Stephanie Spengler

Functional Specialization within Rostral Prefrontal Cortex (Area 10): A Meta-analysis

One of the least well understood regions of the human brain is rostral prefrontal cortex, approximating Brodmanns area 10. Here, we investigate the possibility that there are functional subdivisions within this region by conducting a meta-analysis of 104 functional neuroimaging studies (using positron emission tomography/functional magnetic resonance imaging). Studies involving working memory and episodic memory retrieval were disproportionately associated with lateral activations, whereas studies involving mentalizing (i.e., attending to ones own emotions and mental states or those of other agents) were disproportionately associated with medial activations. Functional variation was also observed along a rostral-caudal axis, with studies involving mentalizing yielding relatively caudal activations and studies involving multiple-task coordination yielding relatively rostral activations. A classification algorithm was trained to predict the task, given the coordinates of each activation peak. Performance was well above chance levels (74% for the three most common tasks; 45% across all eight tasks investigated) and generalized to data not included in the training set. These results point to considerable functional segregation within rostral prefrontal cortex.

Inhibition of imitative behaviour and social cognition

There is converging evidence that the observation of an action activates a corresponding motor representation in the observer through a ‘mirror-matching’ mechanism. However, research on such ‘shared representations’ of perception and action has widely neglected the question of how we can distinguish our own motor intentions from externally triggered motor representations. By investigating the inhibition of imitative response tendencies, as an index for the control of shared representations, we can show that self–other distinction plays a fundamental role in the control of shared representations. Furthermore, we demonstrate that overlapping brain activations can be found in the anterior fronto-median cortex (aFMC) and the temporo-parietal junction (TPJ) area for the control of shared representations and complex social-cognitive tasks, such as mental state attribution. In a functional magnetic resonance imaging experiment, we functionally dissociate the roles of TPJ and aFMC during the control of shared representations. Finally, we propose a hypothesis stating that the control of shared representations might be the missing link between functions of the mirror system and mental state attribution.

Hyperimitation of actions is related to reduced understanding of others' minds in autism spectrum conditions.

BACKGROUND Anecdotal evidence has noted that individuals with autism spectrum conditions (ASC) frequently exhibit heightened spontaneous imitative behavior, with symptoms of echolalia and echopraxia. This is contrasted by empiric reports that ASC results in decreased imitation and an underlying deficit in the mirror system, leading to impaired social understanding. Thus, it remains unclear whether automatic imitation is enhanced in ASC and how this is related to poorer social abilities. METHODS This study investigated spontaneous imitation in 18 high-functioning adults with ASC and 18 age- and IQ-matched control participants during a simple imitation inhibition task. Mentalizing was experimentally assessed in the same participants using both behavioral and functional magnetic resonance imaging measures, as was social interaction using an observational measure. RESULTS Individuals with ASC showed increased imitation of hand actions compared with control participants and this was associated with reduced mentalizing and poorer reciprocal social interaction abilities. In the functional magnetic resonance imaging mentalizing paradigm, ASC participants with increased imitation scores showed less brain activation in areas often found to be active in mental state attribution, namely the medial prefrontal cortex and temporoparietal junction. CONCLUSIONS The results confirm the presence of hyperimitation in ASC, which is accompanied by reduced social cognition, suggesting that a general imitation impairment and a global mirror system deficit are absent. These findings offer an explanation for echopractic features based on theories of atypical functioning of top-down modulation processes in autism.

Control of shared representations relies on key processes involved in mental state attribution

Action observation leads to the automatic activation of the corresponding motor representation in the observer through “mirror‐matching.” This constitutes a “shared representational system,” which is thought to subserve social understanding by motor simulation. However, it is unclear how these shared representations can be controlled and distinguished. Brain imaging suggests that controlling shared representations, indexed by the ability to control automatic imitative responses, activates anterior fronto‐median cortex (aFMC), and temporo‐parietal junction (TPJ). Crucially, these regions are also consistently implicated in mental state attribution and have provided an alternative account for higher‐level social cognition. Here, we directly tested whether social‐cognitive processes involve similar key computational mechanisms as the control of shared representations by using functional brain imaging to reveal overlapping brain circuits. We show in a within‐subject design that commonly activated regions occurred selectively in aFMC and TPJ. Mentalizing and self‐referential thoughts recruited a region in aFMC, which was also activated when controlling imitation. In the TPJ, an area overlapped between mentalizing, agency processing, and imitative control. Behavioral and neural correlates of mentalizing were further related to the individual ability for controlling imitation. Our findings support the assumption of shared key processes and suggest a novel link between embodied and social cognition. Hum Brain Mapp, 2009.

Resisting motor mimicry: Control of imitation involves processes central to social cognition in patients with frontal and temporo-parietal lesions

Perception and execution of actions share a common representational and neural substrate and thereby facilitate unintentional motor mimicry. Controlling automatic imitation is therefore a crucial requirement of such a “shared representational” system. Based on previous findings from neuroimaging, we suggest that resisting motor mimicry recruits the same underlying computational mechanisms also involved in higher-level social cognitive processing, such as self − other differentiation and the representation of mental states. The aim of the present study was to investigate on a behavioral level whether there is a functional association between the inhibition of imitation and tasks, assessing the understanding of mental states and of different perspectives of self and other. In a sample of neuropsychological patients with frontal lesions, a correlation between the ability for mental state attribution and the control of imitation was found, with a similar effect in the control group. Temporo-parietal lesioned patients showed a highly significant correlation between imitative control and visual and cognitive perspective-taking. Even after controlling for executive functions, the results remained significant, indicating the functional specificity of this relationship. These findings provide new insight into the functional processes underlying the control of shared representations and suggest a novel link between embodied and higher-level social cognition.

Neural Correlates of Overcoming Interference from Instructed and Implemented Stimulus–Response Associations

One of the major evolutionary advances of human primates in the motor domain is their ability to use verbal instructions to guide their behavior. Despite this fundamental role of verbal information for our behavioral regulation, the functional and neural mechanisms underlying the transformation of verbal instructions into efficient behavior are still poorly understood. To gain deeper insights into the motor representation of verbal instructions, we investigated the neural circuits involved in overcoming interference from stimulus– response (S-R) mappings that are merely instructed and S-R mappings that are implemented. Implemented and instructed S-R mappings revealed a partly overlapping pattern of fronto-parietal brain activity when compared with a neutral condition. However, the direct contrast revealed a clear difference with stronger activation for the implemented condition in the ACC, bilateral inferior parietal cortex, the cerebellum and the precentral sulcus. This indicates that instructed S-R mappings share some properties with implemented S-R mappings but that they are lacking the motor-related properties of implemented mappings.

Minimizing motor mimicry by myself: Self-focus enhances online action-control mechanisms during motor contagion

Ideomotor theory of human action control proposes that activation of a motor representation can occur either through internally-intended or externally-perceived actions. Critically, sometimes these alternatives of eliciting a motor response may be conflicting, for example, when intending one action and perceiving another, necessitating the recruitment of enhanced action-control to avoid motor mimicry. Based on previous neuroimaging evidence, suggesting that reduced mimicry is associated with self-related processing, we aimed to experimentally enhance these action-control mechanisms during motor contagion by inducing self-focus. In two within-subjects experiments, participants had to enforce their action intention against an external motor contagion tendency under heightened and normal self-focus. During high self-focus participants showed reduced motor mimicry, induced either by mirror self-observation or self-referential judgments. This indicates that a self-focus provoking situation can enhance online action-control mechanisms, needed to resist unintentional motor contagion tendencies and thereby enables a modulation of automatic mirroring responses.