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Alison Fleming

PSY290 9/18/2012 12:44:00 PM LEVELS OF EXPLANATION: Example: Why does a songbird sing in the spring?
 • Because it learned the song during development from adult males (Developmental)
 • Because it has rising levels of T (PROXimal explanation) • Because it ‗wants‘ to mate (FUNCTional) • Because during its species evolution those that did not sing did not reproduce (EVOLutionary/SELECTional) FOCUS: How the Nervous and Endocrine Systems affect Behavior  Nervous system CNS-central nervous system: brain and spinal cord PNS-peripheral nervous system: somatic and autonomic: sensory and motor nerves going to and from the CNS  Endocrine system: different secretory glands: pituitary, adrenal, gonads, thyroid,  Behavior: Perception-see, hear, smell, touch, Movement-run, walk, write, talk, sing, think Motivation- eating, drinking, sexual, maternal Cognition-learning, memory, consciousness September 17, 2012 Functional Neuroanatomy Why Are We Interested in Neuroanatomy? • Structure and function are two sides of the same coin • An object‘s structure imposes physical constraints on its function • Neuroanatomy is best understood within a conceptual framework of the structure-function relationship Neuroanatomy - study of the nervous system‘s structure • Many levels of description • Gross neuroanatomy - general structures and connections visible to the naked eye • Fine neuroanatomy – (microscopic) organization of neurons and their connections Evolution of the Nervous system • Properties of the nervous system: irritability (sensory) , conductivity (within central), contractability (motor) • With evolution of ns there has occurred increasing – Division of labor within ns so different parts play different roles – Centralization of control, so is development of integration within central area – Encephalization or anteriorization at ‗head‘ end Main divisions of brain and overall organization the same among all vertebrates Main differences are in the relative sizes of divisions
 Sizes of divisions dependent on function in life of animal-  eg. Although lamphrey fish has spinal cord, hindbrain, midbrain, diencephalon and telencephalon...has large paired optic lobes in midbrain –visiion is important; frog has large optic tectum,etc. Protozoa (single cell)-amoeba, paramecium: behavior and motor: movement, avoidance by pseudopodia sensory: responds to gravity,temperature, contact, chemicals; has ‗eyespots‘ With evolution and pressures of predation, pressure for more rapid communication and specialization Metazoa Coelenterate:hydra, sea anemone (nerve net)  Behavior and motor: detects prey, shoots poisionous threads, pulls victim into ‗mouth‘, moves along by tumbling, etc. with contractile fibers around body, vertical,horizontal,diagonal  Conductile: nerve net- epidermis, gastrodermis, mesodermis  Sensory: responds to touch,chemicals,vibrations Epidermis outer layer, with sensory receptors; Interstitial nerves fibers between sensory and motor-nerve nets; responsive to touch-turn away, virbrations-contraction; light-avboids extreme; temperature-seeks colder; chemicals-negative responsiveness Flatworm (platyhelminthes) NS. Bilateral symmetry, 2 anterior ganglia, 2 ventral nerve cords; Behavior, motor- layer of muscles fibers: glides, folds, withdraws, approaches Conductile: two nerve cords, anterior ganglia, Sensory-receptors over body, eyespots and responds to touch (withdraw), light (withdraws) vibration (contracts), temperature (towards) Arthropods and Annelids Annelids- segmented worms with NS: two ventral nerve cords fused into one central nerve cord, with ganglia at each segment, repetition of segmentation Motor and locomotion: cicular, longitudinal, and oblique fibers-to constrict and lengthen, shorten and turn. Able to glide, turn, fold, etc. Conductile: 2 ganglia at head end, connects in anterior direction to two ‗eyes‘ and in posterior direction with longitudinal nerve cord Sensory: chemoreceptors all over body; responds to light with puigment cups in anterior end and receptors on body surface respon to light; has touch receptors on sides of body, etc. • Across mammals, differences in brains are mainly quantitative...same subdivisions • Comparison of rat (2g) and human brain( 1400g) but in each case is 2% of total b.w.; but cerebral hemispheres a much larger proportion of brain in humand than in rats • Size of different structures dependent on function-bats locate prey by echolocation, have larger inferior colliculus; bats that locate prey by vision, have larger superior colliculus. • The neuron doctrine – the idea that the nervous system is composed of discrete, autonomous units, or neurons, that can interact but are not physically connected Building Blocks - Neurons 1. Dendrites (input) 2. Cell body (integration) 3. Axon (conduction) 4. Axon terminal (output) Building Blocks – Neurons...they vary according to shape, size and function Glial Cells – The other building blocks The Nervous System major divisions 1. The Central Nervous System (CNS) a) The Brain b) The Spinal Cord 3. The Peripheral Nervous System (PNS) a) the cranial nerves b) the spinal nerves c) the autonomic nervous system The Peripheral Nervous System (PNS) 1. The Cranial Nerves  Nerves pass through small openings in the skull to enter & leave the brain o Known by name & Roman numeral  I, II, & VIII: Sensory pathways to the brain  III, IV, VI, XI, XII: Motor pathways from the brain
  Remaining are both sensory & motor: – V: trigeminal, serves facial sensations, chewing movements – VII: facial, facial muscles & taste sensation – IX: glossopharyngeal, receive sensations 
 from throat & controls muscles there – X: vagus, runs to heart, liver & intestines The Spinal nerves  Made up of a serious of small bones called vertebral  Sensation (input) and motor control (output) – reflexes at the spinal level  Some parts of body do not have motor control (reflex) • The spinal column is made up of a series of small bones called vertebrae • Segments of our bodies correspond to segments of the spinal cord • 4 groups (31 in total) • Peripheral nerves • Bell-Megendie Law – the dorsal roots of the spinal cord are sensory and the ventral roots of the spinal cord are motor The Autonomic Nervous System • Spans both CNS & PNS • Autonomic neurons within the CNS send out axons to innervate 
 neurons in the ganglia - known as preganglionic autonomic cells • These neurons in turn send their axons out to innervate all the major organs – known as postganglionic autonomic cells 
 • • There are 3 division: 1. Sympathetic NS: • prepares the body for action: blood pressure increases, pupils dilate, heart quickens etc. 3. Parasympathetic NS:
 • acts in opposition to the sympathetic nervous system: decrease blood pressure, decrease heart rate etc. 5. Enteric NS:
 • System of neurons that governs the functions of the gut. The Brain - CNS • Nucleus–a large well – defined group of cell bodies
 • Tract or path–a large collection of axons projecting to or away from a nucleus or layer • Nerves–tracts that enter or leave the central nervous system The Brain – Orientation and Terms • Ipsilateral
 • Contralateral • Distal
 • Proximal
 • Afferent
 • Efferent DORSAL VIEW VENTRAL VIEW LATERAL VIEW MEDIAL VIEW • Planes into which brain can be sectioned – Sagittal-divides brain into right and left – Coronal,frontal, transverse-cut brain into front and back – Horizontal-cuts brain into upper and lower The Brain - Meninges • Meninges – protective sheath around the brain and the spinal cord: dura matter, arachnoid layer and pia matter • Meningitis – inflammation of the meninges due to viral or bacterial infection Outline: Brain: major divisions • Ventricles • Hindbrain • Midbrain • Forebrain 
 – Diencephalon-thalamus, hypothalamus 
 – Telencephalon-basal ganglia, limbic system. Cortex 
 • Subdivisions, lobes of cortex The Hind Brain (Rhombencephalon) 1. Myelencephalon (spinal brain) -medulla oblongata (cranial nerves nuclei), reticular formation 2. Metencephalon (across-brain) -cerebellum, pons, reticular formation The Hind Brain Myelencephalon - Medulla • Manycellbodiesofthe 12 cranial nerves reside here • Motorfiberscrossover • Vitalfunctions(e.g., breathing, heart rate) HINDBRAIN • PONS  Pons is a ―bridge‖ between the brain and the cerebellum as well as sensory inputs (vestibular functions, eye movements, auditory info etc). • CEREBELLUM
 • Balance and fine motor movement • Learning and cognition • MEDULLA
 2. Tectum (roof) -superior colliculus-visual
 - inferior colliculus-auditory • TEGMENTUM
 1. Tegmentum (floor)
 - Reticular system (arousal, attention) - Locus of different nuclear groups that synthesizes neurotransmitters • RETICULAR FORMATION The Forebrain (Prosencephalon) 1. Diencephalon (―between brain‖) • Thalamus(―innerchamber‖)
 o Sensoryrelaynuclei(auditory,somatosensory,visual) o Motorrelaynuclei(fromcerebellumandglobuspallidus to motor cortex) o Associationnuclei(betweenassociationareasofcortex, limbic relay nuclei- from hypothalamus to cingulate) • Hypothalamus(―lowerchamber‖) o Approximately 22 nuclei o 0.3% of brain weight yet it is involved in nearly all aspects of motivated behaviour / homeostasis o Feeding, sleeping, sexual behavior, temperature 
 regulation, emotional behavior, maternal behavior, endocrine function o Pituitary gland 2. Telencephalon (―end brain) 1. Cortex
  The Neocortex or Cortex  Higher cognitive functions: planning, attention, memories, language etc.  Gyrus– the protruding rounded surface  Sulcus– the enfolded regions that appear as lines and creases (fissure)  80%ofbrainvolume  2500cm2  Thickness1.5-3.0mm 2. Basal Ganglia  1. Globus pallidus  2. Putamen  3. Caudate nucleus  4. + Substatntia nigra  Supports muscular activity, posture, balance, locomotion, starting and stopping movement 3. Limbic system  Hippocampus  Amygdala  Cingulate  Mammillarybodies  OlfactoryBulb  Hypothalamus  Regulationofemotionand memory Projection Map  Projection map – made by tracing axons from the sensory systems into the brain and from the neocortex to the motor systems in the brain stem and spinal cord  Primary projection areas – areas that first receive a connection from another system  Secondary projection areas – areas that receive inputs from primary areas (thought to be involved in more complex sensory or perceptual or motor functions)  Tertiary areas – areas that lie between the various secondary areas (sometimes referred to as association areas – complex functions such as language, planning, attention and memory) Functional Maps – Wilder Penfield • Mapsoffunctionsmappedout on the cortex • BestknowisPenfield‘smapof motor and sensory cortex • Thesemapsareplastic–they can change in response to experience – decreased or increased use • Monkeyswithtwofingers connected • Severedfingers • Trainingthatrequiresincreased use of particular fingers Cortical Columns, Spots and Stripes Cortical Column • Hypothetical unit of cortical organization • Believed to represent a vertically organized intracortical connectivity that is assumed to correspond to a single functional unit Functional Organization of the Cortex • Alexander Luria–divided cortex into two functional units: • Posterior cortex is the sensory unit (receives sensations, processes them and stores them as information) • Anterior cortex is the motor unit(it formulates intentions, organizes them into programs of action, and executes the programs) • Withineachthereisa3layer hierarchy: primary, secondary and tertiary cortex • Tertiary areas–formulation • Secondary areas–elaboration • Primary areas-execution The Functional Organization of the Brain • Principle 1: The Sequence of Brain Processing Is ―In Integrate Out‖ • Principle 2: Sensory and Motor Divisions Exist Throughout the Nervous 
 System • Principle 3: The Brain‘s Circuits Are Crossed • Principle 4: The Brain Is Both Symmetrical and Asymmetrical • Principle 5: The Nervous System Works Through Excitation and Inhibition • Principle 6: The Central Nervous System Has Multiple Levels of Function • Principle 7: Brain Systems Are Organized Both Hierarchically and in Parallel • Principle 8: Functions in the Brain Are Both Localized and Distributed September 24, 2012 – Lecture 3 My ta email: Ashlyn Swift – [email protected] Never Impulse, Action Potential and Synaptic transmission There are many different Types of neurons in the Nervous System: 1. Sensory neurons – receptors In the skin, in the retina, and muscle, they carry information to central nervous system 2. Interneurons – associate sensory and motor activity in te central nervous system 3. Motor neurons – help to move, send signals from the brain and spinal cord to muscles Glial cells:  Supporting cells  Important  Many more All neurons have dendrites, cell body and axon Coronal section – cut from top to bottom Corpus colossus – the white mass that connects from left to right brain Internal capsule – little dots • Cell body – Large egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order • Dendrite
 – Branch-like extensions thata rise from the cell body – Receive signals from other neurons, muscles, or sense organs – Pass these signals onto the cell body Axons that pass the message to other neurons AGAIN, Cell body Nucleus
 Axon hillock Axon terminal And dendrites When we look more closely
 At the neuron, we see that it has Many other important components Within the cell body, there is a nucleus Cytoplasm, an axon hillock and
 An axon And these parts together Permit electrochemical changes that result in the action potential - Squids have a giant axon - two neurons Neurons at Resting Potential - Resting Potential • Neurons are surrounded by a fluid that has differently charged molecules • Ions: a charged molecule • Anion: a negatively charged 
 ion (proteins) 
 • Cation: a positively charged ion Examples of positive ions (cations): Sodium (NA+), Potassium (K+) Examples of negative ions (anions): Chloride (Cl-), Many Proteins • A neuron contains many anions and fewer cations, hence, more negative in the inside - more negative on the inside then outside • Every living cell has an electrical charge • More negative on the inside (-50 to -80 mV) • Neurons (of jelly fish, insects, reptiles, mammals etc.) are also negative -> use negativity to communicate Why are neurons negatively charged? THREE FORCES AT WORK IN MAINTAINING THE RESTING MEMBRANE POTENTIAL • OSMOSIS
 : If we place a drop of NaCl (salt water) Na+ cl- into a beaker of water, It distributes itself equally and evenly within the medium by a force called osmosis • ELECTROSTATIC FORCE : The cell has membranes
 and does not permit the electrolytes to move freely along their concentration gradients. Instead, there is a membrane that permits some molecules
 To pass through and not others and so there is set up
 2 forces: osmotic force and electrostatic force, where like charges Repel one another and unlike charges attract one another • NA+/K+ PUMP : using energy, so they are working very fast - distribution of ions, neuron in action Action potential - shift from negativity to positivity inside - grated potential, goes up – excitatory potential Action Potential: Nerve impulses that are very brief but are large changes in neuronal polarization that arise initially at the axon hillock • The nerve impulse rapidly travels down the axon • The information that is sent by a neuron is encoded in patterns of these 
 action potentials • HOW ARE ACTION POTENTIALS TRIGGERED? • Hyperpolarization: an increase in membrane potential, so neuron becomes even more negative inside (i.e., from-60mV to -70mV) • Depolarization: is the reverse, a decrease in membrane potential, makes the inside closer to the outside (i.e., from -60mV to -40mV) • APs are therefore a rapid depolarization and repolarization of the membrane • In order for an action potential to be fired, depolarization must be large enough - This is referred to as the threshold: The value of the membrane potential to which the axon must be depolarized to initiate an action potential - All-or-none rule: The amplitude of the AP once initiated, does not depend on the size of the initial depolarization, it either fires or it doesn‘t after threshold • Voltage-gated ion channels are of prime importance in generating action potentials • Open and close according to the membrane potential • They are closed at the resting potential and open as membrane depolarizes • Refractory Period: Stimuli spaced closer together – only the first stimulus is able to elicit an action potential (upper limit of about 1200 impulses per second) • This is a period of unresponsiveness • There are 2 phases during this refractory period 
 – Absolute Refractory Period: a brief period immediately following the production of a AP – no amount of stimulus can produce another AP 
 – Relative Refractory Phase: occurs after the ARP – only a very strong stimulation can produce another AP Positively charged on the inside then the outside : Depolarized Mediation of the AP by Voltage-Gated Na+ Channels 1. Postsynaptic membrane gets depolarized 2. Voltage sensitive Na + gates open up 3. Na+ rushes into the cell making the cell more positive 4. Na+ gates close and K+ rushes out of the cell Saltatory Conduction - Many cells with long axons, are heavily myelinated (Schwann cell) then a gap (Node of Ranvier) and again Schwann cell and then gap - Jumping from node to node so it gets to the end faster - Frontal mode system to spinal cord and toes – long axon, so it takes longer so that is permitted in changes from jumping from node to node – Saltatory Conduction WITHOUT SYNAPSES NEURONS COULD NOT ‗TALK‘ TO ONE ANOTHER AND WE WOULD HAVE NO BEHAVIOR Sensory neuron SYNAPSES on Interneuron SYNAPSES on motor neuron Motor neuron SYNAPSES on muscle interneuron Receptor SYNAPSES on sensory neuron Fig 2.9 A simple sensory-motor (reflex) arc. A simple reflex is set in motion by a stimulus to the skin (or other part of the body). The nerve impulse travels to the spinal cord and then back out to a muscle, which contracts. Reflexes provide an ―automatic‖ protective device for the body. Synapses 1. Structure of the synapse  A. Presynaptic cell o 1.Terminal button
 o 2. Synaptic vesicles
 o 3. Reuptake mechanisms  B. Synaptic cleft
  C. Post-synaptic cell o Postsynaptic membranes and receptors Structure of the neuron. Neurons are the communication links of the nervous system. This diagram highli
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