Investigating somatosensory awareness through high-density EEG : effect of amplitude, bimodal stimulation and production of a report

Abstract

How perceptual awareness arises in the brain and how it might be modulated represents a pivotal question in the neuroscience of consciousness, not only for its philosophical implications but also for its possible application in rehabilitative contexts. Indeed, patients affected by disorders of consciousness are prevented from having a full-fledged perception of the world and need to undertake a path of rehabilitation for their recovery. In this context, a comprehensive investigation of factors influencing and possibly fostering sensory awareness becomes crucial. This Thesis investigates how perceptual awareness can be modulated by different factors, such as stimulation intensity, the presence of a stimulus of a different sensory modality and task relevance, focusing in particular on the somatosensory domain. By using high-density electroencephalography, this Thesis underlines that all three considered factors modulate Somatosensory Evoked Potentials (SEPs). More in detail, while early and late components are modulated by different stimulation intensities (40-60 ms; 100-120 ms; 190-380ms) and by the presence of a concomitant visual stimulus (40-60; 100-120; 120–180), only the Late Component (190-380 ms) is increased by the presence of a task, suggesting a revision of this neural underpinning as a possible correlate of perceptual awareness. This opens several considerations in the neuroscience of consciousness and to new rehabilitative approaches for deficits in perceptual awareness.