The two dimensions of the body representation in women suffering from Anorexia Nervosa (original) (raw)
Related papers
Tactile body image disturbance in anorexia nervosa
Psychiatry Research, 2011
Body image disturbances are central to anorexia nervosa (AN). Previous studies have focused mainly on attitudinal and visual aspects. Studies on somatosensory aspects thus far have been scarce. We therefore investigated whether AN patients and controls differed in tactile perception, and how this tactile body image related to visual body image and body dissatisfaction. The Tactile Estimation Task (TET) measured tactile body image: Two tactile stimuli were applied to forearm and abdomen, and, while blindfolded, participants estimated the distance between the two tactile stimuli between their thumb and index finger. The Distance Comparison Task (DCT) measured visual body image. Compared to controls (n = 25), AN patients (n = 20) not only visualized their body less accurately, but also overestimated distances between tactile stimuli on both the arm and abdomen, which might reflect a disturbance in both visual and tactile body image. High levels of body dissatisfaction were related to more severe inaccuracies in the visual mental image of the body, and overestimation of tactile distances. Our results imply that body image disturbances in AN are more widespread than previously assumed as they not only affect visual mental imagery, but also extend to disturbances in somatosensory aspects of body image.
Aberrant somatosensory perception in Anorexia Nervosa
Psychiatry Research, 2012
Anorexia Nervosa (AN) patients have a disturbed experience of body size and shape. Previously it has been shown that these body representation disturbances extend to enlarged perception of tactile distances. Here we investigated whether misperception of tactile size could be related to inaccurate elementary somatosensory perception. Tactile size perception was measured with the Tactile Estimation Task (TET) (see . Elementary somatosensory perception was assessed with a pressure detection task and two point discrimination (TPD). Compared to controls (n ¼ 28), AN patients (n ¼25) overestimated tactile size, this effect was strongest for the abdomen. Elementary tactile perception deviated in AN as well: Patients had a lower threshold for detecting pressure on their abdomen, and a higher threshold for TPD on both the arm and abdomen. Regression results implied that group membership predicted tactile size estimation on the arm. Both group membership and TPD predicted tactile size estimation on the abdomen. Our results show that AN patients have a disturbance in the metric properties of the mental representation of their body as they overestimate the size of tactile stimuli compared to controls. Interestingly, AN patients and controls differ in elementary somatosensory perception as well. However, this could not solely explain misperception of tactile distances, suggesting that both bottom-up and top-down processes are involved.
Body distortions in Anorexia Nervosa: Evidence for changed processing of multisensory bodily signals
Psychiatry Research-neuroimaging, 2016
Body size and shape distortion is a core feature of Anorexia Nervosa (AN)-patients experience their body as fat while objectively being very thin. The cause of this distortion is unclear and disturbances in body perception could be involved. Body perception comprises estimating shape and location of one's body and requires integrating multisensory signals. We investigated if and how body location perception is changed and tested 23 AN patients and 23 healthy controls (HC) in a Rubber Hand Illusion (RHI) reaching paradigm. We presented two types of multisensory conflicts (visual-proprioceptive hand location; visualtactile touch synchrony) and tested if the impact of visual-proprioceptive and visual-tactile signals on hand location perception differs between AN and HC groups. We found significant group differences in shifts of reaching trajectories, indicating that the influence of proprioceptive signals on hand location estimates is reduced in AN. Hand location estimates were relatively more biased towards external visual information, and shorter illness durations predicted a larger visual bias. Although touch synchrony also significantly influenced hand location estimates, this effect did not differ between groups. Our findings provide compelling evidence that multisensory body location perception-specifically the processing of visualproprioceptive signals-is changed in AN.
Visual body perception in anorexia nervosa
Objective: Disturbance of body perception is a central aspect of anorexia nervosa (AN) and several neuroimaging studies have documented structural and functional alterations of occipito-temporal cortices involved in visual body processing. However, it is unclear whether these perceptual deficits involve more basic aspects of others' body perception.
tactile mental body parts representation in obesity
Obese people's distortions in visually-based mental body-parts representations have been reported in previous studies, but other sensory modalities have largely been neglected. In the present study, we investigated possible differences in tactilely-based body-parts representation between an obese and a healthy-weight group; additionally we explore the possible relationship between the tactile-and the visually-based body representation. Participants were asked to estimate the distance between two tactile stimuli that were simultaneously administered on the arm or on the abdomen, in the absence of visual input. The visually-based body-parts representation was investigated by a visual imagery method in which subjects were instructed to compare the horizontal extension of body part pairs. According to the results, the obese participants overestimated the size of the tactilely-perceived distances more than the healthy-weight group when the arm, and not the abdomen, was stimulated. Moreover, they reported a lower level of accuracy than did the healthy-weight group when estimating horizontal distances relative to their bodies, confirming an inappropriate visually-based mental body representation. Our results imply that body representation disturbance in obese people is not limited to the visual mental domain, but it spreads to the tactilely perceived distances. The inaccuracy was not a generalized tendency but was body-part related.
Disruption of Spatial Task Performance in Anorexia Nervosa
PLoS ONE, 2013
In anorexia nervosa (AN), body distortions have been associated with parietal cortex (PC) dysfunction. The PC is the anatomical substrate for a supramodal reference framework involved in spatial orientation constancy. Here, we sought to evaluate spatial orientation constancy and the perception of body orientation in AN patients. In the present study, we investigated the effect of passive lateral body inclination on the visual and tactile subjective vertical (SV) and body Z-axis in 25 AN patients and 25 healthy controls. Subjects performed visual-and tactile-spatial judgments of axis orientations in an upright position and tilted 90u clockwise or counterclockwise. We observed a significant deviation of the tactile and visual SV towards the body (an A-effect) under tilted conditions, suggesting a multisensory impairment in spatial orientation. Deviation of the Z-axis in the direction of the tilt was also observed in the AN group. The greater A-effect in AN patients may reflect reduced interoceptive awareness and thus inadequate consideration of gravitational inflow. Furthermore, marked body weight loss could decrease the somatosensory inputs required for spatial orientation. Our study results suggest that spatial references are impaired in AN. This may be due to particular integration of visual, tactile and gravitational information (e.g. vestibular and proprioceptive cues) in the PC.
The perception of affective touch in anorexia nervosa
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.
Clinical Medicine, 2019
We combined virtual reality and multisensory bodily illusion with the aim to characterize and reduce the perceptual (body overestimation) and the cognitive emotional (body dissatisfaction) components of body image distortion (BID) in anorexia nervosa (AN). For each participant (20 anorexics, 20 healthy controls) we built personalized avatars that reproduced their own body size, shape, and verisimilar increases and losses of their original weight. Body overestimation and dissatisfaction were measured by asking participants to choose the avatar that best resembled their real and ideal body. Results show higher body dissatisfaction in AN, caused by the desire of a thinner body, and no body size overestimation. Interpersonal multisensory stimulation (IMS) was then applied on the avatar reproducing participant's perceived body, and on the two avatars which reproduced increases and losses of 15% of it, all presented with a first person perspective (1PP). Embodiment was stronger after synchronous IMS in both groups, but did not reduce BID in participants with AN. Interestingly, anorexics reported more negative emotions after embodying the fattest avatar, which scaled with symptoms severity. Overall, our findings suggest that the cognitive emotional, more than the perceptual component of BID is severely altered in AN and that perspective (1PP vs. 3PP) from which a body is evaluated may play a crucial role. Future research and clinical trials might take advantage of virtual reality to reduce the emotional distress related to body dissatisfaction.
Subjective experience of sensation in anorexia nervosa
Behaviour Research and Therapy, 2013
The nature of disturbance in body experience in anorexia nervosa (AN) remains poorly operationalized despite its prognostic significance. We examined the relationship of subjective reports of sensitivity to and behavioral avoidance of sensory experience (e.g., to touch, motion) to body image disturbance and temperament in adult women currently diagnosed with AN (n=20), women with a prior history of AN who were weight restored (n=15), and healthy controls with no eating disorder history (n=24). Levels of sensitivity to sensation and attempts to avoid sensory experience were significantly higher in both clinical groups relative to healthy controls. Sensory sensitivity was associated with body image disturbance (r(56) = .51, p < .0001), indicating that body image disturbance increased with increased global sensitivity to sensation. Sensory sensitivity was also negatively and significantly correlated with lowest BMI (r 2 = −.32, p < .001), but not current BMI (r 2 = .03, p = .18), and to the temperament feature of harm avoidance in both clinical groups. We discuss how intervention strategies that address sensitization and habituation to somatic experience via conditioning exercises may provide a new manner in which to address body image disturbance in AN.