Aikaterini Fotopoulou | University College London (original) (raw)

Papers by Aikaterini Fotopoulou

eLife, Aug 6, 2019

The syndrome of Anosognosia for Hemiplegia (AHP) can provide unique insights into the neurocognit... more The syndrome of Anosognosia for Hemiplegia (AHP) can provide unique insights into the neurocognitive processes of motor awareness. Yet, prior studies have only explored predominately discreet lesions. Using advanced structural neuroimaging methods in 174 patients with a right-hemisphere stroke, we were able to identify three neural systems that contribute to AHP, when disconnected or directly damaged: the (i) premotor loop (ii) limbic system, and (iii) ventral attentional network. Our results suggest that human motor awareness is contingent on the joint contribution of these three systems.

Philosophical Transactions of the Royal Society B, Nov 19, 2016

Affective touch and cutaneous pain are two sub-modalities of interoception with contrasting affec... more Affective touch and cutaneous pain are two sub-modalities of interoception with contrasting affective qualities (pleasantness/unpleasantness) and social meanings (care/harm), yet their direct relationship has not been investigated. In 50 women, taking into account individual attachment styles, we assessed the role of affective touch and particularly the contribution of the C tactile (CT) system in subjective and electrophysiological responses to noxious skin stimulation, namely N1 and N2-P2 laser-evoked potentials. When pleasant, slow (versus fast) velocity touch was administered to the (non-CT-containing) palm of the hand, higher attachment anxiety predicted increased subjective pain ratings, in the same direction as changes in N2 amplitude. By contrast, when pleasant touch was administered to CT-containing skin of the arm, higher attachment anxiety predicted attenuated N1 and N2 amplitudes. Higher attachment avoidance predicted opposite results. Thus, CT-based affective touch can modulate pain in early and late processing stages (N1 and N2 components), with the direction of effects depending on attachment style. Affective touch not involving the CT system seems to affect predominately the conscious perception of pain, possibly reflecting socio-cognitive factors further up the neurocognitive hierarchy. Affective touch may thus convey information about available social resources and gate pain responses depending on individual expectations of social support. This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Scientific Reports

Previous studies suggest a stronger influence of visual signals on body image in individuals with... more Previous studies suggest a stronger influence of visual signals on body image in individuals with eating disorders (EDs) than healthy controls; however, the influence of other exteroceptive sensory signals remains unclear. Here we used an illusion relying on auditory (exteroceptive) signals to manipulate body size/weight perceptions and investigated whether the mechanisms integrating sensory signals into body image are altered in subclinical and clinical EDs. Participants’ footstep sounds were altered to seem produced by lighter or heavier bodies. Across two experiments, we tested healthy women assigned to three groups based on self-reported Symptomatology of EDs (SED), and women with Anorexia Nervosa (AN), and used self-report, body-visualization, and behavioural (gait) measures. As with visual bodily illusions, we predicted stronger influence of auditory signals, leading to an enhanced body-weight illusion, in people with High-SED and AN. Unexpectedly, High-SED and AN participants...

Our perception of our personal space extends beyond the body to incorporate the space where inter... more Our perception of our personal space extends beyond the body to incorporate the space where inter-actions with the environment occur, i.e. peripersonal space (PPS), and the distance we feel comforta-ble in maintaining while interacting with other people, termed interpersonal space. Studies suggest that after positive interpersonal exchanges, PPS expands in order to create a space for interaction, while interpersonal space becomes smaller. However, little is known about how this malleability of our peripersonal and interpersonal space based on social context can be shaped by key individual traits of interpersonal relating, such as attachment style. In a first, exploratory study (N=48) using a visuo-tactile detection task in augmented reality, we found that when people scoring higher in attachment anxiety are in the presence of a stranger, relative to alone, their PPS becomes less defined, whereas the reverse pattern is observed in people scoring lower in attachment anxiety. In a foll...

Social touch has positive effects on social affiliation and stress alleviation. However, its ubiq... more Social touch has positive effects on social affiliation and stress alleviation. However, its ubiquitous presence in human life does not allow the study of social touch deprivation ‘in the wild’. Nevertheless, COVID-19-related restrictions such as social distancing allowed the systematic study of the degree to which social distancing affects tactile experiences and mental health. In this study, 1746 participants completed an online-survey to examine intimate, friendly and professional touch experiences during COVID-19-related restrictions, their impact on mental health and the extent to which touch deprivation results in craving touch. We found that intimate touch deprivation during COVID-19-related restrictions is associated with worse psychological wellbeing, even though this type of touch is still the most experienced during the pandemic. Moreover, intimate touch is reported as the type of touch most craved during this period, thus being more prominent as the days practicing socia...

People tend to evaluate their own traits and abilities favourably and such favourable self-percep... more People tend to evaluate their own traits and abilities favourably and such favourable self-perceptions extend to attractiveness. However, the exact mechanism underlying this self-enhancement bias remains unclear and one possibility could be the identification with attractive others through blurring of self-other boundaries. Across two experiments, we used the enfacement illusion to investigate the effect of the attractiveness of others in the multisensory perception of the self. In a first experiment (N=35), participants were stroked on the cheek while looking at an attractive vs. non-attractive face being stroked on the cheek in synchrony or asynchrony. In the second experiment (N=35), two new faces were used and spatial incοngruency was introduced as a control condition. The results showed that increased ratings of attractiveness of an unfamiliar face lead to blurring of self-other boundaries, allowing the identification of our psychological self with another's physical self, ...

Disruptions in reward processing and anhedonia have long being considered as possible contributor... more Disruptions in reward processing and anhedonia have long being considered as possible contributors to the aetiology and maintenance of Anorexia nervosa (AN). Recently, interoceptive deficits have also been observed in AN, including reduced tactile pleasure. However, the extent to which this tactile anhedonia is specifically liked to an impairment in a specialized, interoceptive C tactile system originating at the periphery, or a more top-down mechanism in the processing of pleasant tactile stimuli remains debated. Here, we investigated two related hypotheses. First, we examined whether the differences, between patients with AN and healthy controls in the perception of pleasantness of touch stimuli delivered in a CT-optimal manner versus a CT non-optimal manner would also be observed in patients recovered from AN. This is important as tactile anhedonia in acute patients may be the secondary result of prolonged malnutrition, rather than a deficit that contributed to the development of...

Our sense of body ownership relies on integrating different sensations according to their tempora... more Our sense of body ownership relies on integrating different sensations according to their temporal and spatial congruency. Nevertheless, there is ongoing controversy about the role ofaffective congruencyduring multisensory integration, i.e. whether the stimuli to be perceived by the different sensory channels are congruent or incongruent in terms of their affective quality. In the present study, we applied a widely used multisensory integration paradigm, the Rubber Hand Illusion, to investigate the role of affective, top-down aspects of sensory congruency between visual and tactile modalities in the sense of body ownership. In Experiment 1 (N = 36), we touched participants with either soft or rough fabrics in their unseen hand, while they watched a rubber hand been touched synchronously with the same fabric or with a ‘hidden’ fabric of ‘uncertain roughness’. In Experiment 2 (N = 50), we used the same paradigm as in Experiment 1, but replaced the ‘uncertainty’ condition with an ‘inco...

Touch can give rise to different sensations including sensory, emotional and social aspects. Tact... more Touch can give rise to different sensations including sensory, emotional and social aspects. Tactile pleasure typically associated with caress-like skin stroking of slow velocities (1-10 cm/s) has been hypothesised to relate to an unmyelinated, slow-conducting C-tactile afferent system (CT system), developed to distinguish affective touch from the ‘‘noise’’ of other tactile information on hairy skin (the so-called ‘social touch hypothesis’). However, to date, there is no psychometric examination of the discriminative and metacognitive processes that contribute to accurate awareness of pleasant touch stimuli. Over two studies (total N= 194), we combined for the first time CT stimulation with signal detection theory and metacognitive measurements to assess the social touch hypothesis on the role of the CT system in affective touch discrimination. Participants’ ability to accurately discriminate pleasantness of tactile stimuli of different velocities, as well as their response bias, wa...

BMJ Open, 2019

IntroductionAnorexia nervosa (AN) is an eating disorder characterised by restriction of energy in... more IntroductionAnorexia nervosa (AN) is an eating disorder characterised by restriction of energy intake, fears of gaining weight and related body image disturbances. The oxytocinergic system has been proposed as a pathophysiological candidate for AN. Oxytocin is a neuropeptide involved in bodily processes (eg, breast feeding) and in the onset of social behaviours (eg, bonding). Studies investigating the effect of intranasal oxytocin (IN-OT) in AN showed that it can improve attentional bias for high-calorie food and fat bodies stimuli, and related stress. However, less is known about the effect of IN-OT on bodily awareness and body image distortions, key features of the disorder linked to its development, prognosis and maintenance. Here, we aim to investigate the effect of IN-OT on the perception of affective, C-tactile-optimal touch, known to be impaired in AN and on multisensory integration processes underlying a body ownership illusion (ie, rubber hand illusion). For exploratory pur...

Journal of Cognitive Neuroscience, 2018

Multisensory integration processes are fundamental to our sense of self as embodied beings. Bodil... more Multisensory integration processes are fundamental to our sense of self as embodied beings. Bodily illusions, such as the rubber hand illusion (RHI) and the size–weight illusion (SWI), allow us to investigate how the brain resolves conflicting multisensory evidence during perceptual inference in relation to different facets of body representation. In the RHI, synchronous tactile stimulation of a participant's hidden hand and a visible rubber hand creates illusory body ownership; in the SWI, the perceived size of the body can modulate the estimated weight of external objects. According to Bayesian models, such illusions arise as an attempt to explain the causes of multisensory perception and may reflect the attenuation of somatosensory precision, which is required to resolve perceptual hypotheses about conflicting multisensory input. Recent hypotheses propose that the precision of sensorimotor representations is determined by modulators of synaptic gain, like dopamine, acetylchol...

Social Cognitive and Affective Neuroscience, 2018

Pain is modulated by social context. Recent neuroimaging studies have shown that romantic partner... more Pain is modulated by social context. Recent neuroimaging studies have shown that romantic partners can provide a potent form of social support during pain. However, such studies have only focused on passive support, finding a relatively late-onset modulation of pain-related neural processing. In this study, we examined for the first time dynamic touch by one's romantic partner as an active form of social support. Specifically, 32 couples provided social, active, affective (vs active but neutral) touch according to the properties of a specific C-tactile afferent pathway to their romantic partners, who then received laser-induced pain. We measured subjective pain ratings and early N1 and later N2-P2 laser-evoked potentials (LEPs) to noxious stimulation, as well as individual differences in adult attachment style. We found that affective touch from one's partner reduces subjective pain ratings and similarly attenuates LEPs both at earlier (N1) and later (N2-P2) stages of cortical processing. Adult attachment style did not affect LEPs, but attachment anxiety had a moderating role on pain ratings. This is the first study to show early neural modulation of pain by active, partner touch, and we discuss these findings in relation to the affective and social modulation of sensory salience.

Oxford Scholarship Online, 2018

Pain and pleasant touch have been recently classified as interoceptive modalities. This reclassif... more Pain and pleasant touch have been recently classified as interoceptive modalities. This reclassification lies at the heart of long-standing debates questioning whether these modalities should be defined as sensations on their basis of neurophysiological specificity at the periphery or as homeostatic emotions on the basis of top-down convergence and modulation at the spinal and brain levels. Here, we outline the literature on the peripheral and central neurophysiology of pain and pleasant touch. We next recast this literature within a recent Bayesian predictive coding framework, namely active inference. This recasting puts forward a unifying model of bottom-up and top-down determinants of pain and pleasant touch and the role of social factors in modulating the salience of peripheral signals reaching the brain.

Developmental cognitive neuroscience, Jan 31, 2018

Increasing evidence shows that maternal touch may promote emotion regulation in infants, however ... more Increasing evidence shows that maternal touch may promote emotion regulation in infants, however less is known about how parental higher-order social cognition abilities are translated into tactile, affect-regulatory behaviours towards their infants. During 10 min book-reading, mother-infant sessions when infants were 12 months old (N = 45), we investigated maternal mind-mindedness (MM), the social cognitive ability to understand an infant's mental state, by coding the contingency of maternal verbal statements towards the infants' needs and desires. We also rated spontaneous tactile interactions in terms of their emotional contingency. We found that frequent non-attuned mind-related comments were associated with touch behaviours that were not contingent with the infant's emotions; ultimately discouraging affective tactile responses from the infant. However, comments that were more appropriate to infant's mental states did not necessarily predict more emotionally-cont...

Scientific reports, Jan 10, 2017

Multisensory integration is a powerful mechanism for constructing body awareness and key for the ... more Multisensory integration is a powerful mechanism for constructing body awareness and key for the sense of selfhood. Recent evidence has shown that the specialised C tactile modality that gives rise to feelings of pleasant, affective touch, can enhance the experience of body ownership during multisensory integration. Nevertheless, no study has examined whether affective touch can also modulate psychological identification with our face, the hallmark of our identity. The current study used the enfacement illusion paradigm to investigate the role of affective touch in the modulation of self-face recognition during multisensory integration. In the first experiment (N = 30), healthy participants were stroked on the cheek while they were looking at another face being stroked on the cheek in synchrony or asynchrony with affective (slow; CT-optimal) vs. neutral (fast; CT-suboptimal) touch. In the second experiment (N = 38) spatial incongruence of touch (cheek vs. forehead) was used as a con...

Scientific reports, Jan 18, 2017

The mammalian need for social proximity, attachment and belonging may have an adaptive and evolut... more The mammalian need for social proximity, attachment and belonging may have an adaptive and evolutionary value in terms of survival and reproductive success. Consequently, ostracism may induce strong negative feelings of social exclusion. Recent studies suggest that slow, affective touch, which is mediated by a separate, specific C tactile neurophysiological system than faster, neutral touch, modulates the perception of physical pain. However, it remains unknown whether slow, affective touch, can also reduce feelings of social exclusion, a form of social pain. Here, we employed a social exclusion paradigm, namely the Cyberball task (N = 84), to examine whether the administration of slow, affective touch may reduce the negative feelings of ostracism induced by the social exclusion manipulations of the Cyberball task. As predicted, the provision of slow-affective, as compared to fast-neutral, touch led to a specific decrease in feelings of social exclusion, beyond general mood effects....

Philosophical Transactions of the Royal Society B: Biological Sciences, 2016

Individuals differ in their awareness of afferent information from within their bodies, which is ... more Individuals differ in their awareness of afferent information from within their bodies, which is typically assessed by a heartbeat perception measure of ‘interoceptive accuracy’ (IAcc). Neural and behavioural correlates of this trait have been investigated, but a theoretical explanation has yet to be presented. Building on recent models that describe interoception within the free energy/predictive coding framework, this paper applies similar principles to IAcc, proposing that individual differences in IAcc depend on ‘precision’ in interoceptive systems, i.e. the relative weight accorded to ‘prior’ representations and ‘prediction errors’ (that part of incoming interoceptive sensation not accounted for by priors), at various levels within the cortical hierarchy and between modalities. Attention has the effect of optimizing precision both within and between sensory modalities. Our central assumption is that people with high IAcc are able, with attention, to prioritize interoception ove...

Psychiatry Research, 2016

Anorexia nervosa (AN) is a disorder characterized by restricted eating, fears of gaining weight, ... more Anorexia nervosa (AN) is a disorder characterized by restricted eating, fears of gaining weight, and body image distortions. The etiology remains unknown; however impairments in social cognition and reward circuits contribute to the onset and maintenance of the disorder. One possibility is that AN is associated with reduced perceived pleasantness during social interactions. We therefore examined the perception of interpersonal, 'affective touch' and its social modulation in AN. We measured the perceived pleasantness of light, dynamic stroking touches applied to the forearm of 25 AN patients and 30 healthy controls using C Tactile (CT) afferents-optimal (3cm/s) and non-optimal (18cm/s) velocities, while simultaneously displaying images of faces showing rejecting, neutral and accepting expressions. CT-optimal touch, but not CT non-optimal touch, elicited significantly lower pleasantness ratings in AN patients compared with healthy controls. Pleasantness ratings were modulated by facial expressions in both groups in a similar fashion; namely, presenting socially accepting faces increased the perception of touch pleasantness more than neutral and rejecting faces. Our findings suggest that individuals with AN have a disordered, CT-based affective touch system. This impairment may be linked to their weakened interoceptive perception and distorted body representation.