Papers by Matthew R Longo
A B S T R A C T Sensory input from and motor output to the two sides of the body needs to be cont... more A B S T R A C T Sensory input from and motor output to the two sides of the body needs to be continuously integrated between the two cerebral hemispheres. This integration can be measured through its cost in terms of processing speed. In simple detection tasks, reaction times (RTs) are faster when stimuli are presented to the side of the body ipsilateral to the body part used to respond. This advantage – the contralateral-ipsilateral difference (also known as the crossed-uncrossed difference: CUD) – is thought to reflect inter-hemispheric interactions needed for sensorimotor information to be integrated between the two hemispheres. Several studies have shown that non-informative vision of the body enhances performance in tactile tasks. However, it is unknown whether the CUD can be similarly affected by vision. Here, we investigated whether the CUD is modulated by vision of the body (i.e., the stimulated hand) by presenting tactile stimuli unpredictably on the middle fingers when one hand was visible (i.e., either the right or left hand). Participants detected the stimulus and responded as fast as possible using either their left or right foot. Consistent with previous results, a clear CUD (5.8 ms) was apparent on the unseen hand. Critically, however, no such effect was found on the hand that was visible (−2.2 ms). Thus, when touch is delivered to a seen hand, the usual cost in processing speed of responding with a contralateral effector is eliminated. This result suggests that vision of the body improves the interhemispheric integration of tactile-motor responses.
Perceiving the external spatial location of touch requires that tactile information about the sti... more Perceiving the external spatial location of touch requires that tactile information about the stimulus location on the skin be integrated with proprioceptive information about the location of the body in external space, a process called tactile spatial remapping. Recent results have suggested that this process relies on a distorted representation of the hand. Here, I investigated whether similar distortions are also found on the forearm and how they are affected by the presence of the wrist joint, which forms a categorical, segmental boundary between the hand and the arm. Participants used a baton to judge the perceived location of touches applied to their left hand or forearm. Similar distortions were apparent on both body parts, with overestimation of distances in the medio-lateral axis compared to the proximo-distal axis. There was no perceptual expansion of distances that crossed the wrist boundary. However, there was increased overestimation of distances near the wrist in the medio-lateral orientation. These results replicate recent findings of a distorted representation of the hand underlying tactile spatial remapping, and show that this effect is not idiosyncratic to the hand, but also affects the forearm. These distortions may be a general characteristic of the mental representation of the arms.
Patients with lesions of the left posterior parietal cortex commonly fail in identifying their fi... more Patients with lesions of the left posterior parietal cortex commonly fail in identifying their fingers, a condition known as finger agnosia, yet are relatively unimpaired in sensation and skilled action. Such dissociations have traditionally been interpreted as evidence that structural body representations (BSR), such as the body structural description, are distinct from sensorimotor representations, such as the body schema. We investigated whether performance on tasks commonly used to assess finger agnosia is modulated by changes in hand posture. We used the 'in between' test in which participants estimate the number of unstimulated fingers between two touched fingers or a localization task in which participants judge which two fingers were stimulated. Across blocks, the fingers were placed in three levels of splay. Judged finger numerosity was analysed, in Exp. 1 by direct report and in Exp. 2 as the actual number of fingers between the fingers named. In both experiments, judgments were greater when non-adjacent stimulated fingers were positioned far apart compared to when they were close together or touching, whereas judgements were unaltered when adjacent fingers were stimulated. This demonstrates that BSRs are not fixed, but are modulated by the real-time physical distances between body parts. Knowledge of the spatial configuration of bodies is mediated by a representation called the body structural description, damage to which results in conditions such as autotopoagnosia 1,2 and finger agnosia 3. Following left parietal lesions, such patients fail to point to body parts on verbal command (autotopoagnosia) or to identify their fingers (finger agnosia), yet may be relatively unimpaired in skilled action 4. For example, a patient described by Sirigu and colleagues 2 was unable to answer questions assessing knowledge of the spatial relations between body parts, such as " is the wrist next to the forearm? " , but could answer questions assessing functional knowledge about body parts, such as " what are the eyes for? ". In finger agnosia, patients are impaired at tasks that require identification of the fingers, especially by naming. A typical task for assessing finger gnosis is the " in-between task " , in which participants estimate the number of unstimulated fingers in-between two touched fingers 3. In order to solve this task, the participant has to perform at least two processing stages: (1) identifying which fingers are touched, and (2) locating the touched fingers within a structural model of the hand that represents at least the touched fingers and the untouched fingers 5. Therefore, this complex coding processing cannot be solved solely using sensory representations, but requires the use of higher-level body structural representations. Studies of neurological patients 6 and healthy adults 7–9 have converged in showing that the left and right parietal cortices may mediate the structural representations of the body (BSR), though the contribution of the two hemispheres may differ qualitatively. A study by Rusconi and colleagues, using a bi-manual version of the in-between task, suggests that the connections between the left anteromedial inferior parietal lobe (a-mIPL) and the precuneus (PCN) provide the core substrate of an explicit bilateral BSR for the fingers that when disrupted can produce the typical symptoms of finger agnosia 9 , compared to the bilateral posterior parietal cortex that contributes to on-line sensorimotor representations 10. Such dissociations have traditionally been interpreted as evidence that structural representations of the body are distinct from sensorimotor representations, such as the body schema 6,11–13. The body schema is a dynamic representation of body position which operates outside of conscious awareness to guide and control skilled action 14,15. For example, Castiello and colleagues 16 have shown that when participants were asked to reach for visual objects which were suddenly displaced after reach onset, they corrected their reach trajectory more than 300 ms before they were consciously aware of the displacement 16. By contrast, the body structural description seems not to be affected by on-line sensorimotor representations of the body. For instance, an autotopagnosic patient (G.L.) who performed poorly when asked to point or identify his own or other people's body parts, nevertheless showed normal preparatory grips necessary to grasp objects 4. In healthy humans, Rusconi and colleagues 5
We have an abundance of perceptual information from multiple modalities specifying our body propo... more We have an abundance of perceptual information from multiple modalities specifying our body proportions. Consequently, it seems reasonable for researchers to assume that we have an accurate perception of our body proportions. In contrast to this intuition, recent research has shown large, striking distortions in people's perceptions of the relative proportions of their own bodies. Specifically, individuals show large distortions when estimating the length of their body parts with a corporal metric, such as the hand, but not with a non-corporal object of the same length (Linkenauger et al., 2015). However, it remains unclear whether these distortions are specific to the perception of the relative proportions of one's own body or whether they generalize to the perception of the relative proportions of all human bodies. To assess this, individuals judged the relative lengths of either their own body parts or the body parts of another individual. We found that people have distorted perceptions of relative body proportions even when viewing the bodies of others. These distortions were greater when estimating the relative body parts of someone of the same gender. These results suggest our implicit full body representation is distorted and influences our perceptions of other people's bodies, especially if the other person's body is similar to our own.
Brief use of a tool recalibrates multisensory representations of the user's body, a phenomenon ca... more Brief use of a tool recalibrates multisensory representations of the user's body, a phenomenon called tool embodiment. Despite two decades of research, little is known about its boundary conditions. It has been widely argued that embodiment requires active tool use, suggesting a critical role for somatosensory and motor feedback. The present study used a visual illusion to cast doubt on this view. We used a mirror-based setup to induce a visual experience of tool use with an arm that was in fact stationary. Following illusory tool use, tactile perception was recalibrated on this stationary arm, and with equal magnitude as physical use. Recalibration was not found following illusory passive tool holding, and could not be accounted for by sensory conflict or general interhemispheric plasticity. These results suggest visual tool-use signals play a critical role in driving tool embodiment.
Recent research has shown that proprioception relies on distorted representations of body size an... more Recent research has shown that proprioception relies on distorted representations of body size and shape. By asking participants to localise multiple landmarks on their occluded hand, perceptual maps of hand size and shape can be constructed and compared to actual hand structure. These maps are different from the actual size and shape of the occluded hand, revealing underestimation of finger length and overestimation of hand width. Here we tested whether the same distorted body model underlies pro-prioceptive imagery (i.e. imagining the hand at a specific location, and in a different posture than it actually is). In Experiment 1, participants placed their left hand under an occluding board (real condition) or imagined their left hand under the board (imagined condition). Highly similar distortions were found in both conditions. Furthermore, results across the two conditions were strongly correlated. In Experiment 2, participants completed the real condition and two imagined conditions. In the imagined-fist condition, participants held their left hand in a fist, in their lap, while in the imagined-flat condition, participants held their left hand flat, with palm down, in their lap. In both imagined conditions, participants were asked to imagine their left hand lying flat, with palm down, under the occluding board. A similar pattern of distortions was found in all three conditions. These results suggest that both proprioception and pro-prioceptive imagery reply on a common stored model of the body's metric properties.
Delusions and misperceptions about the body are a conspicuous feature of numerous neurological an... more Delusions and misperceptions about the body are a conspicuous feature of numerous neurological and psychiatric conditions. In stark contrast to such pathological cases, the immediacy and familiarity of our ordinary experience of our body can make it seem as if our representation of our body is highly accurate, even infallible. Recent research has begun to demonstrate, however, that large and systematic distortions of body representation are a normal part of healthy cognition. Here, I describe this research, focusing on distortions of body representations underlying tactile distance perception and position sense. I also discuss evidence for distortions of higher-order body representations, such as the conscious body image. Finally, I will end with a discussion of the potential relations among different body representations and their distortions. Our body is the core of our sense of self and central to our personal identity as an individual. We experience our body from the outside, as a physical object in the world like any other, but also from the inside, as an object of immediate experience (Bermúdez, Marcel, & Eilan, 1995). The intimate and direct connection we have with our own body can make knowledge of our body seem immune to the usual sources of perceptual error and illusion. Indeed, the very fact that we have multiple ways of knowing about our body (from inside, and from outside) could very well contribute to making the overall perception of the body highly reliable. While distortions and misperceptions of the body are a familiar result of several psychiatric and neurological conditions, it is natural to suppose that healthy adults have highly accurate—even infallible —knowledge about the physical structure of their bodies. In this paper, I describe recent research that has begun to question this assumption, showing large and systematic distortions of body representation in healthy adults. After giving a brief summary of the varied distortions of body representation found in pathological conditions, I describe research showing large distortions of body representations underlying somatosensory perception of tactile distance and position sense. Finally, I discuss other results showing distortions underlying higher level aspects of body representations and end with a discussion of the relationships among the various distortions that I discuss.
Both tactile distance perception and position sense are believed to require that immediate affere... more Both tactile distance perception and position sense are believed to require that immediate afferent signals be referenced to a stored representation of body size and shape (the body model). For both of these abilities, recent studies have reported that the stored body representations involved are highly distorted, at least in the case of the hand, with the hand dorsum represented as wider and squatter than it actually is. Here, we investigated whether individual differences in the magnitude of these distortions are shared between tactile distance perception and position sense, as would be predicted by the hypothesis that a single distorted body model underlies both tasks. We used established tasks to measure distortions of the represented shape of the hand dorsum. Consistent with previous results, in both cases there were clear biases to overestimate distances oriented along the medio-lateral axis of the hand compared to the proximo-distal axis. Moreover, within each task there were clear split-half correlations, demonstrating that both tasks show consistent individual differences. Critically, however, there was no correlation between the magnitudes of distortion in the two tasks. This casts doubt on the proposal that a common body model underlies both tactile distance perception and position sense.
When locating touch, we remap its location from skin-based to external coordinates as a function ... more When locating touch, we remap its location from skin-based to external coordinates as a function of body posture. While remapping is thought to occur whenever there is tactile input, research has focused on a special case, the crossed-hands deficit, where tactile localization is impaired when the limbs are crossed compared with uncrossed. To date, these studies have always stimulated portions of the limbs that are crossed, such as a finger of each hand. It is therefore unknown whether the deficit induced by arm crossing is specific to the crossed portion of the limb or affects the limb as a whole. In Experiments 1 and 2, we stimulated the shoulders and elbows and found that tactile localization, measured with temporal order judgments, was unaffected by crossing the forearms. In Experiment 3, a crossed-limbs deficit was observed for touches on a single skin location when that location was distal— but not proximal—to the crossing point of the arms. In Experiment 4, we found a similar crossed-limbs deficit irrespective of how far distally to the crossing point touch was applied. Together, these results demonstrate that crossing the limbs affects tactile perception only distal to the point of crossing. The process of remapping tactile events does not take into account the end-point location of the limb, but an extremely precise metric description of the touch relative to the configuration of both arms.
To perceive the location of touch in space, we integrate information about skin-location with inf... more To perceive the location of touch in space, we integrate information about skin-location with information about the location of that body part in space. Most research investigating this process of tactile spatial remapping has used the so-called crossed-hands deficit, in which the ability to judge the temporal order of touches on the two hands is impaired when the arms are crossed. This posture induces a conflict between skin-based and tactile external spatial representations, specifically in the left-right dimension. Thus, it is unknown whether touch is affected by posture when spatial relations other than the right-left dimension are available. Here, we tested the extent to which the crossed-hands deficit is a measure of tactile remapping, reflecting tactile encoding in three-dimensional space. Participants judged the temporal order of tactile stimuli presented to crossed and uncrossed hands. The arms were placed at different elevations (up-down dimension; Experiments 1 and 2), or at different distances from the body in the depth plane (close-far dimension; Experiment 3). The crossed-hands deficit was reduced when other sources of spatial information, orthogonal to the left-right dimension (i.e., close-far, up-down), were available. Nonetheless, the deficit persisted in all conditions, even when processing of non-conflicting information in the close-far or up-down dimensions was enough to solve the task. Together, these results demonstrate that the processing underlying the crossed-hands deficit is related to the encoding of tactile localization in three-dimensional space, rather than related uniquely to the cost of processing information in the right-left dimension. Furthermore, the persistence of the crossing effect provides evidence for automatic integration of all available information during the encoding of tactile information.
A growing body of research has focused on the development of assistive devises to improve the rec... more A growing body of research has focused on the development of assistive devises to improve the recovery and ameliorate the quality of life of people suffering from spinal cord injuries (SCI). In their stimulating and timely paper, Pazzaglia and Molinari [1] review the significant progress made by biotechnology studies in providing increasing sophisticated assistive tools (e.g., prostheses and exoskeletons) that extend the functionality of patients' bodies. However , despite this extraordinary technological effort [2], it remains uncertain how these devices can be appropriately embedded into the mental representation of the body. Here, we wish to amplify the points raised by Pazzaglia and Molinari by discussing three challenges facing work on embodying prostheses raised by experimental research on body representation. Pazzaglia and Molinari discuss prostheses in relation both to tool use and to illusions of ownership such as the rubber hand illusion. As has been noted by many authors, however, the subjective experience of wielding a tool is quite different from that of experiencing ownership over a limb [3,4]. Indeed, as Povinelli and colleagues [5] observe, in many cases the whole point of using a tool is that the action performed is something that the body cannot itself do (as when using a knife to slice vegetables) or which would be dangerous to do unaided (as when using a poker to stoke a fire). In such circumstances, it is critical to maintain the distinction between the tool and the body, in contrast to cases such as the rubber hand illusion in which the rubber hand appears to replace the participant's own hand [6]. Thus, it is important to consider whether a prosthesis is primarily meant to be a tool, a replacement for the missing limb, or both, as these might lead to very different implications for the design and functioning of prostheses. A recent study by Luke Miller and his colleagues [7] is particularly intriguing in this context. They found that the plastic changes induced by tool-use on tactile distance perception are modulated by the morphological similarity between the tool and the body. When participants used a long, thin claw to grab objects, plastic changes were observed on the forearm – but not on the hand. In contrast, when they used a large hand-shaped tool, changes were observed on the hand – but not on the arm. This double-dissociation suggests that the embodiment of tools is not driven solely DOI of original article: http://dx.
Our body is a unique entity by which we interact with the external world. Consequently, the way w... more Our body is a unique entity by which we interact with the external world. Consequently, the way we represent our body has profound implications in the way we process and locate sensations and in turn perform appropriate actions. The body can be the subject, but also the object of our experience, providing information from sensations on the body surface and viscera, but also knowledge of the body as a physical object. However, the extent to which different senses contribute to constructing the rich and unified body representations we all experience remains unclear. In this review, we aim to bring together recent research showing important roles for several different sensory modalities in constructing body representations. At the same time, we hope to generate new ideas of how and at which level the senses contribute to generate the different levels of body representations and how they interact. We will present an overview of some of the most recent neuropsychological evidence about multisensory control of pain, and the way that visual, auditory, vestibular and tactile systems contribute to the creation of coherent representations of the body. We will focus particularly on some of the topics discussed in the symposium on Multimodal Contributions to Body Representation held on the 15th International Multisensory Research Forum (2015, Pisa, Italy).
Chronic pain and impaired tactile sensitivity are frequently associated with " blurred " represen... more Chronic pain and impaired tactile sensitivity are frequently associated with " blurred " representations in the somatosensory cortex. The factors that produce such somatosensory blurring, however, remain poorly understood. We manipulated visuo-tactile congruence to investigate its role in promoting so-matosensory reorganization. To this aim we used the mirror box illusion that produced in participants the subjective feeling of looking directly at their left hand, though they were seeing the reflection of their right hand. Simultaneous touches were applied to the middle or ring finger of each hand. In one session, the same fingers were touched (for example both middle fingers), producing a congruent percept; in the other session different fingers were touched, producing an incongruent percept. In the somatosensory system, suppressive interactions between adjacent stimuli are an index of intracortical inhibitory function. After each congruent and incongruent session, we recorded somatosensory evoked potential (SEPs) elicited by electrocutaneous stimulation of the left ring and middle fingers, either individually or simultaneously. A somatosensory suppression index (SSI) was calculated as the difference in amplitude between the sum of potentials evoked by the two individually stimulated fingers and the potentials evoked by simultaneous stimulation of both fingers. This SSI can be taken as an index of the strength of inhibitory interactions and consequently can provide a measure of how distinct the representations of the two fingers are. Results showed stronger SSI in the P100 component after congruent than incon-gruent stimulation, suggesting the key role of congruent sensory information about the body in inducing somatosensory reorganization.
Several studies have shown that the perception of one's own hand size is distorted in propriocept... more Several studies have shown that the perception of one's own hand size is distorted in proprioceptive localization tasks. It has been suggested that those distortions mirror somatosensory anisotropies. Recent research suggests that non-corporeal items also show some spatial distortions. In order to investigate the psychological processes underlying the localization task, we investigated the influences of visual similarity and memory on distortions observed on corporeal and non-corporeal items. In experiment 1, participants indicated the location of landmarks on: their own hand, a rubber hand (rated as most similar to the real hand), and a rake (rated as least similar to the real hand). Results show no significant differences between rake and rubber hand distortions but both items were significantly less distorted than the hand. Experiment 2 and 3 explored the role of memory in spatial distance judgments of the hand, the rake and the rubber hand. Spatial representations of items measured in experiment 2 and 3 were also distorted but showed the tendency to be smaller than in localization tasks. While memory and visual similarity seem to contribute to explain qualitative similarities in distortions between the hand and non-corporeal items, those factors cannot explain the larger magnitude observed in hand distortions.
Mental body representations underlying tactile perception do not accurately reflect the body’s tr... more Mental body representations underlying tactile perception do not accurately reflect the body’s true morphology. For example, perceived tactile distance is dependent on both the body part being touched and the stimulus orientation, a phenomenon called Weber’s illusion. These findings suggest the presence of size and shape distortions, respectively. However, whereas each morphological feature is typically measured in isolation, a com- plete morphological characterization requires the concurrent measurement of both size and shape. We did so in three experiments, manipulating both the stimulated body parts (hand; forearm) and stimulus orientation while requiring participants to make tactile dis- tance judgments. We found that the forearm was significantly more distorted than the hand lengthwise but not widthwise. Effects of stimulus orientation are thought to reflect receptive field anisotropies in primary somatosensory cortex. The results of the present study therefore suggest that mental body representations retain homuncular shape distortions that characterize early stages of somatosensory processing.
Recent studies have revealed that human position sense relies on a massively distorted represent... more Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of landmarks on an occluded hand, Longo and Haggard (2010) constructed implicit perceptual maps of represented hand structure, showing large underestimation of finger length and overestimation of hand width. Here, we investigated the contribution of two potential sources of distortions to such effects: perceptual distortions reflecting spatial warping of the representation of bodily tissue itself, perhaps reflecting distortions of somatotopic cortical maps, and conceptual distortions reflecting mistaken beliefs about the locations of different landmarks within the body. In Experiment 1 we compared distorted hand maps to a task in which participants explicitly judged the location of their knuckles in a hand silhouette. The results revealed the conceptual distortions are responsible for at least part of the underestimation of finger length, but cannot explain overestimation of hand width. Experiment 2 compared distortions of the participant’s own hand based on position sense with a prosthetic hand based on visual memory. Underestimation of finger length was found for both hands, providing further evidence that it reflects a conceptual distortion. In contrast, overestimation of hand width was specific to representation of the participant’s own hand, confirming it reflects a perceptual distortion. Together, these results suggest that distorted body representations do not reflect a single underlying cause. Rather, both perceptual and conceptual distortions contribute to the overall configuration of the hand representation.
Our bodies are the most intimately familiar objects we encounter in our perceptual environment. V... more Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant’s experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups.
Perception, 2015
Hypnotic suggestibility (HS) is the ability to respond automatically to suggestions and to experi... more Hypnotic suggestibility (HS) is the ability to respond automatically to suggestions and to experience alterations in perception and behavior. Hypnotically suggestible participants are also better able to focus and sustain their attention on an experimental stimulus. The present study explores the relation between HS and susceptibility to the rubber hand illusion (RHI). Based on previous research with visual illusions, it was predicted that higher HS would lead to a stronger RHI. Two behavioral output measures of the RHI, an implicit (proprioceptive drift) and an explicit (RHI questionnaire) measure, were correlated against HS scores. Hypnotic suggestibility correlated positively with the implicit RHI measure contributing to 30% of the variation. However, there was no relation between HS and the explicit RHI questionnaire measure, or with compliance control items. High hypnotic suggestibility may facilitate, via attentional mechanisms, the multisensory integration of visuoproprioceptive inputs that leads to greater perceptual mislocalization of a participant’s hand. These results may provide insight into the multisensory brain mechanisms involved in our sense of embodiment.
Perception
The perceived distance between touches on the limbs is generally bigger for distances oriented ac... more The perceived distance between touches on the limbs is generally bigger for distances oriented across the width of the limb than for distances oriented along the length of the limb. The present study aimed to investigate the coherence of such distortions of tactile size perception across different skin surfaces. We investigated distortions of tactile size perception on the dorsal and palmar surfaces of both the left and right hands as well as the forehead. Participants judged which of two tactile distances felt larger. One distance was aligned with the proximodistal axis (along the body), the other with the mediolateral axis (across the body). Clear distortions were found on all five skin surfaces, with stimuli oriented across the width of the body being perceived as farther apart than those oriented along the length of the body. Consistent with previous results, distortions were smaller on the palmar than on the dorsal hand surface. Distortion on the forehead was intermediate between the dorsal and palmar surfaces. There were clear correlations between distortion on the left and right hands, for both the dorsal and palmar skin surfaces. In contrast, within each hand, there was no significant correlation between the two skin surfaces. Distortion on the forehead was not significantly correlated with that on any of the other skin surfaces. These results provide evidence for bilaterally symmetric representations underlying tactile size perception.
Cerebral Cortex
The ability to differentiate one's body from others is a fundamental aspect of social perception ... more The ability to differentiate one's body from others is a fundamental aspect of social perception and has been shown to involve the integration of sense modalities attributable to the self. Though behavioral studies in infancy have investigated infants' discrimination of body-related multisensory stimuli, whether they attribute this information as belonging to the self is still unknown. In human adults, neuroimaging studies have demonstrated the recruitment of a specific set of brain regions in response to body-related multisensory integration. To test whether the infant brain integrates this information similarly to adults, in a first functional near-infrared spectroscopy study we investigated the role of visual-proprioceptive feedback when temporal cues are manipulated by showing 5-month-old infants an online video of their own face while the infant was performing movements. To explore the role of body-related contingency further, in a second study we investigated whether cortical activation in response to self-initiated movements and external tactile stimulation was similar to that found in the first study. Our results indicate that infants' specialized cortical activation in response to body-related contingencies is similar to brain activation seen in response to body awareness in adults.
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Papers by Matthew R Longo