Chapter 3: Neuropsychology PDF

# Nervous System Organization ## 3. Nervous System Organization ### 3.1 Neuroanatomy: Finding Your Way Around the Brain - Knowledge about the orderly arrangement of neurons and their connections aids neuro-psychologists' effort to understand brain function. - There are three reference frames:...

# Nervous System Organization ## 3. Nervous System Organization ### 3.1 Neuroanatomy: Finding Your Way Around the Brain - Knowledge about the orderly arrangement of neurons and their connections aids neuro-psychologists' effort to understand brain function. - There are three reference frames: - with respect to other body parts of the animal - with respect to relative location - with respect to a viewer's perspective. - Structures that lie on the same side of the body are ipsilateral. - If they lie on opposite sides, they are contralateral to each other. - Structures close to one another are proximal. - Those far from one another are distal. - Any movement toward a brain structure is afferent; whereas movement away from it is efferent. ### 3.2 Overview of Nervous System Structure and Function - From an anatomical standpoint, the central nervous system (CNS) consists of the brain and the spinal cord. - The peripheral nervous system (PNS) encompasses everything else. - The somatic (body) nervous system (SNS) consists of two sets of inputs and outputs to the CNS: - the spinal and cranial nerves to and from the sensory organs and the muscles, joints, and skin. - The autonomic (automatic) nervous system (ANS) controls the functioning of the body's internal organs. ### 3.3 Origin and Development of the Central Nervous System - The brain begins as a tube. - The front end of the tube begins to enlarge, eventually producing a three-part structure. - As the tube develops, five regions are recognizable. - The primitive developing brain's three regions are recognizable as a series of enlargements at the end of the embryonic spinal cord. - The anterior prosencephalon develops further to form the cerebral hemispheres. - The posterior prosencephalon, referred to as the diencephalon, includes the thalamus. - Behind the mesencephalon, the rhombencephalon also develops further, subdividing into the metencephalon and the myelencephalon. ### 3.4 The Spinal Cord - The spinal cord communicates with the body through posterior (dorsal) roots, which are sensory, and anterior (ventral) roots, which are motor. - The spinal cord is also divided into segments, each representing a dermatome, or body segment. - The cranial and spinal nerves of the somatic nervous system carry afferent sensory input to the CNS and transmit efferent motor output from the brain to the body. - The autonomic nervous system acts via ganglia either to activate (sympathetic nerves) or to inhibit (parasympathetic nerves) the body's internal organs. ### 3.5 The Brainstem - The brainstem begins where the spinal cord enters the skull and extends upward into the lower areas of the forebrain. - The brainstem core consists of those cranial-nerve nuclei and other nuclei that mediate a variety of regulatory functions. - The most distinctive hindbrain structure is the cerebellum. ### 3.6 The Telencephalon - There are three main telencephalic structures: - the neocortex - the basal ganglia - the limbic system - The basal ganglia ("lower knots,” referring to "knots below the cortex") are a collection of nuclei that form a circuit with the cortex. The ganglia include the putamen, the globus pallidus, and the caudate nucleus. - The basal ganglia perform three main functions: - They connect sensory regions of the cortex to motor regions of the cortex - They regulate movement so that it is fluid - They are involved in associative learning. - Much of what is known about the function of the basal ganglia comes from studying two general kinds of diseases that occur after the ganglia are damaged. These diseases are characterized either by a general loss of movement or by exaggerated movements. - They are not disorders of producing movements, as in paralysis. They are disorders of controlling movements. - Huntington disease is a genetic disorder. - The substantia nigra projections to the forebrain are also important for placing value on things that are rewarding to us and for acquiring both good and bad habits. ### 3.7 The Crossed Brain - Each cortical hemisphere tends to respond to sensory stimulation on the side opposite that hemisphere and produce movements on the opposite side of the body. - Visual pathways ensure that input from each eye travels to the opposite hemisphere. - The brain's anatomy is organized but complex, and the names of its many structures provide a wonderland of nomenclature that reflects the rich history behind efforts to describe the brain and determine the functions of its parts. - The brain is protected by the skull and by the cushioning meninges. A blood-brain barrier excludes many substances from entry into the CNS as well. - The brain's blood supply flows from the internal carotid arteries and the vertebral arteries to distribute blood to specific brain regions through the anterior, middle, and posterior cerebral arteries. - The brain is composed of neurons and glial cells, each present in many forms. - The brain is organized into regions, layers, nuclei, and tracts, with regions, layers, and nuclei appearing gray and tracts appearing white on visual inspection. - The nervous systems of all animals are built on a common plan. - The developing CNS first consists of three divisions surrounding a canal filled with cerebrospinal fluid. - The increased size and complexity of the first and third divisions produce a brain consisting of five separate divisions. # Key Terms * afferent, p. 52 * amygdala, p. 69 * anterior cerebral artery (ACA), p. 55 * anterior root, p. 60 * astroglia, p. 57 * basal ganglia, p. 68 * Bell–Magendie law, p. 61 * bilateral, p. 52 * bipolar neuron, p. 56 * blasts, p. 56 * Brodmann’s map, p. 73 * blood–brain barrier, p. 55 * central sulcus, p. 70 * cerebellum, p. 65 * cerebral aqueduct, p. 59 * cingulate cortex, p. 69 * connectome, p. 75 * contralateral, p. 52 * cranial nerves, p. 62 * cytoarchitectonic maps, p. 73 * decussations, p. 77 * dermatome, p. 60 * diencephalon, p. 58 * distal, p. 52 * efferent, p. 52 * ependymal cells, p. 57 * epithalamus, p. 67 * extension, p. 62 * FACT analysis, p. 76 * flexion, p. 62 * folia, p. 65 * ganglia, p. 58 * gray matter, p. 57 * hemorrhagic strike, p. 50 * hippocampus, p. 69 * homotopic, p. 75 * hydrocephalus, p. 55 * hypothalamus, p. 67 * inferior colliculi, p. 66 * interneurons, p. 56 * ipsilateral, p. 52 * ischemia, p. 50 * limbic system, p. 69 * meninges, p. 54 * mesencephalon, p. 58 * metencephalon, p. 59 * microglia, p. 57 * middle cerebral artery (MCA), p. 55 * motor neurons, p. 57 * myelencephalon, p. 59 * myelin, p. 57 * neocortex, p. 69 * nerves, p. 58 * neural stem cell, p. 56 * nuclei, p. 51 * oligodendroglia, p. 57 * paraplegic, p. 61 * parasympathetic (calming) nerves, p. 53 * periacqueducta gray matter (PAG), p. 66 * posterior cerebral artery (PCA), p. 55 * posterior root, p. 60 * precentral gyrus, p. 53 * progenitor cells, p. 56 * projection map, p. 71 * prosencephalon, p. 58 * proximal, p. 52 * quadriplegic, p. 61 * referred pain, p. 65 * reflexes, p. 62 * reticular formation, p. 66 * reticular matter, p. 57 * rhombencephalon, p. 58 * Schwann cells, p. 57 * secondary areas, p. 72 * sensory receptor, p. 56 * somatosensory neuron, p. 56 * stroke, p. 50 * substantia nigra, p. 66 * superior colliculi, p. 66 * sympathetic (arousing) nerves, p. 53 * tectum, p. 66 * tegmentum, p. 66 * telencephalon, p. 58 * tertiary (association) areas, p. 72 * thalamus p. 67 * tissue plasminogen activator (t-PA), p. 50 * tracts, p. 51 * ventricles, p. 59 * white matter, p. 57