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Chapter 1

NROB60 - Chapter 1

9 Pages
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Department
Neuroscience
Course Code
NROB60H3
Professor
Janelle Leboutillier

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NROB60 Chapter 1 Neuroscience Past, Present, and Future Introduction  Society of Neuroscience: association of professional neuroscientists and was founded in 1970  Scientists who studied neuroscience at first came from disciplines of medicine, biology, psychology, physics, chemistry, mathematics o They realized that the best way to study neuroscience was through an interdisciplinary approach The Origins of Neuroscience  Nervous system includes the brain, spinal cord and nerves of the body o Crucial for life and enables you to sense, move and think  7000 years ago – people bore holes in each other’s skulls to cure headaches and mental disorders o Giving evil spirits an escape o Carried out on live subjects and was not just a ritual conducted after death  Writings from physicians in ancient Egypt (5000 years ago) indicate they were aware of many symptoms of brain damage o However, the heart, not the brain was considered the seat of the soul and repository of memories  After death, the body was carefully preserved for afterlife but the brain was scooped through the nostrils and discarded Views of the Brain in Ancient Greece  Clear correlation between structure and function in the body o Differences in appearance predict differences in function  Head – specialized in sensing the environment (eyes, ears, nose, tongue)  Several Greek scholars concluded that the brain is the organ of sensation o Hippocrates was the most influential and said that the brain dealt with sensation and seated intelligence o Aristotle – Greek philosopher; did not accept Hippocrates view and said the brain was a radiator for the cooling of blood that was overheated by the heart Views of the Brain During the Roman Empire  Galen was the most important figure in Roman medicine; was a Greek physician o Embraced the Hippocratic view of the brain function  Galen conducted many animal dissections  In the sheep brain found the cerebrum and the cerebellum  Since the cerebrum was soft to the touch he suggested that the cerebrum was the recipient of sensations NROB60 Chapter 1 o The doughy feel helped to imprint memories on the brain  The cerebellum was hard to touch so he suggested it commanded the muscles  Today we know that cerebrum actually does deal with sensation and perception o Also the repository of memory  Cerebellum is primarily a movement control center  When Galen cut the brain open he found it to be hollow with ventricles filled with fluids  Galen believe the body functioned according to a balance of four vital fluids/humors  Sensations were registered and movements initiated by the movement of humors to or from the brain ventricles via the nerves (believed to be hollow like blood vessels) Views of the Brain From the Renaissance to the Nineteenth Century  Galen’s view prevailed for almost 1500 years  Andreas Vesalius: great anatomist during the Renaissance o Added more detail about the structure of the brain to Galen’s theory  In the 17 century when French inventors that developing hydraulically controlled mechanical devices, it strengthened Galen and Vesalius’s findings o Fluid forced out of the ventricles through the nerves literally ‘pump you up’ and cause movement of limbs  Rene Descartes: French mathematician; strongly supported this idea however he did not think it could account for a full range of human behavior o It could explain animal behavior  Descartes proposed that brain mechanisms control human behavior only to the extent that this behavior resembles that of the beasts o Human mental capabilities exist outside the brain in the “mind”  He believed that the mind is a spiritual entity that receives sensations and commands movements by communicating with other machinery of the brain via the pineal gland o Still believed today by some people that mind and brain are different entities  17 and 18 century – scientists started breaking away from Galen’s view  These new scientists found that the brain is divided into two parts: gray matter and white matter  White matter: continuous with the nerves of the body and contained the fibers that bring info to and from the gray matter  18 century – nervous system had been completely dissected and gross anatomy had be described in detail  Scientists recognized that the nervous system has a central division, consisting of the brain and spinal cord, a peripheral division, consisting of the network of nerves that course through the body NROB60 Chapter 1  Important breakthrough – observation that the same general patterns of bumps (gyri) and grooves (sulci and fissures) on the surface of the brain o Enables the parceling of the cerebrum into lobes  Basis for speculation that different functions might be localized to different bumps on the brain Nineteenth – Century Views of the Brain  Injury to the brain can disrupt sensations, movement, and though and can cause death  The brain communicates with the body via the nerves  The brain has different identifiable parts, which probably perform different functions  The brain operates like a machine and follows the law of nature Nerves as Wires  Benjamin Franklin set an understanding of electrical phenomena  Luigi Galvani (Italian Scientist) and Emil du Bois – Reymond (German biologist) had shown that muscles can be caused to twitch when nerves are stimulated electrically and that the brain can generate electricity  This created the new concept of nerves being more like ‘wires’ rather than hollow vessels  1810 – Charles Bell (Scottish physician), Francois Magendie (French physiologist) o Magendie showed that dorsal roots carry sensory info into the spinal cord o Bell found that ventral roots damage led to muscle paralysis o They both concluded that within each nerve there is a mixture of many wires  Some bring info into the brain and spinal cord  Others send info out to the muscles o Each sensory and motor nerve fiber, transmission is strictly one way o Two kinds of fibers are bundled together for most of their length but are anatomically segregated when they enter or exit the spinal cord Localization of Specific Functions to Different Parts of the Brain  1811 – Bell proposed that the origin of the motor fibers is the cerebellum and the destination of the sensory fibers is the cerebrum  Experimental ablation method: approach in which parts of the brain are systematically destroyed to determine their function  1823 – Marie-Jean-Pierre Flourens (French psychologist): used ^ this method in a variety of animals (particularly birds) to show that the cerebellum plays a role in coordination of movement o Also showed cerebrum is involved in sensation and perception NROB60 Chapter 1  Franz Joseph Gall (Austrian medical student): proposed that the propensity of personality traits (generosity, secretiveness etc.) could be related to the dimensions of the head  Phrenology: study of correlating structure of the head with personality traits  Flourens criticized Gall’s theory o He performed experimental ablations showing that particular traits are not isolated to the portions of the cerebrum specified by phrenology o Also maintained that all regions of the cerebrum participate equally in all cerebral functions (later to found to be erroneous)  Paul Broca (French neurologists): is credited with tilting the scales of scientific opinion firmly toward localization of function in the cerebrum o After examining a patient could understand language but not speak) he concluded that the lesioned region of the human cerebrum was specifically responsible for production of speech  Gustav Fritsch and Eduard Hitzig showed in 1870 that applying small electrical currents to a region of the exposed surface of the brain could elicit discrete movements  David Ferrier showed that removal of region of cerebrum causes paralysis of muscles  Hermann Munk – presented evidence that occipital lobe of cerebrum was specifically required for vision The Evolution of Nervous Systems  1859 – Charles Darwin (English biologist) published a book articulating the theory of evolution (species of organism evolved from a common ancestor)  Natural selection: process by which differences among species arise o As a result of the mechanisms of reproduction, physical traits of offspring are sometimes different from those of the parents o If these traits are advantageous, the offspring themselves will be more likely to reproduce thus increasing the likelihood that the advantageous traits are passed on to the next generation  Many disciplines today support natural selection as a theory of evolution  Darwin also talked about behavior as a heritable trait o Flight-or-Fight response is seen in many animals suggesting they come from a common ancestor  Many scientists use animal models to understand human mechanisms The Neuron: The Basic Functional Unit of the Brain  Technical advances in microscopy during the early 1800s gave scientis
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