Psych i chap2 ppt

Copyright © Allyn & Bacon 2006

Biology and Behavior

Chapter Two

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• Preparation of any derivative work, including the extraction, in whole or in part, of any images;

• Any rental, lease, or lending of the program.Slide author:

Cynthia K. Shinabarger Reed

Book authors:

Samuel Wood

Ellen G. Wood

Denise Boyd


Chapter Two Overview

The Neurons and the Neurotransmitters

• The Neurons• Neurotransmitters• The Variety of Neurotransmitters



The Central Nervous System• The Spinal Cord• The Brainstem• The Cerebellum• The Midbrain• The Thalamus and Hypothalamus• The Limbic System



The Cerebrum• Components of the Cerebrum• The Frontal Lobes• The Parietal Lobes• The Occipital Lobes• The Temporal Lobes


Chapter Two OverviewThe Cerebral Hemispheres

• The Left Hemisphere• The Right Hemisphere• The Split Brain• Handedness, Culture, and Genes

Discovering the Brain’s Mysteries• The EEG and the Microelectrode• The CT Scan and Magnetic Resonance Imaging• The PET Scan, fMRI, and Other Imaging

Techniques



The Brain Across the Lifespan• The Ever-Changing Brain• Aging and Other Influences on the Brain

The Peripheral Nervous SystemThe Endocrine SystemGenes and Behavioral Genetics

• The Mechanisms of Heredity• Behavioral Genetics


Neurons and the NeurotransmittersNeuron

• A neuron is a specialized cell that conducts impulses through the nervous system.

• Afferent (sensory) neurons relay messages from the sense organs and receptors – eyes, ears, nose, mouth, and skin – to the brain or spinal cord.

• Efferent (motor) neurons convey signals from the central nervous system to the glands and the muscles, enabling the body to move.

• Interneurons carry information between neurons in the brain and between neurons in the spinal cord.


Neurons and the Neurotransmitters

• Anatomy of a Neuron– Cell body (soma)

• The part of the neuron that contains the nucleus and carries out the neuron’s metabolic functions

– Dendrites• The branch-like extensions of a neuron that

receive signals from other neurons• Back propagating

–When dendrites relay messages from the cell body to their own branches



• Anatomy of a Neuron continued– Axon

• The slender, tail-like extension of the neuron that transmits signals to the dendrites or cell body of the other neurons or to muscles or glands




Neurons and the Neurotransmitters• Glial cells

– Specialized cells in the brain and spinal cord that hold the neurons together, remove waste products such as dead neurons, and perform other manufacturing, nourishing, and cleanup tasks

• Synapse– The junction where the axon terminal of a

sending neuron communicates with a receiving neuron across the synaptic cleft


Neurons and the NeurotransmittersThe Neural Impulse• Permeability

– The capability of being penetrated or passed through

• Resting potential– The slight negative electrical potential of the

axon membrane of a neuron at rest, about -70 millivolts

• Action potential– The sudden reversal of the resting potential,

which initiates the firing of a neuron



The Neural Impulse (continued)• “All or none” law

– A neuron either fires completely or does not fire at all

• Refractory period– A period immediately after a neuron fires

in which it cannot fire again for 1 to 2 milliseconds


Neurons and the Neurotransmitters• The Rate of Neural Firing and the Speed of the

Impulse – A weak stimulus may cause few neurons to fire and

at a slow rate– A strong stimulus may cause thousands of neurons

to fire at the same time and at hundreds of times per second

– Impulses travel at speeds from about 1 meter per second to approximately 100 meters per second

– The most important factor in the speed of the impulse is the myelin sheath



• Myelin sheath– The white, fatty coating wrapped

around some axons that acts as insulation

– The myelin sheath has gaps called nodes of Ranvier

– Multiple sclerosis involves deterioration of the myelin sheath



• Neurotransmitter– A chemical that is released into the synaptic

cleft from the axon terminal of a sending neuron, crosses a synapse, and binds to appropriate receptor sites on the dendrites or cell body of a receiving neuron, influencing the cell either to fire or not to fire

• Receptors– Protein molecules on the surfaces of

dendrites and cell bodies


Synaptic TransmissionCopyright © Allyn & Bacon 2006


Neurons and the NeurotransmittersAction of neurotransmitters

Excitatory neurotransmitter–A substance that facilitates and speeds

up the transmission of neural impulses from one neuron to another

Inhibitory neurotransmitter–Prevent or slow down the transmission

of neural impulses across the synaptic cleft



How synaptic vesicles can continually pour out neurotransmitters• The cell body of the neuron is always working

to manufacture more of the neurotransmitter substance

• Unused neurotransmitters in the synaptic cleft may be broken down into their component molecules and reclaimed by the axon terminal to be recycled and used again



How synaptic vesicles can continually pour out neurotransmitters (continued)

• Reuptake– The process by which neurotransmitter

molecules are taken from the synaptic cleft back into the axon terminal for later use, thus terminating their excitatory or inhibitory effect on the receiving neuron


Neurons and the NeurotransmittersThe Variety of Neurotransmitters

– Acetylcholine• A neurotransmitter that exerts excitatory

effects on the skeletal muscle fibers, causing them to contract so that the body can move and has an inhibitory effect on the muscle fibers in the heart, which keeps the heart from beating too rapidly


Neurons and the Neurotransmitters• Neurotransmitters called monoamines

– Dopamine: produces both excitatory and inhibitory effects and is involved in learning, attention, movement, and reinforcement

– Norepinephrine: affects eating habits and plays a major role in alertness and wakefulness

– Epinephrine: affects the metabolism of glucose and energy stored in muscles to be released during exercise

– Serotonin: plays an important role in regulating mood, sleep, impulsivity, aggression, and appetite



Amino acids that serve as neurotransmitters– Glutamate: Primary excitatory neurotransmitter

in the brain; it is active in areas of the brain involved in learning, thought, and emotions

– GABA (gamma-aminobutryic acid): Main inhibitory neurotransmitter in the brain; it is thought to facilitate the control of anxiety

– Endorphins: substances that provide relief from pain or the stress of vigorous exercise and produce feelings of pleasure and well-being


Central Nervous System

• Two parts of a nervous system–Central nervous system

• The brain and the spinal cord–Peripheral nervous system

• Connects the central nervous system to all other parts of the body


Divisions of the Human Nervous System



Central Nervous System• Spinal cord

– A cylinder of neural tissue about the diameter of your little finger

– It reaches from the base of the brain through the neck and down the hollow center of the spinal column

– It transmits messages between the brain and the peripheral nervous system

• Brain structures– Hindbrain (brainstem)– Midbrain– Forebrain


Major Structures of the Human BrainCopyright © Allyn & Bacon 2006


Central Nervous SystemBrainstem: The part of the hindbrain that begins

at the site where the spinal cord enlarges as it enters the skull Medulla: The part of the brainstem that

controls heartbeat, blood pressure, breathing, coughing, and swallowing

Reticular formation (reticular activating system): A structure in the brainstem that plays a crucial role in arousal and attention and that screens sensory messages entering the brain

Pons: A structure in the brainstem that plays a role in body movement and even exerts an influence on sleep and dreaming



CerebellumThe brain structure that executes smooth,

skilled body movementsRegulates muscle tone and postureBeen found to play a role in retaining

memories of motor activitiesSome studies suggest it is involved in

cognitive and social functions as well as motor functions


Central Nervous SystemMidbrain

The structures of this brain region act primarily as relay stations through which the basic physiological functions of the hindbrain are linked to the cognitive functions of the forebrain

Substantia nigra: The midbrain structure that controls unconscious motor movements



The Limbic System–A group of structures in the brain,

including the thalamus, hypothalamus, amygdala and hippocampus, that are collectively involved in emotion, memory, and motivation


Central Nervous SystemCopyright © Allyn & Bacon 2006



The Limbic System• Thalamus

– The structure, located above the brainstem, that acts as a relay station for information flowing into or out of the forebrain

– Affects our ability to learn new verbal information and plays a role in the production of language

– Regulates sleep cycles


Central Nervous System• Hypothalamus

– Regulates the pituitary gland and regulates hunger, thirst, sexual behavior, body temperature, and a wide variety of emotional behaviors

• Amygdala– A structure in the limbic system that plays an

important role in emotion, particularly in response to unpleasant or punishing stimuli

• Hippocampus– A structure in the limbic system that plays a

central role in the storing of new memories, the response to new and unexpected stimuli and navigational ability


Cerebrum• Cerebrum: the largest structure of the

human brain, consisting of the two cerebral hemispheres connected by the corpus callosum and covered by the cerebral cortex

• Cerebral hemispheres: the right and left halves of the cerebrum, covered by the cerebral cortex and connected by the corpus callosum; they control movement and feeling on the opposing sides of the body


Cerebrum

• Corpus callosum– The thick band of nerve fibers that

connects the two cerebral hemispheres and makes possible the transfer of information and the synchronization of activity between them


Cerebrum• Cerebral cortex

– The gray, convoluted covering of the cerebral hemispheres that is responsible for higher mental processes including language, memory, and thinking

– Referred to as gray matter– Andreason and others

• Indicated that the amount of gray matter is positively correlated with human intelligence

– Convolutions• The numerous folds or wrinkles in the cortex


Two Views of the Cerebral HemispheresCopyright © Allyn & Bacon 2006


Cerebrum• Three types of areas of the cerebral cortex

– Sensory input areas: where vision, hearing, touch, pressure, and temperature register

– Motor areas: control voluntary movement– Association areas: house memories and

are involved in thought, perception, and language

• In each cerebral hemisphere there are four lobes – the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe


Cerebrum

• Frontal lobes–The largest of the brain’s lobes–Contains the motor cortex, Broca’s

area, and the frontal association areas


Cerebrum• Motor cortex

– The strip of tissue at the rear of the frontal lobes that controls voluntary body movement

– Discovered by Fritsch and Hitzig– The right motor cortex controls

movement on the left side of the body, and the left motor cortex controls movement on the right side of the body


Cerebrum

• Motor Cortex (continued)– Wilder Penfield

• Applied electrical stimulation to the motor cortex of conscious human patients undergoing neurosurgery

• Mapped the primary motor cortex in humans


Cerebrum

• Motor Cortex (continued)– Plasticity

• The brain’s capacity to adapt to changes such as brain damage

• Plasticity of the motor cortex is maintained throughout life


Cerebrum• Broca’s area

– The area in the left hemisphere that is responsible for the production of speech sounds

– Paul Broca• Among the first scientists to

demonstrate the existence of localized functions in the cerebral cortex; concluded that the site of damage was the part of the brain responsible for speech production


Cerebrum• Broca’s area (continued)

– Aphasia: a loss or impairment of the ability to understand or communicate through the written or spoken word, that results from damage to the brain• Broca’s aphasia: an impairment in the

physical ability to produce speech sounds, or, in extreme cases, an inability to speak at all


Cerebrum

• Frontal association areas–Consists of association areas

involved in thinking, motivation, planning for the future, impulse control, and emotional responses


Cerebrum• Parietal lobes

– The lobes that contain the somatosensory cortex and other areas that are responsible for body awareness and spatial orientation

– Somatosensory cortex• The strip of tissue at the front of the

parietal lobe where touch, pressure, temperature, and pain register in the cerebral cortex


Cerebrum• Occipital lobes

– The lobes that contain the primary visual cortex and association areas involved in the interpretation of visual information

– Primary visual cortex• The area at the rear of the occipital lobes where

vision registers in the cerebral cortex• Each eye is connected to the primary visual cortex

in both right and left occipital lobes• The association areas in the occipital lobes are

involved in the interpretation of visual stimuli


Cerebrum• Temporal lobes

– The lobes that are involved in the reception and interpretation of auditory stimuli

– Primary auditory cortex• The part of the temporal lobes that

receives sound inputs from both ears


Cerebrum• Wernicke’s area

–The language area in the temporal lobe involved in comprehension of the spoken word and in formulation of coherent speech and written language


Cerebrum– Wernicke’s aphasia

• Aphasia that results from damage to Wernicke’s area and in which the person’s spoken language is fluent and articulate, but the actual message does not make sense to listeners

• Another kind of aphasia is auditory aphasia, word deafness


Cerebrum

• Temporal association areas–House memories and are involved

in the interpretation of auditory stimuli

–There is a special association area where familiar melodies are stored


The Cerebral Hemispheres

• Lateralization– The specialization of one of the cerebral

hemispheres to handle certain functions• Left hemisphere

– The hemisphere that controls the right side of the body, coordinates complex movements, and, in 95% of right-handers and 62% of left-handers, controls most functions of speech and written language


The Cerebral Hemispheres• Right hemisphere

– The hemisphere that controls the left side of the body and that, in most people, is specialized for visual-spatial perception and interpreting nonverbal behavior

– The right hemisphere also augments the left hemisphere’s language-processing activities

– Unilateral neglect: Patients with right hemisphere damage may have attentional deficits and be unaware of objects in the left visual field


The Cerebral Hemispheres• Right hemisphere’s role in emotion

– The right hemisphere responds to the emotional message conveyed by another’s tone of voice

– It is also involved in the expression of emotion through tone of voice and facial expressions

– Controls the left side of the face, which usually conveys stronger emotion than the right side of the face

– Lawrence Miller• Describes the facial expressions and the

voice inflection of people with right hemisphere damage as “often strangely blank–almost robotic”


The Cerebral Hemispheres• The Split brain

– Split-brain operation• An operation in which the corpus callosum is

cut, separating the cerebral hemispheres and usually lessening the severity and frequency of grand mal seizures

– Joseph Bogen and Philip Vogel• Found that patients with severe epilepsy could

be helped by surgery that severed their corpus callosum, rendering communication between the two hemispheres impossible


The Cerebral Hemispheres• Split brain (continued)

– Roger Sperry, Michael Gazzaniga, and Jerre Levy• Their research with split-brain patients has

expanded knowledge of the unique capabilities of the individual hemispheres

– Roger Sperry• Found that when the brain was surgically

separated, each hemisphere continued to have individual and private experiences, sensations, thoughts, and perceptions


The Cerebral Hemispheres

• Testing the Split-Brain Patient– Roger Sperry 1981 Nobel Prize

research– The right hemisphere knows and

remembers what it sees just as well as the left, but, unlike the left hemisphere, the right cannot name what it has seen


The Cerebral Hemispheres• Handedness, culture, and genes

– The corpus callosum of left-handers is 11% larger and contains up to 2.5 million more nerve fibers than that of right-handers

– In general, the two sides of the brain are less specialized in left-handers

– Left-handers tend to experience less language loss following an injury to either hemisphere

– Left-handers tend to have higher rates of learning disabilities and mental disorders than right-handers


The Cerebral Hemispheres• Handedness, culture, and genes (continued)

– Studies of ancient populations show that the proportions of left- and right-handers in the human population has been about the same for several thousand years

– Cross-cultural studies show that right-handedness is typically characterized as normal, while left-handedness is associated either with evil or exceptional abilities

– Hepper and others report that of the human fetuses they observed, 94.6% were sucking their right thumb and only 5.4% were sucking their left thumb


Discovering the Brain’s Mysteries• Electroencephalogram (EEG)

– Invented by Hans Berger– The electroencephalograph is a machine that records

the electrical activity occurring in the brain• Beta wave

– The brain wave associated with mental or physical activity

• Alpha wave– The brain wave associated with deep relaxation

• Delta wave– The brain wave associated with slow-wave (deep) sleep


Discovering the Brain’s Mysteries• Microelectrode

– An electrical wire so small that it can be inserted near or into a single neuron without damaging it

– Can be used to monitor the electrical activity of a single neuron or to stimulate activity within it

– Used to discover the exact functions of single cells within the primary visual cortex and the primary auditory cortex


Discovering the Brain’s Mysteries

• CT scan (computerized axial tomography)– A brain-scanning technique involving a

rotating computerized X-ray tube to produce cross-sectional images of the structures of the brain

• MRI (magnetic resonance imagery)– A diagnostic scanning technique that

produces high-resolution images of the structures of the brain without exposing patients to potentially dangerous X-rays


Discovering the Brain’s Mysteries

• PET scan (positron-emission tomography)– A diagnostic scanning technique that

maps the patterns of blood flow, oxygen use, and glucose consumption

• Functional MRI (fMRI)– A brain-imaging technique that reveals

both brain structure and brain activity


Discovering the Brain’s Mysteries• SQUID (superconducting quantum

interference device)– Images brain activity by measuring

magnetic changes produced by the electric current neurons discharge when they fire

• MEG (magnetoencephalography)– Measures magnetic changes and

shows neural activity within the brain as rapidly as it occurs


The Brain Across the LifespanThe Ever-Changing Brain• Synaptogenesis

– Process where synapses develop as a result of growth of both dendrites and axons

– Pruning• The process through which the developing brain

eliminates unnecessary or redundant synapses• Myelination

– The development of myelin sheaths around axons; begins prior to birth but continues well into adulthood


The Brain Across the Lifespan• Hemispheric specialization

– Some degree of hemispheric specialization is present very early in life

– Language processing occurs primarily in the left hemisphere in the fetal brain and in the adult brain

– Spatial perception is not lateralized until around the age of 8

• Plasticity– The ability of the brain to reorganize, to reshape

itself in response to input from both internal and external sources, and to compensate for damage


The Brain Across the Lifespan• Aging and Other Influences on the Brain

– The brain both gains and loses synapses throughout life

– Brain weight begins to decline around age 30– Gray matter, but not white matter, is lost with

normal aging in both hemispheres of the cerebellum

– At every age, the brain is influenced by experience as well as by the presumably genetically-programmed maturational process

– Brain damage can lead to significant changes in brain function


The Brain Across the Lifespan• Stroke

– The most common cause of damage to adult brains, arising when blockage of an artery cuts off the blood supply to a particular area of the brain or when a blood vessel bursts

– A high percentage of stroke survivors suffer from depression

– Patients who receive TPA (a blood clot-dissolving drug) within 3 hours of the onset of a stroke are 30% more likely to have minimal or no disability


The Peripheral Nervous System• Peripheral nervous system (PNS)

– The nerves connecting the central nervous system to the rest of the body

– Contains two subdivisions• Somatic division• Autonomic division – contains two

divisions–Sympathetic division (activates)–Parasympathetic division (inhibits)


The Human Nervous SystemCopyright © Allyn & Bacon 2006


The Peripheral Nervous System

• Somatic division– Consists of all the sensory nerves, which

transmit information from the sense receptors—eyes, ears, nose, tongue, and skin—to the central nervous system

– Consists of all the motor nerves, which relay messages from the central nervous system to all the skeletal muscles of the body


The Peripheral Nervous System

• Autonomic division– Operates without any conscious control

or awareness on your part– Transmits messages between the

central nervous system and the glands, the cardiac muscle, and the smooth muscles that are not normally under voluntary control


The Peripheral Nervous System• Autonomic division (continued)

– Divided into two parts

• Sympathetic nervous system– Mobilizes the body’s resources during stress

and emergencies, preparing the body for action

– Named the fight-or-flight response by Walter Cannon

• Parasympathetic nervous system– brings the heightened bodily responses back

to normal following an emergency


Endocrine System• Endocrine system

– A system of ductless glands located in various parts of the body that manufacture and secrete hormones into the bloodstream, thus affecting cells in other parts of the body

– Hormones• A substance manufactured and released in

one part of the body that affects other parts of the body

• Some of the same chemical substances that are neurotransmitters act as hormones as well


Endocrine SystemCopyright © Allyn & Bacon 2006


Endocrine System• Pituitary gland

– The endocrine gland located in the brain just below the hypothalamus

– often called the “master gland,” because it releases hormones that activate the other endocrine glands

– also releases a growth hormone• Thyroid gland

– Produces the important hormone thyroxin, which regulates the rate at which food is metabolized


Endocrine System• Pancreas

– Regulates the body’s blood sugar levels by releasing the hormones insulin and glucagon into the bloodstream

• Adrenal glands– Produce epinephrine and norepinephrine– Activates the sympathetic nervous system– Release the corticoids, which control the salt

balance in the body– Release small amounts of the sex hormones


Endocrine System

• Gonads– Sex glands; the ovaries in females and

the testes in males– Release the sex hormones that make

reproduction possible and that are responsible for the secondary sex characteristics


Genes and Behavioral Genetics

• Genes– Segments of DNA located on the

chromosomes and are the basic units for the transmission of all hereditary traits

– Genes carry all the genetic information needed to make a human being

– The Human Genome Project is aimed at identifying the functions of all the genes and their locations on the chromosomes



• Chromosomes– structures in the nuclei of body cells that

contain all the genes and carry all the hereditary information

• Zygote– A single cell formed from the union of 23

chromosomes from the male’s sperm and 23 chromosomes from the female’s egg


Genes and Behavioral Genetics• Autosomes

– Matching pairs of chromosomes– 22 of the 23 pairs of chromosomes are

autosomes• Sex chromosomes

– The 23rd pair of chromosomes that carry the genes that determine a person’s sex

– Sex chromosomes of females consist of two Xs (XX)

– Sex chromosomes of males consist of one X and one Y (XY)


Genes and Behavioral Genetics• Dominant-recessive pattern

– A pattern of inheritance in which the presence of a single dominant gene causes a trait to be expressed, but two genes must be present for the expression of a recessive trait

• Homozygous– A person who carries two copies of the same

gene• Heterozygous

– A person who carries two different genes



• Polygenic inheritance– Many genes influence a particular

characteristic• Multi-factorial inheritance

– A pattern of inheritance in which a trait is influenced by both genes and environmental factors


Genes and Behavioral Genetics• Sex-linked inheritance

– Involves the genes on the X and Y chromosomes

– In females, if one chromosome carries a harmful gene, the other usually has a gene that offsets its effects

– In males, if the single X chromosome carries a harmful gene, there is no offsetting gene on the Y chromosome because it is very small and carries only the genes needed to create the male body type


Genes and Behavioral Genetics• Behavioral genetics

– A field of research that investigates the relative effects of heredity and environment on behavior

– Behavioral geneticists study identical (monozygotic) twins and fraternal (dizygotic) twins to determine how much they resemble each other on a variety of characteristics

– Found that genes clearly contribute to individual difference in both intelligence and personality

– Also found that environmental factors influence these characteristics as well


Review of Learning ObjectivesThe Neurons and Neurotransmitters

1. How are messages transmitted through the nervous system?

2. What are neurotransmitters, and what do they contribute to nervous system functioning?

3. What are the functions of some of the major neurotransmitters?


Review of Learning Objectives

The Central Nervous System1. Why is an intact spinal cord important

to normal functioning?2. What are the crucial functions handled

by the brainstem?3. What are the primary functions of the

cerebellum?



The Central Nervous System (continued)4. What important structure is located in

the midbrain?5. What are the functions of the thalamus

and the hypothalamus?6. How does the limbic system influence

mental processes and behavior?



The Cerebrum1. What are the components of the cerebrum?2. Which psychological functions are

associated with the frontal lobes?3. What is the somatosensory cortex, and what

does it do?4. Why are the occipital lobes critical to vision?5. What are the major areas within the temporal

lobes, and what are their functions?


Review of Learning ObjectivesThe Cerebral Hemispheres

1. What are the specialized functions of the left hemispheres?

2. What are the specialized functions of the right hemispheres?

3. What do researchers mean by the term “split brain”?

4. How are handedness and brain function related?


Review of Learning ObjectivesDiscovering the Brain’s Mysteries

1. What does the electroencephalogram (EEG) reveal about the brain?

2. How are the CT scan and MRI helpful in the study of brain function?

3. How are the PET scan and newer imaging techniques used to study the brain?



The Brain across the Lifespan1. In what ways does the brain change

across the lifespan?2. How do aging, learning, and stroke-

related damage affect the brain?



The Peripheral Nervous System1. What is the difference between the

sympathetic and parasympathetic nervous systems?

The Endocrine System1. What functions are associated with the

various glands of the endocrine system?



Genes and Behavioral Genetics1. What patterns of inheritance are

evident in the transmission of genetic traits?

2. What kinds of studies are done by behavioral geneticists?

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Psych i chap2 ppt