Publications by authors named "Andrej Stancak"

58 Publications

Adverse effects of COVID-19-related lockdown on pain, physical activity and psychological well-being in people with chronic pain.

Br J Pain 2021 Aug 21;15(3):357-368. Epub 2020 Nov 21.

Department of Psychology, Institute of Population Health Sciences, University of Liverpool, Liverpool, UK.

Countries across the world imposed lockdown restrictions during the COVID-19 pandemic. It has been proposed that lockdown conditions, including social and physical distancing measures, may disproportionately impact those living with chronic pain and require rapid adaptation to treatment and care strategies. Using an online methodology, we investigated how lockdown restrictions in the United Kingdom impacted individuals with chronic pain (N = 431) relative to a healthy control group (N = 88). Data were collected during the most stringent period of lockdown in the United Kingdom (mid-April to early-May 2020). In accordance with the fear-avoidance model, we hypothesised lockdown-related increases in pain and psychological distress, which would be mediated by levels of pain catastrophising. Responses indicated that people with chronic pain perceived increased pain severity, compared to their estimation of typical pain levels prior to lockdown (p < .001). They were also more adversely affected by lockdown conditions compared to pain-free individuals, demonstrating greater self-perceived increases in anxiety and depressed mood, increased loneliness and reduced levels of physical exercise (p ⩽ .001). Hierarchical regression analysis revealed that pain catastrophising was an important factor relating to the extent of self-perceived increases in pain severity during lockdown (β = .27, p < .001) and also mediated the relationship between decreased mood and pain. Perceived decreases in levels of physical exercise also related to perceptions of increased pain (β = .15, p < .001). Interestingly, levels of pain intensity (measured at two time points at pre and during lockdown) in a subgroup (N = 85) did not demonstrate a significant change. However, individuals in this subgroup still reported self-perceived pain increases during lockdown, which were also predicted by baseline levels of pain catastrophising. Overall, the findings indicate that people with chronic pain suffer adverse effects of lockdown including self-perceived increases in their pain. Remote pain management provision to target reduction of pain catastrophising and increase health behaviours including physical activity could be beneficial for this vulnerable population.
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http://dx.doi.org/10.1177/2049463720973703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8339954PMC
August 2021

A andomisd, controlled, double blind tudy to assess mechanstic effects of combination therapy of dapagflozin with xenatide QW versus dapagliflozin alone i obese patients with ype 2 diabetes mellitus (RESILIENT): study protocol.

BMJ Open 2021 07 20;11(7):e045663. Epub 2021 Jul 20.

Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK.

Introduction: The newer glucose-lowering therapies for type 2 diabetes (T2D), the glucagon-like peptide-1 receptor agonists (GLP1-RAs) and the sodium-glucose co-transporter 2 inhibitors (SGLT2i), have additional clinical benefits beyond improving glycaemic control; promoting weight loss, addressing associated cardiovascular risk factors and reducing macrovascular and microvascular complications. Considering their independent mechanisms of actions, there is a potential for significant synergy with combination therapy, yet limited data exist. This 32-week randomised, double-blind, placebo-controlled trial will gain mechanistic insight into the effects of coadministration of exenatide QW, a weekly subcutaneous GLP1-RA, with dapagliflozin, a once daily oral SGLT2i, on the dynamic, adaptive changes in energy balance, total, regional and organ-specific fat mass and multiorgan insulin sensitivity.

Methods And Analysis: 110 obese patients with diagnosed T2D (glycated haemoglobin, HbA ≥48 mmol/mol) will be treated for 32 weeks with dapagliflozin (10 mg once daily either alone or in combination with exenatide QW (2 mg once weekly); active treatments will be compared with a control group (placebo tablet and sham injection). The primary objective of the study is to compare the adjusted mean reduction in total body fat mass (determined by dual-energy X-ray absorptiometry, DEXA) from baseline following 32 weeks of treatment with exenatide QW and dapagliflozin versus dapagliflozin alone compared with control (placebo). Secondary outcome measures include changes in (1) (energy intake and energy expenditure measured by indirect calorimetry); (2) (between and within meals) and satiety quotient; (3) including visceral adipose tissue, subcutaneous adipose tissue, liver and pancreatic fat. Exploratory outcome measures include in hepatic and peripheral insulin sensitivity (using a two-stage hyperinsulinaemic, euglycaemic clamp), to food images using blood oxygen level-dependent (BOLD) functional MRI (fMRI) and (using transthoracic echocardiography, cardiac MR and duplex ultrasonography).

Ethics And Dissemination: This study has been approved by the North West Liverpool Central Research Ethics Committee (14/NW/1147) and is conducted in accordance with the Declaration of Helsinki and the Good Clinical Practice. Results from the study will be published in peer-reviewed scientific and open access journals and/or presented at scientific conferences and summarised for distribution to the participants.

Trial Sponsor: University of Liverpool.

Trial Registration Number: ISRCTN 52028580; EUDRACT number 2015-005242-60.
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http://dx.doi.org/10.1136/bmjopen-2020-045663DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8292819PMC
July 2021

Investigating the effect of losses and gains on effortful engagement during an incentivized Go/NoGo task through anticipatory cortical oscillatory changes.

Psychophysiology 2021 Jul 12:e13897. Epub 2021 Jul 12.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK.

Losses usually have greater subjective value (SV) than gains of equal nominal value but often cause a relative deterioration in effortful performance. Since losses and gains induce differing approach/avoidance behavioral tendencies, we explored whether incentive type interacted with approach/avoidance motor-sets. Alpha- and beta-band event-related desynchronization (ERD) was hypothesized to be weakest when participants expected a loss and prepared an inhibitory motor-set, and strongest when participants expected a gain and prepared an active motor-set. It was also hypothesized that effort would modulate reward and motor-set-related cortical activation patterns. Participants completed a cued Go/NoGo task while expecting a reward (+10p), avoiding a loss (-10p), or receiving no incentive (0p); and while expecting a NoGo cue with a probability of either .75 or .25. Pre-movement alpha- and beta-band EEG power was analyzed using the ERD method, and the SV of effort was evaluated using a cognitive effort discounting task. Gains incentivized faster RTs and stronger preparatory alpha band ERD compared to loss and no incentive conditions, while inhibitory motor-sets resulted in significantly weaker alpha-band ERD. However, there was no interaction between incentive and motor-sets. Participants were more willing to expend effort in losses compared to gain trials, although the SV of effort was not associated with ERD patterns or RTs. Results suggest that incentive and approach/avoidance motor tendencies modulate cortical activations prior to a speeded RT movement independently, and are not associated with the economic value of effort. The present results favor attentional explanations of the effect of incentive modality on effort.
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http://dx.doi.org/10.1111/psyp.13897DOI Listing
July 2021

Paediatric pelvic injuries: a retrospective epidemiological study from four level 1 trauma centers.

Int Orthop 2021 08 4;45(8):2033-2048. Epub 2021 Jul 4.

Department of Orthopaedics and Traumatology, Third Faculty of Medicine of Charles University, and University Hospital Kralovske Vinohrady, Prague, Czech Republic.

Aim Of The Study: Epidemiologic evaluation of pelvic ring injuries in children.

Methods: Retrospective analysis over a period of 13 years, excluding pathological fractures. AO/OTA type, epidemiological data, type of treatment, and complications were recorded. Data were assessed using Fisher's exact test and Wilcoxon test.

Results: 243 boys, 115 girls, mean age (SD) 14.1 ± 3.0 years, AO/OTA types: 281 A, 52 B, 25 C. Multiple trauma: 62, combined trauma: 59, mono-trauma: 237. 281 patients were treated non-operatively, 97 surgically.

Etiology: traffic accidents 88, falls from a great height 37, crushing injuries four, and sports injuries 192, simple falls 30, others seven. High-energy mechanisms prevailed in types B and C. Low-energy mechanism in type A (p < 0.0001). Similar differences were found between type A (p = 0.0009) and in case type C requiring surgery and cases treated non-operatively (p < 0.0001). Twenty-six patients (7.3%) had complications (pelvic asymmetry 5, neurological deficits 5, non-union 1, ectopic calcification 4, others 7). Higher complication rates were associated with types B and C (p = 0.0015), with surgically treated cases (p < 0.0001) and multiple trauma (p = 0.0305).

Discussion: Results of this trial were comparable with other studies.

Conclusion: Sports injuries accounted for most type A injuries, while types B and C tended to be associated with high-energy trauma. Complications were associated with the severity of pelvic trauma, more common in surgically treated group of patients; this is primarily linked to the surgical cases being more serious as well as the associated injuries.
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http://dx.doi.org/10.1007/s00264-021-05105-2DOI Listing
August 2021

Inhibition of cortical somatosensory processing during and after low frequency peripheral nerve stimulation in humans.

Clin Neurophysiol 2021 07 16;132(7):1481-1495. Epub 2021 Apr 16.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK.

Objective: Transcutaneous low-frequency stimulation (LFS) elicits long-term depression-like effects on human pain perception. However, the neural mechanisms underlying LFS are poorly understood. We investigated cortical activation changes occurring during LFS and if changes were associated with reduced nociceptive processing and increased amplitude of spontaneous cortical oscillations post-treatment.

Methods: LFS was applied to the radial nerve of 25 healthy volunteers over two sessions using active (1 Hz) or sham (0.02 Hz) frequencies. Changes in resting electroencephalography (EEG) and laser-evoked potentials (LEPs) were investigated before and after LFS. Somatosensory-evoked potentials were recorded during LFS and source analysis was carried out.

Results: Ipsilateral midcingulate and operculo-insular cortex source activity declined linearly during LFS. Active LFS was associated with attenuated long-latency LEP amplitude in ipsilateral frontocentral electrodes and increased resting alpha (8-12 Hz) and beta (16-24 Hz) band power in electrodes overlying operculo-insular, sensorimotor and frontal cortical regions. Reduced ipsilateral operculo-insular cortex source activity during LFS correlated with a smaller post-treatment alpha-band power increase.

Conclusions: LFS attenuated somatosensory processing both during and after stimulation.

Significance: Results further our understanding of the attenuation of somatosensory processing both during and after LFS.
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http://dx.doi.org/10.1016/j.clinph.2021.03.024DOI Listing
July 2021

A Behavioral and Electrophysiological Investigation of Effects of Visual Congruence on Olfactory Sensitivity During Habituation to Prolonged Odors.

Chem Senses 2020 12;45(9):845-854

Department of Psychological Sciences, Institute of Psychology, Health, and Society, University of Liverpool, Eleanor Rathbone Building, Bedford Street South, Liverpool, UK.

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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http://dx.doi.org/10.1093/chemse/bjaa065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7872010PMC
December 2020

Shared and distinct functional networks for empathy and pain processing: a systematic review and meta-analysis of fMRI studies.

Soc Cogn Affect Neurosci 2020 09;15(7):709-723

Department of Psychological Sciences, University of Liverpool, Liverpool L697ZA, UK.

Background: Empathy for pain is a complex phenomenon incorporating sensory, cognitive and affective processes. Functional neuroimaging studies indicate a rich network of brain activations for empathic processing. However, previous research focused on core activations in bilateral anterior insula (AI) and anterior cingulate/anterior midcingulate cortex (ACC/aMCC) which are also typically present during nociceptive (pain) processing. Theoretical understanding of empathy would benefit from empirical investigation of shared and contrasting brain activations for empathic and nociceptive processing.

Method: Thirty-nine empathy for observed pain studies (1112 participants; 527 foci) were selected by systematic review. Coordinate based meta-analysis (activation likelihood estimation) was performed and novel contrast analyses compared neurobiological processing of empathy with a comprehensive meta-analysis of 180 studies of nociceptive processing (Tanasescu et al., 2016).

Results: Conjunction analysis indicated overlapping activations for empathy and nociception in AI, aMCC, somatosensory and inferior frontal regions. Contrast analysis revealed increased likelihood of activation for empathy, relative to nociception, in bilateral supramarginal, inferior frontal and occipitotemporal regions. Nociception preferentially activated bilateral posterior insula, somatosensory cortex and aMCC.

Conclusion: Our findings support the likelihood of shared and distinct neural networks for empathic, relative to nociceptive, processing. This offers succinct empirical support for recent tiered or modular theoretical accounts of empathy.
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http://dx.doi.org/10.1093/scan/nsaa090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7511882PMC
September 2020

The cortical oscillatory patterns associated with varying levels of reward during an effortful vigilance task.

Exp Brain Res 2020 Sep 7;238(9):1839-1859. Epub 2020 Jun 7.

Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK.

We explored how reward and value of effort shapes performance in a sustained vigilance, reaction time (RT) task. It was posited that reward and value would hasten RTs and increase cognitive effort by boosting activation in the sensorimotor cortex and inhibition in the frontal cortex, similar to the horse-race model of motor actions. Participants performed a series of speeded responses while expecting differing monetary rewards (0 pence (p), 1 p, and 10 p) if they responded faster than their median RT. Amplitudes of cortical alpha, beta, and theta oscillations were analysed using the event-related desynchronization method. In experiment 1 (N = 29, with 12 females), reward was consistent within block, while in experiment 2 (N = 17, with 12 females), reward amount was displayed before each trial. Each experiment evaluated the baseline amplitude of cortical oscillations differently. The value of effort was evaluated using a cognitive effort discounting task (COGED). In both experiments, RTs decreased significantly with higher rewards. Reward level sharpened the increased amplitudes of beta oscillations during fast responses in experiment 1. In experiment 2, reward decreased the amplitudes of beta oscillations in the ipsilateral sensorimotor cortex. Individual effort values did not significantly correlate with oscillatory changes in either experiment. Results suggest that reward level and response speed interacted with the task- and baseline-dependent patterns of cortical inhibition in the frontal cortex and with activation in the sensorimotor cortex during the period of motor preparation in a sustained vigilance task. However, neither the shortening of RT with increasing reward nor the value of effort correlated with oscillatory changes. This implies that amplitudes of cortical oscillations may shape upcoming motor responses but do not translate higher-order motivational factors into motor performance.
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http://dx.doi.org/10.1007/s00221-020-05825-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7438383PMC
September 2020

Event-related and readiness potentials when preparing to approach and avoid alcohol cues following cue avoidance training in heavy drinkers.

Psychopharmacology (Berl) 2020 May 26;237(5):1343-1358. Epub 2020 Feb 26.

UK Centre for Tobacco and Alcohol Studies, Liverpool, UK.

Rationale: Cue avoidance training (CAT) reduces alcohol consumption in the laboratory. However, the neural mechanisms that underlie the effects of this intervention are poorly understood.

Objectives: The present study investigated the effects of a single session of CAT on event-related and readiness potentials during preparation of approach and avoidance movements to alcohol cues.

Methods: Heavy drinking young adults (N = 60) were randomly assigned to complete either CAT or control training. After training, we recorded participants' event-related and motor readiness potentials as they were preparing to respond.

Results: In the CAT group, N200 amplitude was higher when preparing to approach rather than avoid alcohol pictures. In the control group, N200 amplitudes did not differ for approach and avoidance to alcohol pictures. Regarding the late positive potential (LPP), in the CAT group, the negativity of this was blunted when preparing to avoid alcohol pictures relative to when preparing to avoid control pictures. In the control group, the negativity of the LPP was blunted when preparing to approach alcohol pictures relative to when preparing to approach control pictures. There were no effects on motor readiness potentials. Behavioural effects indicated short-lived effects of training on reaction times during the training block that did not persist when participants were given time to prepare their motor response before executing it during the EEG testing block.

Conclusions: After a single session of CAT, the enhanced N200 when approaching alcohol cues may indicate the engagement of executive control to overcome the associations learned during training. These findings clarify the neural mechanisms that may underlie the effects of CAT on drinking behaviour.
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http://dx.doi.org/10.1007/s00213-020-05462-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7196951PMC
May 2020

Neural underpinnings of value-guided choice during auction tasks: An eye-fixation related potentials study.

Neuroimage 2020 01 19;204:116213. Epub 2019 Sep 19.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK.

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 800 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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http://dx.doi.org/10.1016/j.neuroimage.2019.116213DOI Listing
January 2020

Where Is Itch Represented in the Brain, and How Does it Differ from Pain? An Activation Likelihood Estimation Meta-Analysis of Experimentally-Induced Itch.

J Invest Dermatol 2019 10 2;139(10):2245-2248.e3. Epub 2019 May 2.

Department of Psychological Sciences, University of Liverpool, United Kingdom.

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http://dx.doi.org/10.1016/j.jid.2019.04.007DOI Listing
October 2019

Tracking Economic Value of Products in Natural Settings: A Wireless EEG Study.

Front Neurosci 2018 20;12:910. Epub 2018 Dec 20.

Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool, United Kingdom.

Economic decision making refers to the process of individuals translating their preference into subjective value (SV). Little is known about the dynamics of the neural processes that underpin this form of value-based decision making and no studies have investigated these processes outside of controlled laboratory settings. The current study investigated the spatio-temporal dynamics that accompany economic valuation of products using mobile electroencephalography (EEG) and eye tracking techniques. Participants viewed and rated images of household products in a gallery setting while EEG and eye tracking data were collected wirelessly. A Becker-DeGroot-Marschak (BDM) auction task was subsequently used to quantify the individual's willingness to pay (WTP) for each product. WTP was used to classify products into low, low medium, high medium and high economic value conditions. Eye movement related potentials (EMRP) were examined, and independent component analysis (ICA) was used to separate sources of activity from grand averaged EEG data. Four independent components (ICs) of EMRPs were modulated by WTP (i.e., SV) in the latency range of 150-250 ms. Of the four value-sensitive ICs, one IC displayed enhanced amplitude for all value conditions excluding low value, and another IC presented enhanced amplitude for low value products only. The remaining two value-sensitive ICs resolved inter-mediate levels of SV. Our study quantified, for the first time, the neural processes involved in economic value based decisions in a natural setting. Results suggest that multiple spatio-temporal brain activation patterns mediate the attention and aversion of products which could reflect an early valuation system. The EMRP parietal P200 component could reflect an attention allocation mechanism that separates the lowest-value products (IC7) from products of all other value (IC4), suggesting that low-value items are categorized early on as being aversive. While none of the ICs showed linear amplitude changes that parallel SV's of products, results suggest that a combination of multiple components may sub-serve a fine-grained resolution of the SV of products.
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http://dx.doi.org/10.3389/fnins.2018.00910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306680PMC
December 2018

Intensity expectation modifies gustatory evoked potentials to sweet taste: Evidence of bidirectional assimilation in early perceptual processing.

Psychophysiology 2019 03 15;56(3):e13299. Epub 2018 Nov 15.

Department of Psychological Sciences, Eleanor Rathbone Building, University of Liverpool, Liverpool, L69 7ZA, UK.

Expectations can affect subjective sensory and hedonic ratings of tastes, but it is unclear whether they also shape sensory experience at a perceptual level. The neural correlates of the taste-expectancy relationship were explored through EEG analysis. Using a trial-by-trial cueing paradigm, lingual delivery of 0.05 M or 0.3 M sucrose solutions was preceded by congruent or incongruent visual cues designed to promote anticipation of either a low-sweet or high-sweet solution. When participants were cued to expect low-sweet, but received high-sweet (incongruent cue), intensity ratings for high-sweet decreased. Likewise, expectation of high-sweet increased intensity ratings of low-sweet solutions. Taste-dependent, right central-parietal gustatory ERPs were detected, with greater P1 (associated with greater right insula activation) and P2 peak amplitudes for high-sweet tastes. Valid cue-taste pairings led to specific reduced right-lateralized N400 responses (associated with an attenuation in right insula activation) compared with invalid cue-taste pairings. Finally, P1 amplitudes following invalidly cued low-sweet tastes closely matched those generated by expected high-sweet tastes, and P1 amplitudes for invalidly cued high-sweet tastes resembled those generated by low-sweet tastes. We conclude that, as well as modifying subjective ratings toward the anticipated intensity level, expectations affect cortical activity in a top-down manner to induce bidirectional assimilation in the early perceptual processing of sweet taste and modulate N400 ERP components not previously associated with gustatory stimulation.
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http://dx.doi.org/10.1111/psyp.13299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392116PMC
March 2019

Brain Responses to Emotional Faces in Natural Settings: A Wireless Mobile EEG Recording Study.

Front Psychol 2018 25;9:2003. Epub 2018 Oct 25.

Department of Psychological Sciences, University of Liverpool, Liverpool, United Kingdom.

The detection of a human face in a visual field and correct reading of emotional expression of faces are important elements in everyday social interactions, decision making and emotional responses. Although brain correlates of face processing have been established in previous fMRI and electroencephalography (EEG)/MEG studies, little is known about how the brain representation of faces and emotional expressions of faces in freely moving humans. The present study aimed to detect brain electrical potentials that occur during the viewing of human faces in natural settings. 64-channel wireless EEG and eye-tracking data were recorded in 19 participants while they moved in a mock art gallery and stopped at times to evaluate pictures hung on the walls. Positive, negative and neutral valence pictures of objects and human faces were displayed. The time instants in which pictures first occurred in the visual field were identified in eye-tracking data and used to reconstruct the triggers in continuous EEG data after synchronizing the time axes of the EEG and eye-tracking device. EEG data showed a clear face-related event-related potential (ERP) in the latency interval ranging from 165 to 210 ms (N170); this component was not seen whilst participants were viewing non-living objects. The face ERP component was stronger during viewing disgusted compared to neutral faces. Source dipole analysis revealed an equivalent current dipole in the right fusiform gyrus (BA37) accounting for N170 potential. Our study demonstrates for the first time the possibility of recording brain responses to human faces and emotional expressions in natural settings. This finding opens new possibilities for clinical, developmental, social, forensic, or marketing research in which information about face processing is of importance.
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http://dx.doi.org/10.3389/fpsyg.2018.02003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209651PMC
October 2018

The effects of reward and loss anticipation on attentional bias for reward-related stimuli.

Appetite 2019 02 6;133:93-100. Epub 2018 Oct 6.

Department of Psychological Sciences, University of Liverpool, Eleanor Rathbone Building, Bedford Street South, Liverpool, L69 7ZA, United Kingdom; UK Centre for Tobacco and Alcohol Studies (UKCTAS), Liverpool, United Kingdom.

Attentional biases for reward-related (e.g., food, alcohol) cues are moderated by the expectation of imminent reward availability, but the psychological mechanisms that underlie this effect are unclear. We report two studies in which we investigated if effects of reward gain anticipation are specific to the type of reward that is anticipated, and if anticipation of loss has comparable effects to anticipation of reward gain. We used an eye tracking task to investigate the effects of anticipation of gain (experiment 1) or loss (experiment 2) of alcohol and chocolate on attentional bias for alcohol and chocolate pictures using full crossover designs; the effects of uncertain outcomes were investigated in both experiments. Results indicated robust effects of anticipation of reward gain and uncertainty on attentional bias that were outcome-specific (experiment 1). However attentional bias was not influenced by loss anticipation (experiment 2). Our findings demonstrate that anticipation of reward gain increases attentional bias for the type of reward that is anticipated, but anticipation of loss does not influence attentional bias.
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http://dx.doi.org/10.1016/j.appet.2018.10.007DOI Listing
February 2019

Attentional modulation of desensitization to odor.

Atten Percept Psychophys 2018 Jul;80(5):1064-1071

Department of Psychological Sciences, Institute of Psychology, Health, and Society, University of Liverpool, Eleanor Rathbone Building, Bedford Street South, Liverpool, L69 7ZA, UK.

Subjective and behavioral responsiveness to odor diminishes during prolonged exposure. The precise mechanisms underlying olfactory desensitization are not fully understood, but previous studies indicate that the phenomenon may be modulated by central-cognitive processes. The present study investigated the effect of attention on perceived intensity during exposure to a pleasant odor. A within-subjects design was utilized with 19 participants attending 2 sessions. During each session, participants continuously rated their perceived intensity of a 10-minute exposure to a pleasant fragrance administered using an olfactometer. An auditory oddball task was implemented to manipulate the focus of attention in each session. Participants were instructed to either direct their attention toward the sounds, but still to rate odor, or to focus entirely on rating the odor. Analysis revealed three 50-second time windows with significantly lower mean intensity ratings during the distraction condition. Curve fitting of the data disclosed a linear function of desensitization in the focused attention condition compared with an exponential decay function during distraction condition, indicating an increased rate of initial desensitization when attention is distracted away from the odor. In the focused-attention condition, perceived intensity demonstrated a regular pattern of odor sensitivity occurring at approximately 1-2 minutes intervals following initial desensitization. Spectral analysis of low-frequency oscillations confirmed the presence of augmented spectral power in this frequency range during focused relative to distracted conditions. The findings demonstrate for the first time modulation of odor desensitization specifically by attentional factors, exemplifying the relevance of top-down control for ongoing perception of odor.
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http://dx.doi.org/10.3758/s13414-018-1539-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6061002PMC
July 2018

Simultaneous odour-face presentation strengthens hedonic evaluations and event-related potential responses influenced by unpleasant odour.

Neurosci Lett 2018 04 18;672:22-27. Epub 2018 Feb 18.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK. Electronic address:

Odours alter evaluations of concurrently presented visual stimuli, such as faces. Stimulus onset asynchrony (SOA) is known to affect evaluative priming in various sensory modalities. However, effects of SOA on odour priming of visual stimuli are not known. The present study aimed to analyse whether subjective and cortical activation changes during odour priming would vary as a function of SOA between odours and faces. Twenty-eight participants rated faces under pleasant, unpleasant, and no-odour conditions using visual analogue scales. In half of trials, faces appeared one-second after odour offset (SOA 1). In the other half of trials, faces appeared during the odour pulse (SOA 2). EEG was recorded continuously using a 128-channel system, and event-related potentials (ERPs) to face stimuli were evaluated using statistical parametric mapping (SPM). Faces presented during unpleasant-odour stimulation were rated significantly less pleasant than the same faces presented one-second after offset of the unpleasant odour. Scalp-time clusters in the late-positive-potential (LPP) time-range showed an interaction between odour and SOA effects, whereby activation was stronger for faces presented simultaneously with the unpleasant odour, compared to the same faces presented after odour offset. Our results highlight stronger unpleasant odour priming with simultaneous, compared to delayed, odour-face presentation. Such effects were represented in both behavioural and neural data. A greater cortical and subjective response during simultaneous presentation of faces and unpleasant odour may have an adaptive role, allowing for a prompt and focused behavioural reaction to a concurrent stimulus if an aversive odour would signal danger, or unwanted social interaction.
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http://dx.doi.org/10.1016/j.neulet.2018.02.032DOI Listing
April 2018

Neural correlates of economic value and valuation context: an event-related potential study.

J Neurophysiol 2018 05 14;119(5):1924-1933. Epub 2018 Feb 14.

Department of Psychological Sciences, University of Liverpool , Liverpool , United Kingdom.

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 ∼200 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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http://dx.doi.org/10.1152/jn.00524.2017DOI Listing
May 2018

Neural Mechanisms of Attentional Switching Between Pain and a Visual Illusion Task: A Laser Evoked Potential Study.

Brain Topogr 2018 05 19;31(3):430-446. Epub 2017 Dec 19.

Department of Psychological Sciences, University of Liverpool, Liverpool, L69 7ZA, UK.

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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http://dx.doi.org/10.1007/s10548-017-0613-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5889779PMC
May 2018

Hip arthroscopy learning curve: a prospective single-surgeon study.

Int Orthop 2018 04 18;42(4):777-782. Epub 2017 Oct 18.

Department of Orthopaedics and Traumatology, 2nd Faculty of Medicine, Motol Hospital Prague, Charles University, V Uvalu 84, 15006, Prague, Czech Republic.

Purpose: Arthroscopy of the hip joint is considered a demanding procedure with long learning curve. There are only a few studies that concentrate on this topic. This prospective clinical study evaluates the learning curve of the hip arthroscopy based on clinical outcomes, surgical time, and complication rate.

Materials: In this study, we first evaluated 150 hip arthroscopy procedures performed by a single surgeon. The patient group consisted of 86 females and 64 males with mean age 37 years (range 16-69). Study cohorts were divided into groups of 50 patients. Surgical time, complication rate and clinical results based on NAHS score were recorded for each group. Statistical analysis of differences between groups was performed using the ANOVA method and paired t-test.

Results: We found a statistically significant decrease of complication rate with more procedures performed. There were significantly better clinical outcomes after at least 100 procedures. No difference in surgical time was found, but towards the end of the learning curve, more complex procedures were performed. The only statistical difference was the portal setup time. The learning curves were constructed based on these results.

Conclusions: Hip arthroscopy provides very good clinical outcomes if precisely indicated and performed. It is, however, a demanding procedure with many possible pitfalls and complications. According to our study, at least 100 procedures are needed to gain basic technical and indication skills. The presence of a more skilled surgeon in the beginning of the learning curve is advised to reduce the complication rate.
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http://dx.doi.org/10.1007/s00264-017-3666-0DOI Listing
April 2018

Pleasant and unpleasant odour-face combinations influence face and odour perception: An event-related potential study.

Behav Brain Res 2017 08 14;333:304-313. Epub 2017 Jul 14.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK. Electronic address:

Odours alter evaluations of concurrent visual stimuli. However, neural mechanisms underlying the effects of congruent and incongruent odours on facial expression perception are not clear. Moreover, the influence of emotional faces on odour perception is not established. We investigated the effects of one pleasant and one unpleasant odour paired with happy and disgusted faces, on subjective ratings and ERP responses to faces. Participants rated the pleasantness of happy and disgusted faces that appeared during 3s pleasant or unpleasant odour pulses, or without odour. Odour pleasantness and intensity ratings were recorded in each trial. EEG was recorded continuously using a 128-channel system. Happy and disgusted faces paired with pleasant and unpleasant odour were rated as more or less pleasant, respectively, compared to the same faces presented in the other odour conditions. Odours were rated as more pleasant when paired with happy faces, and unpleasant odour was rated more intense when paired with disgusted faces. Unpleasant odour paired with disgusted faces also decreased inspiration. Odour-face interactions were evident in the N200 and N400 components. Our results reveal bi-directional effects of odours and faces, and suggest that odour-face interactions may be represented in ERP components. Pairings of unpleasant odour and disgusted faces resulted in stronger hedonic ratings, ERP changes, increased odour intensity ratings and respiratory adjustment. This finding likely represents heightened adaptive responses to multimodal unpleasant stimuli, prompting appropriate behaviour in the presence of danger.
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http://dx.doi.org/10.1016/j.bbr.2017.07.010DOI Listing
August 2017

Effects of loss aversion on neural responses to loss outcomes: An event-related potential study.

Biol Psychol 2017 05 8;126:30-40. Epub 2017 Apr 8.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK; Institute for Risk and Uncertainty, University of Liverpool, Liverpool, UK. Electronic address:

Loss aversion is the tendency to prefer avoiding losses over acquiring gains of the same amount. To shed light on the spatio-temporal processes underlying loss aversion, we analysed the associations between individual loss aversion and electrophysiological responses to loss and gain outcomes in a monetary gamble task. Electroencephalographic feedback-related negativity (FRN) was computed in 29 healthy participants as the difference in electrical potentials between losses and gains. Loss aversion was evaluated using non-linear parametric fitting of choices in a separate gamble task. Loss aversion correlated positively with FRN amplitude (233-263ms) at electrodes covering the lower face. Feedback related potentials were modelled by five equivalent source dipoles. From these dipoles, stronger activity in a source located in the orbitofrontal cortex was associated with loss aversion. The results suggest that loss aversion implemented during risky decision making is related to a valuation process in the orbitofrontal cortex, which manifests during learning choice outcomes.
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http://dx.doi.org/10.1016/j.biopsycho.2017.04.005DOI Listing
May 2017

Compensatory changes in energy balance during dapagliflozin treatment in type 2 diabetes mellitus: a randomised double-blind, placebo-controlled, cross-over trial (ENERGIZE)-study protocol.

BMJ Open 2017 01 27;7(1):e013539. Epub 2017 Jan 27.

Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.

Introduction: Sodium glucose cotransporter 2 (SGLT2) inhibitors are effective blood-glucose-lowering medications with beneficial effects on body weight in patients with type 2 diabetes mellitus (T2DM). However, observed weight loss is less than that predicted from quantified glycosuria, suggesting a compensatory increase in energy intake or a decrease in energy expenditure. Studies using dual-energy X-ray absorptiometry (DEXA) have suggested most body weight change is due to loss of adipose tissue, but organ-specific changes in fat content (eg, liver, skeletal muscle) have not been determined. In this randomised, double-blind, placebo-controlled crossover study, we aim to study the compensatory changes in energy intake, eating behaviour and energy expenditure accompanying use of the SGLT2 inhibitor, dapagliflozin. Additionally, we aim to quantify changes in fat distribution using MRI, in liver fat using proton magnetic resonance spectroscopy (H-MRS) and in central nervous system (CNS) responses to food images using blood oxygen level dependent (BOLD) functional MRI (fMRI).

Methods And Analysis: This outpatient study will evaluate the effect of dapagliflozin (10 mg), compared with placebo, on food intake and energy expenditure at 7 days and 12 weeks. 52 patients with T2DM will be randomised to dapagliflozin or placebo for short-term and long-term trial interventions in a within participants, crossover design. The primary outcome is the difference in energy intake during a test meal between dapagliflozin and placebo. Intake data are collected automatically using a customised programme operating a universal eating monitor (UEM). Secondary outcomes include (1) measures of appetite regulation including rate of eating, satiety quotient, appetite ratings (between and within meals), changes in CNS responses to food images measured using BOLD-fMRI, (2) measures of energy expenditure and (3) changes in body composition including changes in liver fat and abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT).

Ethical Approval: This study has been approved by the North West Liverpool Central Research Ethics Committee (14/NW/0340) and is conducted in accordance with the Declaration of Helsinki and the Good Clinical Practice (GCP).

Trial Registration Number: ISRCTN14818531. EUDRACT number 2013-004264-60.
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http://dx.doi.org/10.1136/bmjopen-2016-013539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5278268PMC
January 2017

Functional Connectivity with the Default Mode Network Is Altered in Fibromyalgia Patients.

PLoS One 2016 21;11(7):e0159198. Epub 2016 Jul 21.

Department of Psychological Sciences, Institute of Psychology, Health, and Society, University of Liverpool, Liverpool, United Kingdom.

Fibromyalgia syndrome (FMS) patients show altered connectivity with the network maintaining ongoing resting brain activity, known as the default mode network (DMN). The connectivity patterns of DMN with the rest of the brain in FMS patients are poorly understood. This study employed seed-based functional connectivity analysis to investigate resting-state functional connectivity with DMN structures in FMS. Sixteen female FMS patients and 15 age-matched, healthy control subjects underwent T2-weighted resting-state MRI scanning and functional connectivity analyses using DMN network seed regions. FMS patients demonstrated alterations to connectivity between DMN structures and anterior midcingulate cortex, right parahippocampal gyrus, left superior parietal lobule and left inferior temporal gyrus. Correlation analysis showed that reduced functional connectivity between the DMN and the right parahippocampal gyrus was associated with longer duration of symptoms in FMS patients, whereas augmented connectivity between the anterior midcingulate and posterior cingulate cortices was associated with tenderness and depression scores. Our findings demonstrate alterations to functional connectivity between DMN regions and a variety of regions which are important for pain, cognitive and emotional processing in FMS patients, and which may contribute to the development or maintenance of chronic symptoms in FMS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159198PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956096PMC
July 2017

Data to support observation of late and ultra-late latency components of cortical laser evoked potentials.

Data Brief 2015 Dec 23;5:1031-4. Epub 2015 Nov 23.

Department of Psychological Sciences, University of Liverpool, Liverpool L69 7ZA United Kingdom.

Data are provided to document the presence of late and ultra-late latency components of cortical laser evoked potentials (LEPs) following noxious laser stimulus in Stancak et al. (2015) [3]. The latency components, labeled provisionally as N4, N5, and N6, were observed in 16 healthy human participants who were asked to fully attend their painful and non-painful sensations occurring in association with noxious laser stimulus. Individual laser evoked potential waveforms are provided in support of this observation. Data provided demonstrate the cortical sources of the late and ultra-late laser evoked potentials. The cortical sources of LEPs were reconstructed using the standardized Low Resolution Electromagnetic Tomography (sLORETA) method.
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http://dx.doi.org/10.1016/j.dib.2015.11.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4689109PMC
December 2015

Differential effects of hunger and satiety on insular cortex and hypothalamic functional connectivity.

Eur J Neurosci 2016 05 20;43(9):1181-9. Epub 2016 Feb 20.

Department of Psychological Sciences, Eleanor Rathbone Building, Bedford Street South, Liverpool, L69 7ZA, UK.

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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http://dx.doi.org/10.1111/ejn.13182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4982083PMC
May 2016

Pleasant and Unpleasant Odors Influence Hedonic Evaluations of Human Faces: An Event-Related Potential Study.

Front Hum Neurosci 2015 16;9:661. Epub 2015 Dec 16.

Department of Psychological Sciences, University of Liverpool Liverpool, UK.

Odors can alter hedonic evaluations of human faces, but the neural mechanisms of such effects are poorly understood. The present study aimed to analyze the neural underpinning of odor-induced changes in evaluations of human faces in an odor-priming paradigm, using event-related potentials (ERPs). Healthy, young participants (N = 20) rated neutral faces presented after a 3 s pulse of a pleasant odor (jasmine), unpleasant odor (methylmercaptan), or no-odor control (clean air). Neutral faces presented in the pleasant odor condition were rated more pleasant than the same faces presented in the no-odor control condition, which in turn were rated more pleasant than faces in the unpleasant odor condition. Analysis of face-related potentials revealed four clusters of electrodes significantly affected by odor condition at specific time points during long-latency epochs (600-950 ms). In the 620-640 ms interval, two scalp-time clusters showed greater negative potential in the right parietal electrodes in response to faces in the pleasant odor condition, compared to those in the no-odor and unpleasant odor conditions. At 926 ms, face-related potentials showed greater positivity in response to faces in the pleasant and unpleasant odor conditions at the left and right lateral frontal-temporal electrodes, respectively. Our data shows that odor-induced shifts in evaluations of faces were associated with amplitude changes in the late (>600) and ultra-late (>900 ms) latency epochs. The observed amplitude changes during the ultra-late epoch are consistent with a left/right hemisphere bias towards pleasant/unpleasant odor effects. Odors alter evaluations of human faces, even when there is a temporal lag between presentation of odors and faces. Our results provide an initial understanding of the neural mechanisms underlying effects of odors on hedonic evaluations.
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http://dx.doi.org/10.3389/fnhum.2015.00661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681274PMC
January 2016

Mapping multidimensional pain experience onto electrophysiological responses to noxious laser heat stimuli.

Neuroimage 2016 Jan 23;125:244-255. Epub 2015 Oct 23.

Department of Psychological Sciences, University of Liverpool, Liverpool L69 7ZA, UK.

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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http://dx.doi.org/10.1016/j.neuroimage.2015.10.028DOI Listing
January 2016

Pain Catastrophising Affects Cortical Responses to Viewing Pain in Others.

PLoS One 2015 17;10(7):e0133504. Epub 2015 Jul 17.

Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool, United Kingdom.

Pain catastrophising is an exaggerated cognitive attitude implemented during pain or when thinking about pain. Catastrophising was previously associated with increased pain severity, emotional distress and disability in chronic pain patients, and is also a contributing factor in the development of neuropathic pain. To investigate the neural basis of how pain catastrophising affects pain observed in others, we acquired EEG data in groups of participants with high (High-Cat) or low (Low-Cat) pain catastrophising scores during viewing of pain scenes and graphically matched pictures not depicting imminent pain. The High-Cat group attributed greater pain to both pain and non-pain pictures. Source dipole analysis of event-related potentials during picture viewing revealed activations in the left (PHGL) and right (PHGR) paraphippocampal gyri, rostral anterior (rACC) and posterior cingulate (PCC) cortices. The late source activity (600-1100 ms) in PHGL and PCC was augmented in High-Cat, relative to Low-Cat, participants. Conversely, greater source activity was observed in the Low-Cat group during the mid-latency window (280-450 ms) in the rACC and PCC. Low-Cat subjects demonstrated a significantly stronger correlation between source activity in PCC and pain and arousal ratings in the long latency window, relative to high pain catastrophisers. Results suggest augmented activation of limbic cortex and higher order pain processing cortical regions during the late processing period in high pain catastrophisers viewing both types of pictures. This pattern of cortical activations is consistent with the distorted and magnified cognitive appraisal of pain threats in high pain catastrophisers. In contrast, high pain catastrophising individuals exhibit a diminished response during the mid-latency period when attentional and top-down resources are ascribed to observed pain.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0133504PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4505849PMC
May 2016

Altered cortical processing of observed pain in patients with fibromyalgia syndrome.

J Pain 2015 Aug 12;16(8):717-26. Epub 2015 May 12.

Department Psychological Sciences, Institute of Psychology, Health, and Society, University of Liverpool, Liverpool, United Kingdom.

Unlabelled: Fibromyalgia syndrome (FMS) is characterized by widespread chronic pain, fatigue, sleep disorders, and cognitive-emotional disturbance. Patients with FMS exhibit increased sensitivity to experimental pain and pain-related cues, as well as deficits in emotional regulation. The present study investigated the spatiotemporal patterns of brain activations for observed pain in 19 patients with FMS and 18 age-matched, healthy control individuals using event-related potential analysis. Patients with FMS attributed greater pain and unpleasantness to pain pictures, relative to healthy control participants. An augmented late positive potential (LPP) component (>500 milliseconds) was found in patients viewing both pain and nonpain pictures, and this amplitude difference in the LPP covaried with perceived unpleasantness of pictures. Mid-latency potentials (250-450 milliseconds) demonstrated similar amplitude increases of positive potentials in the FMS patient group. By contrast, the short-latency positive potential (140 milliseconds) was reduced in patients with FMS relative to healthy control participants. Results suggest amplitude increases to mid- to long-latency cortical activations in patients with FMS, which are known to reflect emotional control and motivational salience of stimuli.

Perspective: Patients with FMS demonstrate increased activations associated with pain and nonpain pictures. The findings suggest that even innocuous, everyday visual stimuli with somatic connotations may challenge the emotional state of patients with FMS. Our study points toward the importance of cognitive-emotional therapeutic approaches for the treatment of FMS.
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http://dx.doi.org/10.1016/j.jpain.2015.04.008DOI Listing
August 2015
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