Evoked response amplitudes from somatosensory cortices do not determine reaction times to tactile stimuli (original) (raw)
Related papers
Pain Facilitates Tactile Processing in Human Somatosensory Cortices
Journal of Neurophysiology, 2004
Touch and pain are intimately related modalities. Despite a substantial overlap in their cortical representations interactions between both modalities are largely unknown at the cortical level. We therefore used magnetoencephalography and selective nociceptive cutaneous laser stimulation to investigate the effects of brief painful stimuli on cortical processing of touch. Using a conditioning test stimulus paradigm our results show that painful conditioning stimuli facilitate processing of tactile test stimuli applied 500 ms later. This facilitation applies to cortical responses later than 40 ms originating from primary (S1) and secondary (S2) somatosensory cortices but not to earlier S1 responses.
Neuroscience, 2003
We recorded somatosensory-evoked magnetic fields and potentials produced by painful intra-epidermal stimulation (ES) and non-painful transcutaneous electrical stimulation (TS) applied to the left hand in 12 healthy volunteers to compare cortical responses to noxious and innocuous somatosensory stimulations. Our results revealed that cortical processing following noxious and innocuous stimulations was strikingly similar except that the former was delayed approximately 60 ms relative to the latter, which was well explained by a difference in peripheral conduction velocity mediating noxious (Adelta fiber) and innocuous (Abeta fiber) inputs. The first cortical activity evoked by both ES and TS was in the primary somatosensory cortex (SI) in the hemisphere contralateral to the stimulated side. The following activities were in the bilateral secondary somatosensory cortex (SII), insular cortex, cingulate cortex, anterior medial temporal area and ipsilateral SI. The source locations did not...
A spatiotemporal signature of cortical pain relief by tactile stimulation: An MEG study
NeuroImage, 2016
Recently, the cortical mechanisms of tactile-induced analgesia have been investigated; however, spatiotemporal characteristics have not been fully elucidated. The insular-opercular region integrates multiple sensory inputs, and nociceptive modulation by other sensory inputs occurs in this area. In this study, we focused on the insular-opercular region to characterize the spatiotemporal signature of tactile-induced analgesia using magnetoencephalography in 11 healthy subjects. Aδ (intra-epidermal electrical stimulation) inputs were modified by Aβ (mechanical tactile stimulation) selective stimulation, either independently or concurrently, to the right forearm. The optimal inter-stimulus interval (ISI) for cortical level modulation was determined after comparing the 40-, 60-, and 80-ms ISI conditions, and the calculated cortical arrival time difference between Aδ and Aβ inputs. Subsequently, we adopted a 60-ms ISI for cortical modulation and a 0-ms ISI for spinal level modulation. Sou...
The periodic presentation of a sensory stimulus induces, at certain frequencies of stimulation, a sustained electroencephalographic response of corresponding frequency, known as steady-state evoked potentials (SS-EP). In visual, auditory and vibrotactile modalities, studies have shown that SS-EP reflect mainly activity originating from early, modality-specific sensory cortices. Furthermore, it has been shown that SS-EP have several advantages over the recording of transient event-related brain potentials (ERP), such as a high signal-to-noise ratio, a shorter time to obtain reliable signals, and the capacity to frequency-tag the cortical activity elicited by concurrently presented sensory stimuli. Recently, we showed that SS-EP can be elicited by the selective activation of skin nociceptors and that nociceptive SS-EP reflect the activity of a population of neurons that is spatially distinct from the somatotopically-organized population of neurons underlying vibrotactile SS-EP. Hence, the recording of SS-EP offers a unique opportunity to study the cortical representation of nociception and touch in humans, and to explore their potential crossmodal interactions. Here, (1) we review available methods to achieve the rapid periodic stimulation of somatosensory afferents required to elicit SS-EP, (2) review previous studies that have characterized vibrotactile and nociceptive SS-EP, (3) discuss the nature of the recorded signals and their relationship with transient event-related potentials and (4) outline future perspectives and potential clinical applications of this technique.
Affective modulation of somatosensory-evoked potentials elicited by tactile stimulation
Brain Research, 2006
The present investigation was aimed to evaluate the influence of emotional valence on brain correlates of non-painful somatosensory processing. For this purpose, we examined changes on the somatosensory-evoked potentials (SEP) elicited by frequent and deviant tactile stimuli (probability 14%) when subjects were viewing affective pictures. Twenty healthy volunteers aged between 19 and 47 years old participated in the study. The P50, N80, and P200 components of the SEP, as well as the P200 component of the visual-evoked potentials (VEP) elicited by the affective pictures were analyzed. Overall, a significant P50 amplitude reduction was observed when subjects were viewing unpleasant pictures, in comparison to pleasant pictures. Furthermore, larger SEP amplitudes were obtained in response to the deviant than to the frequent stimuli. In addition, unpleasant pictures elicited larger P200 amplitudes of the VEP than pleasant. Data suggest that affective stimuli may modulate the early processing of somatosensory information in the brain, probably reflecting the existence of an adaptive perceptual/attentional mechanism to motivationally relevant stimuli. ava i l a b l e a t w w w. s c i e n c e d i r e c t . c o m w w w. e l s ev i e r. c o m / l o c a t e / b r a i n r e s
NeuroImage, 2007
The present study was undertaken to investigate after-effects of 7 Hz non-painful prolonged stimulation of the median nerve on somatosensory-evoked fields (SEFs). The working hypothesis that conditioning peripheral stimulations might produce delayed interfering ("gating") effects on the response of somatosensory cortex to test stimuli was evaluated. In the control condition, electrical thumb stimulation induced SEFs in ten subjects. In the experimental protocol, a conditioning median nerve stimulation at wrist preceded 6 electrical thumb stimulations. Equivalent current dipoles fitting SEFs modeled responses of contralateral primary area (SI) and bilateral secondary somatosensory areas (SII) following control and experimental conditions. Compared to the control condition, conditioning stimulation induced no amplitude modulation of SI response at the initial stimulusrelated peak (20 ms). In contrast, later response from SI (35 ms) and response from SII were significantly weakened in amplitude. Gradual but fast recovery towards control amplitude levels was observed for the response from SI-P35, while a slightly slower cycle was featured from SII. These findings point to a delayed "gating" effect on the synchronization of somatosensory cortex after peripheral conditioning stimulations. This effect was found to be more lasting in SII area, as a possible reflection of its integrative role in sensory processing.
Effects of Sensory Behavioral Tasks on Pain Threshold and Cortical Excitability
PLoS ONE, 2013
Background/Objective: Transcutaneous electrical stimulation has been proven to modulate nervous system activity, leading to changes in pain perception, via the peripheral sensory system, in a bottom up approach. We tested whether different sensory behavioral tasks induce significant effects in pain processing and whether these changes correlate with cortical plasticity. Methodology/Principal Findings: This randomized parallel designed experiment included forty healthy right-handed males. Three different somatosensory tasks, including learning tasks with and without visual feedback and simple somatosensory input, were tested on pressure pain threshold and motor cortex excitability using transcranial magnetic stimulation (TMS). Sensory tasks induced hand-specific pain modulation effects. They increased pain thresholds of the left hand (which was the target to the sensory tasks) and decreased them in the right hand. TMS showed that somatosensory input decreased cortical excitability, as indexed by reduced MEP amplitudes and increased SICI. Although somatosensory tasks similarly altered pain thresholds and cortical excitability, there was no significant correlation between these variables and only the visual feedback task showed significant somatosensory learning. Conclusions/Significance: Lack of correlation between cortical excitability and pain thresholds and lack of differential effects across tasks, but significant changes in pain thresholds suggest that analgesic effects of somatosensory tasks are not primarily associated with motor cortical neural mechanisms, thus, suggesting that subcortical neural circuits and/or spinal cord are involved with the observed effects. Identifying the neural mechanisms of somatosensory stimulation on pain may open novel possibilities for combining different targeted therapies for pain control.
European Journal of Neuroscience, 2003
In the present study, high-resolution electroencephalography techniques modelled the spatiotemporal pattern of human anticipatory cortical responses preceding expected galvanic painful stimuli (non-painful stimuli as a control). Do these responses re¯ect the activation of associative other than somatosensory systems? Anticipatory processes were probed by alpha oscillations (6±12 Hz) for the evaluation of thalamocortical channels and by negative event-related potentials for the evaluation of cortical excitability. Compared with the control condition, a progressive reduction of the alpha power was recognized over the primary somatosensory cortex from 2 s before the painful stimulation. In contrast, the anticipatory event-related potentials were negligible during the expectancy period. The results on the alpha power suggest that the expectancy of the painful stimulation speci®cally facilitated the somatosensory thalamocortical channel. Remarkably, the associative frontal-parietal areas were not involved, possibly due to the predictable and repetitive features of the painful stimulus. The present results also suggest that negative event-related potentials are modest preceding warned stimuli (even if painful) with a simple information content.
2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC)
Sensory feedback is a critical component in many human-machine interfaces (e.g., bionic limbs) to provide missing sensations. Specifically, electrotactile stimulation is a popular feedback modality able to evoke configurable sensations by modulating pulse amplitude, duration, and frequency of the applied stimuli. However, these sensations coded by electrotactile parameters are thus far predominantly determined by subjective user reports, which leads to heterogeneous and unstable feedback delivery. Thus, a more objective understanding of the impact that different stimulation parameters induce in the brain, is needed. Analysis of cortical responses to electrotactile afference might be an effective method in this regard. In this study, we used magnetoencephalography (MEG) to investigate the somatosensory evoked fields (SEFs) and equivalent current dipoles (ECDs) locations in nine non-invasive electrotactile stimulation conditions (1.2T, 1.5T, 1.8T) × (1 ms, 10 ms, 100 ms) with fixed 1s interval. T is the subject specific sensory threshold of the left index finger. In all conditions, we observed SEFs peaking at ~ 60 ms in the contralateral primary somatosensory cortex. While the amplitudes of the SEFs around 60 ms followed the increase in the stimulation pulse amplitude, the cortical activations were strongest when the stimulus pulse duration was set to 10 ms. These initial results indicate that the somatosensory cortical activations can provide information on the electrotactile parameters of pulse amplitude and duration, and the prosed methodology might be used for an objective interpretation of different artificial sensory feedback arrangements. Clinical Relevance-Analysis of cortical spatiotemporal representations to electrotactile stimulation can potentially be used for tailoring optimal sensory feedback delivery in patients with sensorimotor impairments.