1. The Biological Bases of Behavior (Chapters 2 and 4)
AP Psychology Unit 2:
The Biological Bases of Behavior (Chapters 2 and 4)

2. An Early History of Biopsychology
Plato: the mind is located in the brain
Franz Gall and Phrenology
Early 1800s
Read bumps on skull to understand traits
Touch my sexy head lumps. Go on….touch them!

3. Biopsychology Today
Everything we do is ultimately controlled by our body and brain
Body/brain composed of cells
Brain cells called neurons communicate electrically and chemically
Different parts of the brain have specific functions
Our brains create meaningful experiences from sensory information
Brain structure and function is influenced by experience

4. Neurons: Defining and Types
A NEURON is a nerve cell.
There are three basic types of neurons (diagram):
Sensory Neurons: Afferent neurons that detect stimuli from sense organs and relay this information TO the brain and/or spinal cord.
Motor Neurons: Efferent neurons that receive signals from the brain and/or spinal cord and relay this information to glands and muscles.
Interneurons: neurons in the brain and spinal cord that coodinate activity between sensory and motor neurons.
Three Types of Neurons in action!
Glial Cells: provide nutrients to neurons, insulate neurons, and remove debris when neurons die.

5. Neuroanatomy (diagram)

6. The Neural Impulse (diagram)
Intraneural transmission: within on neuron
This is an ELECTRICAL process
Occurs as a result of the exchange of charged particles called ions

7. Neural Impulse: Resting Potential
When more negative ions are inside the neuron than outside
Neuron is not transmitting information
Similar to a compressed spring
The neuron is POLARIZED – meaning it has a charge (-)
System WANTS to reach equilibrium and balance charges, but selectively permeable membrane is closed when in this state known as resting potential

8. Neural Impulse: Action Potential
Sudden, massive change in charge in the neuron
Neuron reaches the threshold of excitation when neighboring neurons’ excitatory signals outnumber inhibitory signals
Ions flow across cell membrane down axon (domino effect) facilitated by myelin sheath
Na+ in, K+ out
Neuron fires and DEPOLARIZES – no charge

9. Neural Impulse: All-or-None Law
A neuron either fires or it does not
When it does fire, it will always produce an impulse of the same strength
Intensity of a stimulus is coded by the frequency of action potentials or the number of neurons that fire

10. Neural Impulse: Refractory
Absolute refractory period
Period immediately after an action potential when another action potential cannot occur
Relative refractory period
Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse
During the refractory period, the neuron is trying to get back to resting potential by pumping out K+ ions!

11. So…? Impulse has traveled down the length of the axon
Signal end up at terminal buttons, very end points of the axon terminals
Then what?
Signal must get to other neurons, but how?

12. The Synapse (diagram) The synapse Synaptic space (synaptic cleft)
Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron
Synaptic space (synaptic cleft)
Tiny gap between neurons
Messages must travel across the space to get from one neuron to the next

13. Transmission Between Neurons
Presynaptic
Neuron
Interneural: between neurons
a CHEMICAL process
Synaptic vesicles
Sacs in terminal button that release chemicals into synaptic space
Neurotransmitters
Chemicals released by synaptic vesicles
Receptor sites
Location on receptor neuron for specific neurotransmitter
Lock and key
Reuptake
“Recycling” neurotransmitters
Postsynaptic
Neuron

14. Putting it together…

15. Neurotransmitters and Behavior (diagram)
Neurotransmitters regulate many aspects of behavior
An imbalance of neurotransmitters may cause maladaptive behavior
Neurotransmitters may be inhibitory, excitatory or both

16. Drugs and Neurotransmitters
Drugs’ impact on the body has helped scientists discover neurotransmitters, neuropeptides (e.g. amino acids such as endorphins) and neuromodulators that can increase or decrease the activity of certain neurotransmitters
How do drugs work?
Agonists mimic or prevent reuptake (1, 3)
Antagonists block neurotransmission (2)

17. Psychopharmacology Botulism
Blocks release of ACh at the neuromuscular junction, causing paralysis
“Botox” is botulism toxin used to prevent facial muscles from making wrinkles
Curare – found in vines in S. America; used as poison
Can stun or kill prey quickly
Blocks ACh receptors causing paralysis
Antipsychotic medications
Block dopamine receptors
Reduces schizophrenic hallucinations
Caffeine
Increases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosine
Cocaine
Prevents reuptake of dopamine
Leads to heightened arousal of entire nervous system

18. The Nervous System (diagram)

19. The Autonomic Nervous System (diagram)
Fight-or-flight response
Sympathetic: Arouses
Parasympathetic: Calms

20. Central Nervous System (CNS)
Brain
Spinal Cord
Brain
Enables all functioning
Billions of neurons and their connections
These neurons work together in neural networks to facilitate efficient output.
As we learn, these networks strengthen
Spinal Cord
Connects brain to PNS
Handles reflexes
I rule.

21. The Endocrine System (diagram)
Tell me about it!
I hate being naked in front of all these students…
Helps coordinate and integrate complex psychological reactions
Endocrine glands secrete hormones into the bloodstream
Hormones serve to organize the nervous system and body
Hormones also activate behavior, such as sexual behavior, hunger and aggression

22. Endocrine Glands (diagram)
Dunno.
Got diabeeetus?
Endocrine Glands (diagram)
diabeetusfetus
Thyroid gland
Secretes hormones (primarily thyroxin) that control metabolism
Hypothyroidism and Hyperthyroidism
Pineal gland
Sleep-wake cycle
Secretes melatonin
Pancreas
Regulates blood-sugar levels
Secretes insulin
Diabetes?
Pituitary gland
Referred to as the “master gland”
regulates many other glands
Adrenal glands
Reaction to stress
Secretes adrenaline (epinephrine)
Gonads
Ovaries and testes
secrete estrogens and androgens

23. The Brain Without our brains, we would really be nothing!
“The mind is what the brain does”

24. Studying the Brain Studying the brain through lesions or damaged areas
“Ta” and Phineas Gage
Experiments in rats – hypothalamus lesions
Monitoring Electrical Activity: the EEG
Electroencephalograms provide information about cortical activity
Record electrical activity of neurons on surface of brain (neural firing)
A functional technique

25. Studying the Brain: Structural Neuroimaging Techniques
CT Scan (Computerized tomography)
Computer-assisted x-ray of brain
Used to create overall images of brain
MRI (Magnetic Resonance Imaging)
Produces detailed pictures of soft tissue in brain
Can focus on specific regions when CT cannot produce clear images
CT scan (top) and MRI (bottom) showing a tumor.

26. Studying the Brain: Functional Neuroimaging Techniques
PET (positron emission tomography)
Image created by the rate at which radioactive glucose is metabolized
Which areas of the brain are active during a particular activity
fMRI (functional MRI)
Combines structural and functional techniques
Multiple images of brain created during a particular task
Records changes in blood flow to indicate regions of greater activity

27. Primitive Brain Structures
Brainstem
Oldest part of brain
Contains medulla, controlling heartbeat, blood pressure and breathing
Also contains pons, which helps regulate sensory information and facial expressions
Contains Reticular Formation (RF) for alertness/arousal, sleep/wakefulness
Thalamus
Pair of egg-shaped structures on top of brainstem
Routes all incoming sensory information except for smell to appropriate areas of brain
Cerebellum
“little brain” at read of brainstem
Controls coordination, balance, and muscle tone
These parts of the brain are our “autopilot” so other regions can deal with higher-level “human” functions

28. The Limbic System
Located in between the primitive parts of the brain and the cerebral hemispheres
Hippocampus processes new memories (case of H.M.)
Amygdala controls emotions such as aggression and fear – in animals, the “attack” response (rat study)
Hypothalamus regulates hunger, thirst, body temperature and sex drive – also controls pituitary gland
Rat study – self-stimulation of “pleasure centers”
Human implications? Mild pleasure, addiction tendencies?
Primarily, the limbic system processes drives, smell and various emotional responses

29. The Cortex
Part of the cerebrum, the two large hemispheres comprising 85% of brain weight
Wrinkled outer layer
Why so convoluted?
Higher level functions
Designation of cortical space and “higher level” animals?
Most highly evolved part of the human brain

30. Cortex Breakdown… Each hemisphere is divided into 4 lobes
Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe
The lobes are separated by deep convolutions known as fissures

31. Cortex Breakdown… Occipital Lobes Temporal Lobes Parietal Lobes
Homunculous!
Cortex Breakdown…
Occipital Lobes
Visual cortex
Damage?
Temporal Lobes
Auditory cortex
Auditory hallucinations?
Parietal Lobes
Primary sensory or somatosensory cortex
Allocation of space?
Frontal Lobes
Most evolved
Motor cortex, which allows us to move

32. Motor and Sensory Cortex Revealed!

33. The Cortex: Association Areas
We only use 10% of our brains?
Undifferentiated cortex
Association areas

34. Phineas Gage: A Case Study in Frontal Lobe Association Area Damage
In 1848, railroad foreman Phineas Gage – accident!
No longer “himself”
Emotions, the frontal cortex, and the unchecked limbic system
The skull of Phineas and rogue tamping iron, displayed proudly at Harvard University’s medical school! For real!

35. Hey guys! Check out our phat crib!
Neuroplasticity
Shafted again.
Brain’s to change and reorganize as a result of experience
Mark Rosenzweig’s ( ) Rat Studies (1950s-60s)
Implications for humans?
Hey guys! Check out our phat crib!
Party!

36. Neuroplasticity in Rats

38. Neurogenesis?
Recent evidence has suggested that human brains may be able to generate new brain cells, known as Neurogenesis
Stem cell research?

39. The Two Hemispheres Two halves are NOT identical
Most have a dominant hemisphere – usually the left, which controls the right side of the body
Both sides serve important functions, revealed by studying split-brain patients

40. Split-Brain Epilepsy, seizures and the corpus callosum
Reduction in epileptic seizures
Different abilities in each hemisphere
The story of “Vicki”
Michael Gazzaniga

41. Some Hemispheric Strengths
Left Hemisphere
Language in most people: The cases of Ta of Charles Landry
Logic
Right side of body
Right Hemisphere
Perception
Sense of self
Inferences

42. Hemispheric Dominance: Handedness
90% of humans are right-handed
The 10% of left-handers show less predictable patterns of hemispheric dominance
Causes?
Genetics?
Fetal testosterone levels?
Learned?
Handedness and sexual orientation?
A closer look: a curse or an advantage?

43. Behavior Genetics: What’s the Point?
Behavior Genetics seeks to understand the relative influence of our heredity and our experiences
Nature vs. Nurture? It’s both – but how much of each?

44. Behavior Genetics: Genetics Review
Heredity examines the transmission of trait from one generation to next
Chromosomes
Pairs of thread like bodies that contain genes
Average human cell has 23 pairs
Sex cells?
Deoxyribonucleic acid (DNA)
Organic molecule arranged in a double-helix
Contains the “code of life”
Genes
Basic units of inheritance
Segment of DNA
Genome
“map” for an organism’s genetic complete make-up
Human Genome Project

45. Behavioral Genetics: Studying Nature vs. Nurture
Animal Studies
Strain Studies
Selection Studies
Human Studies
Identical Twins
Fraternal Twins
Separated Twins
Adoption Studies
Family studies

46. Behavioral Genetics: Temperament and Heritability
Temperament refers to emotional reactivity and seems to be set very early in life
Thomas and Chess (easy, difficult, slow-to-warm-up)
Kagan’s “shy child”
Indicates this aspect of behavior is genetically manipulated
Environment can enhance or diminish this genetic predisposition

47. Behavior Genetics: Heritability
Heritability: the extent to which differences among organisms are caused by genes
Does NOT refer to which percentage of a trait is determined by genetics in a given individual!
The more similar and controlled the environment of the organisms is, the more we can attribute differences to genes, and the higher the heritability!

48. So…Nature vs. Nurture…?
Genes and environment interact like “two hands clapping…”
Environment can trigger genetic “switches”
Our genes can provoke us to seek particular environments
e.g. Eating Disorders
Genetic predisposition (some are more susceptible than others)
Cultural regulation (Western culture)
Molecular Genetics
Studies how particular genes influence behavior
e.g. Is there a gene that determines obesity? Sexual orientation?
Promise and peril of molecular genetics?
Genetic engineering
Eugenics

49. Evolutionary Psychology
Whereas behavior geneticists seek to explain our behavioral differences in terms of our genes, evolutionary psychologists focus on our similarities, as dictated by natural selection.
Richard Dawkins The Selfish Gene (1976)
Varied organisms in a population compete to survive
Certain biological and behavioral variations facilitate survival
Surviving organisms may reproduce and pass on their genes
This leads to overall changing characteristics in a population

50. Evolutionary Psychology: Natural Selection, Adaptation and Evolutionary Success
Selection – providing a reproductive advantage, either naturally or artificially (e.g. tame foxes), based on a trait/set of traits
These traits will endure over time
Population will change as a result
Variation can result from mutations (errors in genetic replication right after conception)
Some of these “errors” provide an advantage and are selected for, and therefore persist
The errors are adaptive – increasing our fitness, or our chances to survive (and to reproduce)
Humans have so many shared characteristics – How?
Differences that were not “fit” were not passed on
Those that increased survival were, as these organisms lived and reproduced

51. Evolutionary Psychology
Selection happens SLOWLY and often our world changes faster than the gene pool can (e.g. fatty/sweet food cravings)
Today, evolutionary psychologists examine persistent trends in human behavior and seek to explain them
Keep in mind, however, that genetically driven tendencies only partially govern human behavior!

52. Evolutionary Psychology: Explaining Human Sexuality and Mating
Males of all sexualities generally are more interested in sex, regard sex as a recreational activity and prefer young, attractive mates
Females of all sexualities generally see sex as an outgrowth of relationships and prefer mature, stable, and affluent mates
Have these trends genetically motivated?

53. Evolutionary Psychology: Human Sexuality and Mating
Women
Quality over quantity
More invested in bearing/nurturing children
Seek men who either provide superb genes (he-man strategy) or are good providers (domestic-bliss strategy)
“fast” vs. “coy” females
Men
Quantity over quality
Increase reproductive success by spreading their genes as widely as possible
Attraction to fertile females
Not physically bound to pregnancy
He-man strategy vs. opportunists
Philanderers vs. Stable males?
Perhaps males should invest more in child-rearing?

54. Evolutionary Psychology: Criticism
Do these arguments just provide excuses for bad behavior?
Do humans have more of a social and cultural responsibility to make the world better?
What about environmental influence?
How does the environment reinforce these trends?
How much of a role does environment play in the persistence of these roles?
Who benefits?

55. Parents and Peers Experience and Brain Development Parental Influence?
Critical Periods
Rosenzweig revisited
Brains are shaped by our genes AND experience
Parental Influence?
If abusive or neglectful, can have major impact
In non-extreme cases, parents probably deserve less credit, or less blame!
Parents shape values, beliefs and habits, but not as much as we may believe
Most important to provide unconditional love and support
Peer Influence
Peers teach us how to socialize and cooperate
Selection effect: seeking peers with similar interests

56. Cultural Influences Culture Norms
distinctive values, beliefs, language and characteristics of a society
both tangible (food, clothing) and intangible (values, beliefs).
Norms
Rules that represent the typical behaviors of a particular group
One example is expected personal space, the distance we like to keep ourselves from other people

57. Individualism vs. Collectivism
Individualist cultures place value of singular person over that of the group
Collectivist cultures value the group over the individual
Which type of culture does the US have? Why?
Implications?

58. Gender Development Aggression, Power, and Connectedness
Aggression involves an intent to harm, whether verbal or physical: males admit to and exhibit more than females.
Men are and are perceived as more powerful and engage in behaviors that exhibit and perpetuate this power inequity.
Females place greater emphasis on social connections, choosing careers that involve social interaction or require nurturing roles
Males have more difficulty admitting they are wrong

59. Why Are We Different? Biological Explanations
X and Y Chromosomes
Y triggers sex differentiation during fetal development, causing greater testosterone production in males
Female infants exposed to elevated levels of testosterone exhibit “male” behavioral characteristics
Males with normal male hormones but had their sex reassigned at birth for various reasons often embrace a male identity, despite efforts to raise them as females

60. Why Are We Different? Social Explanations
Gender Roles – expected behaviors for males and females
Women as caregivers?
Men as breadwinners?
The Reality? Women now OUTNUMBER men in the workplace in the US, yet in 87% of families with children, are still the primary caregivers.
Variations across culture and time…
Gender Identity – our sense of being male or female
Gender typing – embracing a traditional masculine/feminine role
Social Learning Theory and Gender Schemas
What do these roles and stereotypes provide for us?
Sense of stability and simplification
Sense of confinement

61. Nature vs. Nurture? Call the Whole Thing Off!
Our genes and our experiences form us
Family, friends, and culture have an influence over the genes that make us
These structures are constantly in flux
We are adaptive creatures
The world changes, and we change with it