The bodily self: Insights from clinical and experimental research

This review article summarizes neuropsychological descriptions of abnormal body representations in brain-damaged patients and recent neuroscientific investigations of their sensorimotor underpinnings in healthy participants. The first part of the article describes unilateral disorders of the bodily self, such as asomatognosia, feelings of amputation, supernumerary phantom limbs and somatoparaphrenia, as well as descriptions of non-lateralized disorders of the bodily self, including Alice in Wonderland syndrome and autoscopic hallucinations. Because the sensorimotor mechanisms of these disorders are unclear, we focus on clinical descriptions and insist on the importance of reporting clinical cases to better understand the full range of bodily disorders encountered in neurological diseases. The second part of the article presents the advantages of merging neuroscientific approaches of the bodily self with immersive virtual reality, robotics and neuroprosthetics to foster the understanding of the multisensory, motor and neural mechanisms of bodily representations

My face through the looking-glass: The effect of mirror reversal on reflection size estimation

People tend to grossly overestimate the size of their mirror-reflected face. Although this overestimation bias is robust, not much is known about its relationships to self-face perception. In two experiments, we investigated the overestimation bias as a function of the presentation of the own face (left-right reversed - as in a mirror - or nonreversed - as in a photograph), the identity of the seen face, and prior exposure to a real mirror. For this we developed a computerized task requiring size estimations of displayed faces. We replicated the observation that people overestimate the size of their mirror-reflected face and showed that the overestimation can be reduced following a brief mirror exposure. We also found that left-right reversal modulates the overestimation bias, depending on the perceived face's identity. These data underline the enhanced familiarity of left-right reversed self-faces and the importance of size perception for understanding mirror reflection processing

Distinct contributions of Brodmann areas 1 and 2 to body ownership

Although body ownership—i.e. the feeling that our bodies belong to us—modulates activity within the primary somatosensory cortex (S1), it is still unknown whether this modulation occurs within a somatotopically defined portion of S1. We induced an illusory feeling of ownership for another person's finger by asking participants to hold their palm against another person's palm and to stroke the two joined index fingers with the index and thumb of their other hand. This illusion (numbness illusion) does not occur if the stroking is performed asynchronously or by the other person. We combined this somatosensory paradigm with ultra-high field functional magnetic resonance imaging finger mapping to study whether illusory body ownership modulates activity within different finger-specific areas of S1. The results revealed that the numbness illusion is associated with activity in Brodmann area (BA) 1 within the representation of the finger stroking the other person's finger and in BA 2 contralateral to the stroked finger. These results show that changes in bodily experience modulate the activity within certain subregions of S1, with a different finger-topographical selectivity between the representations of the stroking and of the stroked hand, and reveal that the high degree of somatosensory specialization in S1 extends to bodily self-consciousnes

High and Low Stimulus-Driven Conflict Engage Segregated Brain Networks, Not Quantitatively Different Resources

Task-irrelevant information is constantly present in our environment and may interfere with the processing of the information necessary to achieve goal-directed behavior. While task goals determine which information must be suppressed, the demand for inhibitory control depends on the strength of the interference induced by incoming, task-irrelevant information. Whether the same or distinct inhibitory processes are engaged to suppress various degrees of interference from task-irrelevant information remains largely unresolved. We investigated this question by manipulating the strength of the conflict induced by automatic word reading in a classical color Stroop task. High conflict was induced by presenting words in participant's native language and low conflict by presenting words in a less familiar language. Behavioral performance and electrical neuroimaging analyses of event-related potentials to the words were analyzed following a two-by-two within-subject design with factors conflict strength (high; low) and color word/word ink congruency (congruent; incongruent). Behaviorally, we observed a significant conflict strength×congruency driven by a smaller Stroop effect in the low- than high conflict condition. Electrophysiologically, we observed a significant conflict strength×congruency interaction at the topographic level during the period of the N450 components, indicative of the engagement of distinct configurations of brain networks. No such interaction was found at the level of response strength. Electrical sources analyses localized the topographic effect within the anterior cingulate cortex and basal ganglia, left middle frontal and occipital areas. We interpret our results in terms of qualitatively distinct executive mechanisms for reactive inhibitory control in conditions of high versus low stimulus-driven conflict

Feeling numbness for someone else's finger

SummaryThe experience that our body and its parts belong to us and are not those of other people is a key aspect of the ‘self’ called body ownership [1]. In six experiments, we have investigated body ownership and its neurophysiology using a tactile illusion [2,3] that disrupts body ownership and tactile sensation robustly, repeatedly, and with no particular apparatus by inducing an illusory feeling of numbness for another person's finger — the ‘numbness illusion’ (NI). Our results show that the NI does not depend primarily on visual or motor signals, but on tactile inputs modulating activity in primary somatosensory cortex

Illusory own body perceptions: case reports and relevance for bodily self-consciousness

Neurological disorders of body representation have for a long time suggested the importance of multisensory processing of bodily signals for self-consciousness. One such group of disorders--illusory own body perceptions affecting the entire body--has been proposed to be especially relevant in this respect, based on neurological data as well as philosophical considerations. This has recently been tested experimentally in healthy subjects showing that integration of multisensory bodily signals from the entire body with respect to the three aspects: self-location, first-person perspective, and self-identification [corrected], is crucial for bodily self-consciousness. Here we present clinical and neuroanatomical data of two neurological patients with paroxysmal disorders of full body representation in whom only one of these aspects, self-identification, was abnormal. We distinguish such disorders of global body representation from related but distinct disorders and discuss their relevance for the neurobiology of bodily self-consciousness.LNC

Effect of butanol and salt concentration on solid-state nanopores resistance

The objective of this study was to demonstrate the possibility of using 1-butanol to detect in a reliable way the open pore current of pyramidal solid-state nanopores produced in silicon wafers. The nanopores were produced through controlled pore formation by neutralizing an etchant (KOH) with a strong acid (HCl). Since nanopores produced by this method have a larger depth than those made in nanometer thick membranes, they behave as nanochannels. As a consequence, the open pore current detection is more challenging. Thus, we report that low amounts of butanol considerably aid in the detection of the open pore current of nanopores.Fil: Vega, M.. Universidad Tecnológica Nacional. Facultad Regional Haedo; ArgentinaFil: Perez, Maximiliano Sebastian. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Granell, Pablo Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Golmar, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Wloka, C.. University of Groningen; Países BajosFil: Maglia, G.. University of Groningen; Países BajosFil: Dieguez, M.J.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Del Valle, E.M.. Universidad de Salamanca; EspañaFil: Lasorsa, Carlos Alberto. Universidad Tecnológica Nacional. Facultad Regional Haedo; ArgentinaFil: Lerner, Betiana. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin