The knowledge of the size of the own body-parts is essential for efficiently moving in the external environment and accurately interacting both with objects and with other people. In an interdisciplinary approach which combines neurophysiological (i.e., non-invasive brain stimulation) and behavioral paradigms, the present dissertation investigates the cognitive and neural signatures underlying the representation of body-parts size. Study #1 demonstrates the casual role of the primary somatosensory cortex in one’s own body-parts size processing. In healthy adults, 1-Hz repetitive Transcranial Magnetic Stimulation over the hand representation in the somatosensory map of both hemispheres leads to perceptual distortions (i.e., overestimation) of the own hand size – as assessed with a visual perceptual task – which do not extend to other body districts (namely, the foot). Instead, cortical excitability shifts induced by repetitive Transcranial Magnetic Stimulation over the right or left inferior parietal lobule do not affect the perceptual estimation of the own hand size. This evidence highlights the causal involvement of the primary somatosensory cortex in the construction and updating of one’s own body metric representation. Study #2 focuses on the plastic changes which occur by manipulating the sense of body ownership, showing that, in healthy adults, the embodiment of external hands bigger (but not smaller) than the own affects the perceptual conscious representation of the own hand dimension. Finally, by comparing body metric representation in typically developing children and healthy adults, Study #3 shows how perceptual distortions of body-parts representation arise during the developmental course. Overall, findings from this dissertation support the extremely flexible nature of one’s own body metric representation, showing how plastic distortions of the own body-parts size develop gradually during the lifespan and can be modulated by neurophysiological changes as well as by illusory manipulations of self-attribution.

La conoscenza della grandezza delle proprie parti corporee è essenziale per muoversi in maniera efficiente nell’ambiente esterno e per interagire accuratamente sia con gli oggetti sia con le altre persone. Attraverso un approccio interdisciplinare che combina paradigmi neurofisiologici (stimolazione cerebrale non invasiva) e comportamentali, la presente tesi indaga i meccanismi cognitivi e neurali sottostanti la rappresentazione della grandezza delle parti corporee. Lo Studio #1 dimostra il ruolo causale della corteccia somatosensoriale primaria nell’elaborazione della grandezza delle proprie parti del corpo. Nei soggetti adulti neurologicamente sani, la Stimolazione Magnetica Transcranica ripetitiva a 1-Hz della rappresentazione della mano nella mappa somatosensoriale di entrambi gli emisferi, induce delle distorsioni percettive (sovrastima) della grandezza della propria mano – come valutato con un compito visuo-percettivo – che non si estendono ad altri distretti corporei (il piede). Invece, cambiamenti nell’eccitabilità corticale indotti da Stimolazione Magnetica Transcranica ripetitiva del lobulo parietale inferiore destro o sinistro non influenzano la stima percettiva della grandezza della propria mano. Tale evidenza sottolinea il coinvolgimento causale della corteccia somatosensoriale primaria nella costruzione e nell’aggiornamento della rappresentazione metrica del proprio corpo. Lo Studio #2 si focalizza sui cambiamenti plastici che avvengono manipolando il senso di appartenenza corporea mostrando che, negli adulti neurologicamente sani, l’embodiment di mani più grandi (ma non più piccole) della propria influenza la rappresentazione percettiva cosciente della dimensione della propria mano. Infine, comparando la rappresentazione metrica del corpo in bambini a sviluppo tipico con quella degli adulti neurologicamente sani, lo Studio #3 mostra come le distorsioni percettive della rappresentazione corporea emergono durante il corso dello sviluppo. Complessivamente, i risultati della presente tesi supportano la natura estremamente flessibile della rappresentazione metrica del proprio corpo, mostrando come le distorsioni plastiche della grandezza delle proprie parti corporee si sviluppano gradualmente nell’arco della vita e possono essere modulate sia da cambiamenti neurofisiologici, sia da manipolazioni illusorie del senso di embodiment.

(2020). PLASTIC MODULATIONS OF THE BODY METRIC REPRESENTATION: NEUROPHYSIOLOGICAL AND BEHAVIORAL EVIDENCE. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2020).

PLASTIC MODULATIONS OF THE BODY METRIC REPRESENTATION: NEUROPHYSIOLOGICAL AND BEHAVIORAL EVIDENCE

GIURGOLA, SERENA
2020

Abstract

The knowledge of the size of the own body-parts is essential for efficiently moving in the external environment and accurately interacting both with objects and with other people. In an interdisciplinary approach which combines neurophysiological (i.e., non-invasive brain stimulation) and behavioral paradigms, the present dissertation investigates the cognitive and neural signatures underlying the representation of body-parts size. Study #1 demonstrates the casual role of the primary somatosensory cortex in one’s own body-parts size processing. In healthy adults, 1-Hz repetitive Transcranial Magnetic Stimulation over the hand representation in the somatosensory map of both hemispheres leads to perceptual distortions (i.e., overestimation) of the own hand size – as assessed with a visual perceptual task – which do not extend to other body districts (namely, the foot). Instead, cortical excitability shifts induced by repetitive Transcranial Magnetic Stimulation over the right or left inferior parietal lobule do not affect the perceptual estimation of the own hand size. This evidence highlights the causal involvement of the primary somatosensory cortex in the construction and updating of one’s own body metric representation. Study #2 focuses on the plastic changes which occur by manipulating the sense of body ownership, showing that, in healthy adults, the embodiment of external hands bigger (but not smaller) than the own affects the perceptual conscious representation of the own hand dimension. Finally, by comparing body metric representation in typically developing children and healthy adults, Study #3 shows how perceptual distortions of body-parts representation arise during the developmental course. Overall, findings from this dissertation support the extremely flexible nature of one’s own body metric representation, showing how plastic distortions of the own body-parts size develop gradually during the lifespan and can be modulated by neurophysiological changes as well as by illusory manipulations of self-attribution.
BOLOGNINI, NADIA
METRICA CORPOREA; PERCEZIONE CORPOREA; TMS; PERCEZIONE MANO; PERCEZIONE TATTILE
BODY METRIC; BODY PERCEPTION; TMS; HAND PERCEPTION; PERCEZIONE TATTILE
M-PSI/02 - PSICOBIOLOGIA E PSICOLOGIA FISIOLOGICA
English
30-gen-2020
NEUROSCIENZE
32
2018/2019
open
(2020). PLASTIC MODULATIONS OF THE BODY METRIC REPRESENTATION: NEUROPHYSIOLOGICAL AND BEHAVIORAL EVIDENCE. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2020).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/261947
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