Movement and mind: a functional imaging study of perception and interpretation of complex intentional movement patterns

Neural systems involved in "theory of mind"

What is the nature of our ability to understand and reason about the beliefs of others--the possession of a "theory of mind", or ToM? Here, we review findings from imaging and lesion studies indicating that ToM reasoning is supported by a widely distributed neural system. Some functional components of this system, such as language-related regions of the left hemisphere, the frontal lobes and the right temporal parietal cortex, are not solely dedicated to the computation of mental states. However, the system also includes a core, domain-specific component that is centred on the amygdala circuitry. We provide a framework in which impairments of ToM can be viewed in terms of abnormalities of the core system, the failure of a co-opted system that is necessary for performance on a particular set of tasks, or the absence of an experiential trigger for the emergence of ToM.

Autism: a cognitive developmental riddle

It has been 60 years since the definitive descriptions of autism, yet it is only in the past decade that related advances in cognitive and basic neuroscience have begun to be incorporated in clinical practice. Some of the resultant clinical advances, which include a trend toward international standardization of diagnosis on the basis of behavioral criteria and which, in turn, seem to allow for earlier, more secure diagnosis and the application of behavioral therapy in early childhood, as well as more thorough genetic studies, are briefly reviewed. The three major defects in thought processing that are postulated by cognitive neuropsychologists to result in aberrant autistic behaviors are also reviewed and linked to recent functional imaging studies in autistic patients and some animal and bench research suggestive of both cortical and subcortical developmental vulnerabilities in autism. Overall it seems at least possible that neuroscientific research may yield results applicable to prevention or remediation of autism, a condition heretofore considered irremediable.

Social interest and the development of cortical face specialization: what autism teaches us about face processing

Investigations of face processing in persons with an autism spectrum disorder (ASD) inform upon theories of the development of "normal" face processing, and the story that emerges challenges some models of the nature and origin of cortical face specialization. Individuals with an ASD possess deficits in face processing and a lack of a fusiform face area (FFA). Evidence from studies of ASD can be conceptualized best using an expertise framework of face processing rather than models that postulate a face module in the fusiform gyrus. Because persons with an ASD have reduced social interest, they may fail to develop cortical face specialization. Face specialization may develop in normal individuals because they are socially motivated to regard the face, and such motivation promotes expertise for faces. The amygdala is likely the key node in the system that marks objects as emotionally salient and could be crucial to the development of cortical face specialization.

The anterior frontomedian cortex and evaluative judgment: an fMRI study

This study investigated the neuronal basis of evaluative judgment. Judgments can be defined as the assessment of an external or internal stimulus on an internal scale and they are fundamental for decision-making and other cognitive processes. Evaluative judgments (I like George W. Bush: yes/no) are a special type of judgment, in which the internal scale is related to the person's value system (preferences, norms, aesthetic values, etc.). We used functional magnetic resonance imaging to examine brain activation during the performance of evaluative judgments as opposed to episodic and semantic memory retrieval. Evaluative judgment produced significant activation in the anterior frontomedian cortex (BA 10/9), the inferior precuneus (BA 23/31), and the left inferior prefrontal cortex (BA 45/47). The results show a functional dissociation between the activations in the anterior frontomedian cortex and in the inferior precuneus. The latter was mainly activated by episodic retrieval processes, supporting its function as a multimodal association area that integrates the different aspects of retrieved and newly presented information. In contrast, the anterior frontomedian cortex was mainly involved in evaluative judgments, supporting its role in self-referential processes and in the self-initiation of cognitive processes.

Automatic and intentional brain responses during evaluation of trustworthiness of faces

Successful social interaction partly depends on appraisal of others from their facial appearance. A critical aspect of this appraisal relates to whether we consider others to be trustworthy. We determined the neural basis for such trustworthiness judgments using event-related functional magnetic resonance imaging. Subjects viewed faces and assessed either trustworthiness or age. In a parametric factorial design, trustworthiness ratings were correlated with BOLD signal change to reveal task-independent increased activity in bilateral amygdala and right insula in response to faces judged untrustworthy. Right superior temporal sulcus (STS) showed enhanced signal change during explicit trustworthiness judgments alone. The findings extend a proposed model of social cognition by highlighting a functional dissociation between automatic engagement of amygdala versus intentional engagement of STS in social judgment.

Mind blindness and the brain in autism

Experimental evidence shows that the inability to attribute mental states, such as desires and beliefs, to self and others (mentalizing) explains the social and communication impairments of individuals with autism. Brain imaging studies in normal volunteers highlight a circumscribed network that is active during mentalizing and links medial prefrontal regions with posterior superior temporal sulcus and temporal poles. The brain abnormality that results in mentalizing failure in autism may involve weak connections between components of this system.

Searching for a baseline: functional imaging and the resting human brain

Functional brain imaging in humans has revealed task-specific increases in brain activity that are associated with various mental activities. In the same studies, mysterious, task-independent decreases have also frequently been encountered, especially when the tasks of interest have been compared with a passive state, such as simple fixation or eyes closed. These decreases have raised the possibility that there might be a baseline or resting state of brain function involving a specific set of mental operations. We explore this possibility, including the manner in which we might define a baseline and the implications of such a baseline for our understanding of brain function.

A functional imaging study of cooperation in two-person reciprocal exchange

Cooperation between individuals requires the ability to infer each other's mental states to form shared expectations over mutual gains and make cooperative choices that realize these gains. From evidence that the ability for mental state attribution involves the use of prefrontal cortex, we hypothesize that this area is involved in integrating theory-of-mind processing with cooperative actions. We report data from a functional MRI experiment designed to test this hypothesis. Subjects in a scanner played standard two-person "trust and reciprocity" games with both human and computer counterparts for cash rewards. Behavioral data shows that seven subjects consistently attempted cooperation with their human counterpart. Within this group prefrontal regions are more active when subjects are playing a human than when they are playing a computer following a fixed (and known) probabilistic strategy. Within the group of five noncooperators, there are no significant differences in prefrontal activation between computer and human conditions.

Movement preparation and motor intention

This paper addresses the functional anatomy of movement representation. We have used associative visuomotor tasks with instructed delays to elicit motor preparatory activity. We regard such activity, when independent from transient stimulus-locked responses, as a likely candidate for the neural basis of movement representation (M. Jeannerod, The Cognitive Neuroscience of Action. Blackwell, Oxford, 1997). In a first event-related fMRI experiment, we found that preparing to move according to arbitrary visuomotor associations relies not only on parietofrontal circuitry, but also on portions of the posterior superior temporal sulcus. In a separate behavioral experiment, we discarded the hypothesis that such activities were confounded by working memory processes. In a second imaging experiment, we have further defined the relative contributions of these parietal, premotor, and temporal areas to the preparatory process and their involvement in motor representations. We conclude that posterior parietal cortex is interested in evaluating the potential motor significance of sensory stimuli, irrespectively of the likelihood of providing a response ("motor intention"). Conversely, preparatory activity in frontal premotor regions appears to be a function of the probability of a subsequent movement. Finally, on the basis of the present and published data, we suggest that posterior temporal cortex might be involved in the extraction of contextual and intentional cues during goal-oriented behavior.

Visual motion and the human brain: what has neuroimaging told us?

Recently, neuroimaging techniques have been applied to the study of human motion perception, complementing established techniques such as psychophysics, neurophysiology and neuropsychology. Because vision, particularly motion perception, has been studied relatively extensively, it provides an interesting case study to examine the contributions and limitations of neuroimaging to cognitive neuroscience. We suggest that in the domain of motion perception neuroimaging has: (1) revealed an extensive network of motion areas throughout the human brain, in addition to the well-studied motion complex (MT+); (2) verified and extended findings from other techniques; (3) suggested extensive top-down influences on motion perception; and (4) allowed experimenters to examine the neural correlates of awareness. We discuss these contributions, along with limitations and future directions for the neuroimaging of motion.

The neurobiology of social cognition

Recent studies have begun to elucidate the roles played in social cognition by specific neural structures, genes, and neurotransmitter systems. Cortical regions in the temporal lobe participate in perceiving socially relevant stimuli, whereas the amygdala, right somatosensory cortices, orbitofrontal cortices, and cingulate cortices all participate in linking perception of such stimuli to motivation, emotion, and cognition. Open questions remain about the domain-specificity of social cognition, about its overlap with emotion and with communication, and about the methods best suited for its investigation.

Medial prefrontal cortex and self-referential mental activity: relation to a default mode of brain function

Medial prefrontal cortex (MPFC) is among those brain regions having the highest baseline metabolic activity at rest and one that exhibits decreases from this baseline across a wide variety of goal-directed behaviors in functional imaging studies. This high metabolic rate and this behavior suggest the existence of an organized mode of default brain function, elements of which may be either attenuated or enhanced. Extant data suggest that these MPFC regions may contribute to the neural instantiation of aspects of the multifaceted "self." We explore this important concept by targeting and manipulating elements of MPFC default state activity. In this functional magnetic resonance imaging (fMRI) study, subjects made two judgments, one self-referential, the other not, in response to affectively normed pictures: pleasant vs. unpleasant (an internally cued condition, ICC) and indoors vs. outdoors (an externally cued condition, ECC). The ICC was preferentially associated with activity increases along the dorsal MPFC. These increases were accompanied by decreases in both active task conditions in ventral MPFC. These results support the view that dorsal and ventral MPFC are differentially influenced by attentiondemanding tasks and explicitly self-referential tasks. The presence of self-referential mental activity appears to be associated with increases from the baseline in dorsal MPFC. Reductions in ventral MPFC occurred consistent with the fact that attention-demanding tasks attenuate emotional processing. We posit that both self-referential mental activity and emotional processing represent elements of the default state as represented by activity in MPFC. We suggest that a useful way to explore the neurobiology of the self is to explore the nature of default state activity.

Acquired mind-blindness following frontal lobe surgery? A single case study of impaired 'theory of mind' in a patient treated with stereotactic anterior capsulotomy

Social insight, specifically the ability to represent thoughts and feelings ('theory of mind'), may have a circumscribed and dedicated neurological substrate. Evidence of deficits in 'theory of mind' following acquired lesions would support this idea. Previous studies of lesions resulting from stroke or head injury have been hampered by lack of detailed lesion information and pre-lesion documentation. We report the case of a 76-year-old man who, following a standard surgical procedure to treat bipolar affective disorder, showed evidence of impaired 'theory of mind'. This case, which is the first of its type, may contribute to the search for the brain basis of social insight.

Developmental origin of the animate-inanimate distinction

The authors examine recent theoretical perspectives of the development of the animate-inanimate distinction in infancy. From these theoretical views emerge 7 characteristic properties, each related to physical or psychological causality, that distinguish animates from inanimates. The literature is reviewed for evidence of infants' ability to perceive and understand each of these properties. Infants associate some animate properties with people by 6 months, but they do not associate the appropriate properties to the broad category of animates and inanimates until at least the middle of the 2nd year. The authors offer a theoretical proposal whereby infants acquire knowledge about the properties of different object kinds through a sensitive perceptual system and a domain general associative learning mechanism that extracts correlations among dynamic and static features.

Dissociation between 'theory of mind' and executive functions in a patient with early left amygdala damage

There have been recent suggestions that the amygdala may be involved in the development or mediation of 'theory of mind'. We report a patient, B.M., with early or congenital left amygdala damage who, by adulthood, had received the psychiatric diagnoses of schizophrenia and Asperger's syndrome. We conducted a series of experimental investigations to determine B.M.'s cognitive functioning. In line with his diagnoses, B.M. was found to be severely impaired in his ability to represent mental states. Following this, we conducted a second series of studies to determine B.M.'s executive functioning. In the literature, there have been frequent claims that theory of mind is mediated by general executive functioning. B.M. showed no indication of executive function impairment, passing 16 tests assessing his ability to inhibit dominant responses, create and maintain goal-related behaviours, and temporally sequence behaviour. The findings are discussed with reference to models regarding the role of the amygdala in the development of theory of mind and the degree of dissociation between theory of mind and executive functioning. We conclude that theory of mind is not simply a function of more general executive functions, and that executive functions can develop and function on-line, independently of theory of mind. Moreover, we conclude that the amygdala may play some role in the development of the circuitry mediating theory of mind.