Sensory stimulation in the early stages of development called sensitive period is necessary for establishing a normal structure and function of the sensory cortex. If animals lack this, their cortex undergoes aberrant structural and functional changes. While several studies have shown that sensory deprivation alters microscopic cortical features such as dendritic branching and axonal terminal clustering, fewer have explored how deprivation alters macroscopic features. Here, novel computational methods based on the Large Deformation Diffeomorphic Metric Mapping (LDDMM) framework will be used to describe changes in the auditory cortex of hearing and congenitally deaf cats at macroscopic, mesocopic and microscopic scales. Segmented supragranular, granular and infragranular cortical layers within stained sections of primary and higher order auditory regions will be used to create a 30 model of the microcircuitry. The model will be used to obtain morphometric measures such as volume, surface area, thickness and curvature and stereologic measures such as density and counts of neurons and cells. Then, these measures will be correlated with functional analysis and effective connectivity measures obtained in parallel studies in order to construct a model of interaction between structure and function of auditory cortex. The combined data will be used to quantify the macroscopic effect of deprivation on structure and function of the sensory cortices. The novel computational methods based on LDDMM will build a morphometric model of the columnar microcircuitry and interareal coupling in the primary and higher order auditory cortices. Biologically meaningful features such as gyral shape, thickness, stratification will be described and their relation with functional activity and connectivity of the corresponding neural structures will be analyzed.
Ultimately, these studies might help deaf people with cochlear implants. Studying the shape of the primary and higher-order auditory cortices in these patients longitudinally with MRI and then PET might refine their habilitation and effects of rehabilitation. The studies such as we propose here constitute the necessary first step toward proving the potential of this approach.
