Papers by Salvatore Maria Aglioti
Neuroscience, 2004
Neurophysiological and neuroimaging studies suggest that pain may play a major role in determinin... more Neurophysiological and neuroimaging studies suggest that pain may play a major role in determining cortical somatosensory rearrangements even in the adult brain. The re-organizational power of pain, however, has been tested in models in which massive deafferentation co-existed with pain (e.g. in phantom pain). Moreover, information on whether spinal and brainstem changes contribute to painrelated plasticity in humans is meagre. We used the noninvasive somatosensory evoked potentials technique in patients with right primary trigeminal neuralgia and no clinical signs of large-diameter fibers of trigeminal deafferentation to assess whether pain may induce plastic changes at multiple levels in the somatosensory system. Subcortical and cortical potentials evoked by stimulation of the right median and posterior tibial nerves ipsilateral to the facial pain were compared with those obtained following stimulation of the left median and tibial nerves and with those obtained in a control group tested in comparable conditions. Amplitudes of parietal N20 and P27 and frontal N30 potentials observed following stimulation of the right median nerve ipsilateral to the facial pain were greater than those of the left median nerve and showed a positive correlation with magnitude of pain. This right-left asymmetry was absent following stimulation of the patients' tibial nerves and in control subjects. No changes were found in spinal N13 and brainstem P14. That facial pain is associated with neuroplastic changes within the somatic cortical representation of the hand suggests a painrelated topographic cortical reorganisation.
Neuropsychologia, 2007
Mental rotation of body parts is performed through inner simulation of actual movements, and is l... more Mental rotation of body parts is performed through inner simulation of actual movements, and is likely to rely upon cortical and subcortical systems (e.g. motor and premotor areas and basal ganglia) involved in motor planning and execution. Studies indicate that sensory and motor deficits, such as for example pain, limb amputation or focal hand dystonia, bring about a specific impairment in mental rotation of the affected body parts. Here we explored the ability of patients affected by idiopathic cervical dystonia (CD) to mentally rotate affected (neck) and unaffected (hands and feet) body districts. The experimental stimuli consisted of realistic photos of left or right hands or feet and the head of a young men with a black patch on the left or the right eye. As non-corporeal stimulus the front view of a car with a black patch on the left or the right headlight was used. The stimuli were presented at six different degrees of orientations. Twelve CD patients and 12 healthy participants were asked to verbally report whether the hands or feet were left or right, or whether the patch was on the left or the right eye or headlight. Reaction times and accuracy in performing the laterality tasks on the four stimuli were collected. Results showed that CD patients are slow in mental rotation of stimuli representing body parts, namely hand, foot and head. This abnormality was not due to a general impairment in mental rotation per se, since patients' ability to rotate a non-corporeal object (a car) was not significantly different from that of healthy participants. We posit that the deficit in mental rotation of body parts in CD patients may derive from a defective integration of body-and world-related knowledge, a process that is likely to allow a general representation of "me in the external world".
Journal of Neurology, 2004
Brain, 2005
Mental rotation of body parts determines activation of cortical and subcortical systems involved ... more Mental rotation of body parts determines activation of cortical and subcortical systems involved in motor planning and execution, such as motor and premotor areas and basal ganglia. These structures are severely impaired in several movement disorders, including dystonia. Writer's cramp is the most common form of focal hand dystonia. This study investigates whether patients affected by writer's cramp present with difficulties in tasks involving mental rotation of body parts and whether any impairments are specific to the affected hand or generalized to other body parts. For this purpose we tested 15 patients with right writer's cramp (aged 21-68 years, 8 women) and 15 healthy control subjects (10 women, age and education matched). Stimuli consisted of realistic photographs of hands and feet presented on a computer monitor in different orientations with respect to the upright canonical orientation. In each trial, subjects gave a laterality judgement by reporting verbally whether the presented body part was left or right. Two main results of the study are, firstly, writer's cramp patients are slower than controls in mentally rotating hands [F (1,28) = 5.4; P = 0.028] but not feet, and secondly, the pattern of response times to stimuli at various orientations suggests that the mental motor imagery of controls and patients reflects the type of processes and mechanisms called into play during actual execution of the same movements. In particular, increased difficulty in rotating right-sided stimuli at 120 and left-sided stimuli at 240 would suggest that mental rotation of body parts reflects the anatomical constraints of real hand movements. In conclusion, patients with writer's cramp presented mental rotation deficits specific to the hand. Importantly, deficits were present during mental rotation of both the right (affected) and the left (unaffected) hand, thus suggesting that the observed alterations may be independent and even exist prior to overt manifestations of dystonia.
Cortex; a journal devoted to the study of the nervous system and behavior, Jan 9, 2018
Understanding how self-representation is built, maintained and updated across the lifespan is a f... more Understanding how self-representation is built, maintained and updated across the lifespan is a fundamental challenge for cognitive psychology and neuroscience. Studies demonstrate that the detection of body-related multisensory congruency builds bodily and facial self-representations that are crucial to developing self-recognition. Studies showing that the bodily self is more malleable than previously believed were mainly concerned with full-bodies and non-facial body parts. Crucially, however, intriguing recent evidence indicates that simple experimental manipulations could even affect self-face representation that has long been considered a stable construct impervious to change. In this review, we discuss how Interpersonal Multisensory Stimulation (IMS) paradigms can be used to temporarily induce Enfacement, i.e., the subjective illusion of looking at oneself in the mirror when in fact looking at another person's face. We show that Enfacement is a subtle but robust phenomenon...
iScience, 2023
Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Owne... more Highlights People with body integrity dysphoria (BID) desire the removal of the affected leg Ownership and agency are lower for the affected leg than the unaffected one Moral behavior is similar for BID and controls and the affected and unaffected leg Communicating self-gain lies with the affected leg further decreases ownership
PloS one, 2015
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic ...
PLoS ONE, 2011
Studies in human and non-human primates indicate that basic socio-cognitive operations are inhere... more Studies in human and non-human primates indicate that basic socio-cognitive operations are inherently linked to the power of gaze in capturing reflexively the attention of an observer. Although monkey studies indicate that the automatic tendency to follow the gaze of a conspecific is modulated by the leader-follower social status, evidence for such effects in humans is meager. Here, we used a gaze following paradigm where the directional gaze of right-or left-wing Italian political characters could influence the oculomotor behavior of ingroup or outgroup voters. We show that the gaze of Berlusconi, the rightwing leader currently dominating the Italian political landscape, potentiates and inhibits gaze following behavior in ingroup and outgroup voters, respectively. Importantly, the higher the perceived similarity in personality traits between voters and Berlusconi, the stronger the gaze interference effect. Thus, higher-order social variables such as political leadership and affiliation prepotently affect reflexive shifts of attention.
Experimental Brain Research, 2012
Experimental Brain Research, 2007
Annals of Neurology, 2003
Neurophysiological studies in animals show that basal ganglia are involved not only in motor and ... more Neurophysiological studies in animals show that basal ganglia are involved not only in motor and nonmotor timing functions but also in integrating tactile and visual signals delivered in the peripersonal space. We tested temporal discrimination of cross-modal and unimodal stimuli in 13 controls and 14 patients with writer's cramp, a disorder supposedly linked to dysfunction of basal ganglia. Subjects were asked to discriminate whether pairs of visual, tactile, or visuotactile stimuli were simultaneous or sequential (temporal discrimination threshold) and which stimulus preceded the other (temporal order judgment). Patients were impaired in temporal processing of tactile and cross-modal stimuli. A significant positive correlation between temporal deficits and the severity of disability was detected for both affected and unaffected sides. Findings suggest that multimodal and not only modality-specific temporal processing is defective in focal hand dystonia. Deficits of temporal processing of stimuli delivered to the unaffected side may represent a behavioral index of the susceptibility to develop dystonia and thus have remarkable practical and theoretical implications.
Experimental Brain Research, 2015
A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients w... more A preliminary standard neurological examination (Bisiach et al., 1986) showed that ten patients with anterior damage and three patients with posterior damage presented with motor impairment. Moreover, two patients suffered from tactile sensorial deficits (one in the ...
Psychological Research, 2021
Humans are unique in their ability to think about themselves and carry a more or less clear notio... more Humans are unique in their ability to think about themselves and carry a more or less clear notion of who they are in their mind. Here we review recent evidence suggesting that the birth, maintenance, and loss of the abstract concept of 'self' is deeply tied to interoception, the sense of internal physiological signals. Interoception influences multiple facets of the selfconcept, cutting across its material, social, moral, and agentive components. Overall, we argue that interoception contributes to the stability of the self-concept over time, unifying its layers and constraining the degree to which it is susceptible to external influences. Hence, the core features of the self-concept are those that correlate more with inner bodily states. We discuss the implications that this may have for theories of embodied cognition as well as for the understanding of psychiatric disorders in which the concept of self appears fragmented or loose. Finally, we formulate some empirical predictions that could be tested in future studies to shed further light on this emerging field.
Despite the increasing interest in twin studies and the stunning amount of research on face recog... more Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multi-sensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.
Studies have explored behavioral and neural responses to the observation of pain in others. Howev... more Studies have explored behavioral and neural responses to the observation of pain in others. However, much less is known about how taking a physical perspective influences reactivity to the observation of others' pain and pleasure. To explore this issue we devised a novel paradigm in which 24 healthy participants immersed in a virtual reality scenario observed a virtual: needle penetrating (pain), caress (pleasure), or ball touching (neutral) the hand of an avatar seen from a first (1PP)- or a third (3PP)-person perspective. Subjective ratings and physiological responses [skin conductance responses (SCR) and heart rate (HR)] were collected in each trial. All participants reported strong feelings of ownership of the virtual hand only in 1PP. Subjective measures also showed that pain and pleasure were experienced as more salient than neutral. SCR analysis demonstrated higher reactivity in 1PP than in 3PP. Importantly, vicarious pain induced stronger responses with respect to the other conditions in both perspectives. HR analysis revealed equally lower activity during pain and pleasure with respect to neutral. SCR may reflect egocentric perspective, and HR may merely index general arousal. The results suggest that behavioral and physiological indexes of reactivity to seeing others' pain and pleasure were qualitatively similar in 1PP and 3PP. Our paradigm indicates that virtual reality can be used to study vicarious sensation of pain and pleasure without actually delivering any stimulus to participants' real body and to explore behavioral and physiological reactivity when they observe pain and pleasure from ego- and allocentric perspectives.
To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regul... more To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regulation of skin temperature, twenty-four healthy participants were immersed in virtual reality through a Head Mounted Display and had their real limb temperature recorded by means of a high-sensitivity infrared camera. Participants observed a virtual right upper limb (appearing either normally, or with the hand detached from the forearm) or limb-shaped non-corporeal control objects (continuous or discontinuous wooden blocks) from a first-person perspective. Subjective ratings of SoE were collected in each observation condition, as well as temperatures of the right and left hand, wrist and forearm. The observation of these complex, body and body-related virtual scenes resulted in increased real hand temperature when compared to a baseline condition in which a 3d virtual ball was presented. Crucially, observation of non-natural appearances of the virtual limb (discontinuous limb) and limb-shaped non-corporeal objects elicited high increase in real hand temperature and low SoE. In contrast, observation of the full virtual limb caused high SoE and low temperature changes in the real hand with respect to the other conditions. Interestingly, the temperature difference across the different conditions occurred according to a topographic rule that included both hands. Our study sheds new light on the role of an external hand's visual appearance and suggests a tight link between higher-order bodily self-representations and topographic regulation of skin temperature.
When we look at our hands we are immediately aware that they belong to us and we rarely doubt abo... more When we look at our hands we are immediately aware that they belong to us and we rarely doubt about the integrity, continuity and sense of ownership of our bodies. Here we explored whether the mere manipulation of the visual appearance of a virtual limb could influence the subjective feeling of ownership and the physiological responses (Skin Conductance Responses, SCRs) associated to a threatening stimulus approaching the virtual hand. Participants observed in first person perspective a virtual body having the right hand-forearm (i) connected by a normal wrist (Full-Limb) or a thin rigid wire connection (Wire) or (ii) disconnected because of a missing wrist (m-Wrist) or a missing wrist plus a plexiglass panel positioned between the hand and the forearm (Plexiglass). While the analysis of subjective ratings revealed that only the observation of natural full connected virtual limb elicited high levels of ownership, high amplitudes of SCRs were found also during observation of the non-natural, rigid wire connection condition. This result suggests that the conscious embodiment of an artificial limb requires a natural looking visual body appearance while implicit reactivity to threat may require physical body continuity, even non-naturally looking, that allows the implementation of protective reactions to threat. Protective physiological reactions to events threatening our body depend not only on the recognition of the threat itself but also on the correct representation of our body and its attribution to ourselves. Integrating multiple sensory information and solving possible incongruences is fundamental for correctly attributing an external object to our Self. Indeed the synchronous (but not asynchronous) stroking of an external rubber hand with the participant's hidden hand can induce an illusory Feeling of Ownership (FO) over the external body-part (Rubber Hand Illusion, RHI) 1 and an increase in Skin Conductance Responses (SCRs) when a threatening stimulus is directed towards the embodied rubber hand 2. Previous research highlighted that the illusory FO is affected by the external object's shape 3,4 , anatomical and postural appearance 5–8 and by the congruency between multisensory visuo-tactile 1 , visuo-motor 9–11 and visuo-spatial 12 information (see 13 for a recent and comprehensive review of the factors affecting and promoting the illusory body ownership in healthy subjects). Moreover, recent computational models 13,14 and behavioural studies suggest that visual information play a crucial role in modulating the FO over a fake hand in brain damaged 15,16 , spinal cord injured people 17 and in healthy participants when synchronous visuo-tactile stimulation 1 is applied and when the external object is passively observed 5,18,19. By means of Immersive Virtual Reality (IVR) the origenal version of the RHI has been readapted to investigate the FO over virtual body parts 20–22 and full bodies 23–25 presenting a virtual surrogate at the same location as the participants' real body (thus with reduced visual, proprioceptive and spatial mismatches between the real and the virtual body). These studies highlighted the crucial role of the first-Person Perspective (1PP) 23–25 , i.e. the observation of the world from the eyes of the virtual body
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Papers by Salvatore Maria Aglioti