Princípios topográficos da plasticidade intermodal no córtex auditivo de indivíduos surdos congenitos

In CrossToPlasticity, we seek to provide commercial efforts focusing on the development of Cochlear Implants (CIs) for congenitally deaf individuals with a fine-grained blueprint with the plastically changed organization of the auditory cortex in deaf individuals, with a particular emphasis on the crucial role of topography in both cross-modal plasticity and preserved organization. We will explore the topographic organization of visual cross-modal processing in the auditory cortex, using cutting-edge modeling of both positive and negative fMRI signals, alongside examining the large-scale organization of the deprived auditory cortex using topological-oriented connectivity. This will provide the industry with a detailed organization profile of the cortical circuitry to be exploited by a novel generation of CIs for sensory rehabilitation. Our efforts will be centered around 2 aims: Aim 1: Mapping retinotopic features of cross-modal responses in the auditory cortex. We will explore the topographical principles involved in cross-modal processing and the representation of low-level visual information in the deprived auditory cortex. Building upon our recent findings (12) which revealed retinotopic-related responses in deaf individuals, we aim to provide a comprehensive understanding of cross-modal plasticity processes. To achieve this, we will implement two novel approaches. Firstly, by incorporating a model that captures negative fluctuations of the BOLD signal and characterizing both positive and negative population receptive field (pRF,(11, 13)) we aim to demonstrate that cross-modal information is decoded by both neuronal activation and deactivation. Secondly, drawing from previous behavioral and neuronal studies demonstrating enhanced processing of the peripheral visual field in deaf individuals (10, 14), we will focus on mapping the peripheral visual field. We hypothesize that these areas play a crucial role in cross-modal plasticity and therefore, detailed mapping of these regions will offer valuable insights into the functional organization and constraints of cross-modal plasticity. Aim 2: Exploring the dynamic large-scale topographic organization of the deaf auditory cortex. While robust neuronal reorganization in deprived sensory cortices is well-documented (3), some studies suggest that these regions can simultaneously develop and maintain their large-scale topographic organizational structure, independent of cross-modal plasticity (4, 5). This preserved internal organization has profound implications for auditory rehabilitation interventions, serving as a foundational element for auditory restoration. However, the stability of such organization in humans, and its modulation by sensory tasks (such as during visual cross-modal tasks) is still underexplored. To address this gap, we will directly compare resting-state connectivity, previously employed to illustrate the preserved organizational structure, with task-state connectivity. An integral part of both aims involves performance assessment in visual behavioral tasks, exploring the intricate relationship between cross-modal plasticity and inherent topographic organization and their influence on the enhanced visual performance in deaf individuals. This understanding will provide a mechanistic comprehension of how to leverage these cortical regions for the implementation of cochlear implants.