Activation patterns during action observation are modulated by context in mirror system areas

The role of the mirror system in action understanding has been widely debated. Some authors have suggested that the mirror system plays an important role in action understanding (Rizzolatti and Sinigaglia, 2010), whereas others have claimed that direct evidence to support this view is lacking (Hickok, 2009). If mirror neurons have an active role in action understanding rather than passive visuomotor transformation during action observation, they should respond differently to the observation of actions depending on the intentions of the observer. In this fMRI study, twenty participants observed identical actions under different instruction contexts. The task was either to understand the actions, identify the physical features of the actions, or passively observe the actions. A multi-voxel pattern analysis revealed unique patterns of activation in ventral premotor cortex and inferior parietal lobule across the different contexts. The results suggest that ventral premotor and inferior parietal areas respond differently to observed actions depending on the mindset of the observer. This is consistent with the view that these regions do not merely process observed actions passively, but play an active role in action understanding

The thing that should not be: predictive coding and the uncanny valley in perceiving human and humanoid robot actions

Using functional magnetic resonance imaging (fMRI) repetition suppression, we explored the selectivity of the human action perception system (APS), which consists of temporal, parietal and frontal areas, for the appearance and/or motion of the perceived agent. Participants watched body movements of a human (biological appearance and movement), a robot (mechanical appearance and movement) or an android (biological appearance, mechanical movement). With the exception of extrastriate body area, which showed more suppression for human like appearance, the APS was not selective for appearance or motion per se. Instead, distinctive responses were found to the mismatch between appearance and motion: whereas suppression effects for the human and robot were similar to each other, they were stronger for the android, notably in bilateral anterior intraparietal sulcus, a key node in the APS. These results could reflect increased prediction error as the brain negotiates an agent that appears human, but does not move biologically, and help explain the ‘uncanny valley’ phenomenon

Perceiving conspecifics as integrated body-gestalts is an embodied process.

We investigated the effect of posture congruence on social perception. Specifically, we tested the hypothesis that completing "body gestalts," rather than being a purely visual process, is mediated by congruence in the postures of observer and stimulus. We developed novel stimuli showing a face and 2 hands that could be combined in various ways to form "body gestalts" implying different postures. In 3 experiments we found that imitative finger movements were consistently faster when the observer's posture matched the posture implied by the configuration of face and hands shown onscreen, suggesting that participants intuitively used their own body schema to "fill in the gaps" in the stimuli. Besides shaping how humans perceive others' bodies, embodied body-gestalt (eBG) completion may be an essential social and survival mechanism, for example, allowing for quick recovery from deceptive actions. It may also partly explain why humans subconsciously align themselves in everyday interactions: This might facilitate optimal corepresentation at higher, conscious levels

On the Role of Object Information in Action Observation: An fMRI Study

Observing other people’s actions activates a network of brain regions that is also activated during the execution of these actions. Here, we used functional magnetic resonance imaging to test whether these “mirror” regions in frontal and parietal cortices primarily encode the spatiomotor aspects or the functional goal-related aspects of observed tool actions. Participants viewed static depictions of actions consisting of a tool object (e.g., key) and a target object (e.g., keyhole). They judged the actions either with regard to whether the objects were oriented correctly for the action to succeed (spatiomotor task) or whether an action goal could be achieved with the objects (function task). Compared with a control condition, both tasks activated regions in left frontoparietal cortex previously implicated in action observation and execution. Of these regions, the premotor cortex and supramarginal gyrus were primarily activated during the spatiomotor task, whereas the middle frontal gyrus was primarily activated during the function task. Regions along the intraparietal sulcus were more strongly activated during the spatiomotor task but only when the spatiomotor properties of the tool object were unknown in advance. These results suggest a division of labor within the action observation network that maps onto a similar division previously proposed for action execution

Dance as a Subject for Empirical Aesthetics

The purpose of this paper is to highlight the possibilities that research on dance appreciation offers empirical aesthetics, as well as the challenges it poses. Behavioral and neuroimaging approaches have, to date, mainly focused on the perception and recognition of human body movement and structure. A small number of studies, nonetheless, have explicitly taken the basic research on the perceptual, emotional and cognitive processes engaged during movement observation, together with their neural concomitants, as a starting point to understand the aesthetic experience triggered by the observation of a dance. We provide an overview of these studies and, thereafter, point out avenues for future research on dance appreciation within the scope of empirical aesthetics. We also note some methodological and conceptual issues that should be taken into account in the design of empirical studies of the aesthetic appreciation of dance, including dance theory scholarship and humanistic approaches to dance practice. Finally, we describe how common movement features of dance styles around the world suggest that humans may be endowed with an evolved cognitive ability to appreciate and to be aesthetically moved by dance

The hierarchical organisation of cortical and basal-ganglia systems: a computationally-informed review and integrated hypothesis

To suitably adapt to the challenges posed by reproduction and survival, animals need to learn to select when to perform different behaviours, to have internal criteria for guiding these learning processes, and to perform behaviours efficiently once selected. To implement these processes, their brain must be organised in a suitable hierarchical fashion. Here we briefly review two types of neural/behavioural/computational literatures, focussed respectively on cortex and on sub-cortical areas, and highlight their important limitations. Then we review two computational modelling works of the authors that exemplify the problems, brain areas, experiments, main concepts and limitations of the two research threads. Finally we propose a theoretical integration of the two views, showing how this allows to solve most of the problems found by the two accounts if taken in isolation. The overall picture that emerges is that the cortical and the basal ganglia systems form two highly-organised hierarchical systems working in close synergy and jointly solving all the challenges of choice, selection, and implementation needed to acquire and express adaptive behaviour

Priming of reach trajectory when observing actions: Hand-centred effects

When another person's actions are observed it appears that these actions are simulated, such that similar motor processes are triggered in the observer. Much evidence suggests that such simulation concerns the achievement of behavioural goals, such as grasping a particular object, and is less concerned with the specific nature of the action, such as the path the hand takes to reach the goal object. We demonstrate that when observing another person reach around an obstacle, an observer's subsequent reach has an increased curved trajectory, reflecting motor priming of reach path. This priming of reach trajectory via action observation can take place under a variety of circumstances: with or without a shared goal, and when the action is seen from a variety of perspectives. However, of most importance, the reach path priming effect is only evoked if the obstacle avoided by another person is within the action (peripersonal) space of the observer

The Observation and Execution of Actions Share Motor and Somatosensory Voxels in all Tested Subjects: Single-Subject Analyses of Unsmoothed fMRI Data

Many neuroimaging studies of the mirror neuron system (MNS) examine if certain voxels in the brain are shared between action observation and execution (shared voxels, sVx). Unfortunately, finding sVx in standard group analyses is not a guarantee that sVx exist in individual subjects. Using unsmoothed, single-subject analyses we show sVx can be reliably found in all 16 investigated participants. Beside the ventral premotor (BA6/44) and inferior parietal cortex (area PF) where mirror neurons (MNs) have been found in monkeys, sVx were reliably observed in dorsal premotor, supplementary motor, middle cingulate, somatosensory (BA3, BA2, and OP1), superior parietal, middle temporal cortex and cerebellum. For the premotor, somatosensory and parietal areas, sVx were more numerous in the left hemisphere. The hand representation of the primary motor cortex showed a reduced BOLD during hand action observation, possibly preventing undesired overt imitation. This study provides a more detailed description of the location and reliability of sVx and proposes a model that extends the original idea of the MNS to include forward and inverse internal models and motor and sensory simulation, distinguishing the MNS from a more general concept of sVx

The role of transients in action observation

A large number of studies have now described the various ways in which the observation of another person’s dynamic movement can influence the speed with which the observer is able to prepare a motor action themselves. The typical results are most often explained with reference to theories that link perception and action. Such theories argue that the cognitive structures associated with each share common representations. Consequently, action preparation and action observation are often said to be functionally equivalent. However, the dominance of these theories in explaining action observation effects has masked the potential contribution from processes associated with the detection of low-level “transients” resulting from observing a body movement, such as motion and sound. In the present review, we describe work undertaken in one particular action observation phenomenon (“social inhibition of return”) and show that the transient account provides the best explanation of the effect. We argue that future work should consider attention capture and orienting as a potential contributing factor to action observation effects more broadly