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PubMed2003

Did a change in sensory control of skilled movements stimulate the evolution of the primate frontal cortex?

The classical view of the evolution of such skilled movements as use of the hand and digits for reaching and grasping posited that these movements had their origin in the primate lineage. The hypothesis was that the permissive influence of adaptations to an arboreal environment led to the evolution and elaboration of these skills. Associated with skilled movements were increases in the size of the frontal lobe, temporal lobe, and cerebellum and the elaboration of new connections between these structures and other cortical regions, the brainstem, and spinal cord. The classical view saw rodents as phylogenetically old and relatively unrelated animals, displaying no skilled movements, and whose normal repertoire of behavior had little dependence on the frontal lobes. Here, evidence is reviewed that shows that the classical view of the origins of skilled movements is incorrect. Skilled movements are phylogenetically old, evolved in relation to food handling, and are especially well developed in rodents. Behavioral evidence also shows that the skilled movements of rodents are dependent upon the function of the frontal cortex. Nevertheless, there are difference in the sensory control of skilled movement in primates and rodents. Skilled movements are largely directed by vision in primates but are directed by hapsis/olfaction in rodents. This difference in sensory control suggests that at a dividing point between primates and rodents, there was a profound behavior/brain transformation. Primates retained the skilled movements exemplified in rodents, but brought these movements under visual control. Correspondingly, along with many other anatomical changes, the primate frontal cortex became relatively larger and move complex under visual influence.

Animals↗

PubMed2003

Face recognition with perspective transformation.

The effect of perspective transformation on transfer of face training was investigated in a yes/no recognition task using face stimuli with 42 degrees, 10 degrees, or no perspective convergence. A strong dependence of recognition performance on the magnitude of perspective transformation was found, with large perspective changes such as from 42 degrees at learning to orthogonal at test producing the strongest impairment and small perspective changes such as from 10 degrees at learning to orthogonal at test the least. In a second experiment, the internal and external features of a face from different perspective convergence were artificially combined to produce identical local features between this composite image and the original but producing an impossible perspective transformation from either. The results of transfer between the composite and untouched images showed face recognition to be strongly affected by local featural similarities and relatively insensitive to global coherence of perspective transformation.

Adult↗

PubMed1999

Target detection against narrow band noise backgrounds.

We studied the detectability of narrow band random noise targets embedded in narrow band random noise backgrounds as a function of differences in center frequency, spatial frequency bandwidth and orientation bandwidth between target and the immediately adjacent background. Unlike most target detection experiments the targets were not added to the background; they replaced the underlying background texture. Simulations showed that target detection probabilities could be accounted for by a simple transformation on the summed outputs of a two layer filter model similar to the complex channels model proposed by Graham, Beck and Sutter (Graham, N., Beck, J., & Sutter, A. (1992). Vision Research, 32, 719-743). Subsequently, the model was tested on the detection of camouflaged vehicle targets with encouraging results.

Contrast Sensitivity↗

PubMedDate not supplied

Bleeding due to needle biopsy: effect of venopirin in an animal model and implications for humans.

PURPOSE: This study was undertaken to address the effect of platelet dysfunction on bleeding associated with percutaneous needle biopsy. MATERIALS AND METHODS: With use of an established animal model, 199 biopsies were performed on the livers of 13 anesthetized pigs (95 on control animals, 104 on venopirin-treated animals). The needles used were 16-22-gauge Chiba type, 18-gauge Tru-Cut, and 18-gauge Menghini. The biopsies were performed under direct vision at laparotomy with consistent technique. Blood loss was measured, and the results were compared. Statistical analysis was performed with the Student t test and the Turkey test, after logarithmic transformation of the data. RESULTS: A substantial increase in blood loss resulting from the biopsy procedures was demonstrated in the animals with platelet dysfunction. This was much greater than the effect of either needle size or prothrombin time prolongation previously reported by the authors. CONCLUSION: Platelet function may be an important factor in determining the risk of bleeding due to percutaneous needle biopsy.

Animals↗

PubMed2006

Accurate calibration of a stereo-vision system in image-guided radiotherapy.

Image-guided radiotherapy using a three-dimensional (3D) camera as the on-board surface imaging system requires precise and accurate registration of the 3D surface images in the treatment machine coordinate system. Two simple calibration methods, an analytical solution as three-point matching and a least-squares estimation method as multipoint registration, were introduced to correlate the stereo-vision surface imaging frame with the machine coordinate system. Both types of calibrations utilized 3D surface images of a calibration template placed on the top of the treatment couch. Image transformational parameters were derived from corresponding 3D marked points on the surface images to their given coordinates in the treatment room coordinate system. Our experimental results demonstrated that both methods had provided the desired calibration accuracy of 0.5 mm. The multipoint registration method is more robust particularly for noisy 3D surface images. Both calibration methods have been used as our weekly QA tools for a 3D image-guided radiotherapy system.

Calibration↗

PubMed1993

1993 Muriel Driver Lecture. Occupational therapy's social vision.

Occupational therapy has tremendous, unfulfilled potential. The lecture critically analyzes that potential in light of occupational therapy's social vision. The analysis is built on emerging views of occupational therapy's core philosophy of client-centered practice using the ordinary occupations of daily life as a form of therapy. Critical analysis shows that foundational features of occupational therapy are consistent with foundational features of social justice. However, analysis also shows that occupational therapy's social vision is narrowed to comply with dominant community, managerial and medical approaches to disability and aging. Given therapists' good intentions, critical analysis is unnerving, but it provides a guide for transforming practice and developing occupational therapy's potential.

Canada↗

PubMed2005

Sensorimotor transformation for visually guided saccades.

Visually guided movements require the brain to perform a sensorimotor transformation. The key to understanding this transformation is to understand the different roles of the superior colliculus (SC) and cerebellum (CB). The SC has a three-layered structure. Cells in the top layer have visual, but not motor, responses. However, cells in the deeper layers have both visual and motor responses. Thus, for a long time it was thought that the SC encoded both the retinal location of a sensory stimulus and the desired change in eye movement needed to acquire it. However, copious evidence has accumulated that shows that the SC encodes only the retinal location of a visual target, and not the movement needed to foveate it. Thus, the information needed to make accurate movements must come from another part of the brain, which is proposed to be the cerebellum. Here it is shown how the cerebellum could perform the sensorimotor transformation.

Brain↗

PubMed2004

Continuum of care must be under region's control.

Lewis and Kouri have provided an overview of the various aspects of regionalization, its implementation and resulting impact across Canada. The authors note that although it has had some success in Canada, it remains unclear as to what the single compelling vision or focus is or should be. This commentary suggests that the inability to include all components of the continuum of care within most models accounts for the lack of "transformational change" that regionalization has as yet been unable to achieve. To expect that any significant gains will be made in the regionalization process until all aspects of the continuum are under a region's control is unrealistic. The commentary proposes that it is time to review the underlying premises for regionalization and its current emphasis on acute care.

Canada↗

PubMed2006

Extracting knowledge from science: a conversation with Elias Zerhouni. Interview by Barbara J. Culliton.

National Institutes of Health (NIH) director Elias Zerhouni is pushing hard for innovation and the risk taking required to make major leaps in medicine. Fully attuned to cutting-edge work that crosses disciplines, he cites nanotechnology, clinical databases designed to answer research questions, systems biology, and an openness to radical ideas among his top priorities. The NIH director's job, he says, "is to have a vision." This requires leveraging NIH funding so that money is spent more wisely and has a cumulative effect on population health. Knowledge can be extracted from science, and health system transformation is made possible.

Databases as Topic↗

PubMedDate not supplied

When is a physician network a group?

Developing a network of physicians into a high-performing group requires a cultural transformation. The hallmarks, as well as the obstacles, to achieving this are reviewed by two experienced consultants. The requirements of highly successful physician organizations range from sharing a common mission, vision, and values to developing an effective infrastructure to having visionary leadership. Barriers to successful physician groups include a lack of clarity of purpose and goals, lack of quality standards, and an absence of shared learning. A blueprint on how to become a successful physician group is provided.

Community Networks↗

PubMedDate not supplied

Transformational leadership and personal values for managers in the new millennium.

Transformational leadership is best suited to the many demands that home health managers face daily. Transformational leaders who are driven by values that remain constant are better able to guide their agency. They are the ones able to make sound decisions now and have a vision for the future.

Attitude of Health Personnel↗

PubMed1998

Development of localized oriented receptive fields by learning a translation-invariant code for natural images.

Neurons in the mammalian primary visual cortex are known to possess spatially localized, oriented receptive fields. It has previously been suggested that these distinctive properties may reflect an efficient image encoding strategy based on maximizing the sparseness of the distribution of output neuronal activities or alternately, extracting the independent components of natural image ensembles. Here, we show that a strategy for transformation-invariant coding of images based on a first-order Taylor series expansion of an image also causes localized, oriented receptive fields to be learned from natural image inputs. These receptive fields, which approximate localized first-order differential operators at various orientations, allow a pair of cooperating neural networks, one estimating object identity ('what') and the other estimating object transformations ('where'), to simultaneously recognize an object and estimate its pose by jointly maximizing the a posteriori probability of generating the observed visual data. We provide experimental results demonstrating the ability of such networks to factor retinal stimuli into object-centred features and object-invariant transformation estimates.

Animals↗

PubMed2005

Reinventing the academic health center.

Academic health centers have faced well-documented internal and external challenges over the last decade, putting pressure on organizational leaders to develop new strategies to improve performance while simultaneously addressing employee morale, patient satisfaction, educational outcomes, and research growth. In the aftermath of a failed merger, new leaders of The Pennsylvania State University College of Medicine and Milton S. Hershey Medical Center encountered a climate of readiness for a transformational change. In a case study of this process, nine critical success factors are described that contributed to significant performance improvement: performing a campus-wide cultural assessment and acting decisively on the results; making values explicit and active in everyday decisions; aligning corporate structure and governance to unify the academic enterprise and health system; aligning the next tier of administrative structure and function; fostering collaboration and accountability-the creation of unified campus teams; articulating a succinct, highly focused, and compelling vision and strategic plan; using the tools of mission-based management to realign resources; focusing leadership recruitment on organizational fit; and "growing your own" through broad-based leadership development. Outcomes assessment data for academic, research, and clinical performance showed significant gains between 2000 and 2004. Organizational transformation as a result of the nine factors is possible in other institutional settings and can facilitate a focus on crucial quality initiatives.

Academic Medical Centers↗

PubMed1993

Optimisation of a computer vision system for the interpretation of American Sign Language.

Presented in this paper is a simulation algorithm for the optimisation of camera position with respect to the signer, to have a full and reliable interpretation of the American Sign Language. The simulation includes a three-dimensional world point into two-dimensional image point transformation algorithm, the effect of the depth information loss and a sign projection correction test. It is concluded that the viewing camera should be positioned at any point in a specified area subtended by a solid angle of 30 degrees, where the centre of the area is located at 45 degrees in the azimuth and 45 degrees in elevation relative to the signer. The theory and the technique are tested with regard to the efficiency of interpreting American Sign Language (ASL) by two adult signers. One of the signers had been using ASL on a regular basis since infancy, and the second signer had signed for the past five years. It is demonstrated that positioning the camera anywhere in the specified area provides a 96 per cent correct interpretation of the 36 signs tested. The results also provide a preliminary indication that signer variability may not present a major problem in interpretation, and that a computer vision system which captures the optimum depth information can distinguish between signs which, to the naked eye, appear to have similar characteristics.

Algorithms↗

PubMed1994

Idiopathic macular hole: a clinical review and current concepts in the diagnosis and management.

BACKGROUND: A full-thickness macular hole is a retinal opening involving the fovea causing severe central vision loss among the elderly. METHODS: This paper examines the pathogenesis and mechanistic constructs for the development and formation of idiopathic macular hole, reviews the stages of evolution, and provides guidelines for management by the primary care clinician. An update of the current methods of diagnosis and the criteria for surgical intervention, including vitrectomy and epiretinal membrane removal are presented. A perspective on the emerging trends in the treatment of macular hole using transforming growth factor beta-2 application is also introduced. CONCLUSIONS: Clinical practice guidelines for the management of patients with macular holes can be established based on an improved understanding of the pathogenesis of macular hole formation, a knowledge of the various stages of evolution, and the primary care clinician's familiarity with improved diagnostic techniques. An enhanced understanding of the pathogenesis of macular hole will help to predict the risk for the fellow eye, will promote more effective patient education and counseling, and will result in more timely surgical intervention. RESULTS: More promising results in the surgical closure of macula holes can prevent or minimize significant central vision loss.

Female↗

PubMed2000

Perceptual learning in visual search generalizes over tasks, locations, and eyes.

In a visual search task, targets containing elementary features are detected in parallel, while a serial search is necessary for the detection of a target without a feature, or for targets containing conjunctions of features. In this study, we re-investigated the role of practice in visual search tasks, using an uncued visual search paradigm. Under some circumstances, initially serial tasks can become parallel with practice. Perceptual learning of feature search tasks is rapid (a few hundreds of trials are sufficient to transform serial into parallel search), long-lasting (a learned task is retained over several months), but far less specific than learning of other visual tasks (see also Sireteanu & Rettenbach, 1995a [Vision Research, 35, 2037-2043]). Learning transfers from one task to another, from one location in the visual field to another, and between the two eyes of a given subject, even if the subject has reduced stereopsis. Search for a conjunction of orientation and colour becomes more efficient, suggesting that a different search strategy emerges after prolonged practice. These results suggest that learning of visual search tasks modifies neural structures located at a high level in the visual pathway, involving different, presumably more central neural circuits, than the learning of visual discriminations and hyperacuity.

Analysis of Variance↗

PubMed2000

Seeing in three dimensions: the neurophysiology of stereopsis.

From the pair of 2-D images formed on the retinas, the brain is capable of synthesizing a rich 3-D representation of our visual surroundings. The horizontal separation of the two eyes gives rise to small positional differences, called binocular disparities, between corresponding features in the two retinal images. These disparities provide a powerful source of information about 3-D scene structure, and alone are sufficient for depth perception. How do visual cortical areas of the brain extract and process these small retinal disparities, and how is this information transformed into non-retinal coordinates useful for guiding action? Although neurons selective for binocular disparity have been found in several visual areas, the brain circuits that give rise to stereoscopic vision are not very well understood. I review recent electrophysiological studies that address four issues: the encoding of disparity at the first stages of binocular processing, the organization of disparity-selective neurons into topographic maps, the contributions of specific visual areas to different stereoscopic tasks, and the integration of binocular disparity and viewing-distance information to yield egocentric distance. Some of these studies combine traditional electrophysiology with psychophysical and computational approaches, and this convergence promises substantial future gains in our understanding of stereoscopic vision.

Journal Article↗

PubMed2001

The untapped potential of Telehealth.

The people of Malaysia generally enjoy a high standard of health. This is largely attributed to the comprehensive range of health services provided by the Government and the private sector at affordable costs. However, there are changing trends that now seriously challenge this status quo. The changing population structure, lifestyle, disease patterns and globalization are causing healthcare costs to rise. New and innovative ways will have to be devised to further improve the health status and at the same time contain costs. Information and Communication Technology (ICT) presents unprecedented opportunities to help the health sector in Malaysia reinvent itself and transform the way health and healthcare is managed and delivered in the future. Malaysia's Telehealth initiative under the Multimedia Super Corridor (MSC) project is designed to realize Malaysia's health vision and goals and meet future health challenges. Multimedia and Internet technology will be fully harnessed to deploy services that will shift the emphasis from episodic management of illness to proactive promotion of lifelong wellness and disease prevention. Health information content and interactive applications will engage the people to work as partners of health with healthcare professionals in maintaining their own health or managing their illnesses.

Delivery of Health Care, Integrated↗