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Chapter 2
The Brain and Behavior
1
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The Nervous System
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Neurons
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Structures of the Brain and Their Functions
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The Endocrine System
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Brain Damage, Plasticity, and Repair
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Genetics and Behavior
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Nervous System
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Electrochemical communication circuitry
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Billions of interconnected cells
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Neuroscience
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Neuroscientists
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Nervous System: Characteristics
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Complexity
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Integration
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Adaptability
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Plasticity
Electrochemical Transmission
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Nervous System: Pathways
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Afferent Nerves
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Efferent Nerves
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Motor nerves
Information out of brain and spinal cord
Neural Networks
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Sensory nerves
Information to brain and spinal cord
Integration of sensory input and motor output
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Nervous System: Divisions
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Nervous System: Primary Divisions
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Central Nervous System (CNS)
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Brain and Spinal Cord
Peripheral Nervous System (PNS)
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Network of nerves connecting CNS to body
Two subdivisions:
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Somatic Nervous System
Autonomic Nervous System
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Nervous System: PNS Divisions
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Somatic Nervous System
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Sensory information from skin and muscles to CNS
Autonomic Nervous System
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Messages to and from internal organs
Two subdivisions:
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Sympathetic Nervous System  arousing
Parasympathetic Nervous System  calming
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Nervous System: Stress
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“Fight or Flight” Reaction
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Corticosteroids
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Function of sympathetic nervous system
Stress hormones
Acute stress is momentary.
Chronic stress is continuous.
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Nervous System: Cells
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Neurons
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Nerve cells
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Information processing
Glial cells
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Support
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Nutritional benefits
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Neurons: Structure
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Cell Body
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Dendrites
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Fibers projecting from neuron
Axon
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Contains nucleus
Carries information from cell body toward other cells
Myelin Sheath
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Layer of fat cells, encasing and insulating most axons
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Neurons: Structure
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Neural Impulse
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Resting potential
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Stable, negative charge of inactive neuron
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Neural Impulse
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Action Potential
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Brief, positive electrical charge, or firing
Abides by the all-or-nothing principle
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Synapses & Neurotransmitters
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Synapses
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Space between neurons (synaptic gap)
Neurotransmitters
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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
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Neurotransmitters are excitatory, inhibitory, or both.
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Acetylcholine (ACh)
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Stimulates firing of neurons
Involved in action of muscles, learning, memory
Alzheimer disease: ACh deficiency
Gamma aminobutyric acid (GABA)
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Keeps many neurons from firing
Anxiety: Low levels of GABA
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Neurochemical Messengers
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Norepinephrine
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Inhibits firing of neurons in CNS
Excites heart muscle, intestines, urogenital tract
Depression: Too little norepinephrine
Agitated, manic states: Too much norepinephrine
Dopamine
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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
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Serotonin
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Endorphins
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Involved in regulation of sleep, mood, attention, learning
Depression: Lowered levels of serotonin
Natural opiates that mainly stimulate firing of neurons
Shield body from pain
Elevate feelings of pleasure
Oxytocin
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Hormone and neurotransmitter
Important role in experience of love and social bonding
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Drugs & Neurotransmitters
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Drugs influence behavior mainly by
interfering with neurotransmitters.
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Agonist
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Drug that mimics or increases effects of
neurotransmitter
Antagonist
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Drug that blocks effects of neurotransmitter
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Neural Networks
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Studying the Brain
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Brain Lesioning
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Staining
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Dyes neurons for tracking neural impulses
Electrical Recording
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Determines effects of brain tissue disruption
on behaviors
Detects brain wave activity
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Brain Imaging
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X-ray
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two-dimensional images
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CT (or CAT) scan
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three-dimensional images
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PET scan
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metabolic changes
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MRI
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brain structure
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f MRI
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brain function
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Organization of the Brain
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Hindbrain
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Midbrain
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Rises above hindbrain
Forebrain
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Adjacent to top part of spinal cord
Uppermost region of brain
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Organization of the Brain
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Hindbrain
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Medulla
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Cerebellum
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Controls vital functions, such as breathing and heart rate
Regulates reflexes
Plays important role in motor coordination
Pons
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Involved in sleep and arousal
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Midbrain
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Brain stem
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Includes much of hindbrain (but not cerebellum)
and midbrain
Determines alertness
Regulates basic survival functions
Reticular Formation
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Involved in stereotyped patterns of behavior, such
as walking and sleeping
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Forebrain
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Limbic System
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Thalamus
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Basal Ganglia
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Hypothalamus
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Cerebral Cortex
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Forebrain: Limbic System
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Important in both memory and emotion
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Two principal structures
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Amygdala
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Hippocampus
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Involved in discrimination of objects necessary for survival
Has special role in storage of memories
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Forebrain: Thalamus & Basal Ganglia
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Thalamus
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Serves as relay station for information
Basal Ganglia
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Works with cerebellum and cerebral cortex to
control and coordinate voluntary movements
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Forebrain: Hypothalamus
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Monitors . . .
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eating, drinking, sex
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emotion, stress, reward
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Helps direct endocrine system
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Regulator of body’s internal state
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Involved in pleasurable feelings
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Forebrain: Cerebral Cortex
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Occipital lobes
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Temporal lobes
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Personality, intelligence, control of voluntary muscles
Parietal lobes
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Hearing, language processing, memory
Frontal lobes
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Responding to visual stimuli
Registering spatial location, attention, motor control
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Forebrain: Cerebral Cortex
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Somatosensory Cortex
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Motor Cortex
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Located just behind frontal lobes
Processes information about voluntary movement
Association Cortex
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Located at front of parietal lobes
Processes information about body sensations
Makes up 75% of cerebral cortex
Integrates information
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Forebrain: Cerebral Cortex
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Cerebral Hemispheres
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Corpus Callosum
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Left Hemisphere
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Receives information from right side of body
Language processing, such as speech and grammar
Right Hemisphere
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Large bundle of axons connecting brain’s two hemispheres
Relays information between two sides
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
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Endocrine System
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Glands
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Set of glands that regulate activities of certain organs
Organs or tissues that create chemicals that control
bodily functions
Hormones
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Chemical messengers produced by endocrine glands
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Endocrine System
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Pituitary Gland
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Controls growth and regulates other glands
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Thyroid & Parathyroid Glands
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Adrenal Glands
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Pancreas
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Regulate mood, energy level, and ability to cope with stress
Performs both digestive and endocrine functions
Ovaries (in women) & Testes (in men)
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Produce hormones related to sexual development and reproduction
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Brain Damage, Plasticity, and Repair
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Collateral Sprouting
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Substitution of Function
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Damaged region’s function is taken over by another
brain area.
Neurogenesis
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Axons of healthy neurons adjacent to damaged cells
grow new branches.
New neurons are generated.
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Brain Tissue Implants
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Brain grafts
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Stem cells
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Implants of healthy tissue into damaged brains
Primitive cells with capacity to develop into
most types of human cells
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Genetics and Behavior
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Chromosomes
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DNA (deoxyribonucleic acid)
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Complex molecule that carries genetic information
Genes
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Threadlike structures containing DNA
Units of hereditary information
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Genetics and Behavior
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The Study of Genetics
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Dominant-Recessive Genes Principle
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If one gene in pair is dominant and one is recessive,
dominant gene overrides recessive gene.
Polygenic Inheritance
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Influence of multiple genes on behavior
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The Study of Genetics
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Molecular Genetics
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Genome
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Manipulation of genes using technology to
determine their effect on behavior
Complete set of genetic instructions for making
an organism
Human Genome Project
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International research program mapping human
genome
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The Study of Genetics
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Selective Breeding
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Behavior Genetics
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Genetic method use to demonstrate importance of
genetic influence on behavior
Study of degree and nature of heredity’s influence
on behavior
Twin Studies
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Identical vs. Fraternal Twins
Minnesota Study of Twins Reared Apart (1996)
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Genes and the Environment
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Genotype
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Phenotype
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Genetic heritage
Observable characteristics
Influenced by genotype and environmental factors
Genetic Expression
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Activity of genes is affected by their environment.
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