A History of Neuropsychology Unit 1 PDF

Unit 1 A History of Neuropsychology Introduction  Psychology is the study of behaviour; specifically, it seeks to describe, explain, modify, and predict human and animal behaviour.  Neuropsychology, a subspecialty of ps...

Unit 1 A History of Neuropsychology Introduction  Psychology is the study of behaviour; specifically, it seeks to describe, explain, modify, and predict human and animal behaviour.  Neuropsychology, a subspecialty of psychology, is the study of how complex properties of the brain allow behaviour to occur.  Neuropsychologists study relationships between brain functions and behaviour; specifically, changes in thought and behaviour that relate to the brain’s structural or cognitive integrity.  Thus, neuropsychology is one way to study the brain by examining the behaviour it produces.  In general, two doctrines have emerged. o Vitalism  It suggests that many behaviours, such as thinking, are only partly controlled by mechanical or logical forces, they are also partially self- determined and are separate from chemical and physical determinants.  Extreme proponents of vitalism argue that spirits or psychic phenomena account for much observable behaviour.  Sigmund Freud’s psychoanalysis would be a good example of this doctrine. o Materialism  It suggests that logical forces, such as matter in motion, determine brain–behaviour functions.  Materialism, in its simplest form, favours a mechanistic view of the brain (as a machine).  Walter Freeman’s lobotomies embraced this idea. Early Hypothesis Trephination  The earliest neuropsychological investigations recognized how diseases and blows to the brain affect behaviour.  Trephination is an ancient surgical operation that involves cutting, scraping, chiselling, or drilling a plug-like piece of bone from the skull.  This procedure relieves pressure related to brain swelling.  Many who underwent trephination clearly survived the operation, because many of the skulls show evidence of healing (new callus tissue); other skulls show no signs of healing, so the patients died during or shortly after the operation.  In some cases, the same skull was trephined more than once.  Researchers have suggested that some cases may have involved a medical reason, such as a skull fracture.  On some skulls, however, trephination was performed on intact crania with no sign of violence. Thus, some investigators suggest that trephination was a “magical” form of healing, perhaps for displays of bizarre behaviours, including epilepsy or schizophrenia.  Similar operations are important in modern neurosurgery. Surgeons widely use two procedures. o The first procedure technique of drilling a number of small holes, involves drilling a hole next to a depressed skull fracture to facilitate the elevation and removal of depressed bone fragments. Incidentally, modern neurosurgeons still use manual drills, which allow them more control during the operation. o The second surgical procedure drains internal bleeding after a blow to the head. With a special drill bit, the surgeon makes a hole over the site of the bleed. Then the surgeon screws a precisely machined bolt into the skull, allowing excessive blood to drain from within the cranium. This procedure reduces the intracranial pressure that is a major cause of death after a head injury. Ancient Greek Theorists  Heraclitus o He called the mind an enormous space with boundaries that we could never reach.  Pythagoras o He was the first to suggest that the brain is at the centre of human reasoning and plays a crucial role in the soul’s life. o They described what is now called the brain hypothesis: the idea that the brain is the source of all behaviour.  Hippocrates o A Greek physician honoured as the founder of modern medicine also believed the brain controls all senses and movements. o Hippocrates suggested that pleasure, merriment, laughter, and amusement, as well as grief, pain, anxiety, and tears, all arise from the brain. o He was the first to recognize that paralysis occurs on the side of the body opposite the side of a head injury, following the areas governed by the right and left hemispheres of the brain.  Plato o He suggested that the soul has three parts: appetite, reason, and temper. o This may have served as the model for Freud’s psychoanalytic subdivision of the psyche into the id, ego, and superego. o Plato believed the rational part of the tripartite soul lay in the brain, because it is the organ closest to the heavens. o Plato also discussed the idea that health is related to harmony between body and mind.  Aristotle o Aristotle erroneously believed the heart to be the source of all mental processes. o He reasoned that because the heart is warm and active, it is the locus of the soul. o Aristotle argued that because the brain is bloodless, it functions as a radiator, cooling hot blood that ascends from the heart. o The influence of Aristotle’s so-called cardiac hypothesis proposing the heart as the seat of such emotions as love and anger can still be seen in words such as heartbroken. The Cell Doctrine  In Egypt, during the third and fourth centuries B.C., the so-called Alexandrian school reached its height.  Reports exist of scientists actually vivisecting subjects—condemned criminals were at the scientists’ disposal.  These dissections allowed scientists to notice different anatomic details, and they hypothesized that specific parts of the brain control different behaviours.  Furthermore, they broke new ground by distinguishing between ascending (sensory) and descending (motor) nerves, and demonstrating that all nerves connect with the central nervous system.  An interesting development during this time was the erroneous suggestion that ventricular cavities within the brain control mental abilities and movement.  The ventricular localization hypothesis postulated that mental as well as spiritual processes reside in the ventricular chambers of the brain.  Thus, brain autopsies might have led investigators to conclude that these cavities contain animal spirits and are in large part responsible for mental faculties.  This hypothesis subsequently became known as the cell doctrine.  According to the cell doctrine, foremost was the cell of common sense, where people thought the soul resided and that connected to nerves leading to the eyes and ears.  Today, people know that the cell doctrine is entirely inaccurate.  The ventricles are actually the anatomic site through which cerebrospinal fluid passes.  This fluid protects the brain and facilitates the disposal of waste material and plays no role in thinking.  Galen o He identified many of the major brain structures and described behavioural changes as a function of brain trauma. o Galen suggested that the brain is a large clot of phlegm from which a pump forced the psychic pneuma out into the nerves. o Galen believed that all physical function, including the brain, as well as the rest of the body, depends on the balance of bodily fluids or humours, specifically blood, mucus, and yellow and black bile, which he related to the four basic elements—air, water, fire, and earth, respectively. Anatomic Discoveries and the Role of Spiritual Soul  Albertus Magnus o Theorized that behaviour results from a combination of brain structures that includes the cortex, midbrain, and cerebellum.  Andreas Vesalius o Vesalius placed more emphasis on the relatively larger overall brain mass of humans as responsible for mediating mental processes. o Vesalius also pioneered the anatomic theatre- a sort of performance dissection, where medical students and doctors could watch from a circular gallery. o Vesalius proceeded to revolutionize medicine through precise drawings of human anatomy.  Rene Descartes o He proposed a strict split or schism between mental processes and physical abilities. o He hypothesized that the mind and body are separate, but interact with each other. o Descartes theorized that mental processes reside in a small anatomic feature, the pineal gland. o He reasoned that because the pineal gland lies in the centre of the brain and is the only structure not composed of two symmetric halves, it was the logical seat for mental abilities.  Thomas Willis o He is best known for his work on blood circulation in the brain, theorized that all mental faculties reside in the corpus striatum, a structure deep within the cerebral hemispheres.  Giovanni Lancisi o He contributed greatly to our knowledge of the aneurysm (an abnormal, blood-filled ballooning of an artery in the brain), selected the corpus callosum, a band of fibres that joins the left and right cerebral hemispheres, as the seat of mental functions. Non- Western Attitudes  Mediterranean and African cultures o There the belief was that a god or gods sent diseases. o For example, Egyptians viewed life as a balance between internal and external forces. o As a result, they treated many mental disorders as integrating physical, psychic, and spiritual factors.  Atharva Veda o In India, one of the earliest and most important medical documents, the Atharva-Veda, proposed that the soul is nonmaterial and immortal.  Arab Countries o During the Middle Ages, Arab countries demonstrated a humanist attitude toward the mentally ill, partly because of the Muslim belief that God loves the insane person. o Because of this, the same treatments were available for the rich and poor. o The treatment of mental patients was humanist and emphasized diets, baths, and even musical concerts especially designed to soothe the patient.  Chinese Culture o Ancient Chinese medical texts also discussed psychological concepts and psychiatric symptoms. o They conceptualized many mental health disorders as illnesses or vascular disorders, as opposed to the prevailing European belief in demonic possession. o The ancient Chinese medical textbook The Yellow Emperor’s Classic of Internal Medicine includes references to dementia, convulsions, and violent behaviour. o Confucian writings reflected early Chinese philosophical thought in proposing that mental functions are not distinct from physical functions and do not reside in any part of the organism, although these writings give the heart special importance as a guide for the mind. Localization Theory Phrenology and Faculty Psychology  Franz Gall o He postulated that the brain consists of a number of separate organs, each responsible for a basic psychological trait such as courage, friendliness, or combativeness. o Gall suggested that mental faculties are innate and depend on the topical structures of the brain. o His theory sought to describe differences in personality and cognitive traits by the size of individual brain areas. o He hypothesized that the size of a given brain area is related to the amount of skill a person has in a certain field. o Craniology is the study of cranial capacity in relation to brain size, which indicated intelligence. o Gall formulated the basis of the localization theory of brain function. o Although Gall was wrong on most counts, he did help shape how we currently perceive brain–behaviour relationships.  Phrenology o From Gall’s basic theory of localization, the science of phrenology was born. o This theory holds that if a given brain area is enlarged, then the corresponding area of the skull will also be enlarged. o Conversely, a depression in the skull signals an underdeveloped area of the cortex. o It is generally accurate that skull configurations closely follow brain configurations. o Phrenology, in its most popular form, involves feeling the cranial bumps to ascertain which cerebral areas are largest. o Sophisticated mechanical equipment was developed, such as the phrenology cap to accurately identify bumps and indentations on the skull to make precise predictions about psychological strengths and weaknesses.   Johann Spurzheim o He carried on Gall’s phrenology teachings, lecturing extensively on phrenology in the United States. o As a result, phrenology societies sprang up in the United States, and the movement became increasingly popular. o To this day, people sometimes make attributions about an individual solely from specific physical characteristics.  Faculty Psychology o Faculty psychology is the idea that the mind is separated into faculties, or sections, and that each of these faculties are assigned to certain mental tasks. Some examples of the mental tasks assigned to these faculties include judgement, compassion, memory, attention, perception, and consciousness. o Faculty psychology and discrete localization theory continued to develop for a century. o Many factors were erroneous and simplistic, but three major developments represented significant progress.  First, scientists were reluctant to accept a single part or component of the brain as responsible for all behaviour, as had proponents of earlier theories.  Second, they placed more emphasis on the role of the cortex, which until then had not been seen as functioning neural tissue but as relatively unimportant protective “bark” (“cortex” in Latin).  Third, and perhaps most important, scientists focused on the brain for their study of behaviour and the mind. Era of Cortical Localization  Paul Broca o Broca’s landmark contribution was in understanding the origins of aphasia. o From his investigations, Broca described the condition of aphasia, an inability to talk because the musculature of speech organs do not receive appropriate brain signals. o Contemporary research methodology proposes that to attribute a precise cognitive function to a specific anatomic section of the brain, research must meet two conditions.   The first condition, which Broca did demonstrate, is that destruction of a localized brain site impairs a specific function, in this case, articulate speech.  The second condition, which Broca did not demonstrate, relates to that damage to any other area of the brain - for example, the patient’s right frontal lobe - should not result in the same deficit. This second condition is called double dissociation.  Carl Wernicke o A decade after Broca’s discovery, Carl Wernicke announced that the understanding of speech was located in the superior, posterior aspects of the temporal lobe. o Wernicke noted that no motor deficit accompanied a loss of speech comprehension caused by damage in this area; only the ability to understand speech was disrupted. o That is, the patient was still able to talk, but his speech made no sense and sounded like some unknown foreign language. o Such speech was called fluent aphasia. o Although Wernicke supported localizationists by locating a specific area important for word comprehension, he also demonstrated that language is not strictly localized. o Broca’s area, or expressive speech, is in the frontal lobes, and Wernicke’s area, or receptive speech, is posterior to that, in the temporal lobe. Critics of Cortical Specialization  Sigmund Freud o Freud suggested that various aphasias could be explained by subcortical lesions in less localized association pathways. o Freud pointed out, quite correctly, that the Broca and Wernicke centres are little more than nodal points in a general and complicated network of neurons. o Freud also described the distinction between the ability to recognize an object and the inability to name it, agnosia; this term remains in use today.   Pierre Flourens o Through an extensive number of experiments and logical arguments, Flourens attempted to disprove Gall’s localization theory. o To support his beliefs, Flourens developed the ablation experiment, in which removing any part of the brain in birds led to generalized disorders of behaviour. o All cerebral material is equipotential; that is, if sufficient cortical material is intact, the remaining material will take over the functions of any missing brain tissue. o Flourens suggested that the brain operated in an integrated fashion, not in discrete faculties, and that mental functions depend on the brain functioning as a whole. Thus, the size of the injury, rather than its location, determines the effects of brain injury. Localization versus Equipotentiality Pierre Marie  He challenged Broca’s findings by examining the preserved brains of the patients Broca had used to support his hypothesis of localization.  Marie found that Leborgne had widespread damage, not a specific lesion, as Broca had suggested.  Marie attacked Broca’s theory, indicating that the patient could not speak because the extensive lesion had caused a general loss of intellect, rather than a specific inability to speak. Hermann Munk  He found that experimental lesions in the association cortex of a dog produced temporary mind-blindness: The animal could see objects but failed to recognize their significance. Joseph Babinski  He was the founder of neurology, introduced the term anosognosia, which means “no knowledge of the disease,” to describe an inability or refusal to recognize that one has a particular disease or disorder, thereby introducing the phenomenon of unawareness. Karl Lashley  He was one of the first to combine behavioural sophistication in experiments with neurologic sophistication.  Lashley formulated his famous principle of mass action: The extent of behavioural impairments is directly proportional to the mass of the removed tissue.  Lashley also emphasized the multipotentiality of brain tissue: Each part of the brain participates in more than one function. Integrative Theories of Brain Function Jackson’s Alternative Model  Hughlings Jackson devoted his research to the investigation of epileptic seizures and the study of connections between limb movements and specific areas in the brain.  Jackson observed that higher mental functions are not unitary abilities, but consist of simpler and more basic skills.  He suggested that one does not have a speech centre; rather, one has the ability to combine certain basic skills, such as hearing, discrimination of speech sounds, and fine-motor control of the speech apparatus, to create more complex higher skills.  Thus, the loss of a specific area of the brain causes the loss or impairment of all higher skills dependent on that one area.  Jackson suggested that, behaviour results from interactions among all the areas of the brain.  But Jackson also argued that each area within the nervous system had a specific function that contributed to the overall system. Thus, his views also had a localizationist flavour. Luria’s Functional Model  Luria was responsible for the most profound changes in our approach to understanding the brain and the mind.  Luria conceived each area in the central nervous system as being involved in one of three basic functions, which Luria labelled units.  The first unit, roughly defined as the brainstem and associated areas, regulates the arousal level of the brain and the maintenance of proper muscle tone.  The second unit, including posterior areas of the cortex, plays a key role in the reception, integration, and analysis of sensory information from both the internal and external environments.  The third unit, the frontal and prefrontal lobes, is involved in planning, executing, and verifying behaviour.  Luria formulated the concept of functional systems, which represent the pattern of interaction among the various areas of the brain necessary to complete a behaviour.  Each area in the brain can operate only in conjunction with other areas of the brain.  Furthermore, no area of the brain is singly responsible for any voluntary human behaviour; thus, each area of the brain may play a specific role in many behaviours.  The multifunctional role of the brain is called pluripotentiality; any given area of the brain can be involved in relatively few or many behaviours.  Luria suggested that behaviour results from several functions or systems of brain areas, rather than from unitary or discrete brain areas. Modern Neuropsychology  Clinical neuropsychology originally emerged in the medical setting within traditional neurosurgery and neurology services.  Early research was primarily concerned with the cortical functioning of patients with penetrating missile wounds or the diagnosis of neurologic disorders such as brain tumours or strokes.  In the late 1930s, neuropsychology engaged the interest of only a few neurologists, psychiatrists, and psychologists.  Neuropsychology was loosely organized, and no journals reflected a focused interest in this area. Wilder Penfield  He pioneered direct electrical stimulation of the brain during surgery by systematic mapping of the brain as a technique for finding damaged areas of the brain.  He also used the services of psychologists as consultants to help him with the diagnosis of neurologic behavioural conditions. Halstead-Reitan Neuropsychological Battery  The first neuropsychology laboratory in the United States was founded in 1935 by Ward Halstead at the University of Chicago.  Halstead worked closely with neurosurgery patients and developed assessment devices that differentiated between patients with and without brain damage  Together with Ralph Reitan, Halstead later developed the popular Halstead-Reitan Neuropsychological Battery, an empirical approach to assessing brain damage. Neuropsychology as a Term  The term neuropsychology itself is of recent origin and was most likely first coined by Sir William Osler in 1913, when he used the word in an inaugural address for a new psychiatric clinic at Johns Hopkins Hospital in Baltimore, Maryland.  In 1936, Karl Lashley also used the term when he addressed the Boston Society of Psychiatry and Neurology.  Hans-Leukas Teuber is credited for first using the term in a national forum during a presentation to the American Psychological Association in 1948, during which he described different aspects of brain–behaviour relationships in war veterans with penetrating brain wounds. Donald Hebb  Iin 1949, Canadian Donald Hebb published his classic, The Organization of Behaviour: A Neuropsychological Theory.  Neuropsychology has enjoyed tremendous growth ever since.  The study of neuropsychology has drawn information and knowledge from many disciplines, including anatomy, biology, physiology, biophysics, and even philosophy.   Thus, many interdisciplinary professionals, including neurologists, neuropsychiatrists, linguists, neuroscientists, speech pathologists, and school psychologists, are interested in the field of brain–behaviour relationships and have contributed to its development. Henry Hécaen  He founded the journal Neuropsychologia.  Hécaen made important contributions to brain–behaviour relationships in health and disease.  One of his discoveries was his demonstration of the functional properties of the right hemisphere.  In the 1940s and 1950s, most scientists believed that the left hemisphere dominated the brain, because it plays an important role in the mediation of language.  Hécaen and his co-workers generated an irrefutable mass of evidence that the right, supposedly minor, hemisphere played a crucial role in mediating visuo- perceptual and visuo-constructional processes. Arthur Benton  The U.S. neuropsychologist Arthur Benton continued to explore the role of the right cerebral hemisphere in behaviour  In the 1940s, Benton established one of the first neuropsychology laboratories in the Neurology Department at the University of Iowa School of Medicine.  He also supervised dissertations in the new field of neuropsychology and authored numerous books and neuropsychological testing instruments, including the Benton Visual Retention Test (BVRT). Oliver Zangwill  Oliver Zangwill founded neuropsychology in Great Britain.  Zangwill was also among the first investigators to show that hemispheric specialization for speech in left-handers did not conform to the then accepted rule of right hemisphere dominance.  He also contributed significantly to understanding of the nature of neuropsychological deficits associated with unilateral brain disease or injury. Norman Geshwind  Among his contributions was his proposal that behavioural disturbances are based on the destruction of specific brain pathways that he called disconnections.  Based on his faith that anatomy must play a central role for the description and operation of many complex mental functions, Geschwind set out to prove that the dominance of the left hemisphere for speech must have an anatomic basis. Muriel Lezak  Muriel Lezak is one of several neuropsychologists who pioneered the assessment approach in clinical neuropsychology.  Since the late 1980s, neuropsychological assessment has played a major role in the development of clinical neuropsychology.  Neuropsychological evaluations have become an important procedure, allowing the generation of useful behavioural, cognitive, and clinical information about diagnosis and the impact of a patient’s limitations on educational, social, and vocational adjustment.  In addition to the development of new testing methods to meet special needs in diagnostic evaluation, there has been a steady increase in the use of neuropsychological assessment techniques in neurology and psychiatry and an expansion of their scope of application into other fields such as education, behavioural medicine, and gerontology.  Lezak proposed that neuropsychological testing is clinically relevant and suggested a flexible approach to assessing the individual patient. Emerging Research Areas in Neuropsychology Forensic Neuropsychology  Forensic assessment is one of the fastest growing areas in the field of clinical psychology, with an increasing number of neuropsychologists presenting and/or evaluating assessment results in the courtroom setting.  Neuropsychologists have become increasingly more involved in evaluating the emotional sequelae of injury, custody evaluations, and the complex appraisal of deception and malingering in assessments performed in the forensic domain. Sports Neuropsychology  Much attention has been given to the study of sports-related concussions, and great strides have been made in understanding this health concern, including the cultivation of neuropsychological assessment tools to diagnose concussions and the refinement of recovery curves after injury.  Concussion injuries are now thought of as significant neuropsychological events with real long-term consequences. Law Enforcement, Terrorism, and Military  There is an increased opportunity for the neuropsychology community to conduct behavioural research and consultation in law enforcement, disaster relief, and the armed forces.  Neuropsychologists have expertise that allows them to provide insight into the cognitive operations of terrorism; they can play an important role in using research in the cognitive sciences to assist in understanding the psychology of terrorism and the mindset of terrorists.  Methods of Investigating the Brain Neurohistology Techniques Golgi Stain  One of the most remarkable developments in the neurosciences came with a discovery made by Camillo Golgi.  This remarkable breakthrough allowed, for the first time, visualization of individual neurons.  The Golgi method enabled detailed study of cell process, often allowing a 3-D view of the cell and its processes.  Researchers have even been able to stain single neurons in a Golgi-like fashion and visualize many of the different cells that make up the brain.  Using this method, they found that Purkinje cells reside in the cerebellum and have a remarkably differentiated dendritic tree.  The Golgi method also led to the classification of neurons based on the length of their axon. Nissl Stain  One drawback of the Golgi stain is that it provides little information about the number of neurons in a specific brain region, because it only affects a few neurons.  It also permits a view only of neural tissue in silhouette and does not allow visualization of the inner structure of the neuron.  Franz Nissl discovered that a simple dye will selectively stain cell bodies in neurons.  As a result, researchers adapted several different stains, originally developed for dyeing cloth, for histologic purposes.  Methylene blue is a neural stain that has an affinity for the inner structures of neural cell bodies.  One of the most popular dyes is cresyl violet, a cell body stain that is not selective for neural cell bodies, but stains all central nervous system cells.  Cresyl violet facilitates the differentiation of fibre bundles, which appear lighter, and nuclei, which appear darker. Myelin Staining  Myelin staining selectively dyes the sheaths of myelinated axons.  As a result, white matter, which consists of myelinated axons, is stained black, whereas other areas of the brain that consist primarily of cell bodies and nuclei are not. Horseradish Peroxide  Researchers inject HRP into a region of the nervous system, and surrounding cell bodies and axon terminals take it up.  In neurons that have incorporated HRP, axonal transport carries the enzyme to other interconnected cell bodies, where researchers can detect it with a simple staining procedure.  Using the axonal transport technique, neuroscientists can study the tracing of pathways in the brain. Radiologic Procedure Skull X-Ray  The principle of X-ray technology is the generation of Roentgen rays, electromagnetic vibrations of very short wavelength that can penetrate biological tissue and can be detected on a photographic plate.  Diagnostic X-ray films are useful for clinical work on various parts of the body, because they demonstrate the presence and position of bones, fractures, and foreign bodies.  A clinical disadvantage of X-ray films, specifically of the head, is that they are two-dimensional (2-D). Thus, positive diagnosis of a 3-D clinical pathology is difficult.  Second, an X-ray film of the head shows little differentiation between brain structures and cerebrospinal fluid (CSF), making clinical use of this procedure ineffective, with the exception of large and vascularized brain tumours or massive bleeds.   Furthermore, X-rays are potentially dangerous, because they are cumulatively absorbed by high-density tissue. Air Encephalography  An air encephalogram, or pneumoencephalogram, is the radiographic visualization of the fluid-containing structures of the brain, the ventricles, and spinal column.  It is similar to X-ray visualization, but it involves withdrawing CSF by lumbar puncture; the CSF is then replaced with a gas such as air, oxygen, or helium.  The gas rises and enters the ventricular system, specifically the four interconnecting cavities of the brain.  Once the gas has filled the ventricles, a technician takes a standard X-ray film of the head.  Because the gas is of much lower density than the surrounding brain, the ventricles appear as a dark shadow on the X-ray film and clearly outline the surrounding brain tissue.  Using this approach, a clinician can make a clinical diagnosis.  The air encephalogram represented an advance on the standard X-ray film because it allowed visualization of the ventricular system.  However, patients did not tolerate the procedure well. o Attendants had to turn patients in various positions, often awkwardly, and invert them in 3-D space to advance the gas to a specific ventricle before the technician could take an X-ray film. o Because gas had replaced the CSF, the cushioning aspects of the CSF had been compromised, which often resulted in excruciating headaches that could last for several days before the gas was reabsorbed. Computed Transaxial Tomography  CT scanning was invented in Great Britain in 1971 and introduced to the United States in 1972.  After placing the patient’s head in the centre of the CT scanner, the technician revolves an X-ray source around the head as detectors monitor the intensity of the X-ray beam passed through the brain.   The technician does not take the images at a perfect horizontal perspective of the head. Rather, they slightly tilt the images at a 20-degree angle to avoid scanning the air-containing sinuses.  Multiple sequential images show the ventricles, basal ganglia, thalamus, and cerebral cortex.  Multiple transaxial images of the brain are obtained from many different angles.  The information obtained by the CT scanner is entered into a computer, which then calculates, in 3-D space, cross sections of the brain within the plane of the horizontal Xray beam and the available density information of the brain.  From these data, the computer generates a picture of the brain that can be in any orientation.  Marked asymmetries of brain structures typically signal a pathologic process.  Neuroradiologists also closely examine the scans for sites of abnormal densities, both hypodensity (associated with low density and perhaps an old lesion) and hyperdensity (typically signalling an abnormal density such as a tumour or a bleed). Enhanced CT Scan  The enhanced CT scan, which involves intravenously injecting an iodinated contrast agent, shows more contrast of brain structures.  In the intact cardiovascular system, the contrast agent does not enter the brain because it remains contained in the vascular system.  But if there is a lesion, increased vascularization (as in an arteriovenous malformation or a tumour), or a defect in the blood–brain barrier, that area shows increased contrast. Angiography  Angiography is the roentgenographic visualization (X-raying) of blood vessels in the brain after introducing contrast material into the arterial or venous bloodstream.  Because the blood vessels of the brain reflect the surrounding brain tissue, angiography is a technique based on the X-ray procedure of examining the brain through its vascular system.   Angiography is particularly important in diagnosing structural abnormalities in the blood vessels themselves or in their arrangement.  As a result, angiography has become a useful tool in the early identification of aneurysms.  Femorocerebral angiography o Developed in the mid-1950s, introduces a catheter into the arterial system. o Previously, physicians injected the contrast material directly into an artery, such as the internal carotid artery, but it is safer to insert a catheter via the femoral artery. o The specialist passes the preshaped, semirigid catheter through a needle inserted in the femoral artery, and then guides it up the aorta to the aortic arch with the assistance of X-ray and television monitoring.  Digital subtraction angiography o Compared with conventional film angiography, is particularly effective in enhancing visualization of blood vessels, including the morphologic and physiologic states of the arterial, capillary, and venous phases of the cerebral circulation.  Intravenous angiography o It is somewhat more complicated than femorocerebral angiography; therefore, clinicians do not use it as routinely. o In intravenous angiography, the specialist inserts the catheter in the patient’s arm but must pass it through the heart, then the lungs, and then to the left side of the heart before it reaches the aortic arch. Sodium Amytal Injections (Wada Technique)  The Wada technique, named after its developer, is similar to the angiogram in that the examiner places a catheter, typically in the left or right internal carotid artery.  Then, a barbiturate sodium amytal is injected, which temporarily anesthetizes one hemisphere.  Only one hemisphere is affected, even though vascular structures connect the two hemispheres.   This difference relates to that the pressure gradients along cerebral arteries in both hemispheres are the same; thus, there is no cross-filling (or crossover) of blood from one hemisphere to the other, except if there is a stroke or other damage to the vascular system. Electrophysiologic Procedures Electroencephalography  The electroencephalogram is a recording of the electrical activity of nerve cells of the brain through electrodes attached to various locations on the scalp.  The Austrian psychiatrist Hans Berger first discovered in 1924 that patterns of electrical activity can be recorded using metal electrodes placed on the human head.  To record an EEG, the technician places small metal electrodes, or leads, on the scalp and connects them via wires to the electroencephalograph machine which amplifies the electrical potential of neurons recording their activity on moving paper, a polygraph.  The electrical signal of a neuron must penetrate through different tissues to reach the electrodes, including the meninges, CSF, blood, the skull, and the scalp, to be measured.  The electrical contribution of each neuron is tiny, and it takes many thousands of neurons firing in concert to generate an electrical signal large enough for EEG to detect.  Thus, the most easily visible EEG wave patterns depend on the synchronicity of millions of neurons.  Brain wave activity may differ in polarity, shape, and frequency.  The amplitude typically ranges from 5 to 100 microvolts and is a measure of the signal strength of neural activity.  The EEG records frequency of the waveforms from 1 to 100 Hz.  EEG is a safe, painless, and relatively simple procedure.  Its use in neuropsychology has been disappointing and limited historically by a lack of relationship between EEG parameters and behavior   Seizures and EEG o Groups of neurons can fire in synchronized oscillations by taking cues from other cells, also known as pacemaker cells or k neurons (k for constant). o Cortical neurons also take cues from other brain structures such as the thalamus, which can act as a powerful pacemaker, even when there is no external sensory input. o Seizures are the most extreme form of synchronous brain activity, during which the whole or large portions of the brain fire with a defined and pronounced synchrony that never occurs during normal behaviour. o During seizures, most, if not all, cortical neurons participate in excitation. o Behaviour is disrupted, and often consciousness is lost. o Seizures themselves are best conceptualized as a symptom, not unlike a fever, and may be triggered by dozens of different causes. o In patients with intractable epilepsy, one intervention is neurosurgery to remove, if possible, the precise site or origin of the pathologic electric discharge. o In such cases, a more precise EEG measurement is needed, which can be obtained by placing electrodes directly on the surface of the brain. o This form of EEG, known as electrocorticography (ECoG), often is performed during temporal lobectomy surgery to isolate a precise location of brain pathology.  Clinical Use o The primary referral for a clinical EEG is to help with diagnosis of a seizure disorder, sleep disorder, level of coma, or presence of brain death. o In fact, EEG is the primary tool in diagnosing epilepsy and can often pinpoint the type and location of seizure disorder. o EEG is also useful in diagnosing sleep disorders. Brain Electrical Activity Mapping  BEAM uses computer technology to provide color-coded mapping of the brain’s electrical activity in real time, that is, as quickly as it is occurring in the patient’s brain.  In general, BEAM is nothing more than a way of enhancing the amount of information available on a standard EEG.   Using an automated, integrated approach to EEG, the computer can calculate color-coded maps of electrical brain activity  Then it codes computed EEG parameters as topographic displays showing neuroelectric activity across the cortex while the patient is performing a neuropsychological task.  BEAM is much more sensitive to electrical correlates of cognitive tasks than the traditional EEG. Evoked Potential  EP involves artificial stimulation of sensory fibres that, in turn, generate electrical activity along the central and peripheral pathways, as well as the specific primary receptive areas in the brain.  In EP, a computer makes it possible to visualize the changes in EEG responses to a specific stimulus cancelling out random electrical activity, but displaying electrical activity related to the potential evoked by the stimulus.  In brainstem auditory-evoked response (BAER), the examiner presents clicks to each ear of the patient individually via headphones.  In visual-evoked response (VER), the examiner presents a visual stimulus separately to each eye of the patient.  In somatosensory-evoked response (SER), the examiner stimulates peripheral nerves via an electrode placed over the median nerve at the patient’s wrist. Electrical Stimulus  Researchers have used electrical stimulation of nerve tissue to empirically map pathways of the cortex.  More recently, clinicians have introduced electrical stimulation in the treatment of Parkinson’s disease.  Direct electrical stimulation of the brain, an invasive medical procedure, is used only in those cases for whom other interventions or diagnostic procedures have not succeeded. Electromyography  Electromyography (EMG) is the electrical analysis of muscles.  In EMG, diagnosticians perform a nerve conduction study of a specific muscle to diagnose neuromuscular disorders.  Patients undergoing EMG receive deep needle stimulation of a muscle, which the technician measures electro-physiologically ventral to the stimulation. Imaging of Brain Metabolism Regional Cerebral Blood Flow  Blood flow in the cerebral hemispheres varies with metabolism and activity.  It can be a sensitive index of the changes in cellular activity in response to cognitive tasks.  The amount of blood flowing through different regions of the brain can indicate the relative neural activity of that region. Single Photon Emission Computed Tomography  A technique for the 3-D imaging of rCBF is single-photon emission computed tomography (SPECT).  SPECT is similar to PET, which uses radionuclides, but unlike positron emission, SPECT does not require an expensive cyclotron.  Using SPECT, it is possible to three-dimensionally image the distribution of a radioactively labelled contrast agent. Positron Emission Tomography  Emission tomography is a new visualization technique that detects a diverse range of physiologic parameters, including glucose and oxygen metabolism, in addition to blood flow, by distributing a radioactively labelled substance in any desired cross section of the head.  The method of PET technology is intravenous injection of a radioactive tracer (specifically positron-emitting substances) and subsequent scanning of the brain for radioactivity.   In the PET procedure, technicians administer radionuclides intravenously that the subject’s brain tissue takes up.  The radio nuclei are unstable, because they have an excess positive charge.  When the radioactive tracer decays, it emits a positron that then travels a short distance before colliding with an electron.  This collision results in the emission of two photons traveling in opposite directions, generating energy that detectors around the scalp can measure.  When two detectors calculate photon absorption at the same approximate time, the computer assumes they originate from the same collision and can then calculate the exact position showing neural “hotspots.”  PET functions by calculating millions of counts from detectors and estimating their origin.  A major finding using PET technology is that metabolic activity is suppressed in patients with a history of head trauma, brain tumours, and stroke, even though structural representation of the brain, using MRI or CT, suggests intact brain anatomy. Magnetic Imaging Procedures Magnetic Resonance Imaging  Magnetic resonance imaging (MRI) is based on the work of Felix Bloch and Edward Purcell.  MRI is based on the hydrogen nucleus, which is present in high concentration in biological systems, generates alterations in a small magnetic field, which can be measured.  When the head is subjected to a strong magnetic field, hydrogen protons magnetize and align in the direction of the magnetic field.  A strong radiofrequency (RF) signal applied at a right angle to the magnetic field can alter the alignment of the hydrogen protons.  The principle of MRI is that the hydrogen atom resonates as a result of the combined effect of the radio waves and the magnetic field.  MRI has become an important diagnostic tool for detecting disease processes.  This usefulness is related to that MRI is sensitive to tissue alteration, including those seen in diseases associated with demyelination (such as multiple sclerosis), haemorrhage (bleeding), and tumour. Functional Magnetic Resonance Imaging  The data from functional MRI (fMRI) can then be superimposed over the structural MRI for a precise mapping of structure and function.  This combined use of MRI and fMRI may revolutionize the study of the activated brain, because it can provide almost continuous real-time data on cerebral activity. Magnetoencephalography  MEG involves measurement of changes in magnetic fields that are generated by underlying electrical activity of active neurons.  Neuronal activity generates not only electrical fields but also magnetic fields.  When neurons fire, the magnetic changes resulting from the electrical fields, which reflect neural activity, can be measured.  Recording the magnetic fields that accompany the electrical activity of neurons is known as MEG.  MEG is the magnetic equivalent of EEG.  Ethical Issues in Research Study Design  According to COPE, good research should be well adjusted, well-planned, appropriately designed, and ethically approved.  To conduct research to a lower standard may constitute misconduct.  To achieve this, a research protocol should be developed and adhered to.  It must be carefully agreed to by all contributors and collaborators, and the precise roles of each team member should be spelled out early, including matters of authorship and publications.  Research should seek to answer specific questions, rather than just collect data.  It is essential to obtain approval from the Institutional Review Board, or Ethics Committee, of the respective organisations for studies involving people, medical records, and anonymised human tissues. Data Analysis  It is the responsibility of the researcher to analyse the data appropriately.  Although inappropriate analysis does not necessarily amount to misconduct, intentional omission of result may cause misinterpretation and mislead the readers.  Fabrication and falsification of data do constitute misconduct.  To ensure appropriate data analysis, all sources and methods used to obtain and analyse data should be fully disclosed.  Failure to do so may lead the readers to misinterpret the results without considering possibility of the study being underpowered. Authorship  It is generally agreed that an author should have made substantial contribution to the intellectual content, including conceptualising and designing the study; acquiring, analysing and interpreting the data.   The author should also take responsibility to certify that the manuscript represents valid work and take public responsibility for the work.  Finally, an author is usually involved in drafting or revising the manuscript, as well as approving the submitted manuscript.  Data collection, editing of grammar and language, and other routine works by itself, do not deserve an authorship. Conflict of Interest  This happens when researchers have interests that are not fully apparent and that may influence their judgments on what is published.  These conflicts include personal, commercial, political, academic or financial interest.  Financial interests may include employment, research funding, stock or share ownership, payment for lecture or travel, consultancies and company support for staff.  This issue is especially pertinent in biomedical research where a substantial number of clinical trials are funded by pharmaceutical company. Redundant Publication and Plagiarism  Redundant publication occurs when two or more papers, without full cross reference, share the same hypothesis, data, discussion points, or conclusions.  However, previous publication of an abstract during the proceedings of meetings does not preclude subsequent submission for publication, but full disclosure should be made at the time of submission.  This is also known as self-plagiarism.  In the increasing competitive environment where appointments, promotions and grant applications are strongly influenced by publication record, researchers are under intense pressure to publish, and a growing minority is seeking to bump up their CV through dishonest means.