Neural Systems Underlying Observation of Humanly Impossible Movements: An fMRI Study

Abstract

Previous studies have indicated that largely overlapping parts of a complex, mainly fronto-parietal, neural network are activated during both observation and execution of an action. If these two processes are inextricably linked, increases of neural activity contingent upon action observation should be found only for movements that can actually be performed. Using functional magnetic resonance imaging, we investigated whether observation of possible and biomechanically impossible movements of fingers activated the same neural systems. Thirteen healthy subjects were scanned during observation of video-clips showing abduction/adduction movements of the right index or the little finger, which were defined as biomechanically possible or impossible according to the range of their angular displacement at the metacarpo-phalangeal joint. The mere observation of possible and impossible hand movements induced a selective activation of left precentral and left inferior frontal regions, thus indicating that motor-related areas map body actions even when they violate the constraints of human anatomy. An increase of the blood oxygen level-dependent signal selectively linked to observation of impossible hand movements was found in sensorimotor parietal regions. Our results suggest that while premotor areas code human actions regardless of whether they are biologically possible or impossible, sensorimotor parietal regions may be important for coding the plausibility of actions.

Automatic imitation of biomechanically possible and impossible actions: Effects of priming movements versus goals.

“…This insensitivity to the difference in movements is consistent with recent neuroimaging and physiological evidence presented by Aglioti and colleagues (Costantini et al, 2005;Romani, Cesari, Urgesi, Facchini, & Aglioti, 2005). Using fMRI, these researchers found similar activation of premotor mirror system regions elicited from observation of biomechanically possible and impossible actions (Costantini et al),; while using TMS, they found similar cortiospinal excitability elicited by the observation of possible and impossible finger movements Imitation of Impossible Movements 17 (Romani et al).…”

“…On the one hand, the behavioral results from Experiment 1 dovetail with recent fMRI (Costantini et al, 2005) and TMS findings that biomechanically possible and impossible actions are coded similarilysimilarly by mirror/common coding mechanisms; on the other, the results of Experiment 2 are consistent with recent behavioral (Casile & Giese, 2006), developmental Sommerville, Woodward, & Needham, 2005), and neuroimaging (Buccino et al, 2004;Calvo-Merino et al, 2005Costantini et al, 2005) studies relating the representation of perceived actions to the observer's own ability to perform the action. Calvo-Merino and colleagues (2006), for example, presented expert ballet dancers with examples of dance moves that either were in their own motor repertoire or were performed only by opposite-gender dancers, finding increased activation in mirror circuits for the samegender moves.…”

Seeing touch in the somatosensory cortex: A TMS study of the visual perception of touch

“…Action observation and execution increases neural activity in both motor and somatosensory areas [Rizzolatti and Craighero, 2004]. Crucially, making the perceived action painful or more salient from a tactile or proprioceptive point of view causes an increase of the activity in SI Betti et al, 2009;Bufalari et al, 2007;Costantini et al, 2005]. A recent study demonstrated that TMS over SI selectively reduced the typical corticospinal mapping of biomechanically impossible movements [Fadiga et al, 1995[Fadiga et al, , 2005Romani et al, 2005], which were associated with aversive somatic feelings, without impacting mirror responses to possible movements that did not evoke somatic feelings in the observer.…”

From visuo-motor interactions to imitation learning: Behavioural and brain imaging studies

“…In more recent research, numerous further issues about the human MNS have been explored, for example its lateralization (Aziz-Zadeh, Koski, Zaidel, Mazziotta, & Iacoboni, 2006;Mü hlau et al, 2005), inhibitory mechanisms (Alegre, Lazaro, Valencia, Iriarte, & Artieda, 2006;Brass, Derrfuss, & von Cramon, 2005), perspective effects (Jackson, Meltzoff, & Decety, 2006;Koski, Iacoboni, Dubeau, Woods, & Mazziotta, 2003), motor versus visuospatial representations (Chaminade, Meltzoff, & Decety, 2005), and the extent to which robot-like (Tai, Scherfler, Brooks, Sawamoto, & Castiello, 2004;but see Press, Bird, Flach, & Heyes, 2005) or biomechanically impossible displays (Costantini et al, 2005) elicit activations in the MNS. A further focus of current research is the conspicuous multifunctionality of the human inferior frontal gyrus beyond action recognition and imitation.…”