Neural processing of intentional biological motion in unaffected siblings of children with autism spectrum disorder: An fMRI study

Despite often showing behaviorally typical levels of social cognitive ability, unaffected siblings of children with autism spectrum disorder have been found to show similar functional and morphological deficits within brain regions associated with social processing. They have also been reported to show increased activation to biological motion in these same regions, such as the posterior superior temporal sulcus (pSTS), relative to both children with autism and control children. It has been suggested that this increased activation may represent a compensatory reorganization of these regions as a result of the highly heritable genetic influence of autism. However, the response patterns of unaffected siblings in the domain of action perception are unstudied, and the phenomenon of compensatory activation has not yet been replicated. The present study used functional magnetic resonance imaging to determine the neural responses to intentional biological actions in 22 siblings of children with autism and 22 matched controls. The presented actions were either congruent or incongruent with the actor’s emotional cue. Prior studies reported that typically developing children and adults, but not children with autism, show increased activation to incongruent actions (relative to congruent), within the pSTS and dorsolateral prefrontal cortex. We report that unaffected siblings did not show a compensatory response, or a preference for incongruent over congruent trials, in any brain region. Moreover, interaction analyses revealed a sub-region of the pSTS in which control children showed an incongruency preference to a significantly greater degree than siblings, which suggests a localized deficit in siblings. A sample of children with autism also did not show differential activation in the pSTS, providing further evidence that it is an area of selective disruption in children with autism and siblings. While reduced activation to both conditions was unique to the autism sample, lack of differentiation to incongruent and congruent intentional actions was common to both children with ASD and unaffected siblings.     

Neural correlates of coherent and biological motion perception in autism

Recent evidence suggests those with autism may be generally impaired in visual motion perception. To examine this, we investigated both coherent and biological motion processing in adolescents with autism employing both psychophysical and fMRI methods. Those with autism performed as well as matched controls during coherent motion perception but had significantly higher thresholds for biological motion perception. The autism group showed reduced posterior Superior Temporal Sulcus (pSTS), parietal and frontal activity during a biological motion task while showing similar levels of activity in MT+/V5 during both coherent and biological motion trials. Activity in MT+/V5 was predictive of individual coherent motion thresholds in both groups. Activity in dorsolateral prefrontal cortex (DLPFC) and pSTS was predictive of biological motion thresholds in control participants but not in those with autism. Notably, however, activity in DLPFC was negatively related to autism symptom severity. These results suggest that impairments in higher-order social or attentional networks may underlie visual motion deficits observed in autism.     

Neural processing of intentional biological motion in unaffected siblings of children with autism spectrum disorder: An fMRI study

Despite often showing behaviorally typical levels of social cognitive ability, unaffected siblings of children with autism spectrum disorder have been found to show similar functional and morphological deficits within brain regions associated with social processing. They have also been reported to show increased activation to biological motion in these same regions, such as the posterior superior temporal sulcus (pSTS), relative to both children with autism and control children. It has been suggested that this increased activation may represent a compensatory reorganization of these regions as a result of the highly heritable genetic influence of autism. However, the response patterns of unaffected siblings in the domain of action perception are unstudied, and the phenomenon of compensatory activation has not yet been replicated. The present study used functional magnetic resonance imaging to determine the neural responses to intentional biological actions in 22 siblings of children with autism and 22 matched controls. The presented actions were either congruent or incongruent with the actor’s emotional cue. Prior studies reported that typically developing children and adults, but not children with autism, show increased activation to incongruent actions (relative to congruent), within the pSTS and dorsolateral prefrontal cortex. We report that unaffected siblings did not show a compensatory response, or a preference for incongruent over congruent trials, in any brain region. Moreover, interaction analyses revealed a sub-region of the pSTS in which control children showed an incongruency preference to a significantly greater degree than siblings, which suggests a localized deficit in siblings. A sample of children with autism also did not show differential activation in the pSTS, providing further evidence that it is an area of selective disruption in children with autism and siblings. While reduced activation to both conditions was unique to the autism sample, lack of differentiation to incongruent and congruent intentional actions was common to both children with ASD and unaffected siblings.     

Categorizing coordination from the perception of joint actions

The ability to perceive others’ actions and coordinate our own body movements accordingly is essential for humans to interact with the social world. However, it is still unclear how the visual system achieves the remarkable feat of identifying temporally coordinated joint actions between individuals. Specifically, do humans rely on certain visual features of coordinated movements to facilitate the detection of meaningful interactivity? To address this question, participants viewed short video sequences of two actors performing different joint actions, such as handshakes, high fives, etc. Temporal misalignments were introduced to shift one actor’s movements forward or backward in time relative to the partner actor. Participants rated the degree of interactivity for the temporally shifted joint actions. The impact of temporal offsets on human interactivity ratings varied for different types of joint actions. Based on human rating distributions, we used a probabilistic cluster model to infer latent categories, each revealing shared characteristics of coordinated movements among sets of joint actions. Further analysis on the clustered structure suggested that global motion synchrony, spatial proximity between actors, and highly salient moments of interpersonal coordination are critical features that impact judgments of interactivity.     

Representing and anticipating human actions in vision

Visual perception of human actions was investigated in a long-term priming experiment. On each trial in the priming phase, participants were presented with a pair of short motion animations showing a person performing a particular whole body movement and had to decide whether the actions were the same or different. In the testing block, the same observers had to determine whether static pictures of a human model showed a possible or an impossible body pose. For each test posture, a subject either (1) had seen a priming animation in which the actor would have reached the test posture if the animation had lasted longer, (2) had seen an animation in which the actor would have been in the test posture if the animation had started earlier, or (3) had not seen a related priming animation. Reliable facilitatory priming effects were obtained only when the test posture was preceded by a motion sequence that would have resulted in the test posture if the human model had continued the action. The findings support the hypothesis that, when confronted with a human action, observers anticipate the future posture of the actor and that this anticipation facilitates later identification of the posture.     

Social perception from visual cues: role of the STS region

Social perception refers to initial stages in the processing of information that culminates in the accurate analysis of the dispositions and intentions of other individuals. Single-cell recordings in monkeys, and neurophysiological and neuroimaging studies in humans, reveal that cerebral cortex in and near the superior temporal sulcus (STS) region is an important component of this perceptual system. In monkeys and humans, the STS region is activated by movements of the eyes, mouth, hands and body, suggesting that it is involved in analysis of biological motion. However, it is also activated by static images of the face and body, suggesting that it is sensitive to implied motion and more generally to stimuli that signal the actions of another individual. Subsequent analysis of socially relevant stimuli is carried out in the amygdala and orbitofrontal cortex, which supports a three-structure model proposed by Brothers. The homology of human and monkey areas involved in social perception, and the functional interrelationships between the STS region and the ventral face area, are unresolved issues.     

触觉的情绪功能及其神经生理机制

触觉是个体探知外部世界的重要感觉通道,其情绪功能在维系社会联结、促进人际沟通等方面具有重要作用。触觉的情绪功能一方面表现为通过触觉动作本身直接传递情绪信息,另一方面则是通过增强注意和锐化社会评价的方式促进个体对跨通道情绪信息的加工。神经生理学研究发现,触觉情绪信息由无髓鞘C纤维介导,经脊髓丘脑束通路投射于岛叶(头面部触觉情绪信息的传导路径尚不明确),并在杏仁核、内侧前额叶、后颞上沟等"社会脑"网络的核心区域被精细加工。未来还应对触觉情绪的人际依赖性、文化独特性、操作标准化,及其在神经水平上与感觉-辨识系统间的关联性与独立性做深入探究。     

The beat goes on: rhythmic modulation of cortical potentials by imagined tapping

A frequency analysis was used to tag cortical activity from imagined rhythmic movements. Participants synchronized overt and imagined taps with brief visual stimuli presented at a constant rate, alternating between left and right index fingers. Brain potentials were recorded from across the scalp and topographic maps made of their power at the alternation frequency between left and right taps. Two prominent power foci occurred in each hemisphere for both overt and imagined taps, one over sensorimotor cortex and the other over posterior parietal cortex, with homologous foci in opposite hemispheres arising from oscillations 180 degrees out of phase. These findings demonstrate temporal isomorphism at a neural level between overt and imagined movements and illustrate a new approach to studying covert actions.     

Infant and adult perceptions of possible and impossible body movements: An eye-tracking study

This study investigated how infants perceive and interpret human body movement. We recorded the eye movements and pupil sizes of 9- and 12-month-old infants and of adults (N=14 per group) as they observed animation clips of biomechanically possible and impossible arm movements performed by a human and by a humanoid robot. Both 12-month-old infants and adults spent more time looking at the elbows during impossible compared with possible arm movements, irrespective of the appearance of the actor. These results suggest that by 12months of age, infants recognize biomechanical constraints on how arms move, and they extend this knowledge to humanoid robots. Adults exhibited more pupil dilation in response to the human's impossible arm movements compared with the possible ones, but 9- and 12-month-old infants showed no differential pupil dilation to the same actions. This finding suggests that the processing of human body movements might still be immature in 12-month-olds, as they did not show an emotional response to biomechanically impossible body movements. We discuss these findings in relation to the hypothesis that perception of others' body movements relies upon the infant's own sensorimotor experience.     

Left posterior auditory-related cortices participate both in speech perception and speech production: Neural overlap revealed by fMRI

Recent neuroimaging studies and neuropsychological data suggest that there are regions in posterior auditory cortex that participate both in speech perception and speech production. An outstanding question is whether the same neural regions support both perception and production or whether there exist discrete cortical fields subserving these functions. Previous neurophysiological studies suggest that there is indeed regional overlap between these systems, but those studies used a rehearsal task to assess production. The present study addressed this question in an event-related fMRI experiment in which subjects listened to speech and in separate trials, performed a covert object naming task. Single subject analysis revealed regions of coactivation for speech perception and production in the left posterior superior temporal sulcus (pSTS), left area Spt (a region in the Sylvian fissure at the parietal-temporal boundary), and left inferior frontal gyrus. These results are consistent with lesion data and previous physiological data indicating that posterior auditory cortex plays a role in both reception and expression of speech. We discuss these findings within the context of a neuroanatomical framework that proposes these neural sites are a part of an auditory-motor integration system.     

Dissociable neural systems support retrieval of how and why action knowledge

In everyday discourse, people typically represent actions in one of two ways: how they are performed or why they are performed. In the present study, we determined the neural systems that support these natural modes of representing actions. Participants underwent functional magnetic resonance imaging while identifying how and why people perform various familiar actions. Identifying how actions are performed produced activity in premotor areas that support the execution of actions and in higher-order visual areas that support the perception of action-related objects; this finding supports an embodied view of action knowledge. However, identifying why actions are performed preferentially engaged areas of the brain associated with representing and reasoning about mental states; these areas were right temporoparietal junction, precuneus, dorsomedial prefrontal cortex, and posterior superior temporal sulcus. Our results suggest that why action knowledge is not sufficiently constituted by information in motor and visual systems, but requires a system for representing states of mind, which do not have reliable motor correlates or visual appearance.     

Recognizing people from their movement

Human observers demonstrate impressive visual sensitivity to human movement. What defines this sensitivity? If motor experience influences the visual analysis of action, then observers should be most sensitive to their own movements. If view-dependent visual experience determines visual sensitivity to human movement, then observers should be most sensitive to the movements of their friends. To test these predictions, participants viewed sagittal displays of point-light depictions of themselves, their friends, and strangers performing various actions. In actor identification and discrimination tasks, sensitivity to one's own motion was highest. Visual sensitivity to friends', but not strangers', actions was above chance. Performance was action dependent. Control studies yielded chance performance with inverted and static displays, suggesting that form and low-motion cues did not define performance. These results suggest that both motor and visual experience define visual sensitivity to human action.     

Infant perception of causal motion produced by humans and inanimate objects

Both the movements of people and inanimate objects are intimately bound up with physical causality. Furthermore, in contrast to object movements, causal relationships between limb movements controlled by humans and their body displacements uniquely reflect agency and goal-directed actions in support of social causality. To investigate the development of sensitivity to causal movements, we examined the looking behavior of infants between 9 and 18 months of age when viewing movements of humans and objects. We also investigated whether individual differences in gender and gross motor functions may impact the development of the visual preferences for causal movements. In Experiment 1, infants were presented with walking stimuli showing either normal body translation or a “moonwalk” that reversed the horizontal motion of body translations. In Experiment 2, infants were presented with unperformable actions beyond infants’ gross motor functions (i.e., long jump) either with or without ecologically valid body displacement. In Experiment 3, infants were presented with rolling movements of inanimate objects that either complied with or violated physical causality. We found that female infants showed longer looking times to normal walking stimuli than to moonwalk stimuli, but did not differ in their looking time to movements of inanimate objects and unperformable actions. In contrast, male infants did not show sensitivity to causal movement for either category. Additionally, female infants looked longer at social stimuli of human actions than male infants. Under the tested circumstances, our findings indicate that female infants have developed a sensitivity to causal consistency between limb movements and body translations of biological motion, only for actions with previous visual and motor exposures, and demonstrate a preference toward social information.     

Adolescents’ neural response to social reward and real-world emotional closeness and positive affect

Feeling emotionally close to others during social interactions is a ubiquitous and meaningful experience that can elicit positive affect. The present study integrates functional magnetic resonance imaging (fMRI) and ecological momentary assessment (EMA) to investigate whether neural response to social reward (1) is related to the experience of emotional closeness and (2) moderates the association between emotional closeness and positive affect during and following social interactions. In this study, 34 typically developing adolescents (ages 14–18 years) completed a social-reward fMRI task, a monetary-reward fMRI task, and a 2-week EMA protocol regarding their social and affective experiences. Adolescents with greater right posterior superior temporal sulcus/temporoparietal junction (pSTS/TPJ) response to social reward reported greater mean momentary emotional closeness. Neural response to social reward in the right pSTS/TPJ moderated how strongly momentary emotional closeness was associated with both concurrent positive affect and future peak happiness, but in different ways. Although emotional closeness had a significant positive association with concurrent positive affect among adolescents at both high and low right pSTS/TPJ response based on a follow-up simple slopes test, this association was stronger for adolescents with low right pSTS/TPJ response. In contrast, emotional closeness had a significant positive association with future peak happiness among adolescents with high right pSTS/TPJ response, but not among those with low right pSTS/TPJ response. These findings demonstrate the importance of neural response to social reward in key social processing regions for everyday experiences of emotional closeness and positive affect in the context of social interactions.     

Neural modeling and imaging of the cortical interactions underlying syllable production

This paper describes a neural model of speech acquisition and production that accounts for a wide range of acoustic, kinematic, and neuroimaging data concerning the control of speech movements. The model is a neural network whose components correspond to regions of the cerebral cortex and cerebellum, including premotor, motor, auditory, and somatosensory cortical areas. Computer simulations of the model verify its ability to account for compensation to lip and jaw perturbations during speech. Specific anatomical locations of the model's components are estimated, and these estimates are used to simulate fMRI experiments of simple syllable production.     

Towards a sensorimotor aesthetics of performing art

The field of neuroaesthetics attempts to identify the brain processes underlying aesthetic experience, including but not limited to beauty. Previous neuroaesthetic studies have focussed largely on paintings and music, while performing arts such as dance have been less studied. Nevertheless, increasing knowledge of the neural mechanisms that represent the bodies and actions of others, and which contribute to empathy, make a neuroaesthetics of dance timely. Here, we present the first neuroscientific study of aesthetic perception in the context of the performing arts. We investigated brain areas whose activity during passive viewing of dance stimuli was related to later, independent aesthetic evaluation of the same stimuli. Brain activity of six na?ve male subjects was measured using fMRI, while they watched 24 dance movements, and performed an irrelevant task. In a later session, participants rated each movement along a set of established aesthetic dimensions. The ratings were used to identify brain regions that were more active when viewing moves that received high average ratings than moves that received low average ratings. This contrast revealed bilateral activity in the occipital cortices and in right premotor cortex. Our results suggest a possible role of visual and sensorimotor brain areas in an automatic aesthetic response to dance. This sensorimotor response may explain why dance is widely appreciated in so many human cultures.     

Visual aftereffects for walking actions reveal underlying neural mechanisms for action recognition

The results of this study illustrate a new high-level visual aftereffect: Observing actors walking forward, without horizontal translation, makes subsequent actors appear to walk backward, and the opposite effect is obtained after observing backward walking. We used this aftereffect, which cannot be explained by simple low-level adaptation to motion direction, to investigate the properties of neural mechanisms underlying recognition of walking actions. Our results suggest that the perception of walking and the perception of static images of actors in walking postures rely on common brain mechanisms that are primarily object centered, rather than viewer centered, and that are blind to the identity of the actor. These results, obtained with human psychophysical adaptation techniques, support previous evidence accumulated using single-unit recording in nonhuman primates. In addition, these results provide evidence that current models of human action recognition require an object-centered processing stage.     

Hierarchical Error Evaluation: The Role of Medial-Frontal Cortex in Postural Control

Motor error evaluation appears to be a hierarchically organized process subserved by 2 distinct systems: a higher level system within medial-frontal cortex responsible for movement outcome evaluation (high-level error evaluation) and a lower level posterior system(s) responsible for the mediation of within-movement errors (low-level error evaluation). While a growing body of evidence suggests that a reinforcement learning system within medial-frontal cortex plays a crucial role in the evaluation of high-level errors made during discrete reaching movements and continuous motor tracking, the role of this system in postural control is currently unclear. Participants learned a postural control task via a feedback-driven trial-and-error shaping process. In line with previous findings, electroencephalographic recordings revealed that feedback about movement outcomes elicited a feedback error–related negativity: a component of the human event-related brain potential associated with high-level outcome evaluation within medial-frontal cortex. Thus, the data provide evidence that a high-level error-evaluation system within medial-frontal cortex plays a key role in learning to control our body posture.     

孤独症谱系障碍者的生物运动探测障碍：基于行为与神经的证据

关于孤独症谱系障碍(autism spectrum disorder, ASD)个体探测生物运动(biological motion)的能力是否受损,已有行为研究尚存分歧。导致分歧的原因可能源于实验刺激、实验任务和测量指标存在差异。然而,神经研究却一致证实其潜在的神经机制存在异常。领域特殊性观点认为该障碍可能是基于后侧颞上沟功能异常也可能是基于镜像神经元功能异常,而领域一般性观点认为该障碍可能是基于背侧视觉流功能异常的视运动知觉障碍也可能基于脑功能联结异常的弱中央统合障碍。据此,本文将从研究范式、行为表现及潜在机制三个方面梳理相关研究,以期为后续研究提供新方向。     

The neural correlates of movement intentions: A pilot study comparing hypnotic and simulated paralysis

The distinct feeling of wanting to act and thereby causing our own actions is crucial to our self-perception as free human agents. Disturbances of the link between intention and action occur in several disorders. Little is known, however, about the neural correlates of wanting or intending to act. To investigate these for simple voluntary movements, we used a paradigm involving hypnotic paralysis and functional magnetic resonance imaging. Eight healthy women were instructed to sequentially perform left and right hand movements during a normal condition, as well as during simulated weakness, simulated paralysis and hypnotic paralysis of the right hand. Right frontopolar cortex was selectively hypoactivated for attempted right hand movement during simulated paralysis while it was active in all other conditions. Since simulated paralysis was the only condition lacking an intention to move, the activation in frontopolar cortex might be related to the intention or volition to move.