RESUMEN
Perceptual judgements about our physical environment are informed by somatosensory information. In real-world exploration, this often involves dynamic hand movements to contact surfaces, termed active touch. The current study investigated cortical oscillatory changes during active exploration to inform the estimation of surface properties and hedonic preferences of two textured stimuli: smooth silk and rough hessian. A purpose-built touch sensor quantified active touch, and oscillatory brain activity was recorded from 129-channel electroencephalography. By fusing these data streams at a single trial level, oscillatory changes within the brain were examined while controlling for objective touch parameters (i.e., friction). Time-frequency analysis was used to quantify changes in cortical oscillatory activity in alpha (8-12 Hz) and beta (16-24 Hz) frequency bands. Results reproduce findings from our lab, whereby active exploration of rough textures increased alpha-band event-related desynchronisation in contralateral sensorimotor areas. Hedonic processing of less preferred textures resulted in an increase in temporoparietal beta-band and frontal alpha-band event-related desynchronisation relative to most preferred textures, suggesting that higher order brain regions are involved in the hedonic processing of texture. Overall, the current study provides novel insight into the neural mechanisms underlying texture perception during active touch and how this process is influenced by cognitive tasks.
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Corteza Sensoriomotora , Percepción del Tacto , Tacto , Electroencefalografía/métodos , Percepción Visual , Corteza SomatosensorialRESUMEN
Previous studies have demonstrated the potential of machine learning (ML) in classifying physical pain from non-pain states using electroencephalographic (EEG) data. However, the application of ML to EEG data to categorise the observation of pain versus non-pain images of human facial expressions or scenes depicting pain being inflicted has not been explored. The present study aimed to address this by training Random Forest (RF) models on cortical event-related potentials (ERPs) recorded while participants passively viewed faces displaying either pain or neutral expressions, as well as action scenes depicting pain or matched non-pain (neutral) scenarios. Ninety-one participants were recruited across three samples, which included a model development group (n = 40) and a cross-subject validation group (n = 51). Additionally, 25 participants from the model development group completed a second experimental session, providing a within-subject temporal validation sample. The analysis of ERPs revealed an enhanced N170 component in response to faces compared to action scenes. Moreover, an increased late positive potential (LPP) was observed during the viewing of pain scenes compared to neutral scenes. Additionally, an enhanced P3 response was found when participants viewed faces displaying pain expressions compared to neutral expressions. Subsequently, three RF models were developed to classify images into faces and scenes, neutral and pain scenes, and neutral and pain expressions. The RF model achieved classification accuracies of 75%, 64%, and 69% for cross-validation, cross-subject, and within-subject classifications, respectively, along with reasonably calibrated predictions for the classification of face versus scene images. However, the RF model was unable to classify pain versus neutral stimuli above chance levels when presented with subsequent tasks involving images from either category. These results expand upon previous findings by externally validating the use of ML in classifying ERPs related to different categories of visual images, namely faces and scenes. The results also indicate the limitations of ML in distinguishing pain and non-pain connotations using ERP responses to the passive viewing of visually similar images.
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Electroencefalografía , Aprendizaje Automático , Humanos , Dolor , Bosques AleatoriosRESUMEN
OBJECTIVES: Tonic spinal cord stimulation (SCS) is accompanied by paresthesia in affected body regions. Comparatively, the absence of paresthesia with burst SCS suggests different involvement of the dorsal column system conveying afferent impulses from low-threshold mechanoreceptors. This study evaluated cortical activation changes during gentle brushing of a pain-free leg during four SCS pulse intensities to assess the effect of intensity on recruitment of dorsal column system fibers during burst and tonic SCS. MATERIALS AND METHODS: Twenty patients using SCS (11 burst, nine tonic) for neuropathic leg pain participated. Brushing was administered to a pain-free area of the leg during four SCS intensities: therapeutic (100%), medium (66%), low (33%), and no stimulation. Whole-brain electroencephalography was continuously recorded. Changes in spectral power during brushing were evaluated using the event-related desynchronization (ERD) method in theta (4-7 Hz), alpha (8-13 Hz), and beta (16-24 Hz) frequency bands. RESULTS: Brushing was accompanied by a suppression of cortical oscillations in the range 4-24 Hz. Stronger intensities of burst and tonic SCS led to less suppression of 4-7 Hz and 8-13 Hz bands in parietal electrodes, and in central electrodes in the 16-24 Hz band, with the strongest, statistically significant suppression at medium intensity. Tonic SCS showed a stronger reduction in 4-7 Hz oscillations over right sensorimotor electrodes, and over right frontal and left sensorimotor electrodes in the 8-13 Hz band, compared to burst SCS. CONCLUSIONS: Results suggest that burst and tonic SCS are mediated by both different and shared mechanisms. Attenuated brushing-related ERD with tonic SCS suggests a gating of cortical activation by afferent impulses in the dorsal column, whereas burst may engage different pathways. Diminished brushing-related ERD at medium and therapeutic intensities of burst and tonic SCS points towards a nonlinear effect of SCS on somatosensory processing.
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Neuralgia , Estimulación de la Médula Espinal , Humanos , Estimulación de la Médula Espinal/métodos , Parestesia , Neuralgia/terapia , Electrodos , Encéfalo , Médula Espinal/fisiologíaRESUMEN
External low-frequency peripheral nerve stimulation (LFS) has been proposed as a novel method for neuropathic pain relief. Previous studies have reported that LFS elicits long-term depression-like effects on human pain perception when delivered at noxious intensities, whereas lower intensities are ineffective. To shed light on cortical regions mediating the effects of LFS, we investigated changes in somatosensory-evoked potentials (SEPs) during four LFS intensities. LFS was applied to the radial nerve (600 pulses, 1 Hz) of 24 healthy participants at perception (1 times), low (5 times), medium (10 times), and high intensities (15 times detection threshold). SEPs were recorded during LFS, and averaged SEPs in 10 consecutive 1-min epochs of LFS were analyzed using source dipole modeling. Changes in resting electroencephalography (EEG) were investigated after each LFS block. Source activity in the midcingulate cortex (MCC) decreased linearly during LFS, with greater attenuation at stronger LFS intensities, and in the ipsilateral operculo-insular cortex during the two lowest LFS stimulus intensities. Increased LFS intensities resulted in greater augmentation of contralateral primary sensorimotor cortex (SI/MI) activity. Stronger LFS intensities were followed by increased α (alpha, 9-11 Hz) band power in SI/MI and decreased θ (theta, 3-5 Hz) band power in MCC. Intensity-dependent attenuation of MCC activity with LFS is consistent with a state of long-term depression. Sustained increases in contralateral SI/MI activity suggests that effects of LFS on somatosensory processing may also be dependent on satiation of SI/MI. Further research could clarify if the activation of SI/MI during LFS competes with nociceptive processing in neuropathic pain.NEW & NOTEWORTHY Somatosensory-evoked potentials during low-frequency stimulation of peripheral nerves were examined at graded stimulus intensities. Low-frequency stimulation was associated with decreased responsiveness in the midcingulate cortex and increased responsiveness in primary sensorimotor cortex. Greater intensities were associated with increased midcingulate cortex θ band power and decreased sensorimotor cortex α band power. Results further previous evidence of an inhibition of somatosensory processing during and after low-frequency stimulation and point toward a potential augmentation of activity in somatosensory processing regions.
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Potenciales Evocados Somatosensoriales , Neuralgia , Estimulación Eléctrica , Potenciales Evocados Somatosensoriales/fisiología , Humanos , Percepción del Dolor/fisiología , Nervios Periféricos , Corteza Somatosensorial/fisiologíaRESUMEN
Research shows cognitive and neurobiological overlap between sign-tracking [value-modulated attentional capture (VMAC) by response-irrelevant, discrete cues] and maladaptive behaviour (e.g. substance abuse). We investigated the neural correlates of sign-tracking in 20 adults using an additional singleton task (AST) and functional magnetic resonance imaging (fMRI). Participants responded to a target to win monetary reward, the amount of which was signalled by singleton type (reward cue: high value vs. low value). Singleton responses resulted in monetary deductions. Sign-tracking-greater distraction by high-value vs. low-value singletons (H > L)-was observed, with high-value singletons producing slower responses to the target than low-value singletons. Controlling for age and sex, analyses revealed no differential brain activity across H > L singletons. Including sign-tracking as a regressor of interest revealed increased activity (H > L singletons) in cortico-subcortical loops, regions associated with Pavlovian conditioning, reward processing, attention shifts and relative value coding. Further analyses investigated responses to reward feedback (H > L). Controlling for age and sex, increased activity (H > L reward feedback) was found in regions associated with reward anticipation, attentional control, success monitoring and emotion regulation. Including sign-tracking as a regressor of interest revealed increased activity in the temporal pole, a region related to value discrimination. Results suggest sign-tracking is associated with activation of the 'attention and salience network' in response to reward cues but not reward feedback, suggesting parcellation between the two at the level of the brain. Results add to the literature showing considerable overlap in neural systems implicated in reward processing, learning, habit formation, emotion regulation and substance craving.
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Señales (Psicología) , Motivación , Condicionamiento Clásico/fisiología , Retroalimentación , Humanos , RecompensaRESUMEN
It is well established that abnormal thalamocortical systems play an important role in the generation and maintenance of primary generalised seizures. However, it is currently unknown which thalamic nuclei and how nuclear-specific thalamocortical functional connectivity are differentially impacted in patients with medically refractory and non-refractory idiopathic generalised epilepsy (IGE). In the present study, we performed structural and resting-state functional magnetic resonance imaging (MRI) in patients with refractory and non-refractory IGE, segmented the thalamus into constituent nuclear regions using a probabilistic MRI segmentation method and determined thalamocortical functional connectivity using seed-to-voxel connectivity analyses. We report significant volume reduction of the left and right anterior thalamic nuclei only in patients with refractory IGE. Compared to healthy controls, patients with refractory and non-refractory IGE had significant alterations of functional connectivity between the centromedian nucleus and cortex, but only patients with refractory IGE had altered cortical connectivity with the ventral lateral nuclear group. Patients with refractory IGE had significantly increased functional connectivity between the left and right ventral lateral posterior nuclei and cortical regions compared to patients with non-refractory IGE. Cortical effects were predominantly located in the frontal lobe. Atrophy of the anterior thalamic nuclei and resting-state functional hyperconnectivity between ventral lateral nuclei and cerebral cortex may be imaging markers of pharmacoresistance in patients with IGE. These structural and functional abnormalities fit well with the known importance of thalamocortical systems in the generation and maintenance of primary generalised seizures, and the increasing recognition of the importance of limbic pathways in IGE.
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Corteza Cerebral/fisiopatología , Conectoma , Epilepsia Refractaria/fisiopatología , Epilepsia Generalizada/fisiopatología , Red Nerviosa/fisiopatología , Núcleos Talámicos/fisiopatología , Adulto , Anciano , Corteza Cerebral/diagnóstico por imagen , Epilepsia Refractaria/diagnóstico por imagen , Epilepsia Generalizada/diagnóstico por imagen , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Red Nerviosa/diagnóstico por imagen , Núcleos Talámicos/diagnóstico por imagen , Adulto JovenRESUMEN
Values are attributed to goods during free viewing of objects which entails multi- and trans-saccadic cognitive processes. Using electroencephalographic eye-fixation related potentials, the present study investigated how neural signals related to value-guided choice evolved over time when viewing household and office products during an auction task. Participants completed a Becker-DeGroot-Marschak auction task whereby half of the stimuli were presented in either a free or forced bid protocol to obtain willingness-to-pay. Stimuli were assigned to three value categories of low, medium and high value based on subjective willingness-to-pay. Eye fixations were organised into five 800â¯ms time-bins spanning the objects total viewing time. Independent component analysis was applied to eye-fixation related potentials. One independent component (IC) was found to represent fixations for high value products with increased activation over the left parietal region of the scalp. An IC with a spatial maximum over a fronto-central region of the scalp coded the intermediate values. Finally, one IC displaying activity that extends over the right frontal scalp region responded to intermediate- and low-value items. Each of these components responded early on during viewing an object and remained active over the entire viewing period, both during free and forced bid trials. Results suggest that the subjective value of goods are encoded using sets of brain activation patterns which are tuned to respond uniquely to either low, medium, or high values. Data indicates that the right frontal region of the brain responds to low and the left frontal region to high values. Values of goods are determined at an early point in the decision making process and carried for the duration of the decision period via trans-saccadic processes.
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Mapeo Encefálico/métodos , Corteza Cerebral/fisiología , Toma de Decisiones/fisiología , Electroencefalografía/métodos , Potenciales Evocados/fisiología , Fijación Ocular/fisiología , Lateralidad Funcional/fisiología , Adulto , Medidas del Movimiento Ocular , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
BACKGROUND: The reward value of palatable foods is often cited as an important influence on eating behaviors, including intake of sugars. However, human neuroimaging studies have generated conflicting evidence on the basic neural representation of taste and reward responses to caloric sweeteners (sucrose and glucose), and most relevant studies have used small subject numbers. OBJECTIVE: We conducted a systematic review and a coordinate-based meta-analysis of studies reporting brain responses to oral sugar solutions. METHODS: A systematic search of MEDLINE, Scopus, and PsycINFO through October 2019 identified fMRI studies (in healthy human adults, including those with overweight or obesity) assessing differences in responses to purified sweet and nonsweet taste stimuli. Data were extracted with the primary objective of quantifying evidence for the activation of brain regions associated with caloric sweet taste sensation. We used activation likelihood estimation meta-analysis methods. We also performed multiple sensitivity analyses to assess the generality of effects. RESULTS: Of 455 unique articles, 15 met the criteria for inclusion. These contributed to 2 primary meta-analyses: 1) sucrose (13 experiments, 179 coordinates, n = 241) and 2) sucrose + glucose (16 experiments, 209 coordinates, n = 262). Consistent activation was apparent in primary taste areas: insula (69.2% of studies) and opercular cortex (76.9% of studies), precentral gyri (53.9% of studies), and globus pallidus and postcentral gyrus (30.8% of studies for each). Evidence of reward activity (caudate) was seen in the primary analyses (30.8% of studies) but not in sensitivity analysis. CONCLUSIONS: We confirm the importance of primary taste areas for gustatory processing in human adults. We also provide tentative evidence for reward-related caudate activity in relation to the sweet taste of caloric sugars. A number of factors affect the observation and interpretation of brain responses, including reward-related activity. Firm conclusions require confirmation with large data set studies.
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Imagen por Resonancia Magnética/métodos , Edulcorantes , Gusto , Humanos , Funciones de Verosimilitud , SacarosaRESUMEN
Congruent visual cues augment sensitivity to brief olfactory presentations and habituation of odor perception is modulated by central-cognitive processing including context. However, it is not known whether habituation to odors could interact with cross-modal congruent stimuli. The present research investigated the effect of visual congruence on odor detection sensitivity during continuous odor exposures. We utilized a multimethod approach, including subjective behavioral responses and reaction times (RTs; study 1) and electroencephalography (EEG, study 2). Study 1: 25 participants received 2-min presentations of moderate-intensity floral odor delivered via olfactometer with congruent (flower) and incongruent (object) image presentations. Participants indicated odor perception after each image. Detection sensitivity and RTs were analyzed in epochs covering the period of habituation. Study 2: 25 new participants underwent EEG recordings during 145-s blocks of odor presentations with congruent or incongruent images. Participants passively observed images and intermittently rated the perceived intensity of odor. Event-related potential analysis was utilized to evaluate brain processing related to odor-visual pairs across the period of habituation. Odor detection sensitivity and RTs were improved by congruent visual cues. Results highlighted a diminishing influence of visual congruence on odor detection sensitivity as habituation occurred. Event-related potential analysis revealed an effect of congruency on electrophysiological processing in the N400 component. This was only evident in early periods of odor exposure when perception was strong. For the first time, this demonstrates the modulation of central processing of odor-visual pairs by habituation. Frontal negativity (N400) responses encode the aspects of cross-modal congruence for odor-vision cross-modal tasks.
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Conducta/fisiología , Fenómenos Electrofisiológicos/fisiología , Habituación Psicofisiológica/fisiología , Olfato/fisiología , Percepción Visual/fisiología , Adulto , Electroencefalografía , Potenciales Evocados , Femenino , Humanos , Masculino , Odorantes , Percepción Olfatoria/fisiología , Tiempo de ReacciónRESUMEN
The value of environmental cues and internal states is continuously evaluated by the human brain, and it is this subjective value that largely guides decision making. The present study aimed to investigate the initial value attribution process, specifically the spatiotemporal activation patterns associated with values and valuation context, using electroencephalographic event-related potentials (ERPs). Participants completed a stimulus rating task in which everyday household items marketed up to a price of £4 were evaluated with respect to their desirability or material properties. The subjective values of items were evaluated as willingness to pay (WTP) in a Becker-DeGroot-Marschak auction. On the basis of the individual's subjective WTP values, the stimuli were divided into high- and low-value items. Source dipole modeling was applied to estimate the cortical sources underlying ERP components modulated by subjective values (high vs. low WTP) and the evaluation condition (value-relevant vs. value-irrelevant judgments). Low-WTP items and value-relevant judgments both led to a more pronounced N2 visual evoked potential at right frontal scalp electrodes. Source activity in right anterior insula and left orbitofrontal cortex was larger for low vs. high WTP at â¼200 ms. At a similar latency, source activity in right anterior insula and right parahippocampal gyrus was larger for value-relevant vs. value-irrelevant judgments. A stronger response for low- than high-value items in anterior insula and orbitofrontal cortex appears to reflect aversion to low-valued item acquisition, which in an auction experiment would be perceived as a relative loss. This initial low-value bias occurs automatically irrespective of the valuation context. NEW & NOTEWORTHY We demonstrate the spatiotemporal characteristics of the brain valuation process using event-related potentials and willingness to pay as a measure of subjective value. The N2 component resolves values of objects with a bias toward low-value items. The value-related changes of the N2 component are part of an automatic valuation process.
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Corteza Cerebral/fisiología , Toma de Decisiones/fisiología , Electroencefalografía/métodos , Potenciales Evocados/fisiología , Juicio/fisiología , Adulto , Potenciales Evocados Visuales/fisiología , Femenino , Humanos , Masculino , Corteza Prefrontal/fisiología , Análisis Espacio-Temporal , Adulto JovenRESUMEN
Previous studies demonstrated that pain induced by a noxious stimulus during a distraction task is affected by both stimulus-driven and goal-directed processes which interact and change over time. The purpose of this exploratory study was to analyse associations of aspects of subjective pain experience and engagement with the distracting task with attention-sensitive components of noxious laser-evoked potentials (LEPs) on a single-trial basis. A laser heat stimulus was applied to the dorsum of the left hand while subjects either viewed the Rubin vase-face illusion (RVI), or focused on their pain and associated somatosensory sensations occurring on their stimulated hand. Pain-related sensations occurring with every laser stimulus were evaluated using a set of visual analogue scales. Factor analysis was used to identify the principal dimensions of pain experience. LEPs were correlated with subjective aspects of pain experience on a single-trial basis using a multiple linear regression model. A positive LEP component at the vertex electrodes in the interval 294-351 ms (P2) was smaller during focusing on RVI than during focusing on the stimulated hand. Single-trial amplitude variations of the P2 component correlated with changes in Factor 1, representing essential aspects of pain, and inversely with both Factor 2, accounting for anticipated pain, and the number of RVI figure reversals. A source dipole located in the posterior region of the cingulate cortex was the strongest contributor to the attention-related single-trial variations of the P2 component. Instantaneous amplitude variations of the P2 LEP component during switching attention towards pain in the presence of a distracting task are related to the strength of pain experience, engagement with the task, and the level of anticipated pain. Results provide neurophysiological underpinning for the use of distraction analgesia acute pain relief.
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Atención/fisiología , Giro del Cíngulo/fisiopatología , Ilusiones/psicología , Potenciales Evocados por Láser/fisiología , Percepción del Dolor/fisiología , Dolor/fisiopatología , Percepción Visual/fisiología , Adulto , Femenino , Mano , Humanos , Masculino , Dimensión del Dolor , Adulto JovenRESUMEN
The origin of the conscious experience of pain in the brain is a continuing enigma in neuroscience. To shed light on the brain representation of a multifaceted pain experience in humans, we combined multivariate analysis of subjective aspects of pain sensations with detailed, single-trial analysis of electrophysiological brain responses. Participants were asked to fully focus on any painful or non-painful sensations occurring in their left hand during an interval surrounding the onset of noxious laser heat stimuli, and to rate their sensations using a set of visual analogue scales. Statistical parametric mapping was used to compute a multivariate regression analysis of subjective responses and single-trial laser evoked potentials (LEPs) at subject and group levels. Standardized Low Resolution Electromagnetic Tomography method was used to reconstruct sources of LEPs. Factor analysis of subjective responses yielded five factors. Factor 1, representing pain, mapped firstly as a negative potential at the vertex and a positive potential at the fronto-temporal region during the 208-260ms interval, and secondly as a strong negative potential in the right lateral frontal and prefrontal scalp regions during the 1292-1340ms interval. Three other factors, labelled "anticipated pain", "stimulus onset time", and "body sensations", represented non-specific aspects of the pain experience, and explained portions of LEPs in the latency range from 200ms to 700ms. The subjective space of pain during noxious laser stimulation is represented by one large factor featuring pain intensity, and by other factors accounting for non-specific parts of the sensory experience. Pain is encoded in two separate latency components with different scalp and brain representations.
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Encéfalo/fisiología , Potenciales Evocados Somatosensoriales/fisiología , Percepción del Dolor/fisiología , Adulto , Mapeo Encefálico , Electroencefalografía , Femenino , Calor/efectos adversos , Humanos , Rayos Láser/efectos adversos , Masculino , Procesamiento de Señales Asistido por Computador , Adulto JovenRESUMEN
The insula cortex and hypothalamus are implicated in eating behaviour, and contain receptor sites for peptides and hormones controlling energy balance. The insula encompasses multi-functional subregions, which display differential anatomical and functional connectivities with the rest of the brain. This study aimed to analyse the effect of fasting and satiation on the functional connectivity profiles of left and right anterior, middle, and posterior insula, and left and right hypothalamus. It was hypothesized that the profiles would be altered alongside changes in homeostatic energy balance. Nineteen healthy participants underwent two 7-min resting state functional magnetic resonance imaging scans, one when fasted and one when satiated. Functional connectivity between the left posterior insula and cerebellum/superior frontal gyrus, and between left hypothalamus and inferior frontal gyrus was stronger during fasting. Functional connectivity between the right middle insula and default mode structures (left and right posterior parietal cortex, cingulate cortex), and between right hypothalamus and superior parietal cortex was stronger during satiation. Differences in blood glucose levels between the scans accounted for several of the altered functional connectivities. The insula and hypothalamus appear to form a homeostatic energy balance network related to cognitive control of eating; prompting eating and preventing overeating when energy is depleted, and ending feeding or transferring attention away from food upon satiation. This study provides evidence of a lateralized dissociation of neural responses to energy modulations.
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Corteza Cerebral/fisiología , Hambre/fisiología , Hipotálamo/fisiología , Adulto , Mapeo Encefálico , Ayuno/psicología , Femenino , Humanos , Imagen por Resonancia Magnética , MasculinoRESUMEN
Hunger and pain are basic drives that compete for a behavioral response when experienced together. To investigate the cortical processes underlying hunger-pain interactions, we manipulated participants' hunger and presented photographs of appetizing food or inedible objects in combination with painful laser stimuli. Fourteen healthy participants completed two EEG sessions: one after an overnight fast, the other following a large breakfast. Spatio-temporal patterns of cortical activation underlying the hunger-pain competition were explored with 128-channel EEG recordings and source dipole analysis of laser-evoked potentials (LEPs). We found that initial pain ratings were temporarily reduced when participants were hungry compared with fed. Source activity in parahippocampal gyrus was weaker when participants were hungry, and activations of operculo-insular cortex, anterior cingulate cortex, parahippocampal gyrus, and cerebellum were smaller in the context of appetitive food photographs than in that of inedible object photographs. Cortical processing of noxious stimuli in pain-related brain structures is reduced and pain temporarily attenuated when people are hungry or passively viewing food photographs, suggesting a possible interaction between the opposing motivational forces of the eating drive and pain.
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Giro del Cíngulo/fisiología , Hambre/fisiología , Nocicepción , Giro Parahipocampal/fisiología , Percepción Visual , Adulto , Apetito , Cerebelo/fisiología , Femenino , Alimentos , Humanos , Potenciales Evocados por Láser , Masculino , Estimulación LuminosaRESUMEN
The present study examined whether people higher in psychopathy experienced less self-reported and psychophysiological nociceptive pressure than people lower in psychopathy. We also examined whether psychopathy affects empathy for others' pain via self-reported and psychophysiological measures. Three hundred and sixty-nine students (18-78 years; M = 26, SD = 9.34) were screened for psychopathic traits using the Youth Psychopathy Inventory (YPI). Stratified sampling was used to recruit 49 adults residing in the highest (n = 23) and lowest (n = 26) 20% of the psychopathy spectrum. Using skin conductance response (SCR) and self-report responses, participants responded to individually adjusted intensities of pneumatic pressure and others' pain images and completed self-reported psychopathy and empathy measures (Triarchic Psychopathy Measure, TriPm; Interpersonal Reactivity Index, IRI). People higher in psychopathy self-reported feeling less nociceptive pressure compared to people lower in psychopathy, yet we did not find any differences in SCR to nociceptive pressure. However, when viewing other people in pain, the high psychopathy group displayed lower SCR and lower self-reported empathy compared to those lower in psychopathy. Our results suggest psychopathic traits relate to problems empathising with others' pain, as well as the perception of nociceptive pressure. We also show support for the theory of dual harm which has been receiving increasing attention. Consequently, psychopathy interventions should focus both on recognising and empathising with the pain of others.
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Trastorno de Personalidad Antisocial , Empatía , Dolor , Humanos , Empatía/fisiología , Masculino , Adulto , Femenino , Adolescente , Persona de Mediana Edad , Dolor/psicología , Dolor/fisiopatología , Trastorno de Personalidad Antisocial/psicología , Trastorno de Personalidad Antisocial/fisiopatología , Adulto Joven , Anciano , Autoinforme , Respuesta Galvánica de la Piel/fisiología , PsicofisiologíaRESUMEN
Previous research investigated cross-modal influence of olfactory stimuli on perception and evaluation of faces. However, little is known about the neural dynamics underpinning this multisensory perception, and no research examined perception for images of oneself, and others, in presence of fragrances. This study investigated the neural mechanisms of olfactory-visual processing using electroencephalography (EEG) and subjective evaluations of self- and other-images. 22 female participants evaluated images of female actors and themselves while being exposed to the fragrance of a commercially available body wash or clean air delivered via olfactometer. Participants rated faces for attractiveness, femininity, confidence and glamorousness on visual analogue scales. EEG data was recorded and event-related potentials (ERPs) associated with onset of face stimuli were analysed to consider effects of fragrance presence on face processing, and interactions between fragrance and self-other image-type. Subjective ratings of confidence, attractiveness and femininity were increased for both image-types in pleasant fragrance relative to clean air condition. ERP components covering early-to-late stages of face processing were modulated by the presence of fragrance. Findings also revealed a cross-modal fragrance-face interaction, with pleasant fragrance particularly affecting ERPs to self-images in mid-latency ERP components. Results showed that the pleasant fragrance of the commercially available body wash impacted how participants perceived faces of self and others. Self- and other-image faces were subjectively rated as more attractive, confident and feminine in the presence of the pleasant fragrance compared to an un-fragranced control. The pleasant fragrance also modulated underlying electrophysiological activity. For the first time, an effect of pleasant fragrance on face perception was observed in the N1 component, suggesting impact within 100â¯ms. Pleasant fragrance also demonstrated greater impact on subsequent neural processing for self, relative to other-faces. The findings have implications for understanding multisensory integration during evaluations of oneself and others.
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Feminidad , Odorantes , Humanos , Femenino , Belleza , Potenciales Evocados/fisiología , ElectroencefalografíaRESUMEN
A proportion of people with fibromyalgia demonstrate small fibre pathology (SFP). However, it is unclear how SFP directly relates to pain phenomenology. Thirty-three individuals with FMS and ten healthy volunteers underwent assessment of SFP and sensory phenotyping using corneal confocal microscopy, validated questionnaires and quantitative sensory testing (QST). Corneal nerve fibre length was used to stratify participants with fibromyalgia into with SFP [SFP+] and without SFP [SFP-]. SFP was detected in 50% of the fibromyalgia cohort. Current pain score and QST parameters did not differ between SFP+ and SFP-. Mechanical pain sensitivity (MPS) demonstrated a significant gain-of-function in the SFP- cohort compared to healthy-volunteers (p = 0.014, F = 4.806, η2 = 0.22). Further stratification revealed a cohort without structural SFP but with symptoms compatible with small fibre neuropathy symptoms and a significant gain in function in MPS (p = 0.020 Chi-square). Additionally, this cohort reported higher scores for both depression (p = 0.039, H = 8.483, η2 = 0.312) and anxiety (p = 0.022, F = 3.587, η2 = 0.293). This study confirms that SFP is present in a proportion of people with fibromyalgia. We also show that in a proportion of people with fibromyalgia, small fibre neuropathy symptoms are present in the absence of structural SFP. Greater mechanical pain sensitivity, depression and anxiety are seen in these individuals.
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Fibromialgia , Neuropatía de Fibras Pequeñas , Humanos , Neuropatía de Fibras Pequeñas/diagnóstico , Dolor , Umbral del Dolor , Fibras Nerviosas/patologíaRESUMEN
Discrimination of pain intensity using machine learning (ML) and electroencephalography (EEG) has significant potential for clinical applications, especially in scenarios where self-report is unsuitable. However, existing research is limited due to a lack of external validation (assessing performance using novel data). We aimed for the first external validation study for pain intensity classification with EEG. Pneumatic pressure stimuli were delivered to the fingernail bed at high and low pain intensities during two independent EEG experiments with healthy participants. Study one (n = 25) was utilised for training and cross-validation. Study two (n = 15) was used for external validation one (identical stimulation parameters to study one) and external validation two (new stimulation parameters). Time-frequency features of peri-stimulus EEG were computed on a single-trial basis for all electrodes. ML training and analysis were performed on a subset of features, identified through feature selection, which were distributed across scalp electrodes and included frontal, central, and parietal regions. Results demonstrated that ML models outperformed chance. The Random Forest (RF) achieved the greatest accuracies of 73.18, 68.32 and 60.42% for cross-validation, external validation one and two, respectively. Importantly, this research is the first to externally validate ML and EEG for the classification of intensity during experimental pain, demonstrating promising performance which generalises to novel samples and paradigms. These findings offer the most rigorous estimates of ML's clinical potential for pain classification.
Asunto(s)
Electroencefalografía , Percepción del Dolor , Humanos , Dimensión del Dolor , Electroencefalografía/métodos , Aprendizaje Automático , DolorRESUMEN
In early 2020, countries across the world imposed lockdown restrictions to curb the spread of the Covid-19 coronavirus. Lockdown conditions, including social and physical distancing measures and recommended self-isolation for clinically vulnerable groups, were proposed to disproportionately affect those living with chronic pain, who already report reduced access to social support and increased isolation. Yet, empirical evidence from longitudinal studies tracking the effects of prolonged and fluctuating lockdown conditions, and potential psychological factors mediating the effects of such restrictions on outcomes in chronic pain populations, is lacking. Accordingly, in the present 13-wave longitudinal study, we surveyed pain intensity, pain interference, and tiredness in people with chronic pain over the course of 11 months of the Covid-19 pandemic (April 2020-March 2021). Of N = 431 participants at baseline, average completion rate was â¼50% of time points, and all available data points were included in linear mixed models. We examined the impact of varying levels of lockdown restrictions on these outcomes and investigated whether psychological distress levels mediated effects. We found that a full national lockdown was related to greater pain intensity, and these effects were partially mediated by depressive symptoms. No effects of lockdown level were found for pain interference and tiredness, which were instead predicted by higher levels of depression, anxiety, pain catastrophising, and reduced exercise. Our findings are relevant for improving patient care in current and future crises. Offering remote management options for low mood could be particularly beneficial for this vulnerable population in the event of future implementation of lockdown restrictions. PERSPECTIVE: This longitudinal study demonstrates the impact of Covid-19 lockdown restrictions on people with chronic pain. Findings suggest a complex interaction of psychosocial factors that impacted various aspects of pain experience in patients, which offer the potential to inform clinical strategies for remote medicine and future crises.
RESUMEN
Introduction: Texture changes occur frequently during real-world haptic explorations, but the neural processes that encode perceptual texture change remain relatively unknown. The present study examines cortical oscillatory changes during transitions between different surface textures during active touch. Methods: Participants explored two differing textures whilst oscillatory brain activity and finger position data were recorded using 129-channel electroencephalography and a purpose-built touch sensor. These data streams were fused to calculate epochs relative to the time when the moving finger crossed the textural boundary on a 3D-printed sample. Changes in oscillatory band power in alpha (8-12 Hz), beta (16-24 Hz) and theta (4-7 Hz) frequency bands were investigated. Results: Alpha-band power reduced over bilateral sensorimotor areas during the transition period relative to ongoing texture processing, indicating that alpha-band activity is modulated by perceptual texture change during complex ongoing tactile exploration. Further, reduced beta-band power was observed in central sensorimotor areas when participants transitioned from rough to smooth relative to transitioning from smooth to rough textures, supporting previous research that beta-band activity is mediated by high-frequency vibrotactile cues. Discussion: The present findings suggest that perceptual texture change is encoded in the brain in alpha-band oscillatory activity whilst completing continuous naturalistic movements across textures.