Neuroscience Psychology: A Concise Introduction 2nd Edition Richard Griggs Chapter 2 Prepared by J. W. Taylor V

The Nervous System and the Endocrine System The Journey… The Neuron The Nervous System and the Endocrine System The Brain

The Neuron The Structure of a Neuron How Neurons Communicate Neurotransmitters, Drugs, and Poisons

Neurons and Glial Cells Neurons are responsible for information transmission throughout the nervous system Glial cells do not directly transmit information, but instead support neurons in their work by disposing of waste products of neurons, keeping their chemical environment stable, and insulating them

The Structure of a Neuron Dendrites are the fibers that project out of the cell body, receiving information from other neurons The cell body contains the nucleus of the cell and other biological machinery to keep the cell alive The axon transmits messages through the neuron The axon terminals are at the end of the axon and send messages to a different neuron

The Structure of a Neuron

How Neurons Communicate Communication within a neuron is electrical Communication between neurons is chemical

The Electrical Impulse Information from the dendrites is either excitatory (telling the neuron to generate an electrical impulse) or inhibitory (telling the neuron not to generate an electrical impulse) The impulse is an “all or nothing” event, meaning that there either is or is not an electrical impulse Stimuli of varying intensities are encoded by the quantity of neurons generating impulses and the number of impulses generated each second by the neurons

The Electrical Impulse The myelin sheath is an insulating layer of fatty white substance that encases the axon, allowing electrical message to be transmitted faster within the neuron Damage to the myelin sheath will slow electrical impulses, and can result in diseases like multiple sclerosis

Chemical Communication Between Neurons Axon terminals contains sacs of neurotransmitters These neurotransmitters are naturally occurring chemicals in the nervous system that specialize in transmitting information between neurons Between the axon terminals of one neuron and the dendrites of another neuron is a small space called the synaptic gap, across which neurotransmitters are sent, allowing neurons to communicate

Brain Scans Brain scans work because neurons require oxygen and other nutrients such as blood sugar Positron Emission Tomography (PET) scans use a dose of radioactive glucose, which moves to the more-active areas of the brain Functional Magnetic Resonance Imaging (MRI) detects active areas of the brain by highlighting those areas that require more oxygen

Neurotransmitters, Drugs, and Poisons Key terms: Agonists Antagonists Drugs and poisons that increase the activity of one or more neurotransmitters Drugs and poisons that decrease the activity of one or more neurotransmitters

Neurotransmitters 1. Acetylcholine (ACh) is involved in both learning and memory and muscle movement 2. Dopmaine impacts our arousal and mood states, thought processes, and physical movement 3. Serotonin and norepinephrine are neurotransmitters involved in levels of arousal and mood, and play a major role in mood disorders such as depression 4. GABA is the main inhibitory neurotransmitter in the nervous system; glutamate is the main excitatory neurotransmitter 5. Endorphins are a group of neurotransmitters that are involved in pain perception and relief

Acetylcholine (ACh) Botulinum poison (botulin) is an antagonist that blocks the release of ACh at muscle junctures, leading to paralysis and even death Curare is an antagonist that paralyzes the body by occupying the receptor sites for ACh, thereby preventing ACh from getting in and carrying its message to a neuron Black widow spider venom is an agonist for Ach, causing the continuous release of ACh, flooding the synapse

Dopamine Low levels are associated with Parkinson’s disease, and excessively high levels are associated with schizophrenia L-Dopa is an agonist that increases production of dopamine Anti-psychotic drugs are antagonists that block the receptor sites for dopamine so that this neurotransmitter cannot send its messages Amphetamine acts as an agonist by stimulating the release of dopamine from axon terminals Cocaine is an agonist that blocks the re-uptake of dopamine

Serotonin and Norepinephrine Some antidepressant drugs work by blocking the reuptake of serotonin and norepinephine Anti-depressant drugs like Prozac, Paxil, and Zoloft are selective serotonin reuptake inhibitors

GABA and Glutamate Anti-anxiety drugs are agonists for GABA Lack of GABA may contribute to epilepsy, a brain disorder resulting in uncontrolled movement and convulsions Glutamate is involved in memory storage and pain perception. Excessive glutamate can lead to neuron death; deficient glutamate has been proposed to explain schizophrenia

Endorphins Morphine and heroin are agonists that bind to receptor sites, thereby increasing endorphin activity

The Nervous and Endocrine Systems The Central Nervous System The Peripheral Nervous System The Endocrine Glandular System Emotions and the Autonomic Nervous System

Nervous System Subdivisions

Types of Neurons Interneurons exist only in the central nervous system Sensory neurons carry information to the central nervous system from sensory receptors in the eyes, muscles, and glands Motor neurons carry movement commands from the central nervous system to the rest of the body

The Central Nervous System Consists of the spinal cord and the brain The spinal cord has two functions Conduit for incoming sensory data and outgoing movement commands Provides for spinal reflexes, which are simple automatic actions not involving the brain The brain is the control center for the entire nervous system

The Peripheral Nervous System Gathers information about the external environment and the body’s internal environment for the brain through sensory neurons Serves as the conduit for the brain’s commands to the rest of the body through motor neurons

The Peripheral Nervous System Consists of two parts: The somatic (or skeletal) nervous system carries sensory input from receptors to the CNS and relays commands from the CNS to the skeletal muscles to control their movement The autonomic nervous system regulates our internal environment and consists of two parts The sympathetic nervous system is in control when we are very aroused and prepares us for defensive action (such as running away or fighting) The parasympathetic nervous system is in control when the aroused state ends to return our body to its normal resting state

The Endocrine Glandular System Not part of the nervous system Works with the autonomic nervous system in responding to stress, and plays a role in basic behaviors and bodily functions such as sex, eating, metabolism, reproduction, and growth Endocrine glands secret hormones, which are chemicals carried by the bloodstream to target sites throughout the body

The Endocrine Glandular System Endocrine glands are controlled by the hypothalamus, which controls the most influential gland, the pituitary Releases hormones essential for human growth and that direct other glands to release their hormones Some other glands: Thyroid gland affects our growth and maturation Adrenal glands are involved in metabolism and help trigger the “fight or flight” response with commands from the autonomic nervous system The pancreas is involved in digestion and maintaining blood-sugar levels

The Endocrine Glandular System

Components of Emotion An emotion is a complex psychological state that involves three components: Physical Behavioral Cognitive A physiological state of arousal triggered by the autonomic nervous system An outward expression including facial expressions, movements and gestures An appraisal of the situation to determine which emotion we are experiencing and how intensely

Components of Emotion The physical component The behavioral component Includes the “fight or flight” response of the autonomic nervous system Heart rate and breathing increase, blood pressure surges, start sweating, pupils dilate, digestion slows The behavioral component Is the product of motor neurons The facial-feedback hypothesis assumes that the facial muscles send messages to the brain, allowing the brain to determine which emotion is being experienced The cognitive component Includes an appraisal of the situation to determine what emotion we are experiencing

Schachter-Singer Two-Factor Theory Theories of Emotion James-Lange Theory Cannon-Bard Theory Schachter-Singer Two-Factor Theory

James-Lange Theory Contends that autonomic nervous system physiological arousal is a response to a stimulus, and that such a physiological response is subsequently interpreted as the emotion For example, if you are crossing the street and see a car speeding toward you, your autonomic nervous system is aroused (e.g., increased heart rate). Based on this arousal, you interpret the stimulus as threatening and pick up your pace across the street.

Cannon-Bard Theory Contends that arousal patterns for different emotions are too physiologically alike to be able to determine what emotion is being experienced Instead, an emotion-provoking stimulus sends messages to both the peripheral nervous system and the brain The brain produces the emotional feeling, the autonomic nervous system produces the physiological response, and the motor neurons produce the behavioral response

Schachter-Singer Two-Factor Theory Contends that there are two important determinants of emotion: Physiological arousal tells us how intense the emotion is The cognitive appraisal of the entire situation allows us to identify the emotion, leading to the emotional feeling

Integrating the Theories LeDoux (1996) contends that there are different brain systems for different emotions Fear, for example, does not require higher-level cognitive processing and is generated almost instantaneously by the amygdala More complex emotions, however, such as love or guilt, that do not require instantaneous responding for survival, may require higher-level processing

The Brain Going up the Brain Stem Processing in the Cerebral Cortex Specializations of the Left and Right Hemispheres Consciousness and the Sleeping Brain

Case 1: A Landscape Artist Scenario Neuroanatomy Related Function Anne the landscape artist is standing at her easel, painting with her right hand as she looks out the window at her garden. She’s listening to classical music as she paints. Left motor cortex Left frontal lobe Visual cortex Both occipital lobes Auditory cortexes Both temporal lobes Right hemisphere Thalamus Frontal lobes Left sensory cortex Left parietal lobe Cerebellum Controls right hand Contains motor cortex Used for vision Contain visual cortex Used to hear music Contain auditory cortexes Spatial ability for painting Relays sensory information Deciding what to paint Feeling the paintbrush Contains sensory cortex Coordinates moving arm

Case 2: A Professional Wrestler Scenario Neuroanatomy Related Function Crazy Eddie, the professional wrestler, is in the ring wrestling. The crowd is yelling and his is taunting him. Eddie yells back at his opponent. The two of them are out of breath and sweating profusely. They continue their well-orchestrated series of wrestling moves. Both motor cortexes Frontal lobes Both sensory cortexes Parietal lobes Visual cortexes Both occipital lobes Right hemisphere Wernicke’s area Left temporal lobe Broca’s area Left frontal lobe Thalamus Medulla Amygdala Reticular formation Cerebellum Hypothalamus Hippocampus Move muscles Contain motor cortexes Needed for sense of touch Contain sensory cortexes Used for vision Contain visual cortexes Spatial ability for wrestling Understanding taunts Contains Wernicke’s area Produces speech (yells) Contains Broca’s area Sensory relay Decision making & attention Regulates heart and breathing Aggression and fear Controls arousal Balance and coordination Regulates temperature Memory for moves

Case 3: A Student Scenario Neuroanatomy Related Function Jill is a law student studying for her exam. She is reading about violent rape and murder cases. She is snacking on popcorn and drinking coffee. Hippocampus Wernicke’s area Left temporal lobe Amygdala Frontal lobes Hypothalamus Angular gyrus Remembering and learning Language comprehension Contains Wernicke’s area Anger and fear about cases Decision making & attention Regulates hunger and thirst Needed for reading Source: Sheldon, J. P. (2000). A neuroanatomy teaching activity using case studies and collaboration. Teaching of Psychology, 27, 126-128.

The Central Core The brain stem The medulla links the spinal cord to the brain and is involved in regulating heartbeat, blood pressure, digestion, and swallowing The reticular formation is a network of neurons running up the center of the brain stem and into the thalamus that is involved in controlling our different levels of arousal and awareness The cerebellum is involved in the coordination of our movements, our sense of balance, and motor and procedural learning The thalamus, located at the top of the brain stem, serves as a relay station for incoming sensory information (except smell) The basal ganglia are on the outer sides of the thamalus and are concerned mainly with the initiation and execution of physical movements

The Central Core Brain Structures

The Limbic System Plays a role in our survival, memory, and emotions The hypothalamus control the pituitary gland, the autonomic nervous system, and plays a major role in regulating basic drives such as eating, thirst, and sex The hippocampus is involved in the formation of memories The amygdala plays a major role in regulating our emotional experiences, especially fear, anger, and aggression

The Limbic System

Processing in the Cerebral Cortex The cerebral cortex is the most important brain structure, serving as the information processing center for the nervous system Is where perception, language, memory, decision making, and all other higher-level cognitive processing occur Consists of two hemispheres connected by a band of neurons called the corpus callosum, allowing the two hemispheres to communicate

Brain Lobes 1. The frontal lobe is the area in the front of each hemisphere and in front of the central fissure and above the lateral fissure 2. The parietal lobe is the area located behind the central fissure and above the lateral fissure 3. The temporal lobe is located beneath the lateral fissure 4. The occipital lobe is located in the lower back of each hemisphere

The Four Lobes and the Sensory-Motor Processing Areas

The Motor Cortex The frontal lobe strip of cortex, directly in front of the central fissure in each hemisphere, allows us to move different parts of our body Each hemisphere controls the voluntary movement of the opposite side of the body (a contralateral relationship) Amount of motor cortex devoted to a specific body part is related to the complexity and precision of movement of which that part is capable

The Somatosensory Cortex The parietal lobe strip of cortex, directly behind the central fissure in each hemisphere, is where body sensations of pressure, temperature, limb position, and pain are processed Contralateral relationship Amount of sensorimotor cortex devoted to a body part is directly proportionate to the sensitivity of that body part

Homunculi for the Motor Cortex and the Somatosensory Cortex

Visual Cortex and Auditory Cortex The visual cortex is located in the occipital lobes at the back of the hemispheres The auditory cortex is in the temporal lobes These primary areas pass the results of their analyses on to areas in the other lobes to complete the brain’s interpretation of the incoming visual or auditory information These secondary cortical processing areas are part of what is termed the association cortex

Association Cortex Consists of the other 70% of the cortex not in one of the previously mentioned areas This is where the higher-level processing such as decision making, reasoning, perception, speech, and language occurs All of which require integration of various types of information

The Case of Phineas Gage Phineas Gage was railroad worker who survived when a metal tamping iron flew through his left cheek and head, exiting through his frontal lobes He became irresponsible, impulsive, disorderly, indecisive, and cursed, leading neuroscientists to think the frontal lobes are important in such behaviors

Language Broca’s area, in the left hemisphere’s temporal lobe, is responsible for fluent speech production When damaged, people cannot generate fluent speech, but can still understand speech easily Singing and musical abilities seem to be housed in the right hemisphere because damage to Broca’s area does not impair these abilities Wernicke’s area is in the left temporal lobe and is responsible for the comprehension of speech and reading

Language

Studying the Two Hemispheres Light waves from the left visual field go to the right half of each eye, and light waves from the right visual field go to the left half of each eye The right half of each eye connects with the right hemisphere, and the left half of each eye connects with the left hemisphere

Pathways for Processing Information in the Left and Right Visual Fields

Studying the Two Hemispheres With split-brained people, the information cannot transfer between hemispheres because the corpus callosum has been cut Split-brain people can only identify information orally when it is presented briefly in the right visual field (and thus processing in the left hemisphere) If a spoon was flashed in the left visual field, split-brained people could not say it was a spoon If the person was blind-folded and told to find the object from a group of objects with the left hand, s/he can do this

What we know… Left hemisphere Right hemisphere Language Math and logic skills More analytical, analyzing wholes into pieces Right hemisphere Spatial perception Solving spatial problems Drawing Face recognition

What we know… Remember, however, that these differences in hemispheric performance are for people whose two hemispheres can no longer communicate When normal people are performing a task, the two hemispheres are constantly interacting and sharing information This is why it is not very accurate to say someone is “left-brained” or “right-brained” Rather, nearly all of us are “whole brained”

Consciousness and the Sleeping Brain Consciousness is a person’s subjective awareness of both their inner thinking and feeling and their external environment The five stages of sleep were determined by use of an electroencephalogram (EEG), which records a real-time graph of a person’s cortical electrical activity in the brain As we slip into sleep and pass through the first four stages, our brain waves change, in general becoming progressively slower, larger, and more irregular, especially in Stages 3 and 4

Five Stages of Sleep Stage 1: Lasts about 5 minutes Characterized by sleep spindles, rapid bursts of mental activity Stage 3: Also known as transitional sleep and is characterized by delta waves, which are large, slow waves Stage 4: Lasts about 30 minutes Parasympathetic nervous system is active, as muscles relax, heartbeat slows, blood pressure declines, and digestion speeds up

Five Stages of Sleep Stage 5: REM (rapid eye movement sleep) occurs after we leave stage 4 sleep and return through the earlier stages of sleep Called paradoxical sleep because your muscles are relaxed, but other body systems, including the brain, are active, much like a waking pattern Characterized by very rapid brain waves somewhat like those of Stage 1 sleep, but one is still sound asleep If awakened during REM sleep, people often report having been dreaming Most dreams are emotional and unpleasant, perhaps because the visual cortex and frontal lobe are inactive during REM sleep; the limbic system structures are active, however, creating irrational imagery and emotional experiences of our dream world REM sleep accounts for 20–25% of total sleep time

Five Stages of Sleep

Five Stages of Sleep These 5 stages (the sleep cycle) repeat themselves about every 90 minutes, with Stages 3 and 4 getting shorter with each cycle, and REM and Stage 2 getting longer with each cycle REM sleep rebound effect is a significant increase in the proportion of REM sleep following deprivation of REM sleep

Why do we sleep and dream? Sleep deprivation results in: Impaired concentration and a general bodily feeling of weakness and discomfort Suppression of the immune system, lessening one’s ability to fight off infection and disease Increased vulnerability to accidents Increased difficulty in concentrating, studying, and taking exams

Why do we sleep and dream? Explanations for dreaming : Sigmund Freud proposed that dreams were disguised outlets for inner conflicts of our unconscious mind, a view not accepted by modern sleep researchers The activation-synthesis hypothesis contends that dreams are merely the sleeping brain’s attempt to make sense of random neural activity without the rational interpretation of the frontal lobe