Chapter 2: Biology and
Behavior
Lecture 3
Learning Outcomes
• Describe the nervous system, including neurons,
neural impulses, and neurotransmitters.
• List the structures of the brain and their
functions.
Learning Outcomes
• Describe evolutionary psychology and the
connections between heredity, behavior, and
mental processes.
The Nervous System: On
Being Wired
1. Neurons
• Neurons, responsible for all our sensations, behaviors and mental processes, our nervous
system composed of those cells
– Cell body-soma, dendrites, axon and axon
terminals
• Glial cells (# increases when we grow up)
– Nourish and insulate neurons
– Direct growth of neurons
– Remove waste products
• Myelin sheath (axon is wrapped w/it, white, fatty)
2. The Anatomy of a Neuron
3. Neurons
• Afferent Neurons/Sensory
– Transmit messages from sensory receptors to
the spinal cord and brain
• Efferent Neurons/Motor
– Transmit messages from bran or spinal cord to
muscles and glands
SAME
4. Neural Impulse
• Electrochemical messages that travel within
neurons
• Resting potential (-70), because of Sodium (Na+) Potassium(K+)
pumps and chloride (Cl-)
– Neuron is not responding to other neurons
• Electrotonic potential (will sum up in soma)
• Action potential
– Conduction of neural impulse along axon
4. Neural Impulse
• Electrochemical messages that travel within
neurons
• Resting potential (-70), because of Sodium (Na+) Potassium(K+)
pumps and chloride (Cl-)
– Neuron is not responding to other neurons
• Action potential
– Conduction of neural impulse along axon
(e.g.,-55ml- Na+ channels open up, and Na+ floods in until +30 or +40, then Na+
channel closes and Potassium K+ channels open up until -80 )
Action Potential
PLAY
VIDEO
5. Firing: Neuron to Neuron
• Firing
– Conduction of neural impulse along the length
of a neuron
• Threshold
– Incoming messages reach a strength at which
neuron will fire (e.g.,-55ml- Na+ channels open up, and Na+ floods in
until +40, then Na+ channel closes and Potassium K+ channels open up until -80 )
6. Firing: Neuron to Neuron
• All-or-none principle
– Every time a neuron fires, it transmits an
impulse of the same strength.
• Refractory period
– Period of recovery time between firings
7. Firing: Neuron to Neuron
• Synapse
– Fluid-filled gap (Synaptic
cleft) between
• Axon terminal from
transmitting neuron,
and
• Dendrite of receiving
neuron
Synaptic Transmission
PLAY
VIDEO
8. Neurotransmitters
• Neurotransmitters
– Chemical substances
that communicate
from one neuron to
another
• Synaptic vesicles
– Contain
neurotransmitters in
the axon terminals
9. Neurotransmitters
• Receptor site
– On dendrite of
receiving neuron
• Reuptake
– Neurotransmitters
reabsorbed
10.Neurotransmitters
• Excitatory neurotransmitter (e.g., Na+ channels open)
– Cause other neurons to fire
• Inhibitory neurotransmitters (e.g., Potassium K+ channels open)
– Prevent other neurons from firing
To Sum up: Firing
• Neurons communicate by firing. Steps:
a). Neurotransmitters are released into synapse by a pre-synaptic neuron
b). Neurotransmitters bind with receptors on the post-synaptic neuron’s dendrites
c). Excitatory and inhibitory messages are compared in the cell body (soma) of the
postsynaptic neuron.
d). If the receptors allow a sufficient excess of excitatory neurotransmitters into the
cell, the postsynaptic neuron will respond by opening its sodium and potassium gates.
e). The charge inside the cell goes from negative to positive
f). The gates open in succession as the information is passed along the axon away
from the cell body and toward terminal buttons.
g). The sodium and potassium gates close, and the neuron returns to its resting
potential
h). The synaptic neuron “reuptakes” the neurotransmitter from the synapse.
11. Neurotransmitters of Interest to
Psychologists
• Acetylcholine (ACh)
– Controls muscle contractions (excitatory between nerves
muscles & inhibitory at the heart and some other locations)
• Paralysis if not enough ACh
– Memory (prevalent in hippocampus, when decrease )
• Alzheimer’s disease
• Acetylcholine (ACh), Dopamine, norepinephrine, serotonin, GABA, and endorphins
12. Neurotransmitters of Interest to
Psychologists
• Dopamine
– Pleasure, voluntary movement, learning,
memory
– Parkinson’s disease (deficiencies in D.)
– Schizophrenia (people have more receptors for dopamine, utilize more
dopamine)
-Phenothiazines block dopamine receptors
•
Acetylcholine (ACh), Dopamine, norepinephrine, serotonin, GABA, and endorphins
13. Neurotransmitters of Interest to
Psychologists
• Norepinephrine in the brain stem
– Excitatory neurotransmitter, also hormone
• Accelerates heart rate, affects eating, linked
to activity levels, learning and remembering
– Mood disorders, depression, bipolar disorder
(more)
-- Deficiency impairs memory
-- Cocaine and amphetamines boost N.
•
Acetylcholine (ACh), dopamine, norepinephrine, serotonin, GABA, and endorphins
14. Neurotransmitters of Interest to
Psychologists
• Serotonin
– Emotional arousal and sleep
– Eating disorders, alcoholism, depression,
aggression, insomnia
– LSDs decrease action of S.
Acetylcholine (ACh), dopamine, norepinephrine, serotonin, GABA, and endorphins
15. Neurotransmitters of Interest to
Psychologists
• Gamma-aminobutyric acid (GABA)
– Inhibitory may help relax anxiety reactions
– Depression
16. Neurotransmitters of Interest to
Psychologists
• Endorphins similar to morphine
– Occur naturally within the brain and
bloodstream
– Inhibit pain
– Increase sense of competence, immune
– May be connected to indifference to pain
• Runner’s high
17. Parts of the Nervous System
• Central Nervous System
– Brain and spinal cord
• Peripheral Nervous System
– Sensory (afferent) and motor (efferent)
neurons
The Divisions of the Nervous System
18. Peripheral Nervous System
•
•
Somatic Nervous System
– Sensory and motor neurons
– Transmits messages to the brain and purposeful body movements from
the brain
Autonomic Nervous System
– Regulates glands and muscles of internal organs
– Contains sympathetic and parasympathetic divisions
19. Branches of Autonomic Nervous System
• Sympathetic
– Most active during emotional responses
– Spend the body’s reserves of energy
• Parasympathetic
– Most active during processes that restore
body’s reserve of energy
20. Central Nervous System
• Spinal Cord –”information superhighway”
– Transmits messages from sensory receptors to
the brain and from the brain to muscle and
glands
• Spinal Reflex- “local government”
– Simple, unlearned response to stimulus
• Gray matter, involved in spinal reflexes
• White matter
The Reflex Arc
The Brain: Wider Than the Sky
Lecture 4.
How Do Researchers Learn About the
Functions of the Brain
• Experimenting with the brain
– Assessing damage from trauma and disease
– Intentionally damaging parts of a brain
– Electrical probes to stimulate parts of the brain
• Electroencephalograph (ECG)
– Measurement of electrical activity – brain
waves
How Do Researchers Learn About the
Functions of the Brain (continued)
• Brain-Imaging Techniques
– Computerized axial tomography (CAT or CT
scan)
– Positron emission tomography (PET scan)
– Magnetic Resonance Imaging (MRI)
– Functional Magnetic Resonance Imaging
(fMRI)
1.Structures and Functions of the Brain
• Hindbrain
– Medulla -heart rate, blood
pressure, respiration/breathing
sleeping, sneezing, coughing.
– Pons- body movements
related to attention, sleep,
alertness, respiration
– Cerebellum- balance,
controls motor behavior-e.g.,
playing guitar , walking to
refrigerator.
2. Structures and Functions of the Brain
• Reticular Activation
System
– Vital to attention,
sleep, arousal
– Injury to the RAS
results in coma
– -alcohol lowers RAS
activity
3. Structures and Functions of the Brain
• Forebrain includes the thalamus,
hypothalamus, limbic system, &
cerebrum
– Thalamus
• Relay station for sensory
stimulation
– Hypothalamus
• Regulates body
temperature, motivation
and emotion
• Hunger, thirst, sexual
behavior, caring for
offspring, aggression
4. Structures and Functions of the Brain
• Forebrain
– Limbic System,
includes the
amygdala,
hippocampus, & parts
of hypothalamus
– Involved in memory,
emotion, hunger, sex
drive, & aggression
• Amygdala- fear
Involved in memory and
emotion
5. Structures and Functions of the Brain
• Cerebrum
– Responsible for
thinking and language
– Cerebral Cortex
• Surface of
cerebrum
– Corpus Callosum
• Connects two
hemispheres
6. The Brain: Corpus Callosum
PLAY
VIDEO
7. The Cerebral Cortex
• Outer layer of
cerebrum
• Two Hemispheres
• Four Lobes
– Frontal, Parietal,
Temporal and
Occipital
8. The Lobes of the Cerebral Cortex
• Occipital Lobe
– Vision
• Temporal Lobe
– Hearing and Auditory
functions
• Parietal Lobe
– Somatosensory
Cortex, m. from skin
• Frontal Lobe
– Motor Cortex
The cerebral cortex.
Which of the following body parts is associated with the greatest amount of brain tissue in the
motor cortex?
9. Thinking, Language, and the Cortex
• Association areas
– Not primarily involved in sensation or motor
activity
– Responsible for learning, thought, memory and
language
• Association areas in frontal lobe
– Responsible for executive functions
10.Language Functions
• Two hemispheres of the brain mirror and differ
– Left hemisphere contains language functions
for nearly all people
– If damaged before age 13, speech functions
would transfer to right hemisphere
• Two key language areas
– Broca’s area & Wernicke’s area
– Damage in either causes aphasia
11. Language Functions
• Wernicke’s Area
– Temporal Lobe
– Wernicke’s aphasia
• Impairs ability to comprehend speech and
think of words to express own thoughts
• Angular Gyrus
– Translates visual into auditory information
– Damage impairs reading ability
12. Language Functions
• Broca’s Area
– Frontal Lobe
– Production of speech
– Broca’s aphasia
• Understand language but speak slowly and
laboriously
13. Left Brain, Right Brain
• Left-brained
– Logical and intellectual
• Right-brained (visual-spacial)
– Intuitive, creative and emotional
• Hemispheres do not act independently
– Exaggerated idea
14. Handedness
• Left-handed
– Somewhat greater-than-average probability of
language problems and certain health
problems
– More likely than right-handed people in gifted
artists, musicians, and mathematicians
• Origins of handedness
– Genetics
–
1 left-handed parent -80% to be right handed; 2 left-handed parents-50%
15. Split-Brain Experiments
• Severe cases of epilepsy may require split-brain
operations
• Examples of “two brain” phenomenon
– Caused by inability of one hemisphere to
communicate with the other
Evolution and Heredity:
The Nature of Nature
Darwin’s Theory of Evolution
• Struggle for existence
• Natural selection
– Species and individuals compete for same
resources
• Mutations
– Random genetic variations explain differences
– Differences which affect the ability to adapt to
change
Evolutionary Psychology
• Ways in which adaptation and natural selection
are connected with behavior and mental
processes
• Behavior patterns evolve and can be transmitted
genetically from generation to generation
– Instinctive or species specific behaviors
Evolutionary Psychology
• Instinct
– Stereotyped patterns of behavior that are
triggered in a specific situation
• Species-specific
– Resists modification, not learned
Heredity, Genetics and Behavioral Genetics
• Heredity
– Transmission of traits from parent to offspring,
based on genes
• Genetics
– Subfield of biology that studies heredity
• Behavioral Genetics
– Focuses on individual differences
Genes and Chromosomes
• Gene
– Basic unit of heredity
• Chromosomes
– Structure within cell nucleus that carry genes
– Humans have 46 chromosomes (23 pairs)
• DNA (deoxyribonucleic acid)
– Substance that forms chromosomes
– Double helix – contains genetic code
– Nucleotides - A and T, C and G
Cells, Chromosomes, and DNA
Genes and Chromosomes
• Genes regulate development of specific traits
– Some traits are determined by one gene
– Other traits are polygenic
Genes and Chromosomes
• Genotype
– Individual’s genetic makeup (nature)
• Phenotype
– Actual appearance, based on genotype and
environmental influences (nurture)
Chromosomes
• Receive 23 chromosomes from father’s sperm
and 23 chromosomes from mother’s egg cell
• 23rd pair of chromosomes are sex chromosomes
– XX – female
– XY – male
• Down syndrome
– Chromosomal abnormality
Kinship Studies
• Focus on presence of traits and behavior patterns
in people who are, or are not related biologically
• Twin studies
– Monozygotic twins
– Dizygotic twins
• Adoption studies
Left Handedness
• 8 to 10% of people are left handed
– More common in boys than girls
– More common in gifted artists than general
population
• Language and Health Problems
– Dyslexia, stuttering
– Migraine headaches, allergies
• Appears to have a genetic component
Selective Breeding
• Process used to enhance desired physical and
behavioral traits
– Done routinely with plants and animals