copyright © houghton mifflin company. all rights reserved. 2–12–1 chapter two biological...

Copyright © Houghton Mifflin Company. All rights reserved. 2–1

Chapter Two

Biological Foundations of

Behavior


Did You Know That…

• Some cells in your nervous system are more than three feet long?

• Our bodies produce natural painkillers that are chemically similar to morphine and other narcotic drugs?

• Fetuses not only suck their thumbs in the womb, but that 95% of them suck their right thumbs?


Did You Know That… (cont.)

• Though a man survived an accident in which a thick metal rod was driven right through his skull, his personality changed so much that people thought he was no longer himself?

• Men’s and women’s bodies produce both male and female sex hormones?


Did You Know That… (cont.)

• Scientists have deciphered the entire human genetic code and posted it on the Internet?

• Raising the body temperature of a finger may relieve the pain of a migraine headache?


Module 2.1

Neurons: The Body’s Wiring


Module 2.1 Preview Questions

• What is a neuron?• What are the parts of a neuron?• What are the types of neurons and types of

cells found in the nervous system?• How is a neural impulse generated and

transmitted from one neuron to another?• What roles do neurotransmitters play in

psychological functioning?


Figure 2.1: The Neuron


Types of Neurons

• Sensory neurons (or “afferent neurons”)

• Motor neurons (or “efferent neurons”)

• Interneurons (or “associative neurons”)


Figure 2.2: An Action Potential


Figure 2.3: How Neurons Communicate


Preventing the Continued Stimulation of Postsynaptic Neurons

• Reuptake• Enzymes in the synapse• Release of neuromodulators


Neurotransmitters

• Normal functioning requires a balance

• Disorders may result from:– Neurotransmitter excess– Neurotransmitter deficit– Irregularities in functioning

• Influenced by drugs– Antagonists– Agonists


Types of Neurotransmitters

• Acetylcholine

• Dopamine

• Glutamate

• GABA

• Serotonin

• Norepinephrine

• Endorphins


Module 2.2

The Peripheral Nervous System: Your Body’s Link to the

Outside World



• How is the nervous system organized?• How is the peripheral nervous system

organized?• What is the autonomic nervous system?• What is the relationship between the

sympathetic and parasympathetic divisions of the autonomic nervous system?


Figure 2.4: Parts of the Nervous System


Figure 2.5: Opposing Effects of Sympathetic and Parasympathetic Nervous Systems


Module 2.3

The Central Nervous System: Your Body’s Master Control Unit



• What are spinal reflexes?• How is the brain organized, and what are the

functions of its various parts?• How is the cerebral cortex organized?• What are the major functions associated with

the four lobes of the cerebral cortex?


Central Nervous System

• Brain

– Hindbrain

– Midbrain

– Forebrain

• Spinal Cord


The Spinal Cord

• Column of nerves extending from brain, protected by spine.

• Reflex: Automatic, unlearned response to particular stimuli.

• Spinal Reflex: A reflex controlled at the level of spinal cord.


Figure 2.6a: The Knee-Jerk Reflex


Figure 2.6b: The Withdrawal Reflex


Figure 2.7: The Brainstem


Figure 2.8: The Size of the Cerebral Cortex in Humans and Other Animals


Figure 2.9:Lobes of the Cerebral Cortex


Figure 2.10: Somatosensory Cortex and Motor Cortex


Module 2.4

Methods of Studying the Brain



• What recording and imaging techniques are used to study brain functioning?

• What experimental methods do scientists use to study brain functioning?


Recording and Imaging Techniques

• EEG (electroencephalograph)

• CT (computed tomography) scan

• PET (positron emission tomography) scan

• MRI (magnetic resonance imaging)

• fMRI (functional MRI)


Experimental Methods

• Lesioning

• Electrical recording

• Electrical stimulation


Module 2.5

The Divided Brain: Specialization of Function



• What are the major differences between the left and right hemispheres?

• What determines handedness?• What can we learn about brain lateralization

from studies of “split-brain” patients?• What are the major causes of brain damage,

and what effects do they have on psychological functioning?


Lateralization of Brain Functions

• Lateralization refers to division of functions between right and left hemispheres.

• Left hemisphere dominant for language abilities, logical reasoning, and problem solving.

• Right hemisphere dominant in nonverbal processing.

• People are not “left-brained” or “right-brained.”


Figure 2.16:Broca’s and Wernicke’s Areas


What Determines Handedness?

• Genetics factors– Neither parent left handed: Odds are 1 in 50– One parent left-handed: Odds are 1 in 6– Both parents left-handed: Odds are 1 in 2

• Social factors• Prenatal hormones


Split-Brain Research

• Severing the corpus callosum as treatment for severe epilepsy.

• Split-brain patients retain intellect and personality.

• But differences in perception, language evident in special testing circumstances.


Figure 2.17: Split-Brain Study


Figure 2.17: Split-Brain Study (cont’d)


Brain Damage and Psychological Functioning

• Case of Phineas Gage: prefrontal cortex damage

• Head trauma– Laceration– Concussion

• Stroke (cerebrovascular accident, CVA)

• Plasticity


Module 2.6

The Endocrine System: The Body’s Other Communication System



• What are the major endocrine glands?• What roles do hormones play in behavior?


Endocrine System

• Also a communication system in the body.• Messages conveyed through blood vessels

using hormones.• Regulates important bodily processes.• Helps body to maintain homeostasis.


Figure 2.19: Major Glands of the Endocrine System


Hormones and Behavior

• Testosterone and aggression

• Thyroid hormones and metabolism– Excess: anxiety and irritability– Deficit: sluggishness

• Premenstrual syndrome (PMS)


Module 2.7

Genes and Behavior: A Case of Nature and Nurture



• What roles do genetic factors play in behavior?

• What are the methods used to study genetic influences on behavior?


Genetic Influences on Behavior

• The nature-nurture problem• Genotype: An organism’s genetic code.• Phenotype: The observable physical and

behavioral characteristics of the organism.• Genetic and environmental influences interact

in complex ways to shape our personality.


Kinship Studies

• Rationale: to distinguish the roles of heredity and environment in behavior

• Types:– Familial association studies– Twin studies

• Identical (MZ) vs. fraternal (DZ) twins• Concordance rates

– Adoptee studies


Figure 2.20: Genetic Overlap Among Family Members


Figure 2.21:Familial Risk in Schizophrenia


Module 2.8

Application: Biofeedback Training: Learning by Listening to the Body



• What is biofeedback training?


Biofeedback Training (BFT)

• Monitoring equipment provides information about internal functioning such as:– Heart rates– Blood pressure– Muscle tension– Temperature

• Through feedback, gain some degree of conscious control over physiological functioning.

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