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Characterizing the Occipital Oscillatory Activity in Blindness

Periodic Reporting for period 1 - COcOAB (Characterizing the Occipital Oscillatory Activity in Blindness)

Reporting period: 2016-04-01 to 2018-03-31

The massive reorganization of the occipital regions as a consequence of lack of vision represents one of the most remarkable examples of the plastic potentialities of the human brain. Despite the large amount of neuroimaging evidence proving the involvement of occipital areas of blind individuals in non-visual input processing (i.e. auditory, tactile), the functional role of this sensory reorganized region is still matter of intense debate. The goal of COcOAB (Characterizing the Occipital Oscillatory Activity in Blindness) is to use the magnetoencephalography (MEG) technique to assess the functional characteristics of the neuronal activity within the occipital cortex in blind humans. Moreover, COcOAB aims to investigate the interactions between this region and the rest of the brain, to address whether the visual cortex is integrated into new functional networks to serve non-visual functions. The functional profile of these areas are assessed in relation with the onset timing of visual loss, thus contributing to assess the differential impact of visual deprivation occurring at different stages of development. My goal is to prove that we can predict whether a faint sound will be heard or not by a blind individual by analyzing both the modulation of the local occipital activity and the long-range communication of this area with other brain regions — in particular, those areas involved in auditory perception. This result would be in support to the assumption that these effects are not just epiphenomenal, but play a causal role in auditory perception, is provided. In this way, COcOAB contributes to the understanding of the mechanisms subtending crossmodal plasticity, sheding light on how the brain machinery dinamically reorganizes to face challenges occurring during development.
During COcOAB, the experimental paradigm most suitable to address our experimental question has been defined, tested in a pilot study and optimized to make it suitable for a blind individuals population. Pilot data collected in sighted participants provided evidence that auditory stimulation presented near individual threshold is a promising paradigm to assess the activity prior stimulation and its functional relevance for the following performance. The data collection on blind participants is currently ongoing and will be completed in the upcoming year. The project as well as the preliminary data have been presented and discussed not only among members of the scientific community, but also on the occasion of informative events with the general public and educational initiatives for pre-college students.
COcOAB offers the invaluable opportunity to explore the functional profile of occipital neurons and their brain‐wide interaction pattern in blind individuals, in order to assess the functional relevance of the occipital cortex in non‐visual activity. This goal is addressed via (1) an underexploited neuroimaging technique in this field, MEG and (2) in an experimental domain — auditory stimulation at threshold — that has been so far neglected in the field of sensory deprivation. This type of stimulation has the advantage of investigating under which circumstances stimulation processing fluctuates on a trial-by-trial basis between, a detected and an unnoticed percept. Since the stimulus delivered is physically constant throughout the experimental session, it can be assumed that such variability in the self-reported perception might be attributable to modulations in the brain states of the perceiver. Although COcOAB pertains to basic research, possible future clinical applications cannot be excluded. In particular, the study of functional organization of the visual cortex will allow advancing hypotheses about the mechanisms underlying visual deprivation, and, possibly, improving our ability to detect early markers of visual diseases.