We compared three-dimensional structure-from-motion (3D-SFM) processing in awake monkeys and humans using functional magnetic resonance imaging. Occipital and midlevel extrastriate visual areas showed similar activation by 3D-SFM stimuli in both species. In contrast, intraparietal areas showed significant 3D-SFM activation in humans but not in monkeys. This suggests that human intraparietal cortex contains visuospatial processing areas that are not present in monkeys.To reconstruct the third dimension from a two-dimensional (2D) retinal image, our brain uses binocular as well as monocular cues such as shading, texture, and occlusion. Both humans and monkeys are also able to extract the 3D structure of an object from motion parallax cues that activate occipitoparietal areas in both species (1-3). Because neurons in the middle temporal area (MT/V5) are sensitive for speed gradients that reflect planes tilted in depth (4, see also 5), this area might play a crucial role in the extraction of depth from motion. Supporting evidence has been gleaned from a functional magnetic resonance imaging (fMRI) study showing 3D-SFM sensitivity in the human MT/V5 complex (hMT/V5ϩ) (6 ). These human fMRI results raise a first question: To what extent can they be generalized to the primate visual system? Furthermore, anatomical evidence suggests that there might be functional differences between human and monkey intraparietal cortex: The intraparietal sulcus separates area 5 from area 7 in the monkey, whereas in humans these two areas belong to the superior parietal lobe. In addition, in humans, the intraparietal lobe separates area 7 from areas 39 and 40, which have no clear counterpart in monkeys (7 ). Therefore, our second goal was to determine whether monkey intraparietal cortex is as important for motion-dependent depth processing as implied by human imaging (6 ).To address these issues, we turned to recently developed fMRI techniques (8) in awake (9-12) rather than anesthetized (13-14 ) monkeys. By performing human fMRI with virtually identical experimental procedures as in the awake monkey fMRI experiments, reliable interspecies comparisons could be made.The stimuli were displays of nine randomly connected lines, rotating in depth, that created a clear 3D percept (movie S1). Control stimuli consisted of the same displays that were either static or moving in one plane. We controlled for potential attentional differences between the 3D and 2D conditions by using a 1-back task in humans, as well as a demanding high-acuity fixation task (8, 9) in both species.In line with earlier reports (4-6, 13), area MT/V5 was activated more by 3D than by 2D moving random-line displays. In addition, the area in the fundus of the superior temporal sulcus (FST) also exhibited significant 3D-SFM sensitivity (Fig. 1A). Figure 2A shows the (3D -2D) pattern of activation for a single human subject, and the average activation for a group of eight subjects is shown in Fig. 2B. These results are similar to those obtained in an earlier study in which so...

We compared neural substrates of two-dimensional shape processing in human and nonhuman primates using functional magnetic resonance (MR) imaging in awake subjects. The comparison of MR activity evoked by viewing intact and scrambled images of objects revealed shape-sensitive regions in occipital, temporal, and parietal cortex of both humans and macaques. Intraparietal cortex in monkeys was relatively more two-dimensional shape sensitive than that of humans. In both species, there was an interaction between scrambling and type of stimuli (grayscale images and drawings), but the effect of stimulus type was much stronger in monkeys than in humans. Shape-and motion-sensitive regions overlapped to some degree. However, this overlap was much more marked in humans than in monkeys. The shape-sensitive regions can be used to constrain the warping of monkey to human cortex and suggest a large expansion of lateral parietal and superior temporal cortex in humans compared with monkeys.

Using functional magnetic resonance imaging (fMRI), we mapped the retinotopic organization throughout the visual cortex of fixating monkeys. The retinotopy observed in areas V1, V2, and V3 was completely consistent with the classical view. V1 and V3 were bordered rostrally by a vertical meridian representation, and V2 was bordered by a horizontal meridian. More anterior in occipital cortex, both areas V3A and MT-V5 had lower and upper visual field representations split by a horizontal meridian. The rostral border of dorsal V4 was characterized by the gradual transition of a representation of the vertical meridian (dorsally) to a representation of the horizontal meridian (more ventrally). Central and ventral V4, on the other hand, were rostrally bordered by a representation of the horizontal meridian. The eccentricity lines ran perpendicular to the ventral V3-V4 border but were parallel to the dorsal V3-V4 border. These results indicate different retinotopic organizations within dorsal and ventral V4, suggesting that the latter regions may not be merely the lower and upper visual field representations of a single area. Moreover, because the present fMRI data are in agreement with previously published electrophysiological results, reported distinctions in the retinotopic organization of human and monkey dorsal V4 reflect genuine species differences that cannot be attributed to technical confounds. Finally, aside from dorsal V4, the retinotopic organization of macaque early visual cortex (V1, V2, V3, V3A, and ventral V4) is remarkably similar to that observed in human fMRI studies. This finding indicates that early visual cortex is mostly conserved throughout hominid evolution.

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We reviewed the literature concerning the prevalence and correlates of metabolic syndrome (MetS) in older adults and assessed the impact of MetS with regard to life expectancy and comorbidity in the elderly (aged 65 years and over). Using the PubMed database and the Cochrane Library, we found 16 eligible studies, of which 8 were prospective cohort studies, 7 cross-sectional studies, and 1 a case-control study. The World Health Organisation (WHO) and National Cholesterol Education Program (NCEP) are the most popular definitions to describe MetS experienced by the elderly. The prevalence of metabolic syndrome in an elderly population varied from 11% to 43% (median 21%) according to the WHO, and 23% to 55 % (median 31%) according to NCEP. Obesity and hypertension are the most prevalent individual components. MetS in an elderly population is a proven risk factor for cardiovascular (CV) morbidity, especially stroke and coronary heart disease (CHD), and mortality. Preventing and treating MetS would be useful in preventing disability and promoting normal aging. Results from the different studies of elderly population-based cohorts provide support for earlier investigations in middle-aged populations to prevent MetS components. In conclusion, it is possible to say that the results from the different elderly study populations link the presence of the MetS with the development of cardiovascular disease (CVD) and functional disability, and further underscore the importance of recognising and treating its individual components, particularly high blood pressure.

Abstract& The prefrontal cortex supports many cognitive abilities, which humans share to some degree with monkeys. The specialized functions of the prefrontal cortex depend both on the nature of its inputs from other brain regions and on distinctive aspects of local processing. We used functional MRI to compare prefrontal activity between monkey and human subjects when they viewed identical images of objects, either intact or scrambled. Visual object-related activation of the lateral prefrontal cortex was observed in both species, but was stronger in monkeys than in humans, both in magnitude (factors 2-3) and in spatial extent (fivefold or more as a percentage of prefrontal volume). This difference was observed for two different stimulus sets, at two field strengths, and over a range of tasks. These results suggest that there may be more volitional control over visual processing in humans than in monkeys. &

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This paper deals with the identification of the post-necking strain hardening behavior of pure titanium sheet. Biaxial tensile tests using a servo-controlled multi-axial tube expansion testing machine revealed that commercial pure titanium sheet exhibits significant differential work hardening (DWH). The latter phenomenon implies that the shapes of the work contours significantly change during plastic deformation which is accurately measured in the first quadrant of the stress space up to an equivalent plastic strain of approximately 0.3. In this paper we focus on the plastic material behavior beyond the point of maximum uniform strain in a quasi-static tensile test. To this purpose, the material is subjected to a post-necking tensile experiment during which the strain field in the diffuse necking zone is measured using a dedicated Digital Image Correlation (DIC) system. The key point in the identification of the post-necking strain hardening is the minimization of the discrepancy between the external work and internal work in the necking zone. In this study, we scrutinize the influence of DWH in the pre-necking regime on the identification of the post-necking strain hardening behavior of pure titanium sheet. Finally, a strain hardening model which enables disentangling pre -and post-necking hardening behavior is presented.