Eric L. Schwartz - US grants

The long term objective of the present research is to provide accurate mathematical, computational, and theoretical models of the functional architecture of the neo-cortex. The specific aims are to build the basic computational and theoretical tools and models required for a quantitative understanding of functional architecture in sensory cortex. Two aspects of this work are described in the present proposal: 1.)A prototype system for reconstructing cortex in 2-D and 3-D, from serial sections, has been constructed. A second generation software system for computer aided neuroanatomy will be constructed in which human interactive requirements and computer intensive stages of prototype system will be minimized. This work will be publicly distributed, along with the earlier prototype system. Serial section data sets, for the purpose of testing, calibrating, and learning to use the software tools, will also be distributed. 2.) Pilot data is shown which indicates that an accurate and concise model of the primary visual cortical map and ocular dominance column system can be constructed. It is proposed to develop these pilot studies into a full model and simulation of topographic and columnar architecture. This work represents a computational approach to the description of anatomical patterns. By standardizing and distributing data sets, software, and descriptive techniques, animal usage can be reduced. It provides fundamental methods and algorithms for reconstructing both the biological data and the neuronal patterns which are contained within that data. A careful measurement and characterization of these patterns is of critical importance to full understanding of the relationship between brain and behavior.

This research seeks to develop and apply recent advances in algorithmic methods for the construction of real time space-variant active vision systems. The term space-variant refers to sensor architectures in which pixel size, and possibly neighborhood topology, vary with position. Although inspired by biological vision (e.g. foveal vision, and its cortical expression in terms of the log-polar mapping) , space-variant architectures form a natural synergy with active vision: movement of the fixation point of a sensor, either via electronic pan-scroll, or via robotic actuators, is mandatory for space-variant systems. Since it has been shown that log-polar architecture can provide a form of data reduction that is on the order of two to three orders of magnitude for current computer vision systems, there is an important niche for application of space-variant imaging in robotic and computer vision. During the past year, an extension of the 2D Fourier Transform to log-polar image formats (the exponential chirp transform) has been developed. This transform has been demonstrated to provide the analog of a full-field (space-variant) 2D Fourier Transform at real-time rates on standard PC platforms. The goal of this research is to apply the exponential chirp transform to develop applications in the areas of real-time image tracking, template matching for recognition and motion de-blur, and to provide demonstrations indicating the achievement of complex visual functionality with minimal hardware and software complexity, for application on small, lightweight, and mobile active vision systems.

[unreadable] DESCRIPTION (provided by applicant): This proposal seeks to extend the ability of fMRI to accurately and quantitatively image high-resolution spatial structure in the human brain, and, at the same time, to expand mathematical and computational understanding of the basic functional architecture of visual cortex. Pilot data indicates that there is a super-modular structure linking multiple topographic maps in macaque and human visual cortex. This V1-V2-V3 complex can be modeled as a single map structure, and it is suggested that the MT-MST complex may be a second instance of the same super-modular organization. In order to test and extend this modeling, the new, state-of-the-art 7T fMRI scanner at Harvard MGH will be used, along with the existing 3T facility, to produce high resolution, minimal distortion, wide visual field reconstructions of human V1, V2, and V3 topographic mappings. A variety of specialized methods is proposed to improve the signal-to-noise ratio and to minimize spatial distortion and other artifacts which exist in current fMRI imagery. Special head coils designed to optimize recording from human occipital cortex have been prototyped. A novel, wide-field visual stimulation device has been designed, which will allow, for the first time, stimulation of the entire visual field from fovea to far periphery within the narrow bore of the fMRI scanner, rather than the para-foveal only stimulation that has been performed to date. All software and distortion correction methods developed under this proposal will be made available and maintained on the MGH web site, as well as source code for modeling the V1-V2-V3 complex, and all instrumental and electronic details for fMRI resolution enhancement and head coil design, as well as the novel full field visual stimulator designed for fMRI use will be made publicly available. The goal of this proposal is to join the efforts of the leading research groups in topographic map modeling and fMRI imaging, in order to extend and validate current understanding of the spatial structure of primary and extra-striate visual cortex and to extend the precision and resolution of fMRI imaging--two goals which can only be accomplished by a joint modeling and experimental collaboration. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (06) Enabling Technologies and specific Challenge Topic 06-AT-101: In this project, we propose two project areas based on the use of Magnetic Resonance Imaging modalities at both the cerebral (brain) and sub-cerebral (spinal) levels. Our first project area is to assess and compare the dose-response relationships of mindfulness and compassion meditation, studying subjects that are part of a large (N=360) research trial (NIH 1R01AT004698-01) beginning at Emory University. In the present proposal, we will longitudinally assess the trainees in the Emory study at pre-training and post-training stages by measuring changes in brain activation (fMRI) and structure (e.g. cortical thickness) measures that have previously been developed and applied to more advanced meditation practitioners at Massachusetts General Hospital. The second project area is to perform the first MRI exploration of the nature of bodily states of awareness that are traditionally reported in conjunction with advanced yoga meditation practices, such as Tibetan gTummo meditation. Here, we will use three-dimensional high resolution MRI based thermometry to accurately measure changes in internal body temperature, particularly in the region of the spinal cord, following meditation practices which are traditionally viewed as causing such changes. Together, these cerebral and sub-cerebral MRI imaging studies will provide important insight into the physiological and anatomical changes associated over time with two standard meditation protocols that are already in widespread use for stress reduction (mindfulness and compassion), and one more advanced protocol (gTummo) which so far has received little study but which is considered fundamental to more advanced practices. PUBLIC HEALTH RELEVANCE: The increasing use of meditation as a treatment for a variety of stress-related medical conditions highlights the public health importance of identifying mechanisms by which meditation may improve health, both to confirm efficacy for this widely used intervention and to better identify disease states toward which meditation might be optimally applied. The proposed study will test the hypothesis that meditation reduces stress- related inflammatory responses via reductions in autonomic activation in the face of perceived psychosocial stress. If confirmed, the long-term health implications of this hypothesis are far reaching, given evidence that activation of innate immune inflammatory pathways represents an important mechanism by which stress promotes and/or worsens a wide range of serious medical and psychiatric conditions (i.e. vascular disease, diabetes, cancer, HIV, major depression) to which meditation is being increasingly applied as an intervention.