Multisensory mechanisms in temporo-parietal cortex support self-location and first-person perspective

Self-consciousness has mostly been approached by philosophical enquiry and not by empirical neuroscientific study, leading to an overabundance of diverging theories and an absence of data-driven theories. Using robotic technology, we achieved specific bodily conflicts and induced predictable changes in a fundamental aspect of self-consciousness by altering where healthy subjects experienced themselves to be (self-location). Functional magnetic resonance imaging revealed that temporo-parietal junction (TPJ) activity reflected experimental changes in self-location that also depended on the first-person perspective due to visuo-tactile and visuo-vestibular conflicts. Moreover, in a large lesion analysis study of neurological patients with a well-defined state of abnormal self-location, brain damage was also localized at TPJ, providing causal evidence that TPJ encodes self-location. Our findings reveal that multisensory integration at the TPJ reflects one of the most fundamental subjective feelings of humans: the feeling of being an entity localized at a position in space and perceiving the world from this position and perspective.

Neuroscience of Bodily Self-Consciousness

Olaf Blanke, Estelle Palluel, Christian Pfeiffer

We review recent research about human subjectivity and self-consciousness that has focused on cognitive psychology and neuroimaging of bodily self-consciousness. Multidisciplinary research on the fields of neurology, cognitive neuroscience and virtual reality opens new avenues to investigate brain mechanisms underlying a fundamental sense of the bodily self. Clinical evidence for the implication of right temporo-parietal junction for bodily self-consciousness has received support by studies in which virtual-reality based own body illusions are evoked in healthy participants to study the underlying processes. A series of experiments will be reviewed in which it was shown that the experiences of self-location, self-identification and the first-person perspective can be manipulated experimentally and rely on the integration of multisensory stimuli (touch, vision, proprioception, vestibular information). Specific protocols are available to predictably influence the different aspects of bodily self consciousness. We predict that the understanding of fundamental brain mechanisms of bodily self-consciousness will lead to unprecedented empirical insights that are of broad relevance for science, virtual reality, engineering, the humanities, as well as medicine and psychotherapy.

2011

Turning Body and Self Inside Out

Lukas Heydrich

What is the self? This major philosophical question has been considered too complex to be studied in neuroscience. However, during the last 20 years, researchers from different disciplines within the cognitive neurosciences have started investigating the neural correlates of self-consciousness, using a range of behavioural paradigms and functional imaging techniques. Where as many researchers have studied highorder representational aspects of self-consciousness, such as language (i.e. the use of the self-referential pronoun "I" or "Me"), converging evidence suggests that the most basic sense of self, e.g. the sensation that we possess a stable and coherent representation of our body, that we identify with our body and that we perceive the self as being located within the bodily boundaries (e.g. bodily self-consciousness), is due to integration of bodily signals from different exteroceptive sensory modalities (vision, touch, proprioception). Others have highlighted the importance signals related to internal signals (homeostasis, interoception) for self-consciousness. Using lesion analysis, we could demonstrate a causal link between damage to the right temporo-parietal junction and an altered state of bodily self-consciousness, e.g out-of-body experiences. This was confirmed using functional magnetic resonance imaging, multisensory exteroceptive conflicts and virtual reality: if healthy participants perceived themselves as "disembodied", activity in the same cortical region (i.e. temporo-parietal junction) was systematically modulated. Moreover, we were able to demonstrate in a second line of experiments that interoceptive signals can be used to systematically alter bodily self-consciousness and somatosensory processing, extending previous paradigms that focused exclusively on exteroceptive signals. This was strengthened by our finding that the left posterior insula, repeatedly linked to the representation and integration of internal and external bodily signals, is implicated in another state of altered bodily self-consciousness, e.g. heautoscopy. Our results demonstrate that bodily self-consciousness is based on a neural network that represents and integrates both external and internal signals from the body.

EPFL2012

Turning Body and Self Inside Out

Lukas Heydrich

EPFL2012