1,721,109 research outputs found
Sistemi neurali coinvolti nella percezione del corpo. Studi neurofisiologici
No full textStudi di neurofisiologia e di neuroanatomia funzionale nell’uomo e nei primati non umani hanno mostrato il ruolo di aree temporali e fronto-parietali nell’analisi della forma del corpo umano e dei suoi movimenti. Sarà presentata una serie di studi in cui la tecnica della stimolazione magnetica transcranica ripetitiva e a singolo impulso è stata utilizzata in soggetti sani al fine di dimostrare il ruolo causale di tali aree nel riconoscimento della morfologia e del movimento corporeo. I risultati di questi studi, complementari alle tecniche di neuroimmagine funzionale, hanno messo in evidenza il coinvolgimento specifico dell’extrastriate body area nel riconoscimento della morfologia del corpo umano ma non dei suoi movimenti. Al riconoscimento e alla comprensione di azioni, anche quando rappresentate in immagini statiche (implied actions), contribuisce in modo funzionalmente necessario l’area premotoria ventrale. Il disturbo indotto dalla stimolazione magnetica nel riconoscimento di azioni fornisce la prima evidenza diretta che l’attività di aree premotorie implicate nella pianificazione ed esecuzione di azioni è necessaria alla comprensione delle azioni dei conspecifici. L’accoppiamento tra osservazione ed esecuzione di azioni pone il problema della soggettività delle proprie azioni, cioè della discriminazione tra azioni proprie e azioni degli altri. Il senso di appartenenza delle proprie azioni sembra scaturire dall’integrazione di informazioni motorie e multisensoriali, cui contribuisce in modo sostanziale la corteccia parietale posteriore
Familiarity modulates motor activation while other species' actions are observed: a magnetic stimulation study
No full textObserving other people's actions facilitates the observer's motor system as compared with observing the same individuals at rest. This motor activation is thought to result from mirror-like activity in fronto-parietal areas, which enhances the excitability of the primary motor cortex via cortico-cortical pathways. Although covert motor activation in response to observed actions has been widely investigated between conspecifics, how humans cope with other species' actions has received less attention. For example, it remains unclear whether the human motor system is activated by observing other species' actions, and whether prior familiarity with the non-conspecific agent modulates this activation. Here, we combined single-pulse transcranial magnetic stimulation and motor-evoked potential recording to explore the impact of familiarity on motor activation during the observation of non-conspecific actions. Videos displaying actions performed either by a conspecific (human) or by a non-conspecific (dog) were shown to individuals who had prior familiarity or no familiarity at all with the non-conspecific agent. We found that, whereas individuals with long-lasting familiarity showed similar levels of motor activation for human and canine actions, individuals who had no familiarity showed higher motor activation for human than for canine actions. These findings suggest that the human motor system is flexible enough to resonate with other species, and that familiarity plays a key role in tuning this ability
Contextual modulation of motor resonance during the observation of everyday actions
No full textNeuroimaging studies on action observation suggest that context plays a key role in coding high-level components of motor behavior, including the short-term and the end-goal of an action. However, little is known about the possible role of context in shaping lower-levels of action processing such as reading action kinematics and simulating muscular activity. Here, we combined single-pulse TMS and motor-evoked potentials (MEPs) recording to explore whether top-down contextual information is capable of modulating low-level motor representations. We recorded MEPs from FDI and FCR muscles while participants watched videos about everyday actions embedded in congruent, incongruent or ambiguous contexts. Videos were interrupted before action ending, and participants were requested to predict the course of the observed action. A contextual modulation of corticospinal excitability was observed only for the FDI muscle, which is specifically involved in the execution of reaching-to-grasping movements, and whose corticospinal pathway is influenced by the observation of the very same movements. This modulation was reflected in a selective decrease of corticospinal excitability during the observation of actions embedded in incongruent as compared to congruent and ambiguous contexts. These findings indicate that motor resonance is not an entirely automatic process, but it can be modulated by high-level contextual representations
Neural underpinnings of superior action prediction abilities in soccer players.
Full text linkThe ability to form anticipatory representations of ongoing actions is crucial for effective interactions in dynamic environments. In sports, elite athletes exhibit greater ability than novices in predicting other players actions, mainly based on reading their body kinematics. This superior perceptual ability has been associated with a modulation of visual and motor areas by visual and motor expertise. Here, we investigated the causative role of visual and motor action representations in experts ability to predict the outcome of soccer actions. We asked expert soccer players (outfield players and goalkeepers) and novices to predict the direction of the ball after perceiving the initial phases of penalty kicks that contained or not incongruent body kinematics. During the task, we applied repetitive transcranial magnetic stimulation (rTMS) over the superior temporal sulcus (STS) and the dorsal premotor cortex (PMd). Results showed that STS-rTMS disrupted performance in both experts and novices, especially in those with greater visual expertise (i.e. goalkeepers). Conversely, PMd-rTMS impaired performance only in expert players (i.e. outfield players and goalkeepers), who exhibit strong motor expertise into facing domain-specific actions in soccer games. These results provide causative evidence of the complimentary functional role of visual and motor action representations in experts action prediction
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