The present thesis aimed to investigate the time course and the neural substrates of body recognition and action representation using electrophysiological and neuroimaging studies. Previous evidence has shown that the presentation of a body in upside-down orientation resulted in decreased discrimination ability and increased N190 component, suggesting a disruption of configurational processing. In this thesis, the relationship between body recognition, orientation, and attention was assessed by presenting the participants with body postures and structures of cubes in either upright or inverted orientation. We predicted an effect of inversion on the perception of bodies but not cubes. The body inversion led to a slower stimulus processing (slower anterior N2) and enhanced attention allocation (larger Selection Negativity and P300) required to recognize and classify the target. Stronger recruitment of attention-related prefrontal regions was also found using swLORETA source reconstruction. No modulation of these components was shown for the cubes due to the lack of natural orientation. This first experiment provided evidence for an orientation-dependent recognition of the human body. Several studies have found the engagement of fronto-parieto-temporal regions in action perception, modulated as a function of expertise. Here, a dancer’s muscular effort was used as a tool to investigate the impact of ballet expertise on action representation. Compared to controls, a more refined and automatic effort encoding was expected in dancers due to their increased expertise with the repertoire of movement. Expert dancers and non-dancers were presented with effortful and effortless technical gestures and instructed to reproduce each of them mentally. A faster stimulus processing (faster posterior P2) and early bilateral engagement of the occipito-temporal cortex (OTC; posterior N2 and swLORETA) was found in dancers vs. controls during action observation. The experts also showed an increased anterior P300 and parietal Late Positivity (LP) in response to effortful than effortless steps. This was interpreted as an index of refined action coding due to their acquired motor knowledge. The non-experts only showed a modulation of the occipital LP likely due to enhanced processing of dance kinematics. The swLORETA indicated the recruitment of visuomotor regions in dancers, and visual and prefrontal areas in controls. During the motor imagery task a larger Anterior Negativity (AN) was found in experts compared to non-experts. Also, the effortful (vs. effortless) steps elicited a more negative AN in controls, while the opposite effect was found in ballet dancers. The swLORETA indicated bilateral recruitment of visuomotor and temporal areas in dancers and superior and medial frontal regions in controls. The evidence from the second study suggested a strong role of expertise in the modulation of the neural processes underlying action representation and an expertise-dependent contribution of the OTC to action coding during both observation and motor imagery. The final study of this thesis explored the neural correlates of action timing representation. The volunteers judged the aesthetical appraisal of videos depicting dance sequences reproduced with a uniform or varied acceleration, showing a preference for the varied version. Enhanced activity within OTC and fronto-central regions was expected as a function of increased acceleration changes. We found that the varied (vs. uniform) version of the sequences engaged a broader network of areas cortical and subcortical areas. The OTC, premotor and supplementary motor areas, inferior parietal lobule, inferior frontal gyrus, insula, thalamus, and putamen exhibited a crucial role in the representation of action timing. These results suggest a strong embodied response during the processing of dance kinematics as a function of time variation.

La presente tesi si propone di studiare i decorsi temporali e correlati neurali legati al riconoscimento del corpo e alla codifica dell’azione utilizzando studi elettrofisiologici e di neuroimaging. È stato dimostrato come la capacità di riconoscimento di un corpo diminuisca se osservato capovolto indicando di una perturbazione dei processi di elaborazione configurazionale. Nella presente tesi è stata indagata la relazione tra riconoscimento del corpo, orientamento e attenzione, utilizzando immagini di posture corporee e strutture di cubi in orientamento canonico o capovolto. È stato ipotizzato un effetto dell’inversione sulla percezione dei corpi, ma non dei cubi. L’inversione del corpo ha portato ad una elaborazione dello stimolo più lenta (N2 anteriore più tardiva) e ad un aumento della selezione attentiva (Selection Negativity e P300 più ampie) necessaria per riconoscerlo e classificarlo. La ricostruzione della sorgente (swLORETA) ha confermato un maggior reclutamento di regioni attentive prefrontali. Per i cubi non è stata riscontrata una modulazione di tali componenti per via della mancanza di un orientamento naturale. I risultati hanno indicato come il riconoscimento del corpo sia dipendente dall’orientamento. Diversi studi hanno mostrato il coinvolgimento di regioni fronto-parieto-temporali durante l’osservazione di un’azione e l’effetto dell’expertise nel modulare l’attività di tali aree. In questo studio, lo sforzo muscolare è stato utilizzato come strumento per investigare l’effetto della pratica della danza sulla codifica dell’azione, ipotizzando una codifica maggiormente raffinata nei danzatori (vs. controlli). Gesti tecnici caratterizzati da sforzo lieve e intenso sono stati mostrati a danzatori e controlli durante un compito di immaginazione motoria. Nei danzatori sono stati riscontrati processi di elaborazione più rapidi (P2 posteriore precoce) e un coinvolgimento bilaterale della corteccia occipito-temporale (N2 posteriore e swLORETA). Gli esperti hanno anche mostrato un aumento della P300 anteriore e della Late Positivity (LP) parietale in risposta agli stimoli a sforzo intenso, indicando una codifica dell’azione più raffinata in virtù della conoscenza dei programmi motori. I controlli hanno mostrato una modulazione della LP occipitale dovuta ad un aumento dell’elaborazione delle informazioni cinematiche. La swLORETA ha indicato una maggiore attività nelle regioni visuomotorie nei danzatori, nelle regioni visive e prefrontali nei controlli. Durante il compito di immaginazione motoria è stata trovata una Anterior Negativity (AN) più ampia negli esperti. I movimenti a sforzo intenso hanno anche portato ad una AN più ampia nei controlli, mentre il risultato inverso è stato trovato nei danzatori. La swLORETA ha mostrato attività bilaterale nelle regioni visuomotorie e temporali nei danzatori e in regioni frontali superiori e mediali nei controlli. I risultati del secondo studio hanno suggerito una forte modulazione dei processi di rappresentazione dell’azione in base all’expertise acquisita e il contributo della corteccia occipito-temporale alla codifica dell’azione. L’ultimo studio ha esplorato i correlati neurali della rappresentazione di aspetti temporali dell’azione. I volontari hanno giudicato la piacevolezza estetica di sequenze di danza riprodotte con accelerazione uniforme o variata, indicando una preferenza per le variazioni temporali. È stato ipotizzato un maggiore coinvolgimento di regioni occipito-temporali e fronto-centrali in funzione dell’accelerazione crescente. Le sequenze variate hanno attivato regioni corticali e sottocorticali, tra cui la corteccia occipito-temporale, aree premotorie e motorie supplementari, lobulo parietale inferiore, giro frontale inferiore, insula, talamo e putamen. I risultati hanno suggerito un forte effetto di risonanza motoria durante l’elaborazione di aspetti cinematici legati alle variazioni temporali.

(2019). ACTION REPRESENTATION IN THE HUMAN BRAIN: ELECTROPHYSIOLOGICAL MARKERS AND NEUROFUNCTIONAL CORRELATES. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2019).

ACTION REPRESENTATION IN THE HUMAN BRAIN: ELECTROPHYSIOLOGICAL MARKERS AND NEUROFUNCTIONAL CORRELATES

ORLANDI, ANDREA
2019

Abstract

The present thesis aimed to investigate the time course and the neural substrates of body recognition and action representation using electrophysiological and neuroimaging studies. Previous evidence has shown that the presentation of a body in upside-down orientation resulted in decreased discrimination ability and increased N190 component, suggesting a disruption of configurational processing. In this thesis, the relationship between body recognition, orientation, and attention was assessed by presenting the participants with body postures and structures of cubes in either upright or inverted orientation. We predicted an effect of inversion on the perception of bodies but not cubes. The body inversion led to a slower stimulus processing (slower anterior N2) and enhanced attention allocation (larger Selection Negativity and P300) required to recognize and classify the target. Stronger recruitment of attention-related prefrontal regions was also found using swLORETA source reconstruction. No modulation of these components was shown for the cubes due to the lack of natural orientation. This first experiment provided evidence for an orientation-dependent recognition of the human body. Several studies have found the engagement of fronto-parieto-temporal regions in action perception, modulated as a function of expertise. Here, a dancer’s muscular effort was used as a tool to investigate the impact of ballet expertise on action representation. Compared to controls, a more refined and automatic effort encoding was expected in dancers due to their increased expertise with the repertoire of movement. Expert dancers and non-dancers were presented with effortful and effortless technical gestures and instructed to reproduce each of them mentally. A faster stimulus processing (faster posterior P2) and early bilateral engagement of the occipito-temporal cortex (OTC; posterior N2 and swLORETA) was found in dancers vs. controls during action observation. The experts also showed an increased anterior P300 and parietal Late Positivity (LP) in response to effortful than effortless steps. This was interpreted as an index of refined action coding due to their acquired motor knowledge. The non-experts only showed a modulation of the occipital LP likely due to enhanced processing of dance kinematics. The swLORETA indicated the recruitment of visuomotor regions in dancers, and visual and prefrontal areas in controls. During the motor imagery task a larger Anterior Negativity (AN) was found in experts compared to non-experts. Also, the effortful (vs. effortless) steps elicited a more negative AN in controls, while the opposite effect was found in ballet dancers. The swLORETA indicated bilateral recruitment of visuomotor and temporal areas in dancers and superior and medial frontal regions in controls. The evidence from the second study suggested a strong role of expertise in the modulation of the neural processes underlying action representation and an expertise-dependent contribution of the OTC to action coding during both observation and motor imagery. The final study of this thesis explored the neural correlates of action timing representation. The volunteers judged the aesthetical appraisal of videos depicting dance sequences reproduced with a uniform or varied acceleration, showing a preference for the varied version. Enhanced activity within OTC and fronto-central regions was expected as a function of increased acceleration changes. We found that the varied (vs. uniform) version of the sequences engaged a broader network of areas cortical and subcortical areas. The OTC, premotor and supplementary motor areas, inferior parietal lobule, inferior frontal gyrus, insula, thalamus, and putamen exhibited a crucial role in the representation of action timing. These results suggest a strong embodied response during the processing of dance kinematics as a function of time variation.
PROVERBIO, ALICE MADO
effetto inversione; codifica azione; sforzo; accelerazione; ERP
inversion effect; action coding; effort; acceleration; ERP
M-PSI/02 - PSICOBIOLOGIA E PSICOLOGIA FISIOLOGICA
English
8-feb-2019
PSICOLOGIA, LINGUISTICA E NEUROSCIENZE COGNITIVE - 77R
31
2017/2018
open
(2019). ACTION REPRESENTATION IN THE HUMAN BRAIN: ELECTROPHYSIOLOGICAL MARKERS AND NEUROFUNCTIONAL CORRELATES. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2019).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/241203
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