A comparison of the self-awareness and kinesthetic-visual matching theories of self-recognition: autistic children and others

The Neurological Asymmetry of Self-Face Recognition

While the desire to uncover the neural correlates of consciousness has taken numerous directions, self-face recognition has been a constant in attempts to isolate aspects of self-awareness. The neuroimaging revolution of the 1990s brought about systematic attempts to isolate the underlying neural basis of self-face recognition. These studies, including some of the first fMRI (functional magnetic resonance imaging) examinations, revealed a right-hemisphere bias for self-face recognition in a diverse set of regions including the insula, the dorsal frontal lobe, the temporal parietal junction, and the medial temporal cortex. In this systematic review, we provide confirmation of these data (which are correlational) which were provided by TMS (transcranial magnetic stimulation) and patients in which direct inhibition or ablation of right-hemisphere regions leads to a disruption or absence of self-face recognition. These data are consistent with a number of theories including a right-hemisphere dominance for self-awareness and/or a right-hemisphere specialization for identifying significant social relationships, including to oneself.

Mirror self-recognition and its relationship to social cognition in chimpanzees

Chimpanzees and humans are capable of recognizing their own reflection in mirrors. Little is understood about the selective pressures that led to this evolved trait and about the mechanisms that underlie it. Here, we investigated the hypothesis that mirror self-recognition in chimpanzees is the byproduct of a developed form of self-awareness that was naturally selected for its adaptive use in social cognitive behaviors. We present here the first direct attempt to assess the social cognition hypothesis by analyzing the association between mirror self-recognition in chimpanzees, as measured by a mirror-mark test, and their performance on a variety of social cognition tests. Consistent with the social cognition hypothesis, chimpanzees who showed evidence of mirror self-recognition in the mark test tended to perform significantly better on the social cognition tasks than those who failed the mark test. Additionally, the data as a whole fit the social cognition hypothesis better than the main competing hypothesis of mirror self-recognition in great apes, the secondary representation hypothesis. Our findings strongly suggest that the evolutionary origins of great apes' and humans' capacity to understand ourselves, as revealed by our capacity to recognize ourselves in mirrors, are intimately linked to our ability to understand others.

Investigating individual differences in chimpanzee mirror self-recognition and cortical thickness: A vertex-based and region-of-interest analysis

Mirror self-recognition (MSR), a recently evolved cognitive trait, is one of the most significant abilities that separate humans and great apes from more distantly related nonhuman primates. MSR may serve as the foundation for a number of related but more complex social cognitive abilities unique to humans and great apes including imitation, empathy, theory-of-mind, perspective taking and deception. However, our understanding of the neural basis of MSR in nonhuman primates remains largely unknown. The current study aimed to begin to fill this gap in the literature by investigating the neuroanatomical foundations of MSR in a sample of 67 captive chimpanzees. Vertex-based and region-of-interest analysis revealed significant differences in cortical thickness, particularly in males, in the cingulate cortex, inferior frontal gyrus and superior temporal and frontal cortex. The current study provides further evidence for the neuroanatomical foundations of mirror self-recognition abilities in chimpanzees.

A neuroanatomical predictor of mirror self-recognition in chimpanzees

The ability to recognize one's own reflection is shared by humans and only a few other species, including chimpanzees. However, this ability is highly variable across individual chimpanzees. In humans, self-recognition involves a distributed, right-lateralized network including frontal and parietal regions involved in the production and perception of action. The superior longitudinal fasciculus (SLF) is a system of white matter tracts linking these frontal and parietal regions. The current study measured mirror self-recognition (MSR) and SLF anatomy in 60 chimpanzees using diffusion tensor imaging. Successful self-recognition was associated with greater rightward asymmetry in the white matter of SLFII and SLFIII, and in SLFIII's gray matter terminations in Broca's area. We observed a visible progression of SLFIII's prefrontal extension in apes that show negative, ambiguous, and compelling evidence of MSR. Notably, SLFIII's terminations in Broca's area are not right-lateralized or particularly pronounced at the population level in chimpanzees, as they are in humans. Thus, chimpanzees with more human-like behavior show more human-like SLFIII connectivity. These results suggest that self-recognition may have co-emerged with adaptations to frontoparietal circuitry.

The influence of AVPR1A genotype on individual differences in behaviors during a mirror self-recognition task in chimpanzees (Pan troglodytes)

The mark/rouge test has been used to assess mirror self-recognition (MSR) in many species. Despite consistent evidence of MSR in great apes, genetic or non-genetic factors may account for the individual differences in behavioral responses that have been reported. We examined whether vasopressin receptor gene (AVPR1A) polymorphisms are associated with MSR-related behaviors in chimpanzees since vasopressin has been implicated in the development and evolution of complex social relations and cognition and chimpanzees are polymorphic for the presence of the RS3-containing DupB region. We compared a sample of DupB+/- and DupB-/- chimpanzees on a mark test to assess its role on social behavior toward a mirror. Chimpanzees were administered two, 10-min sessions where frequencies of mirror-guided self-directed behaviors, contingent actions and other social behaviors were recorded. Approximately one-third showed evidence of MSR and these individuals exhibited more mirror-guided self-exploratory behaviors and mouth contingent actions than chimpanzees not classified as passers. Moreover, DupB+/- males exhibited more scratching and agonistic behaviors than other male and female cohorts. Our findings support previous studies demonstrating individual differences in MSR abilities in chimpanzees and suggest that AVPR1A partly explains individual differences in MSR by influencing the behavioral reactions of chimpanzees in front of a mirror.

The association between imitation recognition and socio-communicative competencies in chimpanzees (Pan troglodytes)

Imitation recognition provides a viable platform from which advanced social cognitive skills may develop. Despite evidence that non-human primates are capable of imitation recognition, how this ability is related to social cognitive skills is unknown. In this study, we compared imitation recognition performance, as indicated by the production of testing behaviors, with performance on a series of tasks that assess social and physical cognition in 49 chimpanzees. In the initial analyses, we found that males were more responsive than females to being imitated and engaged in significantly greater behavior repetitions and testing sequences. We also found that subjects who consistently recognized being imitated performed better on social but not physical cognitive tasks, as measured by the Primate Cognitive Test Battery. These findings suggest that the neural constructs underlying imitation recognition are likely associated with or among those underlying more general socio-communicative abilities in chimpanzees. Implications regarding how imitation recognition may facilitate other social cognitive processes, such as mirror self-recognition, are discussed.

Different neural processes accompany self-recognition in photographs across the lifespan: an ERP study using dizygotic twins

Our appearance changes over time, yet we can recognize ourselves in photographs from across the lifespan. Researchers have extensively studied self-recognition in photographs and have proposed that specific neural correlates are involved, but few studies have examined self-recognition using images from different periods of life. Here we compared ERP responses to photographs of participants when they were 5-15, 16-25, and 26-45 years old. We found marked differences between the responses to photographs from these time periods in terms of the neural markers generally assumed to reflect (i) the configural processing of faces (i.e., the N170), (ii) the matching of the currently perceived face to a representation already stored in memory (i.e., the P250), and (iii) the retrieval of information about the person being recognized (i.e., the N400). There was no uniform neural signature of visual self-recognition. To test whether there was anything specific to self-recognition in these brain responses, we also asked participants to identify photographs of their dizygotic twins taken from the same time periods. Critically, this allowed us to minimize the confounding effects of exposure, for it is likely that participants have been similarly exposed to each other's faces over the lifespan. The same pattern of neural response emerged with only one exception: the neural marker reflecting the retrieval of mnemonic information (N400) differed across the lifespan for self but not for twin. These results, as well as our novel approach using twins and photographs from across the lifespan, have wide-ranging consequences for the study of self-recognition and the nature of our personal identity through time.

Functional MRI to evaluate "sense of self" following perforator flap breast reconstruction

BACKGROUND

Breast reconstruction is associated with high levels of patient satisfaction. Previous patient satisfaction studies have been subjective. This study utilizes functional magnetic resonance imaging (fMRI) to objectively evaluate "sense of self" following deep inferior epigastric perforator (DIEP) flap breast reconstruction in an attempt to better understand patient perception.

METHODS

Prospective fMRI analysis was performed on four patients before and after delayed unilateral DIEP flap breast reconstruction, and on four patients after immediate unilateral DIEP flap breast reconstruction. Patients were randomly cued to palpate their natural breast, mastectomy site or breast reconstruction, and external silicone models. Three regions of interest (ROIs) associated with self-recognition were examined using a general linear model, and compared using a fixed effects and random effects ANOVA, respectively.

RESULTS

In the delayed reconstruction group, activation of the ROIs was significantly lower at the mastectomy site compared to the natural breast (p<0.01). Ten months following reconstruction, activation of the ROIs in the reconstructed breast was not significantly different from that observed with natural breast palpation. In the immediate reconstruction group, palpation of the reconstructed breast was also similar to the natural breast. This activity was greater than that observed during palpation of external artificial models (p<0.01).

CONCLUSIONS

Similar activation patterns were observed during palpation of the reconstructed and natural breasts as compared to the non-reconstructed mastectomy site and artificial models. The cognitive process represented by this pattern may be a mechanism by which breast reconstruction improves self-perception, and thus patient satisfaction following mastectomy.

Perceiving a stranger's voice as being one's own: a 'rubber voice' illusion?

We describe an illusion in which a stranger's voice, when presented as the auditory concomitant of a participant's own speech, is perceived as a modified version of their own voice. When the congruence between utterance and feedback breaks down, the illusion is also broken. Compared to a baseline condition in which participants heard their own voice as feedback, hearing a stranger's voice induced robust changes in the fundamental frequency (F0) of their production. Moreover, the shift in F0 appears to be feedback dependent, since shift patterns depended reliably on the relationship between the participant's own F0 and the stranger-voice F0. The shift in F0 was evident both when the illusion was present and after it was broken, suggesting that auditory feedback from production may be used separately for self-recognition and for vocal motor control. Our findings indicate that self-recognition of voices, like other body attributes, is malleable and context dependent.

Faces and ascriptions: mapping measures of the self

The 'self' is increasingly used as a variable in cognitive experiments and correlated with activity in particular areas in the brain. At first glance, this seems to transform the self from an ephemeral theoretical entity to something concrete and measurable. However, the transformation is by no means unproblematic. We trace the development of two important experimental paradigms in the study of the self, self-face recognition and the adjective self ascription task. We show how the experimental instrumentalization has gone hand in hand with a simplification of the self-concept, and how more conceptual and theoretical reflections on the structure, function and nature of self have either disappeared altogether or receded into the background. We argue that this development impedes and complicates the interdisciplinary study of self.

Self-recognition, theory-of-mind, and self-awareness: what side are you on?

A fashionable view in comparative psychology states that primates possess self-awareness because they exhibit mirror self-recognition (MSR), which in turn makes it possible to infer mental states in others ("theory-of-mind"; ToM). In cognitive neuroscience, an increasingly popular position holds that the right hemisphere represents the centre of self-awareness because MSR and ToM tasks presumably increase activity in that hemisphere. These two claims are critically assessed here as follows: (1) MSR should not be equated with full-blown self-awareness, as it most probably only requires kinaesthetic self-knowledge and does not involve access to one's mental events; (2) ToM and self-awareness are fairly independent and should also not be taken as equivalent notions; (3) MSR and ToM tasks engage medial and left brain areas; (4) other self-awareness tasks besides MSR and ToM tasks (e.g., self-description, autobiography) mostly recruit medial and left brain areas; (5) and recent neuropsychological evidence implies that inner speech (produced by the left hemisphere) plays a significant role in self-referential activity. The main conclusions reached based on this analysis are that (a) organisms that display MSR most probably do not possess introspective self-awareness, and (b) self-related processes most likely engage a distributed network of brain regions situated in both hemispheres.

The uncanny mirror: a re-framing of mirror self-experience

Mirror self-experience is re-casted away from the cognitivist interpretation that has dominated discussions on the issue since the establishment of the mirror mark test. Ideas formulated by Merleau-Ponty on mirror self-experience point to the profoundly unsettling encounter with one's specular double. These ideas, together with developmental evidence are re-visited to provide a new, psychologically and phenomenologically more valid account of mirror self-experience: an experience associated with deep wariness.

Engaging with the self

Children with autism achieve mirror self-recognition appropriate to developmental age, but are nonetheless reported to have problems in other aspects of a sense of self. We observed behaviour in the mirror in 12 pre-school children with autism, 13 pre-school children with Down syndrome (DS) and 13 typically developing (TD) toddlers. Reliable differences in reflecting actions, social relatedness and positive affect towards themselves, and an absence of coy smiles differentiated the children with autism from the others. The children with DS showed the highest interest in their own faces. These differences were largely independent of mirror self-recognition (MSR), broadly supporting arguments for dissociation between interpersonal and conceptual aspects of self. Mirror behaviour may be a subtle but easily elicited measure of the social quality of a sense of self.

Memory and the self in autism: A review and theoretical framework

This article reviews research on (a) autobiographical episodic and semantic memory, (b) the self-reference effect, (c) memory for the actions of self versus other (the self-enactment effect), and (d) non-autobiographical episodic memory in autism spectrum disorder (ASD), and provides a theoretical framework to account for the bidirectional relationship between memory and the self in ASD. It is argued that individuals with ASD have diminished psychological self-knowledge (as a consequence of diagnostic social and communication impairments), alongside intact physical self-knowledge, resulting in an under-elaborated self-concept. Consequently, individuals with ASD show impaired autobiographical episodic memory and a reduced self-reference effect (which may each rely on psychological aspects of the self-concept) but do not show specific impairments in memory for their own rather than others' actions (which may rely on physical aspects of the self-concept). However, it is also argued that memory impairments in ASD (e.g., in non-autobiographical episodic memory) may not be entirely accounted for in terms of self-related processes. Other factors, such as deficits in memory binding, may also play a role. Finally, it is argued that deficits in autobiographical episodic memory and future thinking may result in a diminished temporally extended self-concept in ASD.

Autistic spectrum disorders as functional disconnection syndrome

We outline the basis of how functional disconnection with reduced activity and coherence in the right hemisphere would explain all of the symptoms of autistic spectrum disorder as well as the observed increases in sympathetic activation. If the problem of autistic spectrum disorder is primarily one of desynchronization and ineffective interhemispheric communication, then the best way to address the symptoms is to improve coordination between areas of the brain. To do that the best approach would include multimodal therapeusis that would include a combination of somatosensory, cognitive, behavioral, and biochemical interventions all directed at improving overall health, reducing inflammation and increasing right hemisphere activity to the level that it becomes temporally coherent with the left hemisphere. We hypothesize that the unilateral increased hemispheric stimulation has the effect of increasing the temporal oscillations within the thalamocortical pathways bringing it closer to the oscillation rate of the adequately functioning hemisphere. We propose that increasing the baseline oscillation speed of one entire hemisphere will enhance the coordination and coherence between the two hemispheres allowing for enhanced motor and cognitive binding.

A call to arms: Somatosensory perception and action

Somatosensory processing for action guidance can be dissociated from perception and memory processing. The dorsal system has a global bias and the ventral system has a local processing bias. Autistics illustrate the point, showing a bias for part over wholes. Lateralized differences have also been noted in these modalities. The multi-modal dysfunction observed may suggest more an issue of interhemispheric communication.

Touching a rubber hand: feeling of body ownership is associated with activity in multisensory brain areas

In the "rubber-hand illusion," the sight of brushing of a rubber hand at the same time as brushing of the person's own hidden hand is sufficient to produce a feeling of ownership of the fake hand. We shown previously that this illusion is associated with activity in the multisensory areas, most notably the ventral premotor cortex (Ehrsson et al., 2004). However, it remains to be demonstrated that this illusion does not simply reflect the dominant role of vision and that the premotor activity does not reflect a visual representation of an object near the hand. To address these issues, we introduce a somatic rubber-hand illusion. The experimenter moved the blindfolded participant's left index finger so that it touched the fake hand, and simultaneously, he touched the participant's real right hand, synchronizing the touches as perfectly as possible. After approximately 9.7 s, this stimulation elicited an illusion that one was touching one's own hand. We scanned brain activity during this illusion and two control conditions, using functional magnetic resonance imaging. Activity in the ventral premotor cortices, intraparietal cortices, and the cerebellum was associated with the illusion of touching one's own hand. Furthermore, the rated strength of the illusion correlated with the degree of premotor and cerebellar activity. This finding suggests that the activity in these areas reflects the detection of congruent multisensory signals from one's own body, rather than of visual representations. We propose that this could be the mechanism for the feeling of body ownership.

The central role of the parietal lobes in consciousness

There are now various approaches to understand where and how in the brain consciousness arises from neural activity, none of which is universally accepted. Difficulties among these approaches are reviewed, and a missing ingredient is proposed here to help adjudicate between them, that of "perspectivalness." In addition to a suitable temporal duration and information content of the relevant bound brain activity, this extra component is posited as being a further important ingredient for the creation of consciousness from neural activity. It guides the development of what is termed the "Central Representation," which is supposed to be present in all mammals and extended in humans to support self-consciousness as well as phenomenal consciousness. Experimental evidence and a theoretical framework for the existence of the central representation are presented, which relates the extra component to specific buffer working memory sites in the inferior parietal lobes, acting as attentional coordinators on the spatial maps making up the central representation. The article closes with a discussion of various open questions.