Chapter 3: Biological Bases of Behavior

1
Chapter 3 Biological Bases of Behavior
2

• Heredity and Behavior

3
Evolution and Natural Selection

• Charles Darwin- The Origin of Species
• Natural Selection- theory that favorable
  adaptations to features of the environment allow
  some members of a species to reproduce more
  successfully than others
• What does this mean?

4
Evolution and Natural Selection

• ? Over time organisms producing more favorable
  traits for survival will become more numerous
  than others
• AKA Survival of
• the fittest

5
Evolution and Natural Selection

• Short-term effects

6
Evolution and Natural Selection

• Long-term effects

7
Genotype vs. Phenotype

• Genotype

• Phenotype

• Inherited genetic structure from parents
• Determines development and behavior

• Determines observable appearance
• Resulting from interaction between genotype and
  environment

8
Process of Natural Selection
Environmental Pressure
Competition
Selection of Fittest
Reproductive Success
Frequency of Genotype
9
Language

• Most important milestone for human species

10
Language

• Vital for
• Instruction
• Sharing experiences
• Social Bonds
• Transmitting wisdom

11
Language

• Basis for cultural evolution
• Allows for rapid adjustments to environmental
  changes
• Culture is possible because of the potential of
  human genotype changes

12
Variation in Human Genotype

• Heredity- the inheritance of physical and
  psychological traits from ancestors transmission
  of traits from parents to offspring
• Genetics- the study of heredity

13
Basic Genetics

• DNA is found in the nucleus of each human cell
• DNA- the physical basis for genetic information
• DNA is organized into genes
• Genes- biological units of herdity

14
Genes

• Contain the instruction for phenotypic traits
  (some examples)
• - body build
• - physical strength
• - intelligence
• Found on chromosomes

15
Sex Chromosomes

• Contain coding for male or female characteristics
• Mother contributes X chromosome
• Father contributes X or Y chromosome
• XX female
• XY male

16
Genes

• 50 of genes in common with siblings
• Set of genes is unique
• Difference in genes and environment determine
  traits

17
Goal

• Important goal of psychology is to understand the
  balance between your genetics and your environment

18
Genes and Behavior

• Human behavior genetics- unites genetics and
  psychology to explore the relationship between
  inheritance and behavior

19
Happiness

• Researchers propose that happiness has a strong
  genetic component, less than an environmental
  component
• Is happiness set
• at birth?

20
Genes

• Conclusion
• Genes you receive from your parents have broader
  effects than determining hair and eye color
• Sociobiologists use evolutionary explanations to
  analyze social behavior and social systems

21
Sad Brain ? Happy Brain ?

• Read Sad Brain, Happy Brain and answer all
  questions on handout

22

• Biology and Behavior

23
People to Know

• Rene Descartes- French Philosopher
• - human action is mechanical reflex to
  environmental stimulation

24
People to Know

• Sir Charles Sherrington-
• - discovered reflexes are direct connections
  between sensory and motor nerve fibers
• - nervous system involves increasing and
  decreasing neural activity

25
People to Know

• Santiago Ramon y Cajal-
• - detected gaps between adjacent neurons and
  theorized how info flowed from one to another

26
People to Know

• Donald Hebb-
• - believed the brain was integrated series of
  structures (cell assemblies) performing specific
  functions

27
Neuroscience

• Neuroscience- study of the brain and the links
  between brain activity and behavior

28
Phineas Gage

• Pre-accident level-headed, calm
• Post-accident hostile, impulsive, extremely
  emotional, obscene language

29
Phineas Gage

• Loss of tissue revealed the relationship between
  frontal lobes and control of emotional behavior

30
Paul Broca

• Studied brains role in language
• Discovered area of brain connected to language-
  now known as Brocas area- translates thoughts
  into speech or signs

31
Lesions

• Researchers began method of destroying or
  injuring brain tissue on purpose to study results
• Damages are lesions
• Experimental work on non-humans only

32
Lobes of the Brain
33
Brocas Area
34
People to Know

• Walter Hess- pioneered use of electrical currents
  in the brain
• - determined what part of the brain performs
  specific functions

35
Recording Brain Activity

• EEG- traces electrical activity of the brain
• PET Scan- image produced by recording
  radioactivity emitted by cells during different
  activities
• MRI- scan of brain using radio waves and magnetic
  fields
• fMRI- combines PET and MRI

36

• The Nervous System

37
Organization of Nervous System
38

• Brain Structures and Functions

39
Brain

• Brain- most important component of your CNS
• Brain Stem- regulates the bodys basic life
  processes
• Medulla- center for breathing, blood pressure and
  heart rate
• Pons- connects spinal cord with brain

40
Brain

• Reticular Formation- arouses cerebral cortex to
  incoming sensory signals
• - responsible for consciousness and
• awakening from sleep
• - massive damage ? coma
• Thalamus- channels incoming sensory into to
  appropriate area of cerebral cortex

41
Brain

• Cerebellum- attached at base of skull
• - responsible for body movement, posture, and
  equilibrium

42
Brain
43
Limbic System

• Hippocampus- involved in the ability to acquire
  memories
• - injury can effect recall of
• memory
• Amygdala- role in emotional control and formation
  of emotional memories

44
Limbic System

• Hypothalamus- regulates/maintains homeostasis,
  involved in motivated behavior
• Equilibrium- consistency of the bodys internal
  conditions

45
Cerebrum

• Cerebrum- regulates brains higher cognitive and
  emotional functions 2/3s of brain
• Cerebral Cortex- outer surface
• Corpus Callosum- nerve fibers connecting 2
  hemispheres of cerebrum

46
Cerebrum

• Frontal Lobe- responsible for motor control and
  cognitive activities- planning, decision making,
  goal setting
• Parietal Lobe- responsible for sensations, touch,
  pain, and temp contains somatosensory complex

47
Cerebrum

• Occipital Lobe- contains primary visual cortex
• Temporal Lobe- contains primary hearing

48
Cerebrum

• Motor Cortex- controls the actions of the bodys
  voluntary muscles
• Somatosensory Cortex- processes information about
  temp, touch, body position, and pain devoted to
  parts of body that provide sensory input (lips,
  tongue, thumb, index finger)

49
Cerebrum

• Auditory Cortex- receives information from both
  ears ? processes auditory info
• Visual Cortex- devoted to visual input and
  transmits detailed visual info

50
Cerebrum

• Association Cortex- portion of the brain where
  high level brain process occur, such as planning
  and decision making occur

51
Cerebrum
52
Hemispheric Lateralization

• Info from the right visual field goes to the left
  hemisphere
• - Vice versa
• In most people this info is shared quickly
  between the two hemispheres via the corpus
  callosum

53
Hemispheric Lateralization

• Speech is controlled by the left hemisphere in
  most individuals
• Speech is the most highly lateralized function of
  the brain
• This doesnt mean the left hemisphere is better!
• Right hemi controls more manual tasks

54
Hemispheric Lateralization

• Conclusion
• The right hemisphere controls the left side of
  your body
• The left hemisphere controls the right side of
  your body

55
Whos Better at What?

• Look over the handout Whos Better at What?
• Respond to the following questions
• - Do you agree/disagree with the info on the
  handout?
• - Are you a left brain or right brain
  person?

56
Hemispheric Lateralization

1. Women have greater density of neurons in a
   portion of the temporal cortex involved in
   language
2. Different brain areas develop more strongly for
   men and women
3. Hemis of womens brain shares more functions
   than mens

57
Neurons

• Neuron- cell that receives, processes and
  transmits into to other cells

58
Neurons

• PARTS
• Dendrites- receive incoming signals
• Soma- cell body contains nucleus passes info to
  the axon
• Axon- conducts info away from soma to the
  terminal buttons

59
Neurons

• 4. Myelin Sheath- covers axon to increase speed
  of info
• - MS cells attack and deteriorate myelin sheath
• 5. Terminal Buttons- bulb-like structures through
  which neurons stimulate nearby glands, muscles,
  or other neurons release neurotrans.

60
Types of Neurons

1. Sensory (Afferent) Neurons- carry messages from
   sense receptor cells towards the CNS (sensitive
   to light and sound)
2. Motor (Efferent) Neurons- carry messages away
   from CNS towards muscles and glands
3. Interneurons (in brain)- relay messages from
   sensory neurons to other interneurons, or to
   motor neurons

61
Glial Cells

• Hold neurons in place
• Housekeeping- clean-up damaged or dead neurons
• Absorb excess neurotransmitters
• Insulation- form the myelin sheath
• Prevent toxic substances in blood from reaching
  brain cells

62
Action Potentials

• Neurons receive excitatory (fire) or inhibitory
  (dont fire) inputs
• Neural communication is produced by the flow of
  elec. charged particles ions
• Inactive/Resting State- more potassium ions
  inside, more sodium ions outside the neuron
• Membrane of the cell has a pump to keep this in
  balance

63
Action Potentials

• Fluid inside the membrane has a slight negative
  charge (polarized)
• This polarization resting potential
• When nerve cells get excitatory or inhibitory
  inputs the balance of ions will change

64
Action Potential

• Inhibitory inputs cause ion channels to work
  harder to keep the inside of cell negatively
  charged ? wont fire
• Excitatory inputs allow ion pump to allow sodium
  in which allows the cell to fire (sodium ions
  have a positive charge)

65
Action Potentials

• Action Potential begins when the inside of the
  cell is depolarized and sodium rushes into the
  cell ? makes the ion positively charged
• A domino effect propels the action potential down
  the axon ? successive depolarization

66
Action Potentials

• Neuron returns to a resting state when neuron
  becomes positive, channels that allowed sodium
  in? close, channels that stopped potassium ? open
• Cell returns to negative charge and ready for
  next stimulation

67
All or None!

• All or None- action potential is not affected
  by increases in intensity of stimulation once
  threshold level is reached and is firing
• If threshold is not reached ? no firing

68
Refractory Period

• Action potential has passed
• Absolute refractory period- no stimulation can
  generate another action potential
• Relative refractory period- neurons will only
  fire in response to a stronger stimulus
• This ensures that action potential will only
  travel in one direction ? cant move backward b/c
  earlier parts of axon are in refractory state

69
Synaptic Transmission

1. Action potential reaches terminal buttons
2. Synaptic vesicles rupture and neurotransmitters
   are released
3. Neurotransmitters disperse across synaptic cleft
4. Neurotransmitters attach to receptor molecules

70
Synaptic Transmission

• Neurotransmitters attach to the postsynaptic
  membrane only if 2 conditions are met
• - the only neurotransmitter attached to that
  receptor molecule
• - shape of neurotransmitter must match the shape
  of the receptor molecule
• 5. Once job is complete ? detaches and decomposes
  or is reabsorbed