Transcript Chapter 2

Chapter 3
Biopsychology and the
Foundations of Neuroscience
Copyright © Allyn & Bacon 2007
What is Biopsychology?
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Biopsychology: The specialty in psychology
that studies the interaction of biology,
behavior, and mental processes
Neuroscience: Interdisciplinary field that
focuses on the brain and its role in
psychological processes
How Are Genes and
Behavior Linked?
Evolution has fundamentally
shaped psychological
processes because it favors
genetic variations that
produce adaptive behavior.
How Are Genes and
Behavior Linked?
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Innate: Inborn; present at birth; part of the
organism’s biological heritage
Evolution: The gradual process of biological
change that occurs in a species as it adapts
to its environment
Evolution and Natural Selection
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Natural selection: The driving force behind
evolution, by which the environment
“selects” the fittest organisms
How Natural Selection Works
Environmental pressure
(changes in the environment)
Competition
(for resources)
Selection of fittest phenotype
(from among a variety of phenotypes)
Reproductive success
(genotype corresponding to fittest
phenotypes passed to next generation)
Frequency of that genotype increases
(in next generation)
Genes and Inheritance
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Genotype: An organism’s genetic makeup
Phenotype: An organism’s observable
physical characteristics
Mutations: Genetic variations, which occur
randomly, especially during the
recombination of chromosomes in sexual
reproduction
Chromosomes, Genes, and DNA
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DNA: A long, complex molecule that encodes
genetic characteristics
Genes: The functional units of a chromosome
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Composed of nucleotides
Chromosomes: Tightly coiled threadlike
structures along which the genes are organized
Sex chromosomes: The X and Y chromosomes
that determine our physical sex characteristics
Genes influence our psychological
characteristics as well as our physical traits
How Does the Body
Communicate Internally?
The body’s two
communication systems, the
nervous system and the
endocrine system, both use
chemical messengers to
communicate with targets
throughout the body
The Neuron
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Types of Neurons (specialized cell
that responds to and sends signals)
• Sensory neurons: carry messages
from sense receptors towards the
CNS (afferent – approach CNS)
• Motor neurons: carry messages
from CNS toward muscles and
glands (efferent – exit CNS)
• Interneurons: carry messages
between nerve cells
The Structure of a Neuron
The Neural Impulse
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Resting potential: Electrical charge of a neuron when
it is ready to fire; it’s inactive state (-70mv)
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(+) potassium inside; (+) sodium outside; sodium wants in!
Action potential: Nerve impulse caused by a reversal
in the electrical charge across the axon (- to +)
Depolarization: sodium gates open; let sodium (+) in
 Repolarization: sodium gates close, potassium gates
open and let potassium (+) out; potassium gates
close when charge is leveled (back to -)
Refractory period: time period in which the neuron
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cannot reach its action potential; repolarizing to return
to its resting potential (polarized)
The Neural Impulse
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All-or-none principle: Action potential occurs
full blown or not at all; must cross threshold
(minimum level of stimulation needed)
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Impulses only move in one direction!!!
Synapse: Gap that serves as a communication
link between neurons
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b/w terminal buttons of one neuron and dendrites
of another neuron
Synaptic transmission: relaying of info across
the synapse by means of neurotransmitters
Plasticity and Glial Cells
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Plasticity: Ability of the nervous system to
adapt or change as the result of experience
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Sometimes helps the nervous system adapt to
physical damage
Neurons make new connections
Example - sprout new dendrites
Glial cells
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Provide structural support for neurons
Help in forming new synapses
Form myelin sheath
Cleans up dead cells
Neurotransmitters
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Neurotransmitters: Chemical messengers that
relay neural messages across the synapse
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Diffuse across synapse & connect like lock and key
Agonist: drug/chemical that enhances or mimics
the effects of NTs – facilitates messages; turns up
volume
Antagonist: drug/chemical that inhibits the effects
of NTs – blocks receptor sites; turns down volume
Reuptake: recycling of NT back into the presynaptic neuron
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Turns message volume down
SSRI – inhibits reuptake, so turns
up volume of serotonin
Reuptake in the Synapse
Neurotransmitters
Dopamine
Normal Function:
Norepinephrine
Produces sensations of
pleasure and reward; used
by CNS neurons in
voluntary movement
Acetylcholine
Problems with Imbalance:
GABA
Schizophrenia, Parkinson’s
disease
Glutamine
Substances that Affect:
Endorphins
Cocaine, amphetamines,
Ritalin, alcohol
Serotonin
Neurotransmitters
Dopamine
Serotonin
Norepinephrine
Acetylcholine
GABA
Glutamine
Endorphins
Normal Function:
Regulates sleep and
dreaming, mood, pain,
aggression, appetite and
sexual behavior
Problems with Imbalance:
Depression, certain anxiety
disorders, obsessivecompulsive disorder
Substances that Affect:
Prozac, hallucinogenics
(e.g. LSD)
Neurotransmitters
Dopamine
Serotonin
Norepinephrine
Normal Function:
Controls heart rate, sleep,
sexual responsiveness,
stress, vigilance and
appetite
Acetylcholine
Problems with Imbalance:
GABA
High blood pressure,
depression
Glutamine
Substances that Affect:
Endorphins
Tricyclic antidepressants,
beta blockers
Neurotransmitters
Normal Function:
Dopamine
Serotonin
Norepinephrine
Primary transmitter used by
neurons carrying messages
from CNS; involved in
some kinds of learning and
memory
Acetylcholine
Problems with Imbalance:
GABA
Certain muscular disorders,
Alzheimer’s disease
Glutamine
Substances that Affect:
Endorphins
Nicotine, botulism toxin,
curare, atropine
Neurotransmitters
Dopamine
Normal Function:
Serotonin
Most prevalent inhibitory
neurotransmitter in neurons
of CNS
Norepinephrine
Problems with Imbalance:
Acetylcholine
Anxiety, epilepsy
GABA
Substances that Affect:
Glutamine
Barbiturates, tranquilizers
(e.g. Valium, Librium),
alcohol
Endorphins
Neurotransmitters
Dopamine
Serotonin
Norepinephrine
Acetylcholine
Normal Function:
Primary excitatory
neurotransmitter in CNS;
involved in learning and
memory
Problems with Imbalance:
GABA
Brain damage after stroke
Glutamine
Substances that Affect:
Endorphins
PCP (“angel dust”)
Neurotransmitters
Dopamine
Serotonin
Norepinephrine
Acetylcholine
Normal Function:
Pleasurable sensations and
control of pain
Problems with Imbalance:
GABA
Lowered levels resulting
from opiate addiction
Glutamine
Substances that Affect:
Endorphins
Opiates: opium, heroin,
morphine, methadone
The Organization of the
Nervous System
Nervous system
Peripheral nervous
system
Autonomic
nervous system
Sympathetic
nervous system
Central nervous
system (CNS)
Somatic
nervous system
Parasympathetic
nervous system
The Endocrine System
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The body’s chemical messenger system
The Endocrine System
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Pituitary gland :
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Master gland
Produces hormones influencing the
secretions of all other endocrine
glands
Produces hormone that influences
growth
Attached to hypothalamus
How Does the Brain
Produce Behavior and
Mental Processes?
The brain is composed of
many specialized modules
that work together to create
mind and behavior.
Windows on the Brain
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Brain waves: Patterns of electrical activity
generated by the brain
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EEG (electroencephalograph): Records brain
waves; electrodes placed on scalp
Windows on the Brain
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Brain scans: Recordings of the brain’s electrical
or biochemical activity at specific sites
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CAT/CT (computerized tomography) – soft tissue,
structure, x-ray
PET (positron emission tomography) – activity, not
structure, detects glucose in active circuits
fMRI (magnetic resonance imaging) – moving pic.
of brain in action
The Four Lobes of the
Cerebral Cortex
Frontal lobes (AKA pre-frontal cortex):
planning, deciding, thinking, motor cortex,
personality?
Parietal lobes:
touch sensation, spatial relationships,
somatosensory cortex
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Occipital lobes:
contain visual cortex
Temporal lobes:
sounds, including speech,
auditory cortex
Three Layers of the Brain
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Brain stem structures, cerebellum, and
thalamus
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Limbic system
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Drive vital functions, such as heart rate,
breathing, digestion
Adds emotions, complex motives, increased
memory abilities
Cerebrum
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Enables reasoning, planning, creating,
problem solving
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Cerebrum :
The Cerebrum
Topmost layer of the brain; the
bulbous cap over the limbic system
Cerebral cortex :
Thin gray-matter covering of the
cerebrum; carries on thinking and
perceiving (higher-order processes)
Cerebral hemispheres :
The two walnut shaped halves of
the cerebrum, connected by the
corpus callosum
Important Areas
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Thalamus
Pons
Cerebellum
Medulla
Brain stem
Reticular
Formation
The Limbic System
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Hypothalamus –
Serves as the
brain’s bloodtesting
laboratory,
constantly
monitors blood
to determine the
condition of the
body
The Limbic System
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Amygdala –
Involved in
memory and
emotion,
particularly fear
and aggression
The Limbic System
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Hippocampus –
Involved in establishing
long-term memories
Aphasia
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The impairment of language (speech
or understanding)
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Broca’s Area – interferes w/ speech
production (frontal lobe damage)
 can understand language
 words not properly formed
 speech is slow and slurred
 some aware of deficits
Wernicke’s Area – loss of ability to
understand language (parietal/temporal)
 can speak clearly most of the time
 words put together make no sense;
word salads
 not aware of deficits
The Cooperative Brain
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Association cortex: Cortical regions that
combine information from various other
parts of the brain
Cerebral dominance: Tendency of each
brain hemisphere to exert control over
different functions
Specialization of the
Cerebral Hemispheres
Left Hemisphere
Right Hemisphere
• Spontaneous
speaking and
writing
• Responses to
complex commands
• Word rec./ speech
• Memory for words
and numbers
• Sequences of
movements
• Feelings of anxiety
• Positive emotion
• Repetitive but not
spontaneous
speaking
• Responses to simple
commands
• Facial recognition
• Memory for shapes
and music
• Spatial interpretation
• Emotional
responsiveness
• Negative emotion
The Split Brain
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Split-brain patients:
Individuals who have had
the corpus callosum
surgically severed
Duality of consciousness:
Condition in which a splitbrain patient has a
separate consciousness in
each hemisphere