Neural adaptation to thin and fat bodies in the fusiform body area and middle occipital gyrus: An fMRI adaptation study

Abstract

Visual perception can be strongly biased due to exposure to specific stimuli in the environment, often causing neural adaptation and visual aftereffects. In this study, we investigated whether adaptation to certain body shapes biases the perception of the own body shape. Furthermore, we aimed to evoke neural adaptation to certain body shapes. Participants completed a behavioral experiment (n = 14) to rate manipulated pictures of their own bodies after adaptation to demonstratively thin or fat pictures of their own bodies. The same stimuli were used in a second experiment (n = 16) using functional magnetic resonance imaging (fMRI) adaptation. In the behavioral experiment, after adapting to a thin picture of the own body participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. The fusiform body area (FBA) and the right middle occipital gyrus (rMOG) show neural adaptation to specific body shapes while the extrastriate body area (EBA) bilaterally does not. The rMOG cluster is highly selective for bodies and perhaps body parts. The findings of the behavioral experiment support the existence of a perceptual body shape aftereffect, resulting from a specific adaptation to thin and fat pictures of one's own body. The fMRI results imply that body shape adaptation occurs in the FBA and the rMOG. The role of the EBA in body shape processing remains unclear. The results are also discussed in the light of clinical body image disturbances.

Independent Aftereffects of Fat and Muscle: Implications for neural encoding, body space representation, and body image disturbance

“…In line with our predictions, observers showed aftereffects of body size after prolonged viewing of large and small bodies (main effects of adaptation direction). These results are consistent with past research regarding body size adaptation, which found that size aftereffects occur such that the point of perceived normality shifts in the direction of the adapting bodies171820213637.…”

“…Previous studies manipulated images by stretching the entire image horizontally21, by expanding the image principally around the waist-hip region17, through the distortion of different body “zones”36, or by manipulating computer generated bodies18. Instead, we used advanced image morphing techniques to create more realistic manipulations.…”

“…As with face distortion aftereffects, adaptation to images of bodies that have been compressed or stretched horizontally to simulate smaller or larger body sizes results in perceptions of what is average shifting to appear more similar to the adaptation images21, along with effects on judgements of attractiveness41424344. This effect has been replicated using more realistic computer generated bodies18 and real photographs36. Importantly, researchers have demonstrated that body size aftereffects can transfer between adaptation images of other individuals and test images depicting one’s self171937.…”

“…Consequently, a face that previously appeared normal now appears contracted. This norm shift is thought to be the result of the reduction of sensitivity that is known to result from prolonged stimulation of cells in the visual system3536.…”

Localized Brain Volume and White Matter Integrity Alterations in Adolescent Anorexia Nervosa

“…The fusiform gyrus is an important structure in external body recognition 51 and body size perception. 52 Importantly, previous research found GM and WM in this area related to body weight changes, 53 and this region is consistently activated when viewing food images. 54 Furthermore, hippocampus and parahippocampus show decreased activation during satiety states.…”