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Chapter 2The Brain and Behavior
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The Nervous System
Neurons
Structures of the Brain and Their Functions
The Endocrine System
Brain Damage, Plasticity, and Repair
Genetics and Behavior
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Nervous System
Electrochemical communication circuitry
Billions of interconnected cells
Neuroscience Neuroscientists
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Nervous System: Characteristics
Complexity
Integration
Adaptability Plasticity
Electrochemical Transmission
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Nervous System: Pathways
Afferent Nerves Sensory nerves Information to brain and spinal cord
Efferent Nerves Motor nerves Information out of brain and spinal cord
Neural Networks Integration of sensory input and motor output
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Nervous System: Divisions
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Nervous System: Primary Divisions
Central Nervous System (CNS) Brain and Spinal Cord
Peripheral Nervous System (PNS) Network of nerves connecting CNS to body Two subdivisions:
Somatic Nervous System Autonomic Nervous System
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Nervous System: PNS Divisions
Somatic Nervous System Sensory information from skin and muscles to CNS
Autonomic Nervous System Messages to and from internal organs Two subdivisions:
Sympathetic Nervous System arousing Parasympathetic Nervous System calming
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Nervous System: Stress
“Fight or Flight” Reaction Function of sympathetic nervous system
Corticosteroids Stress hormones
Acute stress is momentary. Chronic stress is continuous.
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Nervous System: Cells
Neurons Nerve cells
Information processing
Glial cells Support
Nutritional benefits
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Neurons: Structure
Cell Body Contains nucleus
Dendrites Fibers projecting from neuron
Axon Carries information from cell body toward other cells
Myelin Sheath Layer of fat cells, encasing and insulating most axons
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Neurons: Structure
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Neural Impulse
Resting potential Stable, negative charge of inactive neuron
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Neural Impulse
Action Potential Brief, positive electrical charge, or firing Abides by the all-or-nothing principle
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Synapses & Neurotransmitters
Synapses Space between neurons (synaptic gap)
Neurotransmitters Stored in synaptic vesicles (sacs) within terminal
buttons Chemical signals which allow electrical impulses
to cross synaptic gaps
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Synapses & Neurotransmitters
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Neurochemical Messengers
Neurotransmitters are excitatory, inhibitory, or both.
Acetylcholine (ACh) Stimulates firing of neurons Involved in action of muscles, learning, memory Alzheimer disease: ACh deficiency
Gamma aminobutyric acid (GABA) Keeps many neurons from firing Anxiety: Low levels of GABA
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Neurochemical Messengers
Norepinephrine Inhibits firing of neurons in CNS Excites heart muscle, intestines, urogenital tract Depression: Too little norepinephrine Agitated, manic states: Too much norepinephrine
Dopamine Helps to control voluntary movement Affects sleep, mood, attention, learning, rewards Parkinson disease: Low levels of dopamine Schizophrenia: High levels of dopamine
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Neurochemical Messengers
Serotonin Involved in regulation of sleep, mood, attention, learning Depression: Lowered levels of serotonin
Endorphins Natural opiates that mainly stimulate firing of neurons Shield body from pain Elevate feelings of pleasure
Oxytocin Hormone and neurotransmitter Important role in experience of love and social bonding
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Drugs & Neurotransmitters
Drugs influence behavior mainly by interfering with neurotransmitters.
Agonist Drug that mimics or increases effects of
neurotransmitter
Antagonist Drug that blocks effects of neurotransmitter
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Neural Networks
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Studying the Brain
Brain Lesioning Determines effects of brain tissue disruption
on behaviors
Staining Dyes neurons for tracking neural impulses
Electrical Recording Detects brain wave activity
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Brain Imaging
X-ray two-dimensional images
CT (or CAT) scan three-dimensional images
PET scan metabolic changes
MRI brain structure
f MRI brain function
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Organization of the Brain
Hindbrain Adjacent to top part of spinal cord
Midbrain Rises above hindbrain
Forebrain Uppermost region of brain
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Organization of the Brain
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Hindbrain
Medulla Controls vital functions, such as breathing and heart rate Regulates reflexes
Cerebellum Plays important role in motor coordination
Pons Involved in sleep and arousal
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Midbrain
Brain stem Includes much of hindbrain (but not cerebellum)
and midbrain Determines alertness Regulates basic survival functions
Reticular Formation Involved in stereotyped patterns of behavior, such
as walking and sleeping
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Forebrain
Limbic System
Thalamus
Basal Ganglia
Hypothalamus
Cerebral Cortex
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Forebrain: Limbic System
Important in both memory and emotion
Two principal structures Amygdala
Involved in discrimination of objects necessary for survival
Hippocampus Has special role in storage of memories
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Forebrain: Thalamus & Basal Ganglia
Thalamus Serves as relay station for information
Basal Ganglia Works with cerebellum and cerebral cortex to
control and coordinate voluntary movements
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Forebrain: Hypothalamus
Monitors . . . eating, drinking, sex
emotion, stress, reward
Helps direct endocrine system Regulator of body’s internal state Involved in pleasurable feelings
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Forebrain: Cerebral Cortex
Occipital lobes Responding to visual stimuli
Temporal lobes Hearing, language processing, memory
Frontal lobes Personality, intelligence, control of voluntary muscles
Parietal lobes Registering spatial location, attention, motor control
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Forebrain: Cerebral Cortex
Somatosensory Cortex Located at front of parietal lobes Processes information about body sensations
Motor Cortex Located just behind frontal lobes Processes information about voluntary movement
Association Cortex Makes up 75% of cerebral cortex Integrates information
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Forebrain: Cerebral Cortex
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Cerebral Hemispheres
Corpus Callosum Large bundle of axons connecting brain’s two hemispheres Relays information between two sides
Left Hemisphere Receives information from right side of body Language processing, such as speech and grammar
Right Hemisphere Receives information from left side of body Processing non-verbal information, such as spatial perception,
visual recognition, and emotion
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Cerebral Hemispheres
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Endocrine System
Endocrine System Set of glands that regulate activities of certain organs
Glands Organs or tissues that create chemicals that control
bodily functions
Hormones Chemical messengers produced by endocrine glands
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Endocrine System
Pituitary Gland Controls growth and regulates other glands
Thyroid & Parathyroid Glands
Adrenal Glands Regulate mood, energy level, and ability to cope with stress
Pancreas Performs both digestive and endocrine functions
Ovaries (in women) & Testes (in men) Produce hormones related to sexual development and reproduction
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Brain Damage, Plasticity, and Repair
Collateral Sprouting Axons of healthy neurons adjacent to damaged cells
grow new branches.
Substitution of Function Damaged region’s function is taken over by another
brain area.
Neurogenesis New neurons are generated.
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Brain Tissue Implants
Brain grafts Implants of healthy tissue into damaged brains
Stem cells Primitive cells with capacity to develop into
most types of human cells
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Genetics and Behavior
Chromosomes Threadlike structures containing DNA
DNA (deoxyribonucleic acid) Complex molecule that carries genetic information
Genes Units of hereditary information
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Genetics and Behavior
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The Study of Genetics
Dominant-Recessive Genes Principle If one gene in pair is dominant and one is recessive,
dominant gene overrides recessive gene.
Polygenic Inheritance Influence of multiple genes on behavior
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The Study of Genetics
Molecular Genetics Manipulation of genes using technology to
determine their effect on behavior
Genome Complete set of genetic instructions for making
an organism
Human Genome Project International research program mapping human
genome
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The Study of Genetics
Selective Breeding Genetic method use to demonstrate importance of
genetic influence on behavior
Behavior Genetics Study of degree and nature of heredity’s influence
on behavior Twin Studies
Identical vs. Fraternal Twins Minnesota Study of Twins Reared Apart (1996)
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Genes and the Environment
Genotype Genetic heritage
Phenotype Observable characteristics Influenced by genotype and environmental factors
Genetic Expression Activity of genes is affected by their environment.
