA
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Francis ST, Kelly EF, Bowtell R, Dunseath WJ, Folger SE, McGlone F. fMRI of the responses to vibratory stimulation of digit tips. Neuroimage 2000; 11:188-202. [PMID: 10694461 DOI: 10.1006/nimg.2000.0541] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Three studies were carried out to assess the applicability of fMRI at 3.0 T to analysis of vibrotaction in humans. A novel piezoelectric device provided clean sinusoidal stimulation at 80 Hz, which was initially applied in separate runs within a scanning session to digits 2 and 5 of the left hand in eight subjects, using a birdcage RF (volume) coil. Significant clusters of activation were found in the primary somatosensory cortex (SI), the secondary somatosensory cortex (SII), subcentral gyrus, the precentral gyrus, posterior insula, posterior parietal regions (area 5), and the posterior cingulate. Digit separation in SI was possible in all subjects and the activation sites reflected the known lateral position of the representation of digit 2 relative to that of digit 5. A second study carried out in six additional subjects using a surface coil, replicated the main contralateral activation patterns detected in study one and further improved the discrimination of the digits in SI. Significant digit separation was also found in SII and in the posterior insula. A third study to investigate the frequency dependence of the response focused on the effect of an increase in vibrotactile frequency from 30 to 80 Hz, with both frequencies applied to digit 2 during the same scanning session in four new subjects. A significant increase in the number of pixels activated within both SII and the posterior insula was found, while the number of pixels activated in SI declined. No significant change in signal intensity with frequencies was found in any of the activated areas.
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Affiliation(s)
- S T Francis
- Magnetic Resonance Centre, NG7 2RD, United Kingdom
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Abstract
Dense multichannel recordings of scalp electroencephalogram (EEG) were obtained in the vicinity of primary somatosensory cortex, time-locked to repetitive vibrotactile stimulation of sites on the right index finger of a single human subject. Frequency-domain analysis of cross-trial averages revealed prominent 'driving' responses in the EEG at the frequency of stimulation, which under specific stimulus conditions displayed pronounced changes in amplitude and topographic organization over brief (4 s) durations of stimulus exposure. The changes were systematic and physiologically coherent, evolving toward driving-response topographies observed in the same subject in conjunction with periodic microstimulation of single mechanoreceptive afferents whose receptive fields occupied corresponding positions on the digit. This dynamic process was orderly and reproducible, and could be controlled by manipulating factors such as the amplitude, frequency, and temporal spacing of the stimuli. The results are tentatively interpreted in light of a previously proposed neurophysiological model of stimulus-driven response plasticity in mammalian somatosensory cortex.
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Affiliation(s)
- E F Kelly
- Department of Diagnostic Sciences and Dental Research Center, 112 DRC, CB #7455, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7455,
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Hollins M, Sigurdsson A, Fillingim L, Goble AK. Vibrotactile threshold is elevated in temporomandibular disorders. Pain 1996; 67:89-96. [PMID: 8895235 DOI: 10.1016/0304-3959(96)03083-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Experimental pain can elevate vibrotactile threshold, a phenomenon attributed in the literature to the operation of a 'touch gate.' It is not known, however, whether clinical pain produces similar effects. To explore this possibility, we measured vibrotactile threshold in patients with temporomandibular disorders (TMD) whose pain had a prominent myalgic component. Two-interval forced-choice tracking was used to determine threshold for a 25-Hz vibratory stimulus presented on the cheek. Threshold was found to be significantly elevated in the TMD group, compared to an age- and gender-matched control group of pain-free individuals. Within the TMD group, those with a supra-median level of muscle tenderness (corrected for background levels of spontaneous pain) had significantly higher threshold than those with lower levels of palpation pain. These findings are consistent with the idea of a touch gate, and suggest the usefulness of further research in this area with clinical pain populations. The effects of an adapting stimulus (25 Hz, 20 dB SL) were also studied, and found to produce parallel elevations in vibrotactile threshold in the TMD and pain-free groups. This result indicates that at least some adaptation occurs at a higher (subsequent) level of somatosensory information processing than does the touch gating implied by the unadapted thresholds.
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Affiliation(s)
- Mark Hollins
- Dental Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7455, USA Department of Pscyhology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7455, USA Department of Endodontics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7455, USA
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Sinclair RJ, Burton H. Discrimination of vibrotactile frequencies in a delayed pair comparison task. PERCEPTION & PSYCHOPHYSICS 1996; 58:680-92. [PMID: 8710447 DOI: 10.3758/bf03213100] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This study quantified human short-term-memory decay functions for delayed vibrotactile frequency discriminations. Subjects indicated which of two successive intervals contained the higher or lower frequency of a pair separated by delay periods of 0.5-30 sec. Performance decreased as a function of length of delay and was higher when delays were unfilled than when they were filled with a backwards-counting task. This interpolated task may have interfered with rehearsal of a coded representation of the remembered vibrotactile frequency. A change in decay rate after 5-sec delays suggests a switch from reliance on sensory memory to the coded frequency representation. Performance and decay rate depended on presentation order of higher or lower frequency within pairs. Reciprocal performance asymmetries seen in high-versus low-frequency ranges did not result from simple response bias.
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Affiliation(s)
- R J Sinclair
- Department of Anatomy and Neurobiology, Washington University, School of Medicine, St. Louis, MO 63110, USA.
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Kelly EF, McLaughlin DF, Dunseath WJ, Folger S, Jones F, Hudnell HK. Frequency-domain measurement of vibrotactile driving responses in first-order afferent populations. Exp Brain Res 1996; 109:500-6. [PMID: 8817281 DOI: 10.1007/bf00229635] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Surface recordings made at the wrist during moderate vibrotactile stimulation of a digit display rhythmic activity at the frequency of the driving stimulus. This activity is abolished by local anesthesia of the stimulated digit and by substitution of the corresponding digit of the opposite hand with the recording geometry and the load on the stimulator unchanged. Several additional features of the response are similarly incompatible with an artifactual origin in properties of the stimulus motion or the associated electromagnetic field, but consistent with previous neurophysiological observations. The frequency-domain analysis extends readily to the single-trial level, making the technique potentially useful for a variety of basic research and clinical purposes.
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Affiliation(s)
- E F Kelly
- Department of Diagnostic Sciences, University of North Carolina at Chapel Hill 27599-7455, USA
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Abstract
The ultrastructure and location of sensory nerve endings in the shoulder-joint capsule, its tendinous reinforcements and in the periarticular connective and muscle tissue have been studied by means of light and electron microscopy in adult female white NMRI-F2 laboratory mice, aged 2.5-13 months. Most of the sensory nerve endings were detected in the fibrous layer of the joint capsule or in the inserting tendons. The identified lamellated corpuscles of the Pacini type are small and sometimes associated with Golgi tendon-organs. Large Vater-Pacini corpuscles were not detected. Ruffini corpuscles are found in small numbers only in the moderately dense connective tissue of the joint capsule. Golgi tendon organs were found mainly at the muscle-tendon junction of the muscles surrounding the joint. Muscle spindles have been identified mainly in periarticular muscles close to the muscle-tendon junctions. The number and distribution of the different types of mechanoreceptors investigated in the present study suggest that periarticular corpuscular sensory nerve endings play an important role in shoulder-joint control and mobility. The occurrence of small uniformly shaped lamellated corpuscles of the Pacini type in qualitatively different areas of surrounding tissue implies that they are susceptible to different kinds of mechanical stimuli.
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Affiliation(s)
- U Backenköhler
- University of Hamburg, Department of Functional Anatomy, Germany
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Hollins M, Delemos KA, Goble AK. Vibrotactile adaptation on the face. PERCEPTION & PSYCHOPHYSICS 1991; 49:21-30. [PMID: 2011449 DOI: 10.3758/bf03211612] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Threshold amplitude for vibration is elevated if testing is preceded by extended exposure to a vibratory adapting stimulus of appropriate amplitude and frequency. This phenomenon, previously studied almost exclusively on the hand, is here shown for the first time to occur on the face as well. Adaptation is then used analytically to determine that the two-branched threshold-versus-frequency function obtained on the face by Verrillo and Ecker (1977) represents the activity of two distinct mechanisms. Action spectra of vibrotactile adaptation reveal the presence of both mechanisms even in subjects whose unadapted threshold function (like that reported by Barlow, 1987) shows no sign of duplexity. Finally, the data suggest that on the face (unlike the hand), cross-channel adaptation may occur at high adapting amplitudes.
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Affiliation(s)
- M Hollins
- Department of Psychology, University of North Carolina, Chapel Hill 27599
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