Goal representation in the infant brain

It is well established that, from an early age, human infants interpret the movements of others as actions directed towards goals. However, the cognitive and neural mechanisms which underlie this ability are hotly debated. The current study was designed to identify brain regions involved in the representation of others’ goals early in development. Studies with adults have demonstrated that the anterior intraparietal sulcus (aIPS) exhibits repetition suppression for repeated goals and a release from suppression for new goals, implicating this specific region in goal representation in adults. In the current study, we used a modified paired repetition suppression design with 9-month-old infants to identify which cortical regions are suppressed when the infant observes a repeated goal versus a new goal. We find a strikingly similar response pattern and location of activity as had been reported in adults; the only brain region displaying significant repetition suppression for repeated goals and a release from suppression for new goals was the left anterior parietal region. Not only does our data suggest that the left anterior parietal region is specialized for representing the goals of others’ actions from early in life, this demonstration presents an opportunity to use this method and design to elucidate the debate over the mechanisms and cues which contribute to early action understanding

Inhibition of left anterior intraparietal sulcus shows that mutual adjustment marks dyadic joint-actions in humans

Creating real-life dynamic contexts to study interactive behaviors is a fundamental challenge for the social neuroscience of interpersonal relations. Real synchronic interpersonal motor interactions involve online, inter-individual mutual adaptation (the ability to adapt one's movements to those of another in order to achieve a shared goal). In order to study the contribution of the left anterior Intra Parietal Sulcus (aIPS) (i.e. a region supporting motor functions) to mutual adaptation, here, we combined a behavioral grasping task where pairs of participants synchronized their actions when performing mutually adaptive imitative and complementary movements, with the inhibition of activity of aIPS via non-invasive brain stimulation. This approach allowed us to investigate whether aIPS supports online complementary and imitative interactions. Behavioral results showed that inhibition of aIPS selectively impairs pair performance during complementary compared to imitative interactions. Notably, this effect depended on pairs' mutual adaptation skills and was higher for pairs composed of participants who were less capable of adapting to each other. Thus, we provide the first causative evidence for a role of the left aIPS in supporting mutually adaptive interactions and show that the inhibition of the neural resources of one individual of a pair is compensated at the dyadic level

Why behaviour matters: Studying inter-brain coordination during child-caregiver interaction

Modern technology allows for simultaneous neuroimaging from interacting caregiver-child dyads. Whereas most analyses that examine the coordination between brain regions within an individual brain do so by measuring changes relative to observed events, studies that examine coordination between two interacting brains generally do this by measuring average intra-brain coordination across entire blocks or experimental conditions. In other words, they do not examine changes in inter-brain coordination relative to individual behavioural events. Here, we discuss the limitations of this approach. First, we present data suggesting that fine-grained temporal interdependencies in behaviour can leave residual artifact in neuroimaging data. We show how artifact can manifest as both power and (through that) phase synchrony effects in EEG and affect wavelet transform coherence in fNIRS analyses. Second, we discuss different possible mechanistic explanations of how inter-brain coordination is established and maintained. We argue that non-event-locked approaches struggle to differentiate between them. Instead, we contend that approaches which examine how interpersonal dynamics change around behavioural events have better potential for addressing possible artifactual confounds and for teasing apart the overlapping mechanisms that drive changes in inter-brain coordination

fNIRS: An Emergent Method to Document Functional Cortical Activity during Infant Movements

The neural basis underlying the emergence of goal-directed actions in infants has been severely understudied, with minimal empirical evidence for hypotheses proposed. This was largely due to the technological constraints of traditional neuroimaging techniques. Recently, functional near-infrared spectroscopy (fNIRS) technology has emerged as a tool developmental scientists are finding useful to examine cortical activity, particularly in young children and infants due to its greater tolerance to movements than other neuroimaging techniques. fNIRS provides an opportunity to finally begin to examine the neural underpinnings as infants develop goal-directed actions.In this methodological paper, I will outline the utility, challenges, and outcomes of using fNIRS to measure the changes in cortical activity as infants reach for an object. I will describe the advantages and limitations of the technology, the setup I used to study primary motor cortex activity during infant reaching, and example steps in the analyses processes. I will present exemplar data to illustrate the feasibility of this technique to quantify changes in hemodynamic activity as infants move. The viability of this research method opens the door to expanding studies of the development of neural activity related to goal-directed actions in infants. I encourage others to share details of techniques used, as well, including analyticals, to help this neuroimaging technology grow as others, such as EEG and fMRI have

Are advanced methods necessary to improve infant fNIRS data analysis? An assessment of baseline-corrected averaging, general linear model (GLM) and multivariate pattern analysis (MVPA) based approaches

In the last decade, fNIRS has provided a non-invasive method to investigate neural activation in developmental populations. Despite its increasing use in developmental cognitive neuroscience, there is little consistency or consensus on how to pre-process and analyse infant fNIRS data. With this registered report, we investigated the feasibility of applying more advanced statistical analyses to infant fNIRS data and compared the most commonly used baseline-corrected averaging, General Linear Model (GLM)-based univariate, and Multivariate Pattern Analysis (MVPA) approaches, to show how the conclusions one would draw based on these different analysis approaches converge or differ. The different analysis methods were tested using a face inversion paradigm where changes in brain activation in response to upright and inverted face stimuli were measured in thirty 4-to-6-month-old infants. By including more standard approaches together with recent machine learning techniques, we aim to inform the fNIRS community on alternative ways to analyse infant fNIRS datasets

Selective facial mimicry of native over foreign speakers in preverbal infants.

Mimicry, the spontaneous copying of others' behaviors, plays an important role in social affiliation, with adults selectively mimicking in-group members over out-group members. Despite infants' early documented sensitivity to cues to group membership, previous work suggests that it is not until 4 years of age that spontaneous mimicry is modulated by group status. Here we demonstrate that mimicry is sensitive to cues to group membership at a much earlier age if the cues presented are more relevant to infants. 11-month-old infants observed videos of facial actions (e.g., mouth opening, eyebrow raising) performed by models who either spoke the infants' native language or an unfamiliar foreign language while we measured activation of the infants' mouth and eyebrow muscle regions using electromyography to obtain an index of mimicry. We simultaneously used functional near-infrared spectroscopy to investigate the neural mechanisms underlying differential mimicry responses. We found that infants showed greater facial mimicry of the native speaker compared to the foreign speaker and that the left temporal parietal cortex was activated more strongly during the observation of facial actions performed by the native speaker compared to the foreign speaker. Although the exact mechanisms underlying this selective mimicry response will need to be investigated in future research, these findings provide the first demonstration of the modulation of facial mimicry by cues to group status in preverbal infants and suggest that the foundations for the role that mimicry plays in facilitating social bonds seem to be present during the first year of life. [Abstract copyright: Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.

Emergence of Cortical Activity Patterns as Infants Develop Functional Motor Skills.

Despite the careful examination of the developmental changes in overt behavior and the underlying muscle activity and joint movement patterns, there is very little empirical evidence on how the brain and its link to behavior evolves during the first year of life. The dynamic systems approach and theory of neuronal group selection provides a framework that hypothesizes the development of the CNS early in life. However, the direct examination of the changes in brain activation that underlie the development of functional motor control in infants have yet to be determined or tested. The goal of my dissertation was to use functional near-infrared spectroscopy (fNIRS) to document the changes in brain activation patterns as infants acquired functional motor skills. My studies show that fNIRS is a viable and useful tool to examine brain activity in the context of infant movements. My findings demonstrate that as the behavioral and motor outcomes improve, the underlying neural activation patterns emerge. When functional motor skills are unstable and not fully functional, larger areas of the broad brain regions are recruited. As the skills become more reliable and functional, the brain activation patterns become refined and show an increase in strength of activity. The results from the studies in my dissertation take an important first step of describing the typical neural patterns that emerge with functional motor skills early in life. This work will help future studies build the body of empirical evidence that will improve our knowledge regarding the developing link between brain development and behavior. Finally, these studies provide foundational knowledge to better understand the atypical development of the CNS in those with disabilities.PhDKinesiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133452/1/ryonish_1.pd

The mentalizing triangle: how interactions among self, other and object prompt mentalizing

To smoothly interact with other people requires individuals to generate appropriate responses based on other’s mental states. The ability we rely on is termed mentalizing. As humans it seems that we are endowed with the abilities to rapidly process other’s mental states, either by taking their perspectives or using mindreading skills. These abilities allow us to go beyond our direct experience of reality and to see or infer some of the contents of another’s mental world. Due to the complexity of social contexts, our mentalizing system needs to address a variety of challenges which put different requirements on either time or flexibility. During years of research, investigators have come up with various theories to explain how we cope with these challenges. Among them, the two-system account raised up by Apperly and colleagues (2010) has been favoured by many studies. Concisely, the two-system account claims that we have a fast-initiated mentalizing system which guarantees us to make quick judgments with limited cognitive resource; and a flexible system which allows deliberate thinking and enables mentalizing to generalize to multiple targets. Such a framework provides good explanations to debates such as whether preverbal young children can process mentalizing or not. But it is still largely unknown how healthy adults engage in mentalizing in everyday life. Specifically, why it seems easier for some targets to activate our mentalizing system, but with some others, we frequently fail to consider their perspectives or beliefs? To give an explanation to this question, I adopted a different research orientation in my PhD from the two-system account, which considers the dynamic interactions among three key elements in mentalizing: the self, agent(s), and object(s). I put forward a mentalizing triangle model and assume the interactions in these triadic relationships act as gateways triggering mentalizing. Thus, with some agents, we feel more intimate with them, which makes it easier for us to think about their minds. Similarly, in certain context, the agent may have frequent interactions with the object, thus we become more motivated to engage in mentalizing. In the following chapters, I first reviewed current literatures and illustrate evidence that could support or oppose the triangle model, then examined these triangle hypotheses both from behavioural and neuroimaging levels. In Study 1, I first measured mentalizing in the baseline condition where no interaction in the triangle relationships was provided. By adapting the false belief paradigm used by Kovacs, Teglas, & Endress (2010), I imported the Signal Detection theory to obtain more indices which could reflect participants mentalizing processes. Results of this study showed that people have a weak tendency to ascribe other’s beliefs when there is no interaction. Then, in Study 2, we added another condition which included the ‘agent-object’ interaction factor while using a similar paradigm in Study 1. Results in the noninteractiond condition replicated our findings of Study 1, but adding ‘agent-object’ interactions didn’t boost mentalizing. Study 3 and 4 tested the ‘self-agent’ interaction hypothesis in visual perspective taking (VPT), another basic mentalizing ability. In Study 3, I adopted virtual reality approach and for the first time investigated how people select which perspective to take when exposed to multiple conflicting perspectives. Importantly, I examined whether the propensity to engage in VPT is correlated with how we perceive other people as humans, i.e. the humanization process. Congruent with our hypotheses, participant exhibited stronger propensity to take a more humanised agent’s perspective. Then in Study 4, I used functional near-infrared spectroscopy (fNIRS) and investigated the neural mechanism underlying this finding. In general, the ‘selfagent’ hypothesis in the mentalizing triangle model was supported but not for the ‘agentobject’ hypothesis, which we consider may due to several approach limitations. The findings in this thesis are derived from applying novel approaches to classic experimental paradigms, and have shown the potentials of using new techniques, such as VR and fNIRS, in investigating the philosophical question of mentalizing. It also enlights social cognitive studies by considering classic psychological methods such as the Signal Detection Theory in future research

Adults imitate to send a social signal

Humans are prolific imitators, even when copying may not be efficient. A variety of explanations have been advanced for this phenomenon, including that it is a side-effect of learning, that it arises from a lack of understanding of causality, to imitation being a mechanism to boost affiliation. This thesis systematically outlines the hypothesis that imitation is a social signal sent between interacting partners, which rests on testing whether our propensity to imitate is modulated by the social availability of the interaction partner (i.e., whether our interaction partner is watching us or not). I developed a dyadic block-moving paradigm that allowed us to test this hypothesis in a naturalistic manner in four behavioural and neuroimaging studies using functional near-infrared spectroscopy (fNIRS). I found that imitative fidelity was modulated by whether the interaction partner was watching the participant make their move or not, and this effect replicated across all four studies, in both neurotypicals and autistic participants. I also examined the neural correlates of responding to irrational actions, and of being watched. I found that being watched led to a robust deactivation in the right parietal cortex across both neurotypicals (in two studies) and autistic participants (one study). Among autistic participants we also found strong engagement in the left superior temporal sulcus (STS) when being watched. For responding to irrational actions, in one study of neurotypicals we found greater deactivation in the right superior parietal lobule (SPL) when making more irrational responses. In another study of autistic and neurotypical participants we found deactivation in the bilateral inferior parietal cortex (IPL) in neurotypicals when responding to irrational actions, while this deactivation appeared confined to the left IPL for autistic participants. Autistic participants also showed differentially higher engagement in the left occipitotemporal regions when responding to irrational actions. This thesis supports the social-signalling hypothesis of imitation and is accompanied by suggestions for future directions to explore this theory in more detail