Latest News
UnReal? Investigating the Sense of Reality and Psychotic Symptoms with Virtual Reality
Our Sense of Reality (SoR) is our ability to differentiate real from unreal experiences (i.e. hallucinations, delusions). Although malfunctions of SoR are common in neurological and psychiatric disorders, there is no current model for how SoR is constructed in the mind. In our recent study, published in the Journal of Clinical Medicine, we proposed a novel approach for investigating SoR using virtual reality (VR). We used immersive VR to create parametric manipulations of visual reality. We measured both highly consistent and correlated perceptual sensitivity thresholds (JNDs) as well as consistent and correlated reductions in subjective reality ratings across different manipulations and levels. Our results validate our novel approach to the study of SoR. Furthermore, psychophysical thresholds denoting sensitivity to visual manipulations of the bodily self, were correlated with prodromal psychotic symptoms, suggesting a potential for this approach in clinical research of psychosis spectrum disorders.
In this study, we used a novel virtual-reality task allowing the manipulation of the visual feedback of a motor action across different aspects, to show that the sensitivity of agency is different across aspects. Furthermore, agency judgments are correlated across aspects within subjects and bias toward attributing the viewed action to the self or to an external source is correlated as well. Taken together, our results suggest that sensorimotor prediction mechanisms underlying SoA are related between different aspects and that people have a predisposition for the directionality of agency judgments.
The Anterior Insula integrates information from inside the body (Interoceptive) and information from the external world (Exteroceptive). In this study we followed up on our previous finding showing that the insula is involved in suppressing from awareness visual stimuli presented synchronously with the heartbeat (Salomon et al., 2016). Here we tested patients with brain lesions to the insula or other regions, as well as healthy participants on the same experiment. We replicated our previous finding and showed that damage to the anterior insular region eliminates the suppression of cardio-visual stimuli. This shows converging evidence fr the role of the insula in the integration of interoceptive and exteroceptive signals shaping the self model.
Salomon, R., Ronchi, R., Dönz, J., Bello-Ruiz, J., Herbelin, B., Faivre, N., ... & Blanke, O. (2018). Insula mediates heartbeat related effects on visual consciousness. Cortex, 101, 87-95.
Upper limb cortical maps in amputees with targeted muscle and sensory reinnervation
Amputation of a limb is known to cause cortical reorganisation in sensorimotor regions. A novel approach in neuroprosthetics named "Targeted muscle and sensory reinnervation (TMSR)" consists of rerouting motor and sensory nerves from the residual limb towards intact muscles and skin regions. Movement of a myoelectric prosthesis is enabled via decoded electromyography activity from reinnervated muscles and touch sensation on the missing limb is enabled by stimulation of the reinnervated skin areas. In this paper, (published in Brain ), we investigated using ultra high-field (7 T) fmri how motor control using TMSR affected the maps of the upper limb in primary motor (M1) and primary somatosensory (S1) cortex,and their functional connections. We found that M1 maps in TMSR patients were similar to healthy controls and different from non-TMSR amputees. These results show how that TMSR may counteract maladaptive cortical plasticity typically found after limb loss in M1.
No deficit of Body Ownership in Schizophrenia
Schizophrenia patients experience an altered sense of self. For example, they show deficits of Agency in which they feel that an external force is controlling their actions. However, another central aspect of the sense of self, the feeling that one's body belongs to the self (i.e. Body Ownership) has not been thoroughly investigated. In this paper, published in Schizophrenia Bulletin , we show that in a large cohort of chronic schizophrenia patients and controls there is no deficit in their sense of Body Ownership as measured by the Full Body Illusion . We also employed meta-analytical approach to show that there is little evidence for such a deficit in previous research on this topic. This finding gives us a more realistic view of Self related deficits in this population.
Unconscious mutlisensory integration impacts peripersonal space and bodily self consciousness
In a recent paper by Salomon et al. published in Cognition we show how the integration of unconscious multisensory signals modulates both peripersonal space and bodily self consciousnesses.While it has been assumed that these processes are pre-reflexive and do not require any awareness of the underlying sensory signals, this is the first empirical evidence showing that this is the case.
How does the brain create and maintain the Self?
This review paper outlines the cognitive and neural mechanisms by which the brain creates and maintains models of the self. Specifically, it details my theory of the role of sensorimotor processing in the formation of the minimal self and how these affect social processes and are disrupted in psychiatric conditions such as psychosis and schizophrenia.
Salomon, R. (2017). The assembly of the self from sensory and motor foundations. Social Cognition, 35(2), 87-106.
Salomon Lab is Hiring!
Interested in Consciousness and the Self? Our new lab is seeking highly motivated students and programmers, to lead our research on perceptual and self consciousness. To tackle these questions, we use behavioural studies, virtual reality, electrophysiology (EEG/MEG ) and fMRI. Enthusiastic candidates with excellent collaboration skills and backgrounds in Psychology, Neuroscience, Engineering or Computer Sciences are welcome to send a CV to Dr.Roy Salomon roy.salomon at biu.ac.il
The Salomon lab focuses on the cognitive and neural processes underlying perceptual consciousness (i.e. the objects of our experience) and bodily self consciousness (i.e. the subject who is experiencing). We use a combination of virtual reality, physiological signals, psychophysics and neuroimaging (EEG, MEG, fMRI) to study these processes in homo sapiens.
We work both with healthy populations as well as clinical populations showing deficits in self representation (e.g. Schizophrenia & Parkinson's patients).