Cross-modal reorganization following the loss of input from a sensory modality can recruit sensory-deprived cortical areas to process information from the remaining senses. Specifically, in early-deaf cats, the anterior auditory field (AAF) is unresponsive to auditory stimuli but can be activated by somatosensory and visual stimuli. Similarly, AAF neurons respond to tactile input in adult-deafened animals. To examine anatomical changes that may underlie this functional adaptation following early or late deafness, afferent projections to AAF were examined in hearing cats, and cats with early- or adult-onset deafness. Unilateral deposits of biotinylated dextran amine were made in AAF to retrogradely label cortical and thalamic afferents to AAF. In early-deaf cats, ipsilateral neuronal labeling in visual and somatosensory cortices increased by 329% and 101%, respectively. The largest increases arose from the anterior ectosylvian visual area and the anterolateral lateral suprasylvian visual area, as well as somatosensory areas S2 and S4. Consequently, labeling in auditory areas was reduced by 36%. The age of deafness onset appeared to influence afferent connectivity, with less marked differences observed in late-deaf cats. Profound changes to visual and somatosensory afferent connectivity following deafness may reflect corticocortical rewiring affording acoustically deprived AAF with cross-modal functionality.

Brain atlases play an important role in effectively communicating results from neuroimaging studies in a standardized coordinate system. Furthermore, brain atlases extend analysis of functional magnetic resonance imaging (MRI) data by delineating regions of interest over which to evaluate the extent of functional activation as well as measures of inter-regional connectivity. Here, we introduce a three-dimensional atlas of the cat cerebral cortex based on established cytoarchitectonic and electrophysiological findings. In total, 71 cerebral areas were mapped onto the gray matter (GM) of an averaged T1-weighted structural MRI acquired at 7 T from eight adult domestic cats. In addition, a nonlinear registration procedure was used to generate a common template brain as well as GM, white matter, and cerebral spinal fluid tissue probability maps to facilitate tissue segmentation as part of the standard preprocessing pipeline for MRI data analysis. The atlas and associated files can also be used for planning stereotaxic surgery and for didactic purposes.

Cross-modal plasticity following peripheral sensory loss enables deprived cortex to provide enhanced abilities in remaining sensory systems. These functional adaptations have been demonstrated in cat auditory cortex following early-onset deafness in electrophysiological and psychophysical studies. However, little information is available concerning any accompanying structural compensations. To examine the influence of sound experience on areal cartography, auditory cytoarchitecture was examined in hearing cats, early-deaf cats, and cats with late-onset deafness. Cats were deafened shortly after hearing onset or in adulthood. Cerebral cytoarchitecture was revealed immunohistochemically using SMI-32, a monoclonal antibody used to distinguish auditory areas in many species. Auditory areas were delineated in coronal sections and their volumes measured. Staining profiles observed in hearing cats were conserved in early- and late-deaf cats. In all deaf cats, dorsal auditory areas were the most mutable. Early-deaf cats showed further modifications, with significant expansions in second auditory cortex and ventral auditory field. Borders between dorsal auditory areas and adjacent visual and somatosensory areas were shifted ventrally, suggesting expanded visual and somatosensory cortical representation. Overall, this study shows the influence of acoustic experience in cortical development, and suggests that the age of auditory deprivation may significantly affect auditory areal cartography.

The integration of photogrammetric images and lidar data is becoming a powerful procedure that can be applied in the optimisation of photogrammetric mapping techniques. The complementary nature of lidar and photogrammetric data optimises the performance of many procedures used to extract 3D spatial information from data. For example, photogrammetric imagery enables the accurate extraction of building borders and lidar provides accurate 3D points that give information on the physical surfaces of buildings. These properties demonstrate the usefulness of combining the two types of data to achieve a more robust and complete reconstruction of 3D objects. Photogrammetric procedures require the exterior orientation parameters (EOPs) of the images to extract mapping information. Despite the availability of GPS ⁄ INS systems, which greatly assist in direct georeferencing of the imagery, the majority of commercially available photogrammetric systems require control information in order to carry out photogrammetric mapping. Due to improvements in the accuracy of lidar systems in recent years, lidar data is considered a viable source of photogrammetric control. Point features are the principal source of control for photogrammetric triangulation, although linear features and planar patches have also been used. This paper presents a method of georeferencing photogrammetric images using lidar data. The method uses the centroids of rectangular building roofs as control points in the photogrammetric procedure. The centroid of a rectangular building roof derived using lidar data is equivalent to a single control point with 3D coordinates, and can therefore be used in traditional photogrammetric systems. Two photogrammetric experiments were carried out to verify the feasibility of the methodology. The results obtained from these experiments confirm the feasibility of applying the proposed methodology to the georeferencing of photogrammetric images using lidar data.

Twenty-nine mildly disabled patients with multiple sclerosis underwent serial clinical and magnetic resonance imaging (MRI) evaluations (pre- and postgadolinium cranial and spinal cord MRI) on at least 3 occasions at 13-week intervals and during periods of suspected relapse. Using clinical judgment of the presence of recent active disease as the gold standard, combined MRI studies confirmed the clinical impression of active disease in 93% of follow-up visits (sensitivity) and the absence of active MS in 63% of follow-up visits (specificity). None of the cranial and spinal MRI-detected abnormalities disappeared. Gadolinium administration particularly increased the yield of spinal MRI. Cranial MRI alone detected 80% of the MRI-active visits. Clinical and MRI concordance was significantly better for the presence of recent disease activity than for the anatomical localization of the presumed site of activity. MRI evidence of apparent ongoing disease activity was seen more frequently in patients believed to have active multiple sclerosis in the preceding year (13 of 21) than in patients who had been in clinical remission for at least the 2 preceding years (2 of 8). Although clinical evidence of new disease activity was much less common in patients with active, chronic-progressive disease (1 of 8) than in patients with active, relapsing disease (9 of 13), the proportion of patients with either infrequent relapses, frequent relapses, or slow chronic-progressive disease in the preceding year in whom MRI activity developed and the pattern of this new MRI activity was similar between these types of active patients.(ABSTRACT TRUNCATED AT 250 WORDS)

In complex environments, tripping over an unexpected obstacle evokes the stumbling corrective reaction, eliciting rapid limb hyperflexion to lift the leg over the obstruction. While stumbling correction has been characterized within a single limb in the cat, this response must extend to both forelegs and hindlegs for successful avoidance in naturalistic settings. Furthermore, the ability to remember an obstacle over which the forelegs have tripped is necessary for hindleg clearance if locomotion is delayed. Therefore, memory-guided stumbling correction was studied in walking cats after the forelegs tripped over an unexpected obstacle. Tactile input to only one foreleg was often sufficient in modulating stepping of all four legs when locomotion was continuous, or when hindleg clearance was delayed. When obstacle height was varied, animals appropriately scaled step height to obstacle height. As tactile input without foreleg clearance was insufficient in reliably modulating stepping, efference, or proprioceptive information about modulated foreleg stepping may be important for producing a robust, long-lasting memory. Finally, cooling-induced deactivation of parietal area 5 altered hindleg stepping in a manner indicating that animals no longer recalled the obstacle over which they had tripped. Altogether, these results demonstrate the integral role area 5 plays in memory-guided stumbling correction.

A working memory of obstacles is essential for navigating complex, cluttered terrain. In quadrupeds, it has been proposed that parietal cortical areas related to movement planning and working memory may be important for guiding the hindlegs over an obstacle previously cleared by the forelegs. To test this hypothesis, parietal areas 5 and 7 were reversibly deactivated in walking cats. The working memory of an obstacle was assessed in both a visually dependent and tactilely dependent paradigm. Reversible bilateral deactivation of area 5, but not area 7, altered hindleg stepping in a manner indicating that the animals did not recall the obstacle over which their forelegs had stepped. Similar deficits were observed when area 5 deactivation was restricted to the delay during which obstacle memory must be maintained. Furthermore, partial memory recovery observed when area 5 function was deactivated and restored within this maintenance period suggests that the deactivation may suppress, but not eliminate, the working memory of an obstacle. As area 5 deactivations incurred similar memory deficits in both visual and tactile obstacle working memory paradigms, parietal area 5 is critical for maintaining the working memory of an obstacle acquired via vision or touch that is used to modify stepping for avoidance.

To determine the factors which may alter NMR relaxation times in multiple sclerosis (MS) lesions we measured the proton T1 and T2, specific gravity (SG), and histology in the central nervous system (CNS; 13-19 levels per animal) in the myelin basic protein (MBP) and CNS-induced acute and relapsing EAE models in 44 juvenile Hartley guinea pigs. In the MBP model, T1 is unchanged but T2 is prolonged before symptoms and pathological changes occur. T2 remains prolonged during the acute phase of MBP-induced EAE. In the acute CNS model, T1 and T2 were not different from control despite advanced pathological changes of inflammation and demyelination and changes in specific gravity, indicating a marked change in tissue water content. No single variable, pathological or SG, could predict T1 or T2 values in the CNS-induced model. In active disease in the MBP model, when edema occurs in the presence or absence of parenchymal infiltration, T2 values are increased. However, as the factors which influence tissue NMR characteristics are complex in these MS models, it is likely difficult to infer specific pathological events from MRI findings in patients with MS.