Early nociceptive evoked potentials (NEPs) recorded from the scalp (original) (raw)
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Steady-state evoked potentials to tag specific components of nociceptive cortical processing.
Studies have shown that the periodic repetition of a stimulus induces, at certain stimulation frequencies, a sustained electro-cortical response of corresponding frequency, referred to as steady-state evoked potential (SSEP). Using infrared laser stimulation, we recently showed that SSEPs can be used to explore nociceptive cortical processing. Here, we implemented a novel approach to elicit such responses, using a periodic intra-epidermal electrical stimulation of cutaneous Aδ-nociceptors (Aδ-SSEPs). Using a wide range of frequencies (3-43Hz), we compared the scalp topographies and temporal dynamics of these Aδ-SSEPs to the Aβ-SSEPs elicited by non-nociceptive transcutaneous electrical stimulation, as well as to the transient ERPs elicited by the onsets of the 10-s stimulation trains, applied to the left and right hand. At 3Hz, we found that the topographies of Aβ- and Aδ-SSEPs were both maximal at the scalp vertex, and resembled closely that of the late P2 wave of transient ERPs, suggesting activity originating from the same neuronal populations. The responses also showed marked habituation, suggesting that they were mainly related to unspecific, attention-related processes. In contrast, at frequencies >3Hz, the topographies of Aβ- and Aδ-SSEPs were markedly different. Aβ-SSEPs were maximal over the contralateral parietal region, whereas Aδ-SSEPs were maximal over midline frontal regions, thus indicating an entrainment of distinct neuronal populations. Furthermore, the responses showed no habituation, suggesting more obligatory and specific stages of sensory processing. Taken together, our results indicate that Aβ- and Aδ-SSEPs offer a unique opportunity to study the cortical representation of nociception and touch.
Brain Topography
Monitoring nociceptive processing is a current challenge due to a lack of objective measures. Recently, we developed a method for simultaneous tracking of psychophysical detection probability and brain evoked potentials in response to intra-epidermal stimulation. An exploratory investigation showed that we could quantify nociceptive system behavior by estimating the effect of stimulus properties on the evoked potential (EP). The goal in this work was to accurately measure nociceptive system behavior using this method in a large group of healthy subjects to identify the locations and latencies of EP components and the effect of single- and double-pulse stimuli with an inter-pulse interval of 10 or 40 ms on these EP components and detection probability. First, we observed the effect of filter settings and channel selection on the EP. Subsequently, we compared statistical models to assess correlation of EP and detection probability with stimulus properties, and quantified the effect of...
What do pain-evoked potentials really measure? Revisited
Pain Forum, 1998
he article by Chen et al. makes a number of important points regarding pain laser-evoked potentials (LEPs). The authors emphasize that interpretation of these potentials is controversial and that basic laboratory procedures have not been standardized. They suggest that the potentials are directly related to the nociceptive-sensory-discriminative aspects of stimulation. They also describe how to standardize procedures for LEP experiments. We would like to suggest an alternative interpretation that seems to us to be based on a broader understanding of the potentials. We would also like to clarify a misunderstanding concerning certain studies, including our own [20]. This misunderstanding has led Chen et al. to propose a set of laboratory recommendations that, if implemented, may hinder or prevent investigation into the cognitive origins of the EP. Furthermore, the standards they propose introduce, unintentionally, cognitive effects to the LEP. Consensus is lacking among researchers as to the interpretation of the LEP. Current interpretations of the LEP form a continuum. Certain workers [1,4,8,9,18], including Chen et aI., consider the pain EP to represent, if not the actual nociceptive signal itself, events related to it. Being a "pain-specific" response, the EP can then be employed for analysis of conditions in which nociceptive pathways are damaged and for assessment of procedures that affect the sensory perception of pain. Other workers hold that the pain EP constitutes a mixture, either overlapping or separate, of nociceptive and cognitive responses [2,3,10,15,17]. For example, Siedenberg
Pneumatic evoked potential. Sensory or auditive potential?
Neurophysiologie Clinique/Clinical Neurophysiology, 2013
Study aim. -In this study, evoked potentials (EPs) to a pneumatic, innocuous, and calibrated stimulation of the skin were recorded in 22 volunteers. Methods. -Air-puff stimuli were delivered through a home-made device (INSA de Lyon, Laboratoire Ampère, CHU de Saint-Étienne, France) synchronized with an EEG recording (Micromed ® ).
On the use of evoked potentials for quantification of pain
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2012
Pain is a subjective and individual sensation causing major discomfort. So, it is necessary to put into practice methods to objectively quantify it. Several studies indicate that evoked potentials (EP) generate responses which may reflect painful processes. This study reports the results of the application of two different protocols by using biopotentials to objectively measure pain. The first (protocol 1) evaluates the relation between pain, induced by electrical stimulation, and subjective perception and also with nociceptive flexion reflex (NFR) represented by muscle activity (electromyography) detected on the femoral biceps after sural nerve stimulation. The second protocol (protocol 2) verifies whether there is some correlation between M-wave parameters and subjective pain sensation. The results obtained from protocol 1 suggest that the area of the EMG envelope and entropy estimated from the EMG activity are correlated with subjective sensation of pain. The analysis of data obt...
Somatosensory evoked potentials in clinical practice: a review
Arquivos de Neuro-Psiquiatria, 2021
The authors present a review of the current use of somatosensory evoked potentials (SSEPs) in neurological practice as a non-invasive neurophysiological technique. For this purpose we have reviewed articles published in English or Portuguese in the PubMed and LILACS databases. In this review, we address the role of SSEPs in neurological diseases that affect the central nervous system and the peripheral nervous system, especially in demyelinating diseases, for monitoring coma, trauma and the functioning of sensory pathways during surgical procedures. The latter, along with new areas of research, has become one of the most important applications of SSEPs.
Evaluation of an automated analysis for pain-related evoked potentials
Current Directions in Biomedical Engineering
This paper presents initial steps towards an auto-mated analysis for pain-related evoked potentials (PREP) to achieve a higher objectivity and non-biased examination as well as a reduction in the time expended during clinical daily routines. While manually examining, each epoch of an en-semble of stimulus-locked EEG signals, elicited by electrical stimulation of predominantly intra-epidermal small nerve fibers and recorded over the central electrode (Cz), is in-spected for artifacts before calculating the PREP by averag-ing the artifact-free epochs. Afterwards, specific peak-latencies (like the P0-, N1 and P1-latency) are identified as certain extrema in the PREP’s waveform. The proposed automated analysis uses Pearson’s correlation and low-pass differentiation to perform these tasks. To evaluate the auto-mated analysis’ accuracy its results of 232 datasets were compared to the results of the manually performed examina-tion. Results of the automated artifact rejection were compa-rab...
Somatosensory & Motor Research, 2020
Objective: Scalp-recorded evoked potentials elicited by applying afferent electrical stimulation at the tragus region of the human external ear have shown inconsistent results. We aim to disentangle discrepant findings and interpretations, and put forward novel physiological explanations on the origin of the vagus nerve somatosensory evoked potentials (VSEP). Methods: We systematically search and critically appraise in PubMed, Web of Science, and Scielo databases the scientific reports publishing VSEP findings elicited by afferent electrical stimulation at the tragus region from individuals without brain disorders. Eligible studies published from January 2000 to April 2020 were extracted. The following information was identified from each article: number of participants; age; gender; stimulating/recording and grounding electrodes as well as stimulus side, intensity, duration, frequency, and polarity. Information about physiological parameters and neurobiological variables was also extracted. Representative vignettes with novel scalp responses induced by stimulating the tragus were also included to add support to our conclusions. Results: 140 healthy participants were identified from six selected reports. Mean age ranged from 24.3 to 61.5 years. Stimulating and recording aspects were miscellaneous among studies. Scalp responses marked as the VSEP were recorded in 76% of participants, and showed high variability, low validity and poor reproducibility. Age correlated with response latencies. There were not gender differences in scalp response parameters. Cardiovascular function was unaltered by tragus stimulation. Vignettes showed that the VSEP was scalp muscle responses. Conclusion: VSEP did not fulfil evoked potential guidelines. VSEP corresponded to volume conduction propagating from muscles surrounding scalp recording sites.
Evoked potential measurement and analysis on a small laboratory computer
Computer Programs in Biomedicine, 1978
A program is described for the collection and subsequent analysis of somatosensory evoked potentials using a LINC-8 computer. The program allows simple evoked-potentials analysis in centers where a small laboratory computer may be available but sophisticated instrumentation such as a computer of average transients is not available. This program provides an efficient method of easily obtaining information concerning the conduction pathways of the nervous system as well as the cerebral function; the program can be implemented on small laboratory computers which most hospitals currently own, without the associated cost or complexity of additional hardware in the laboratory. Combining utilization of a small laboratory computer with an easily programmable method provides an approach for evoked potential analysis which is well within the financial and technical scope of most neurophysiology laboratories.
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.