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Zachariah Campbell

Chapter 1: The Development of Neuropsychology Traumatic Brain Injury (TBI) – a wound to the brain that results from a blow to the head.  LD’s case where his trauma was helped with TBI but there were still residual problems Neuropsychology – the study of the relation between behavior and brain function.  2 investigations: o The Brain Hypothesis – the idea that the brain is the source of behavior o The Neuron Hypothesis – the idea that the unit of brain structure and function is the neuron, or nerve cell. The Brain Hypothesis What Is the Brain? Brain – Old English word for the tissue found within the skull. It has symmetrical halves called hemispheres, one on the left side of the body and the other on the right. Cerebrospinal Fluid (CSF) – a tube filled with salty fluid called that cushions the brain and may play a role in removing metabolic waste. Parts of the covering of the tube have bulged outward and folded  Cerebral Cortex – the crinkled tissue (of the CSF tube) that has expanded from the front of the tube to such an extent that it folds over and covers much of the rest of the brain forming an outer layer.  Cortex = “bark” in Latin  Gyri – the folds of the cortex, Gyrus = “circle” in Greek  Sulci – the creases between the Gyri, Sulcus = “trench” in Greek o Fissures – some large sulci  longitudinal fissure – divides the two hemispheres  lateral fissure – divides each hemisphere into halves. The cortex of each hemisphere is divided into 4 lobes: 1. The Temporal Lobe – Area of the cortex found laterally on the head, below the lateral sulci adjacent to the temporal bones. 2. The Frontal Lobe – above the temporal lobe, at the front of the brain. 3. The Parietal Lobe – behind the frontal lobe 4. The Occipital Lobe – area at the back of each hemisphere. Commissures – the brain’s hemispheres are connected by these pathways, the largest of which is the corpus callosum. The cerebral cortex constitutes most of the Forebrain - it develops from the front part of the tube that makes up an embryo’s primitive brain.  It mediates cognitive functions Brainstem - the remaining “ tube” underlying the cortex. It is connected to the spinal cord, which descends down the back in the vertebral column.  Brainstem mediates regulatory functions such as eating, drinking, and moving  Spinal cord is responsible for sending commands to the muscles. To visualize the relations among these parts of the brain, again imagine your upraised fist: the folded fingers represent the cortex, the heel of the hand represents the brainstem, and the arm rep-resents the spinal cord. How is the Brain Related to the Rest of the Nervous System? Central Nervous System (CNS) – the brain and spinal cord. It is connected to the rest of the body through nerve fibres. This DOES NOT regenerate after damage. Peripheral Nervous System (PNS) - Some nerve fibres carry information away from the CNS, and others bring information to it. This DOES regenerate after damage.  Somatic & Autonomic Nervous System Sensory Pathways – collections of fibres carry messages for specific sensory systems, such as hearing, vision, and touch.  Somatic Nervous System – subdivision of the PNS that carry information collected on one side of the body mainly to the cortex in the opposite hemisphere. o The brain uses this information to construct its current images of the world, its memories of past events, and its expectations about the future. Motor Pathways – the groups of nerve fibres that connect the brain and spinal cord to the body’s muscles through the SNS.  Eg. Eye movements, hand movements and the posture of your body. Sensory and motor pathways also influence the Autonomic Nervous System – subdivision of PNS; The part of the nervous system that controls the functions of all the parts of the body, with the exception of the skeletal muscles, so that the body and its organs are prepared for rest or for vigorous activity.  Specifically: organs muscles of your internal organs, the contractions of your stomach, and the raising and lowering of your diaphragm. The Brain Versus the Heart Alcmaeon of Croton & Empedocles of Acragas: Alcmaeon located mental processes in the brain  brain hypothesis; Empedocles located them in the heart  cardiac hypothesis. Hippocrates & Galen: argues strongly for the brain hypothesis. Galen noted the behavioural conseuqences of TBI and saw that brain damage caused impairments not the heart. Cardiac hypothesis left its mark in our language Eg. love is in the heart Aristotle: The Mind Aristotle: the first person to develop a formal theory of behaviour. He proposed that a nonmaterial psyche was responsible for human thoughts, perceptions, and emotions and for such processes as imagination, opinion, desire, pleasure, pain, memory, and reason. The psyche was independent of the body but worked through the heart to produce action  Christianity’s concept of the soul Mentalism - the philosophical position that a person’s mind is responsible for behaviour, “ of the mind.”  The brain was thought to work as a whole, but this argues for different parts of the brain having different functions. Descartes: The Mind-Body Problem René Descartes: described a relation between the mind and the brain. Described as nonmaterial and without spatial extent, the mind, it was different from the body. The body operated on principles similar to those of a machine, but the mind decided what movements the machine should make.  Located the site of action of the mind in the pineal body – a small structure high in the brainstem – because it’s the only structure in the nervous system not composed of two bilaterally symmetrical halves and it is located close to the ventricles. The cortex was just a covering. The mind, working through the pineal body, controlled valves that allowed CSF to flow from the ventricles through nerves to muscles, filling them and making them move.  Today when the pineal body is damaged, no real changes in behaviour.  Animals do not have minds and are machinelike  justified inhumane treatment Dualism – the position that mind and body are separate but can interact Mind–Body Problem – for Descartes, a person is capable of being conscious and rational only because of having a mind, but how can a nonmaterial mind produce movements in a material body?  In order for the mind to affect the body, it would have to expend energy, adding new energy to the material world. The spontaneous creation of new energy violates a fundamental law of physics, the law of conservation of matter and energy.  No real support for dualists, so they say the mind and body are parallel not interacting or the body can affect the mind and the mind cannot affect the body. Monists – avoid the mind– body problem saying the mind and body are simply a unitary whole. Darwin and Materialism Alfred Russell Wallace and Charles Darwin: Materialism – the idea that rational behaviour can be fully explained by the working of the nervous system without any need to refer to a nonmaterial mind. Darwin: all living things are said to have Common Descent - as the descendants of that original organism spread into various habitats through millions of years, they developed structural and behavioural adaptations that suited them for new ways of life, while retaining many similar characteristics that reveal their relatedness to one another.  Eg. Nervous system is a common characteristic emerging from one animal evolution The idea that the brain is responsible for behaviour is rejected by religions but the two can correlate. Experimental Approached to Brain Function Localization of Function Franz Joseph Gall & Johann Casper Spurzheim: The first general theory to present the idea that different parts of the brain have different functions. They proposed that the cortex and its gyri were functioning parts of the brain and not just coverings for the pineal body. They showed the brain’s most distinctive motor pathway, the corticospinal (cortex to spinal cord) tract, leads from the cortex of each hemisphere to the spinal cord on the opposite side of the body; the cortex sends instructions to the spinal cord to command movement of the muscles. Gall: The brain might produce differences in individual abilities into a theory called localization of function. Eg. a well- developed memory area of the cortex located behind the eyes would cause the eyes to protrude; the frontal lobes are the seat of intelligence. They also studied phrenology: bump on the skull indicated a well-developed underlying cortical gyrus and therefore a greater capacity for a particular behavior; a depression in the same area indicated an underdeveloped gyrus and a concomitantly reduced faculty. Spurzheim: Named it Phrenology - the study of the relation between the skull’s surface features and a person’s faculties. Phrenological Map – the map of the relation between brain functions and the skull surface. Gall: First complete account of a case in which left-frontal-lobe brain damage was followed by loss of the ability to speak. Phrenology was used to make specific personality assessments.  Cranioscopy – a device was placed around the skull to measure the bumps and depressions there. o Measures are correlated with the phrenological map to determine behavioural traits. Characteristics are impossible to define and to quantify objectively. The outer skull does not mirror even the inner skull, much less the surface features of the cortex. However, Gall’s concept was the foundation for modern views of localization of function. Localization and Lateralization of Language Bouillaud: Certain functions are localized in the cortex and, specifically, that speech is localized in the frontal lobes, specifically in the left hemisphere, in accordance with Gall’s theory. Dax: disorders of speech were associated with damage in the left hemisphere Auburtin: a patient who lost the ability to speak when pressure was applied to his ex- posed frontal lobe Broca: Auburtin was correct: the left frontal lobe was the focus of Tan’s lesion. He located speech in the third convolution (gyrus) of the frontal lobe on the left side of the brain. He demonstrated that language was localized; thus different regions of the cortex could have specialized functions. Because speech is thought to be central to human consciousness, the left hemisphere is the dominant hemisphere.  Lateralization - functions could be localized to a side of the brain.  Broca’s Area – the anterior speech region of the brain  Broca’s Aphasia – syndrome that results from damage in Broca’s Area. Sequential Programming and Disconnection Strict Localizationists – people who interpreted Broca’s findings as evidence that language resides totally in one part of the brain Wernicke:  auditory cortex – part of the cortex that receives the sensory pathway, or projection, from the ear – Is located in the temporal lobe, behind Broca’s area  against strict localizationists. A relation between the functioning of hearing and that of speech, and he described cases in which aphasic patients had lesions in this auditory projection area that differed from those described by Broca in four ways: i. Damage was evident in the first temporal gyrus. ii. No opposite- side paralysis was observed (Broca’s aphasia is frequently associated with paralysis of the right arm and leg, as described for Tan). iii. Patients could speak fluently, but whatthey said was confused and made little sense (Broca’s patients could not articulate, but they seemed to understand the meaning of words). iv. Although the patients were able to hear, they could neither understand nor repeat what was said to them.  Wernicke’s aphasia is sometimes called temporal-lobe aphasia or fluent aphasia.  Wernicke’s Area – the region of the temporal lobe associated with this form of aphasia.  He proposed that auditory information travels to the temporal lobes from the ears. o In Wernicke’s area, sounds are processed into auditory images/ideas of objects and stored. o From Wernicke’s area, auditory ideas can be sent through a pathway called the arcuate fasciculus leading to Broca’s area, where the representations of speech movements are stored. o From Broca’s area, neural instructions are sent to muscles that control movements of the mouth to produce the appropriate sounds.  If the temporal lobe were damaged, speech movements could still be mediated by Broca’s area but the speech would make no sense, because the person would be unable to monitor words. Because damage to Broca’s area produces a loss of speech movements without the loss of sound images, Broca’s aphasia is not accompanied by a loss of understanding.  He predicted Conduction Aphasia – A speech deficit that occurs if the arcuate fibers connecting the two speech areas were cut, disconnecting the areas but without inflicting damage on either one. o Speech sounds and movements and comprehension retains, but speech is still impaired because the person cannot judge the sense of the words that he or she heard. Joseph Dejerine: described a case in which th
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