Sense of external agency is sustained by multisensory functional integration in the somatosensory cortex

Theories of consciousness and psychiatric disorders - A comparative analysis

Disorders of consciousness represent an efficient way to test theories of consciousness' (ToCs) predictions. So far, ToCs have mostly focused on disorders of quantitative awareness such as coma, vegetative state, spatial neglect and hemianopia. Psychiatric disorders, by contrast, have received little attention, leaving their contribution to consciousness research almost unexplored. Therefore, this paper aims to assess the relation between ToCs and psychiatric disorders - that is, the extent to which current ToCs can account for psychiatric symptomatology. First, I review direct and indirect evidence linking each ToC to psychiatry disorders. Next, I differentiate ToCs based on their theoretical and methodological ground, highlighting how they distinctively address neural, cognitive, and phenomenological aspects of conscious experience and, in turn, psychiatric symptoms. Finally, I refer to one specific symptom to directly compare ToCs' explanatory power. Overall, Temporospatial Theory of Consciousness (TTC) appears to provide a more comprehensive account of psychiatric disorders, suggesting that a novel dimension of consciousness (i.e., form of consciousness) may be needed to address more qualitative alterations in conscious experience.

Neuromodulation of the right temporoparietal junction alters amygdala functional connectivity to authority pressure

Past historical events and experimental research have shown that complying with orders from an authority has a strong impact on harming/destructive behavior, but no one has ever looked into the potential intervention and its neural underpinning to reveal the toll of coercion. We used a paradigm of virtual obedience to authority, in which an experimenter ordered a volunteer to press a handheld button to initiate actions that carried different consequences, including harming or helping others. In this study, we scanned the brain with functional neuroimaging and applied transcranial direct current stimulation (tDCS) to modulate the activation of the right temporoparietal junction (rTPJ) in healthy volunteers in a single-blinded, sham-controlled, crossover trial with anodal, cathodal, and sham stimulation. We observed that cathodal stimulation, compared to anodal and sham stimulation, significantly reduced reaction times (RTs) to initiating harming actions. The effect of tDCS on the rTPJ, orbitofrontal cortex, and anterior cingulate cortex had opposite directions depending on coercive harming or helping actions. Cathodal tDCS-induced changes in the strength of the functional connectivity between the rTPJ and amygdala predicted the effect of cathodal tDCS on harming RTs. The findings provide evidence supporting the rTPJ having a role in coercion-induced changes in the sense of agency. Neuromodulation with tDCS might help in unveiling the power of authority and assisting in the emergence of prosocial behavior, thus shedding light on coping strategies against coercion beyond merely examining its effects.

Towards functional robotic training: motor learning of dynamic tasks is enhanced by haptic rendering but hampered by arm weight support

Background

Current robot-aided training allows for high-intensity training but might hamper the transfer of learned skills to real daily tasks. Many of these tasks, e.g., carrying a cup of coffee, require manipulating objects with complex dynamics. Thus, the absence of somatosensory information regarding the interaction with virtual objects during robot-aided training might be limiting the potential benefits of robotic training on motor (re)learning. We hypothesize that providing somatosensory information through the haptic rendering of virtual environments might enhance motor learning and skill transfer. Furthermore, the inclusion of haptic rendering might increase the task realism, enhancing participants’ agency and motivation. Providing arm weight support during training might also enhance learning by limiting participants’ fatigue.

Methods

We conducted a study with 40 healthy participants to evaluate how haptic rendering and arm weight support affect motor learning and skill transfer of a dynamic task. The task consisted of inverting a virtual pendulum whose dynamics were haptically rendered on an exoskeleton robot designed for upper limb neurorehabilitation. Participants trained with or without haptic rendering and with or without weight support. Participants’ task performance, movement strategy, effort, motivation, and agency were evaluated during baseline, short- and long-term retention. We also evaluated if the skills acquired during training transferred to a similar task with a shorter pendulum.

Results

We found that haptic rendering significantly increases participants’ movement variability during training and the ability to synchronize their movements with the pendulum, which is correlated with better performance. Weight support also enhances participants’ movement variability during training and reduces participants’ physical effort. Importantly, we found that training with haptic rendering enhances motor learning and skill transfer, while training with weight support hampers learning compared to training without weight support. We did not observe any significant differences between training modalities regarding agency and motivation during training and retention tests.

Conclusion

Haptic rendering is a promising tool to boost robot-aided motor learning and skill transfer to tasks with similar dynamics. However, further work is needed to find how to simultaneously provide robotic assistance and haptic rendering without hampering motor learning, especially in brain-injured patients.

Trial registrationhttps://clinicaltrials.gov/show/NCT04759976

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-00993-w.

The Seven Selves of Dementia

The self is a complex and multifaceted phenomenon, encompassing a variety of cognitive processes and psychosocial influences. Considering this, there is a multiplicity of "selves," the current review suggesting that seven fundamental self-processes can be identified that further our understanding of the experience of dementia. These include (1) an embodied self, manifest as corporeal awareness; (2) an agentic self, related to being an agent and influencing life circumstances; (3) an implicit self, linked to non-conscious self-processing; (4) a critical self, which defines the core of self-identity; (5) a surrogate self, based on third-person perspective information; (6) an extended self, including external objects or existences that are incorporated into the self; and, finally, (7) an emergent self, a property of the self-processes that give rise to the sense of a unified self. These are discussed in relation to self-awareness and their use in making sense of the experience of dementia.

Sense of external agency is sustained by multisensory functional integration in the somatosensory cortex

"Sense of agency" (SoA), the feeling of control for events caused by one's own actions, is deceived by visuomotor incongruence. Sensorimotor networks are implicated in SoA, however little evidence exists on brain functionality during agency processing. Concurrently, it has been suggested that the brain's intrinsic resting-state (rs) activity has a preliminary influence on processing of agency cues. Here, we investigated the relation between performance in an agency attribution task and functional interactions among brain regions as derived by network analysis of rs functional magnetic resonance imaging. The action-effect delay was adaptively increased (range 90-1,620 ms) and behavioral measures correlated to indices of cognitive processes and appraised self-concepts. They were then regressed on local metrics of rs brain functional connectivity as to isolate the core areas enabling self-agency. Across subjects, the time window for self-agency was 90-625 ms, while the action-effect integration was impacted by self-evaluated personality traits. Neurally, the brain intrinsic organization sustaining consistency in self-agency attribution was characterized by high connectiveness in the secondary visual cortex, and regional segregation in the primary somatosensory area. Decreased connectiveness in the secondary visual area, regional segregation in the superior parietal lobule, and information control within a primary visual cortex-frontal eye fields network sustained self-agency over long-delayed effects. We thus demonstrate that self-agency is grounded on the intrinsic mode of brain function designed to organize information for visuomotor integration. Our observation is relevant for current models of psychopathology in clinical conditions in which both rs activity and sense of agency are altered.