The Brain Essays - Motor System, Neuroanatomy, Brainstem

The Brain Essays - Motor System, Neuroanatomy, Brainstem The Brain A.M.D.G 27th October 1996 The Brain By Manuel Socarrs In the central nervous system of animals, the brain is a segregated group of nerve cells, or neurones, within the cranium, or skull, in vertebrates, and within the head segment in lower forms of animals. The brain varies in size and complexity from rudimentary ganglia (a group of nerve-cell bodies) in the central nervous systems of primitive worms to the large and complex human brain. As the central control organ of the body, the brain governs the functioning of the body's other organs. Sensory nerve cells feed external and internal information from all parts of the body to the brain. At least four medical subspecialties have a primary concern with the human brain: neurology, psychobiology, neurosurgery, and psychiatry. The average human brain at birth weighs 390 g (14 oz); its average maximum weight, reached at age 15, is 1,315 g (46 oz). The total number of neurones in the human brain is approximately 10 billion. In contrast, the brain of a whale may weigh more than 5 kg (11 lb.), four times as much as a human brain, and the brain of a grasshopper contains no more than a few thousand neurones. A theory has been proposed which states that behavioural capacity, a broad term indicating intelligence, is related not to the size of brain but to the index of cephalisationthe amount of brain tissue in excess of that required for transmitting impulses to and from the brain. Studies have shown that a progressive evolutionary encephalisation relative to body size occurs in vertebrates and culminates in humans. Of equal importance to encephalisation has been the evolutionary development of the human forebrain, a greatly expanded and convoluted mantle containing neuronal centres necessary for understanding and producing language, for conceptualisation and abstraction, for judgement, and for the capacity of humans to contemplate and influence their lives. ANATOMY AND FUNCTION Localisation of function is defined by two investigative techniques: ablation and stimulation. Ablation, the removal of a small area of the brain, may result in a neurological deficit that is considered in terms of a lost function, one that is assigned to the area of the brain that was ablated. In humans, correlation of the indications of brain dysfunction during life with lesions of the brain found at autopsy has added greatly to the Human Brain The human brain has three major structural components: the large dome-shaped cerebrum (top), the smaller somewhat spherical cerebellum (lower right), and the brainstem (centre). Prominent in the brainstem are the medulla oblongata (the egg-shaped enlargement at centre); and the thalamus (between the medulla and the cerebrum). The cerebrum is responsible for intelligence and reasoning. The cerebellum helps to maintain balance and posture. The medulla is involved in maintaining involuntary functions such as respiration, and the thalamus acts as a relay centre for electrical impulses travelling to and from the cerebral cortex. knowledge of localised functions. Movements and sensations can be produced in conscious humans by stimulating the brain electrically in appropriate areas. A portion of the skull may be removed (a craniotomy) under local anaesthesia, giving access to the brain in a conscious patient. Gray and white matter may be cut, stimulated, or cauterised without the patient experiencing pain. Apparently no nerve endings sensitive to pain exist within the brain substance. Large blood vessels supplying the brain and certain sensory nerves attached to the brain stem are pain sensitive. Brain Stem The most notable structures of the adult human brain are the brain stem, the cerebellum, and the cerebrum (cerebral hemispheres). The lowest, or most caudal, portion of the brain stem, the medulla oblongata, is continuous with the spinal cord. Above it, the pons bulges prominently and is continuous with the midbrain, into which the cerebral peduncles (stem-like connections) extend. The cerebral peduncles carry upper motor neurone fibres that originate in the cerebral cortex to the cell bodies of cranial nerves in the brain stem and to cells in the spinal cord, called lower motor neurones, which cause certain muscles to move. The brain stem contains all afferent and efferent nerve fibres between the spinal cord and the higher brain centres. Some upper motor neurone fibres cross in the brain stem, whereas others do not. Most cranial

Business-writing radio launched - Emphasis

Business-writing radio launched Business-writing radio launched Free podcasts offer expert help with writing reports, proposals, emails and more A new source of free help is at hand for anyone who has ever grappled with writing a make or break proposal or report, or wondered how best to handle sensitive customer correspondence. It comes in the shape of a series of podcasts that give expert advice on how to improve your business-writing skills. The podcasts, called Write On, offer help with everything from creating effective reports and proposals to writing speeches and emails. The high-quality programmes have been produced by leading business-writing trainers Emphasis and are presented by BBC radio presenter Clare McDonnell. They offer a wealth of practical tips and advice, as well as interviews with executives from major public and private-sector organisations about the latest thinking on business writing. They are just one of the many resources available on the Emphasis website that enable everyone to access business-writing advice, free of charge, in their own time. Companies can lose millions of pounds every year through poorly written proposals or badly worded customer service letters, explains Rob Ashton, Emphasis Chief Executive. But often people dont know how to improve their written work and may not want to admit publicly that they struggle with writers block or grammar, for instance. The beauty of the podcasts is that you acan listen to them in private, anywhere improving your writing skills even while travelling to work, for example. The podcasts are available to download here, where users can subscribe through iTunes or RSS feed to automatically receive each show as its released. They play equally well on an iPod or computer. Press enquiries For more information, please contact us 01273 738 888 or email us here. For information on training courses or to access free online resources, visit emphbootstrap.wpengine.com. Notes for editors Emphasis Training Ltd are the UKs leading business-writing trainers, providing bespoke courses for a huge range of private and public sector organisations, both in the UK and internationally. Since 1998, they have helped thousands of people in government departments, law firms, blue-chip companies, universities and charities to produce first-class business writing. With headquarters in Brighton, East Sussex, Emphasis have a dedicated team of experienced, specialist trainers who run bespoke courses on-site for organisations across the UK. They also run open courses for smaller groups or individuals throughout the year in London.