Neurosciences - A neurosurgeon's perspective.
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The advancements in the field of science in the past fifty years have highlighted the need to integrate all fields of human endeavours and have emphasised interdependency of various disciplines. The separation of humanities, therefore, from neurosciences is a preposterous practical joke on all thinking men. With the human genome project on the anvil, biotechnology is making significant headway holding out promise for organ regeneration. Macro evolution is over, but micro-evolution continues in the brain. Neural Darwinism thus, continues to evolve as long as individual remains conscious and has memory. In the milieu of widely varying internal physiological mechanisms and external stimuli, an alternative theory to preprogrammed directionalism is proposed by three mechanisms namely developmental variation and selection, experiential selections and reentrant signalling. Reentrant signalling reorients and correlates the external inputs leading to psychic development preceding the development of consciousness. The cholinergic and aminergic neuro-modelling systems are well suited to serve as value systems. The main achievement of consciousness is to bring together the many categorizations involved in perceptions into a SCENE. Another part of evolution involved capacity of reentrant signalling to be guided by a value system where it is provided with a lot of choices. With 10(13) neurons and 10(16) connections, freedom of choice may manifest into a 'Buddha' or a 'Hitler'. As part of the evolutionary process, it was interesting how capacity to categorize the need to worship by referring to environment outside evolved into a search within our minds. As the next stage of evolution, neuroscience may, thus, serve as the next gateway to understanding the mind and soul. (+info)
Estimation of the number of synapses in the cerebral cortex: methodological considerations.
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In the present work we discuss several sampling procedures commonly used for counting synapses in the cerebral cortex. We compare, within the same tissue, two frequently used sterereological methods for determining the numerical density of synapses per unit volume, using as an example the estimation of the number of types of synapses by layers in the neuropil of the adult human temporal neocortex. These two methods are a size-frequency method (formula N(A)/d) and the disector method (sigmaQ-/a x h). Since the size-frequency method is assumption-based and the disector method is considered to be an unbiased method, the latter is often recommended for the quantification of synapses and other objects. We obtained, however, similar estimates for the numerical density of the different types of synapses using both methods, although they presented different technical difficulties and statistical properties. In addition, we show that the size-frequency method is more efficient and easier to apply than the disector method. Nevertheless, there are other methods for quantification which may also be valid, depending on the aim of the research; but the data reported in many articles are often complicated, which makes it very difficult for the reader to follow all the steps of the calculation. If certain basic information were given, this would facilitate the interpretation and sharing of important information with other laboratories, regardless of the method used for quantification. Finally, based on our present results and previous literature, we propose a simple general protocol for estimating the numerical synaptic density by volume in the neuropil of the cerebral cortex. (+info)
Levels and loops: the future of artificial intelligence and neuroscience.
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In discussing artificial intelligence and neuroscience, I will focus on two themes. The first is the universality of cycles (or loops): sets of variables that affect each other in such a way that any feed-forward account of causality and control, while informative, is misleading. The second theme is based around the observation that a computer is an intrinsically dualistic entity, with its physical set-up designed so as not to interfere with its logical set-up, which executes the computation. The brain is different. When analysed empirically at several different levels (cellular, molecular), it appears that there is no satisfactory way to separate a physical brain model (or algorithm, or representation), from a physical implementational substrate. When program and implementation are inseparable and thus interfere with each other, a dualistic point-of-view is impossible. Forced by empiricism into a monistic perspective, the brain-mind appears as neither embodied by or embedded in physical reality, but rather as identical to physical reality. This perspective has implications for the future of science and society. I will approach these from a negative point-of-view, by critiquing some of our millennial culture's popular projected futures. (+info)
The impact of molecular biology on neuroscience.
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How our brains work is one of the major unsolved problems of biology. This paper describes some of the techniques of molecular biology that are already being used to study the brains of animals. Mainly as a result of the human genome project many new techniques will soon become available which could decisively influence the progress of neuroscience. I suggest that neuroscientists should tell molecular biologists what their difficulties are, in the hope that this will stimulate the production of useful new biological tools. (+info)
Quo vadis neurohypophysial hormone research?
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Here we highlight just a few of the outstanding questions in the field of neurohypophysial hormones that we envisage will be addressed successfully in the new millennium. To begin, we focus on the regulation of receptors. Despite intensive investigation with new drugs, molecular modelling and transgenic models, the determinants of receptor selectivity remain elusive; there may even be more vasopressin or oxytocin receptor subtypes to be discovered. We discuss the controversy over the interesting studies that indicate modulation of oxytocin receptor-binding by steroids. Oxytocin and vasopressin release and action in the brain are discussed from several aspects. Dendritically released oxytocin acting locally is important for the milk ejection reflex, and similarly released vasopressin is important in regulating patterning of vasopressin neurone activity. Such dendritically released oxytocin and vasopressin is likely to be important in paracrine modulation of neural circuitry involved in neuroendocrine control, and for a range of behaviours. Is it possible that the whole range of behaviours that comprise 'social' (or 'anti-social') or 'maternal' behaviour can be engineered by modifying the expression of just these one or two peptides and their receptors? However, whether gene expression and knockout approaches will answer all the open questions about the real functions of oxytocin and vasopressin remains to be shown. (+info)
Gross anatomy of the head and neck and neuroscience in an integrated first-year medical school curriculum.
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The curriculum for first year medical students at the University of Cincinnati has changed. Beginning in the fall of 1998, material in the first year was presented in an Integrated Educational Program. The goal of this program was to provide students with an understanding of the normal structure, function, and development of the human body. The purpose of this report is to discuss the unique integration that occurs in a block offered during the Spring Quarter. The two components of this block are Gross Anatomy of the Head and Neck and Brain and Behavior I. Brain and Behavior I is a new offering combining neuroanatomy, neurophysiology, neurology, and a psychiatry/behavioral component. The unique combinations offered in this block are logical, educationally sound, and have been enthusiastically received by both the students and faculty. (+info)
Student test scores are improved in a virtual learning environment.
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This study evaluates the effectiveness of delivering the core curriculum of an introductory neuroscience course using a software application referred to as a virtual learning interface (VLI). The performance of students in a virtual learning environment (VLE) is compared with that of students in a conventional lecture hall in which the same lecturer presented the same material. This study was not designed to determine whether grades are improved by augmenting a lecture with other information. The VLI takes advantage of audio, video, animation, and text in a multimedia computer environment. Our results indicate that raw average scores on weekly examinations were 14 percentage points higher for students in the VLE compared with those for students in a conventional lecture hall setting. Moreover, normalized test scores were over 5 points higher for students in the VLE. This analysis suggest that a core curriculum can be effectively presented to students using the VLE, thereby making it possible for faculty to spend less class time relaying facts and more time engaging students in discussion of scientific theory. (+info)
Reproducibility of peer review in clinical neuroscience. Is agreement between reviewers any greater than would be expected by chance alone?
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We aimed to determine the reproducibility of assessments made by independent reviewers of papers submitted for publication to clinical neuroscience journals and abstracts submitted for presentation at clinical neuroscience conferences. We studied two journals in which manuscripts were routinely assessed by two reviewers, and two conferences in which abstracts were routinely scored by multiple reviewers. Agreement between the reviewers as to whether manuscripts should be accepted, revised or rejected was not significantly greater than that expected by chance [kappa = 0.08, 95% confidence interval (CI) -0.04 to -0.20] for 179 consecutive papers submitted to Journal A, and was poor (kappa = 0.28, 0.12 to 0. 40) for 116 papers submitted to Journal B. However, editors were very much more likely to publish papers when both reviewers recommended acceptance than when they disagreed or recommended rejection (Journal A, odds ratio = 73, 95% CI = 27 to 200; Journal B, 51, 17 to 155). There was little or no agreement between the reviewers as to the priority (low, medium, or high) for publication (Journal A, kappa = -0.12, 95% CI -0.30 to -0.11; Journal B, kappa = 0.27, 0.01 to 0.53). Abstracts submitted for presentation at the conferences were given a score of 1 (poor) to 6 (excellent) by multiple independent reviewers. For each conference, analysis of variance of the scores given to abstracts revealed that differences between individual abstracts accounted for only 10-20% of the total variance of the scores. Thus, although recommendations made by reviewers have considerable influence on the fate of both papers submitted to journals and abstracts submitted to conferences, agreement between reviewers in clinical neuroscience was little greater than would be expected by chance alone. (+info)