Neural Communication. Neural Communication. Myers PSYCHOLOGY - Chapter 2: Neuroscience and Behavior. Definitions

Transcription

1 Myers PSYCHOLOGY - Chapter 2: Neuroscience and Behavior 1. Neural communication - Neurons - How Neurons Communicate - How Neurotransmitters Influence Us 2. The nervous system 3. The endocrine system 4. The brain C2:1 Axonal Transmission Synaptic Transmission Model Neuron Skeletal Peripheral Sympathetic Neuroscience Nervous System Autonomic Central Brain Methods Primitive Cerebral Cortex C2:2 Endocrine System Parasympathetic Neurotransmitters Divided Brain Definitions C2:3 - Biological Psychology Branch of psychology concerned with links between biology and behavior Some biological psychologists called behavioral neuroscientists, neuro-psychologists, behavior geneticists, physiological psychologist, or biopsychologists - Neuron Basic building block of nervous system Nervous system consists of innumerable Neurons or Nerve Cells interconnected in complex ways (+1) Need to understand neuronal communication - How messages transmitted within each neuron - How messages transmitted between neurons - C2:4 C2:5 C2:6 - Dendrite Bushy, branching extensions of neuron that receive messages and conduct impulses toward cell body - Axon Extension of neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands - Myelin [MY-uh-lin] Sheath Layer of fatty cells segmentally encasing fibers of many neurons Makes possible vastly greater transmission speed of neural impulses 1

2 C2:7 C2:8 - Action Potential Neural impulse: brief electrical charge that travels down axon Generated by movement of positively charges atoms in and out of channels in axon s membrane - Threshold Level of stimulation required to trigger an action potential Excitatory inputs MINUS Inhibitory inputs - Qualities of Neuronal Transmission All or None: axon either fires or not, no gradation except in rate of firing Constant Strength: no weakening as signal travels down the axon C2:9 C2:10 - Synapse [SIN-aps] (+1) Junction between axon tip of sending neuron and dendrite or cell body of receiving neuron Tiny gap at this junction is called synaptic gap or cleft - Neurotransmitters (+1 ) Chemical messengers that traverse synaptic gaps between neurons When released by sending neuron, neuro-transmitters travel across synapse and bind to receptor sites on receiving neuron, thereby influencing whether it will generate neural impulse Reuptake: Neurotransmitters in synapse reabsorbed into sending neurons C2:11 C2:12 - Acetylcholine [ah-seat-el-ko-leen] Neurotransmitter that, among its functions, triggers muscle contraction - Endorphins [en-dor-fins] morphine within Natural, opiate-like neurotransmitters Linked to pain control and to pleasure 2

3 C2:13 C2:14 Serotonin Pathways Dopamine Pathways Neural Communication C2:15 - Chapter 2: Neuroscience and Behavior Outline C2:16 1. Neural communication 2. The nervous system - Peripheral Nervous System (PNS) - Central Nervous System (CNS) 3. The brain 4. The endocrine system The Nervous System C2:17 The Nervous System C2:18 - Nervous System Body s speedy, electrochemical communication system Consists of all nerve cells of peripheral and central nervous systems - Central Nervous System (CNS) Brain and Spinal Cord - Peripheral Nervous System (PNS) Sensory and Motor neurons that connect central nervous system (CNS) to rest of body 3

4 The Nervous System C2:19 The Nervous System C2:20 - Skeletal (Somatic) Nervous System Division of peripheral nervous system that controls body s skeletal muscles - Autonomic Nervous System Part of peripheral nervous system that controls glands and muscles of internal organs (such as heart) Sympathetic Nervous System - Division of autonomic nervous system that arouses body, mobilizing its energy in stressful situations Parasympathetic Nervous System - Division of autonomic nervous system that calms body, conserving its energy The Nervous System C2:21 - Nerves Neural cables containing many axons (e.g., optic nerve) Part of peripheral nervous system Connect CNS with muscles, glands, and sense organs - Sensory Neurons Carry incoming information from sense receptors to CNS - Motor Neurons Carry outgoing information from CNS to muscles and glands - Interneurons CNS neurons that communicate internally and intervene between sensory inputs and motor outputs Reflex - Simple, automatic, inborn response to a sensory stimulus C2:22 C2:23 C2:24 - The Nervous System - Neural Networks Interconnected neural cells Networks learn with experience, as feedback strengthens or inhibits connections that produce certain results Computer simulations of neural networks show analogous learning 4

5 Connectionism C2:25 Connectionism C2:35 Output Units Stay Time Tray Tree Stay Time Tray Tree Hidden Units R A T E L M Input Units Stimulus TREE Outline C2:36 The Endocrine System C2:37 - Chapter 2: Neuroscience and Behavior 1. Neural communication 2. The nervous system 3. The endocrine system 4. The brain - Endocrine System Body s slow chemical communication system Set of glands that secrete hormones into the bloodstream Neural and Hormonal Systems C2:38 C2:39 - Hormones Chemical messengers, mostly manufactured by endocrine glands, that are produced in one tissue and affect another - Pituitary Gland Under influence of hypothalamus, pituitary regulates growth and controls other endocrine glands - Adrenal [ah-dreen-el] Glands Pair of endocrine glands just above kidneys Secrete hormones Epinephrine (adrenaline) and Norepinephrine (noradrenaline), which help to arouse body in times of stress (+1) - Testis Testosterone and Aggression (+2) 5

6 C2:40 C2:41 Outline - Chapter 2: Neuroscience and Behavior - 1. Neuronal communication - 2. The nervous system - 3. The endocrine system - 4. The brain Tools of Discovery Older Brain Structures Cerebral Cortex The Divided Brain Brain:Tools of Discovery - Clinical Observations Brain Lesion: Naturally or Experimentally caused destruction of brain tissue - Strokes - Gun shots - Auto accidents - Disease - Surgery (e.g., epilepsy) - C2:42 Brain: Tools - Electroencephalogram (EEG) Amplified recording of waves of electrical activity that sweep across brain s surface Waves measured by electrodes placed on scalp C2:43 Brain: Methods C2:44 - Brain Imaging Methods CT (computed tomography) Scan - Series of x-ray photographs from different angles and combined by computer into composite representation of slice through body. Also called CAT scan. PET (positron emission tomography) Scan - Visual display of brain activity that detects where radioactive form of glucose goes while brain performs a given task. MRI (magnetic resonance imaging) - Technique that uses magnetic fields and radio waves to produce computer generated images that distinguish among different types of soft tissue; allows us to see structures within brain. - Functional MRI (fmri): image brain while task being performed MRI Scan - Brain of Normal Person (left) and Person with Schizophrenia (right) C2:46 6

7 C2:47 Brain:Tools Older Brain Structures C2:48 - Experimental Tasks Lateralized presentation of materials to left or right hemisphere of brain More on Split Brain later - Brainstem (top right) Medulla: controls heartbeat and breathing Reticular Formation: filters and relays information, arousal Thalamus: sensory switchboard - Cerebellum (top) Coordinates voluntary movement, implicit learning - Limbic System (bottom) Hippocampus: learning (+1) Amygdala: rage and fear Hypothalamus (hypo = below) - Monitors blood chemistry and controls secretion of hormones - Hunger, Thirst, Temperature, Sex - Reward centre (+2) C2:49 Mirror Tracing Apparatus C2:50 C2:51 Cerebral Cortex: Structures C2:52 - Electrode implanted in reward center 7

8 C2:53 Cerebral Cortex: Functions C2:54 Cortex in Humans and Other Animals - Motor Cortex (+1) Area at the rear of frontal lobes that controls voluntary movements Penfield s stimulation studies - Sensory Cortex (+1) Area at front of parietal lobes that registers and processes body sensations - Visual and Auditory Cortex (+2 +3) Visual: Occipital lobes Auditory: Temporal lobes Sensory-Motor Cortex C2:55 Visual and Auditory Cortex C2:56 Visual Cortex C2:57 Association Areas of Cortex C2:58 - Functional MRI scan of visual cortex activated by light shown in subject s eyes` Areas not involved in primary motor or sensory functions Origin of myth we only use 10% of brains Higher mental functions such as learning, remembering, thinking, and speaking - E.g., Frontal lobes: planning, inhibition, control (Phineas Gage, +1) 8

9 Phineas Gage s Skull & Brain C2:59 - Aphasia Impairment of language, usually caused by Left Hemisphere damage to: Broca s area: impaired speaking, or Wernicke s area: impaired understanding C2:60 Language Areas of Cortex Language Areas C2:61 Brain Reorganization C2:62 - Brain activity when hearing, seeing, and speaking words - Demonstrates Specialization and Integration of Brain functions - Plasticity Capacity to modify brain organization following damage - Especially in children - Experiments on effects of experience on brain development People normal without large parts of brain due to congenital conditions or surgery (+1) C2:63 C2:64 Summary of Brain Structures and Functions 9

10 Divided Brain C2:65 - Split Brain Condition in which two hemispheres of brain are isolated by cutting connecting fibers Corpus Callosum: Large bundle of nerve fibers connecting hemispheres. Carry messages between hemispheres Our Divided Brain - Information highway from eyes to brain - Used to test split-brain patients (+1) C2:66 Split Brain C2:67 Single & Dual Discrimination Task C2:68 - Gazzaniga & Sperry (1966) Reaction Time (RT) to make Red/Green or Dark/Light discriminations with Left and Right hands, either alone or simultaneously Controls 40% slower in dual task, but not Split-Brain participants Below is RT for one of patients Before and After surgery Before After Trials Right Alone Right + Left No interference after Right + Left No interference after Right Alone Disappearing Southpaws C2:69 10