FMR Imaging of Eye Stabilization Processes

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DESCRIPTION: (Applicant's Abstract) Vision requires the images projected on the retina to remain stable. Visual eye-stabilization mechanisms detect perturbations of the retinal images and generate eye movements aimed at compensating for such disturbances. In humans and monkeys, with sophisticated foveal binocular vision, there are ultra-fast, highly specialized cortical eye-stabilization systems able to decode and compensate for the complex visual perturbations caused by the observer's own motion in a structured three-dimensional environment. The proposed pilot study will be centered on developing the technology and the experimental protocols needed for the functional magnetic resonance imaging (fMRI) of such processes in alert behaving monkeys and the acquisition of preliminary data on which a in-depth study proposal will then be developed. Extensive behavioral and single-unit studies in monkeys have shown that, even if cortical in origin, the neuronal activation and related oculomotor responses associated with such systems are closely time-locked to the stimulus onset and of machine-like repeatability. This makes them ideal for fMRI studies. Furthermore, there is strong evidence that such responses are generated by cortical areas directly linked to visual perception. A systematic manipulation of the visual stimuli can therefore be used to probe the underlying neuronal processes on which perception is then constructed. Their reflex-like nature will also be used as tool for the optimization of fMRI sequences and extraction algorithms, and the analysis of the temporal development of the fMRI signal, included the recently discovered "fast response". The matching of neuronal data from invasive studies with fMRI data obtained with identical protocols in the same animals will be an invaluable starting point for the interpretation of similar fMRI studies on humans. Comparative studies of those responses have highlighted almost astonishing similarities between the two species, suggesting a similar underlying neuronal structure. There are many open questions regarding the neuro anatomical and functional correspondences between monkeys and humans and the goal of this pilot study is to propose a novel, powerful tool for solving such issues of critical importance for the understanding of the human brain.