2. 3
Biology and BehaviorBiology and Behavior
• Cells of the Nervous System
• Neural Transmission
• The Nervous System
• The Peripheral Nervous System: Keeping in Touch with the World
• The Central Nervous System: Making Sense of the World
• Techniques for Studying Human Brain Function and Structure
• The Chemistry of Behavior: Neurotransmitters
• The Endocrine System: Coordinating the Internal World
• Linked Exercises
3. 3
Biological PsychologyBiological Psychology
• All behavior and mental processes are based
on biology.
– But, are also influenced by the environment
• Two primary systems direct the activities of the
body.
– The nervous system
– The endocrine system
5. 3
Cells of the Nervous SystemCells of the Nervous System
What are neurons,What are neurons,
and what do they do?and what do they do?
6. 3
Cells of the Nervous SystemCells of the Nervous System
• NeuronsNeurons
– Have the ability to send and receive signalsHave the ability to send and receive signals
– Organized in neural networks
• Glial cellsGlial cells
– Help neurons communicateHelp neurons communicate
– Malfunctions may lead to problemsMalfunctions may lead to problems
7. 3
A Typical Neuron
• Cell body
– Similar to other cells
• Axon
– Sends signals to
other neurons
• Dendrites
– Receive signals from
other neurons
8. 3
Axons
• Function:
– Carry signals away from the cell body.
– Myelin sheath helps speed the action potential
• Type of Signal Carried:
– The action potential
• An all-or-nothing electrochemical signal
• Travels down the axon, releasing
neurotransmitters from vesicles
9. 3
Dendrites
• Function:
– Detect and carry signals to the cell body.
• Type of Signal Carried:
– Excitatory postsynaptic potential: electrochemical
signal which encourages a neuron to fire.
or
– Inhibitory postsynaptic potential: electrochemical
signal which discourages a neuron from firing.
10. 3 | 1
The Cell Body of a Neuron
• Outer membrane
– passes some
substances, blocks
others
• Nucleus
– Genetic information
• Mitochondria
– convert glucose and
oxygen into energy
Back to TOC
11. 3 | 1
Neural Transmission
How do neurons communicate?
13. 3 | 1
Synapses
• Areas for the transfer of signals between
neurons
• Neurotransmitters cross to receptors on other
cells
14. 3 | 1
A Synapse
This photograph shows part of a
synaptic gap between two neurons,
magnified 50,000 times. The ending of
the presynaptic cell’s axon is shaded
green, the green ovals are mitochondria,
and the red spots are the vesicles.
The synapse itself is the narrow gap
between the first cell’s green-shaded
axon and the blue-shaded dendrite of
the cell below.
15. 3 | 1
Neurotransmitters
• Chemicals released by one cell that bind to the
receptors on another cell
• Tell the next cell to fire or not to fire its own
action potential
16. 3 | 1
Receptors
• Proteins on the cell membrane that receive
chemical signals
• Recognize specific neurotransmitters
– Allows them to begin postsynaptic potentials in the
dendrite
17. 3 |
Integration of Neural Signals
• Signals arrive from many
neighboring cells
– Excitatory signals
encourage firing
– Inhibitory signals
discourage firing
• Firing depends on which
messages predominate
– The all-or-nothing law
Back to TOC
18. 3 | 1
The Nervous System
The nervous system has two major divisions
– Central Nervous System (CNS)
– Peripheral Nervous System (PNS)
Back to TOC
19. 3 |
The Peripheral NervousThe Peripheral Nervous
System: Keeping in TouchSystem: Keeping in Touch
with the Worldwith the World
How do sights and soundsHow do sights and sounds
reach my brain?reach my brain?
20. 3 |
Autonomic Nervous SystemAutonomic Nervous System
• Controls activities normally outside ofControls activities normally outside of
conscious control.conscious control.
• Two SubsystemsTwo Subsystems
– Sympathetic nervous systemSympathetic nervous system
• ““Spends” energySpends” energy
– Parasympathetic nervous systemParasympathetic nervous system
• ““Preserves” energyPreserves” energy
21. 3 | 2
Somatic Nervous System
• Sensory neurons (afferent neurons)
– Send sensory information to CNS
• Motor neurons (efferent neurons)
– Send messages from CNS to muscles
Back to TOC
22. 3 |
The Central Nervous System:The Central Nervous System:
Making Sense of the WorldMaking Sense of the World
How is my brainHow is my brain “wired”?“wired”?
23. 3 | 2
The Spinal Cord
• Relays signals from the senses to the brain.
• Relays signals from the brain to the muscles.
• Directs reflexes.
24. 3 |
A Reflex Pathway
Tapping your knee at just the right spot stimulates sensory neurons to fire,
triggering spinal neurons to fire. This stimulates the firing of motor neurons
with axons ending in your thigh muscles, causing you to kick. Information
about all this also goes to your cerebral cortex, but the reflex happens
without waiting for guidance from the brain.
Back to TOC
25. 3 | 2
Techniques for Studying
Human Brain Function
and Structure
Taking a Closer Look
26. 3 |
EEGEEG
(Electroencephalography)(Electroencephalography)
• Technique:Technique:
– Multiple electrodes pasted to outside of headMultiple electrodes pasted to outside of head
– Senses electrical fields resulting from neural activitySenses electrical fields resulting from neural activity
• What it shows:What it shows:
– General electrical activity of the brainGeneral electrical activity of the brain
– Represented as a line on a graph or screenRepresented as a line on a graph or screen
27. 3 |
EEGEEG (cont(cont’d)’d)
• Advantages:Advantages:
– Detects very rapid changes in electrical activityDetects very rapid changes in electrical activity
– Allows analysis of stages of cognitive activityAllows analysis of stages of cognitive activity
– May be combined with magnetoencephalographyMay be combined with magnetoencephalography
(MEG) to localize activity(MEG) to localize activity
• Disadvantages:Disadvantages:
– Poor spatial resolution of the source of activityPoor spatial resolution of the source of activity
28. 3 | 2
PET (Positron Emission Tomography)
and
SPECT (Single-Photon Emission
Computerized Tomography)
• Technique
– Positrons and photons emitted by radioactive substances
• What they show
– Indicate specific changes in neuronal activity
29. 3 | 2
PET and SPECT (cont’d)
• Advantages
– Allow functional and biochemical studies
– Provide visual image corresponding to anatomy
– Better spatial resolution better than EEG
• Disadvantages
– Require exposure to low levels of radioactivity
– Inferior spatial resolution to MRI
– Cannot follow changes faster than 30 seconds
30. 3 |
MRIMRI
(Magnetic Resonance Imaging)(Magnetic Resonance Imaging)
• Technique:Technique:
– Expose the brain to a magnetic field and measureExpose the brain to a magnetic field and measure
radio frequency wavesradio frequency waves
• What it shows:What it shows:
– High resolution image of brain anatomyHigh resolution image of brain anatomy
31. 3 |
MRI (cont)MRI (cont)
• AdvantagesAdvantages
– No radioactivityNo radioactivity
– High resolution of anatomical details (<1 mm)High resolution of anatomical details (<1 mm)
– High temporal resolution (<1/10 of a second)High temporal resolution (<1/10 of a second)
• Disadvantages
– Does not indicate functions as they happen
32. 3 | 3
Combining a PET Scan and
Magnetic Resonance Imaging
Combining these techniques provides
three-dimensional views of living brains
33. 3 | 3
Functional MRI (fMRI)
• Combines the advantages of PET and MRI
• Detects changes in blood flow and oxygen that
reflect ongoing changes in neural activity
• Resulting computer analysis shows areas of the
brain that appear activated during a task
• Exciting developments:
– Discovery of the mirror neuron mechanism
– Investigating the effects of acupuncture
35. 3 | 3
Critical Thinking about fMRI
• Indicates location of brain activity, but not cause
• Does not tell us how brain works
• Does not measure brain cell activity directly, but
measures change in blood flow and oxygen
• Subject to experimenter bias in interpretation
36. 3 |
TMSTMS
(Transcranial Magnetic Stimulation)(Transcranial Magnetic Stimulation)
• Technique:Technique:
– Temporarily disrupt activity of a small region of theTemporarily disrupt activity of a small region of the
brain with an intense magnetic fieldbrain with an intense magnetic field
• What it shows:What it shows:
– Loss of normal function of a particular brain regionLoss of normal function of a particular brain region
37. 3 |
TMSTMS (cont(cont’d.)’d.)
• AdvantagesAdvantages
– Shows brain regions needed for given tasksShows brain regions needed for given tasks
– May treat depression and migraine headaches
• DisadvantagesDisadvantages
– Long-term safety not well establishedLong-term safety not well established
38. 3 |
Video: Brain Organization,Video: Brain Organization,
Structure and FunctionStructure and Function
40. 3 |
Major Structures of the Hindbrain
• Medulla oblongata
– Controls vital functions
– blood pressure
– heart rate
– breathing
• Reticular formation
– Arousal
– Attention
• Cerebellum
– Coordinates movement
– Timing
• Locus coeruleus
– Directs attention
41. 3 |
Major Structures of the Forebrain
• Cerebral cortex
– Processes complex
information
• Suprachiasmatic nuclei
– Maintain circadian
rhythms
• Striatum & substantia nigra
– Coordinate smooth
movement
• Corpus callosum
– Connects left and right
hemispheres
• Thalamus
– Relays and processes
sensory signals
42. 3 |
Major Structures of the Forebrain
The Limbic System
• Amygdala
– Involved in emotion
• Hippocampus
– Formation of memories
– Affected by Alzheimer’s
disease
• Hypothalamus
– Regulates drives
• Septum
– Pleasure
– Anger suppression
43. 3 | 4
Anatomical Areas
of the Cerebral Cortex
Each hemisphere is into four lobes:
• Frontal
• Parietal
• Occipital
• Temporal
Divided by
• Gyri (ridges)
• Sulci (valleys)
44. 3 | 4
Functional Areas
of the Cerebral Cortex
• Motor cortex
• Controls movement
• Sensory cortex
• Receives sensory information
• Association cortex
• Integrates information
• Wernicke’s area
• Language interpretation
• Broca’s area
• Language organization
• Speech production
45. 3 | 4
Motor and Somatosensory Cortices
• Motor cortex
– Moves parts of the body
– Areas controlling movement
of neighboring parts of the
body occupy neighboring
parts of the motor cortex
• Somatosensory cortex
– Receives sensory input from
body parts
– Areas receiving input from
neighboring body parts are
near one another in the
sensory cortex
46. 3 |
Lateral Dominance in Normal Brains
• Hemispheric Differences
– Left:
• logical abilities
• language abilities
– Right:
• spatial abilities
• artistic abilities
• musical abilities
• facial recognition
– Individual variability in the
precise nature and degree of
lateralization
– Differences should not be
exaggerated
• Corpus callosum allowsCorpus callosum allows
the two hemispheres tothe two hemispheres to
work closely togetherwork closely together
47. 3 |
Split-Brain StudiesSplit-Brain Studies
• Apparatus for studying split-brain patients
– Presents image to selected visual fieldPresents image to selected visual field
• In left visual field:In left visual field:
– Can name the objectCan name the object
• In right visual field:In right visual field:
– Cannot describeCannot describe
object in wordsobject in words
– Can pick the objectCan pick the object
out of a groupout of a group
48. 3 |
Neural PlasticityNeural Plasticity
• CNS can:CNS can:
– Strengthen neural connections at synapsesStrengthen neural connections at synapses
– Establish new neural connectionsEstablish new neural connections
• Basis for forming new memories and learningBasis for forming new memories and learning
• Limits to plasticity in repairing brain damageLimits to plasticity in repairing brain damage
49. 3 | 4
Helping the CNS to Heal
• Transplant fetal tissue into the adult’s brain
• Coax brain to make its own new neurons
– Problem: Synaptic connections must be reestablished.
• Block the action of the CNS protein, “Nogo”
• “Growth factor” proteins
• Special mental and physical exercise programs
• Neural stem cells in adults’ brains
– Special glial cells can form new tissue, including neurons
Back to TOC
50. 3 | 5
Linkages: Human Development
and the Changing Brain
• Correlation between changes in neural activity
and the behavior of newborns and infants
– Newborns:
• High activity in thalamus
• Purposeful sweeping movements of arms and legs
– 2-3 months old:
• Increased activity in much of the cortex
• Loss of reflexes such as grasping
– 8-9 months old:
• Increased activity in frontal cortex
• Increased cognitive activity
51. 3 |
Linkages: Human Development
and the Changing Brain
Childhood and adolescence
• 6-7 years old:
– More dendrites than adult brains
– Use twice the metabolic fuel of
adult brains
• Adolescence:
– Pruning of synapses
– Loss of gray matter
• Developmental changes reflect
plasticity, not appearance of
new cells
52. 3 |
Linkages: Human Development
and the Changing Brain (cont’d)
• Genes determine basic pattern of growth and major
lines of connections.
• Enriched environments encourage neural
development
Back to Linked Exercises
Back to TOC
53. 3 |
The Chemistry of Behavior:The Chemistry of Behavior:
NeurotransmittersNeurotransmitters
How do biochemicalsHow do biochemicals
affect my mood?affect my mood?
54. 3 |
The Chemistry of Behavior
• Neurotransmitter systems:
groups of neurons that uses
the same neurotransmitter to
communicate
– Play dominant roles in
particular functions.
• Neuromodulators act on
receptors at synapses.
– Modify or “modulate” a cell’s
response to other
neurotransmitters.
55. 3 | 5
Small Molecule Neurotransmitters
Neurotransmitter Normal Function Disorder Associated with Malfunction
Acetylcholine Memory, movement Alzheimer’s disease
Norepinephrine Mood, sleep, learning Depression
Serotonin Mood, appetite, impulsivity Depression
Dopamine Movement, reward Parkinson’s disease, schizophrenia
GABA Sleep, movement Anxiety, Huntington’s disease, epilepsy
Glutamate Memory Damage after cardiovascular accident
56. 3 | 5
Other Classes of Neurotransmitters
Neurotransmitter Normal Function Disorder Associated with Malfunction
Peptides
Endorphins Pain control No established disorder
Gases
Nitric oxide Memory No established disorder
Back to TOC
57. 3 |
The Endocrine System:The Endocrine System:
CoordinatingCoordinating
the Internal Worldthe Internal World
How can my hormonesHow can my hormones
help me in a crisis?help me in a crisis?
58. 3 |
The Endocrine System
• Regulates functions
– Stress responses
– Physical growth
• Communicates by
secreting hormones
• Controlled by
hypothalamus via
pituitary gland
• Negative feedback
system
Back to TOC
59. 3 |
Linked Exercises
• Linkages: Human Development and the Changing Brain
• Thinking Critically:Thinking Critically: What Can fMRI Tell Us about Behavior and Mental Processes?What Can fMRI Tell Us about Behavior and Mental Processes?
• Focus on Research Methods: Manipulating Genes in Animal Models of Human Disease
60. 3 |
Thinking Critically:Thinking Critically: What Can fMRI Tell Us aboutWhat Can fMRI Tell Us about
Behavior and Mental Processes?Behavior and Mental Processes?
• What am I being asked to believe or accept?What am I being asked to believe or accept?
– fMRI is a 21fMRI is a 21stst
century version of phrenologycentury version of phrenology
• Is evidence available to support the claim?Is evidence available to support the claim?
– Neuron firing rates may cancel each other out onNeuron firing rates may cancel each other out on
scansscans
– Problems with interpreting fMRI resultsProblems with interpreting fMRI results
– Difference rules are decided by experimentersDifference rules are decided by experimenters
– Differences do not necessarily reflect actual thinkingDifferences do not necessarily reflect actual thinking
differencesdifferences
61. 3 |
Thinking Critically:Thinking Critically: What Can fMRI Tell Us aboutWhat Can fMRI Tell Us about
Behavior and Mental Processes?Behavior and Mental Processes? (cont(cont’d.)’d.)
• Can that evidence be interpreted another way?Can that evidence be interpreted another way?
– Image changes mirror thinking and feeling changesImage changes mirror thinking and feeling changes
– fMRI led to discovery of mirror neuron mechanismsfMRI led to discovery of mirror neuron mechanisms
• What evidence would help evaluate theWhat evidence would help evaluate the
alternatives?alternatives?
– Actual relationship between scanned activity andActual relationship between scanned activity and
actual behavior and mental processesactual behavior and mental processes
– Evidence about correlation and causation in fMRIEvidence about correlation and causation in fMRI
researchresearch
62. 3 |
Thinking Critically:Thinking Critically: What Can fMRI Tell Us aboutWhat Can fMRI Tell Us about
Behavior and Mental Processes?Behavior and Mental Processes? (cont(cont’d.)’d.)
• What conclusions are most reasonable?What conclusions are most reasonable?
– Unlikely to explain how the brain creates behaviorUnlikely to explain how the brain creates behavior
and mental processes.and mental processes.
– Careful analysis of fMRICareful analysis of fMRI’s value is important.’s value is important.
Back to Linked Exercises
63. 3 |
Focus on Research Methods: Manipulating
Genes in Animal Models of Human Disease
• What was the researchers’ question?
– Are the proteins that are found in plaques and tangles
the cause of Alzheimer’s disease?
• How did the researchers
answer the question?
– Inserted a gene for a mutant
form of beta-amyloid precursor
protein into mice.
64. 3 |
Focus on Research Methods:
Manipulating Genes (cont’d)
• What did the researchers find?
– Mice showed memory impairments and developed
plaques, no tangles.
– Plaques and tangles did appear in transgenic mice
with faulty tau, but cannot be the main cause of
Alzheimer’s.
Human brains with Alzheimer’s disease (bottom row) and those without it.
65. 3 |
Focus on Research Methods:
Manipulating Genes (cont’d)
• What do the results mean?
– Transgenic mice can be used to evaluate the roles of mutations
in proteins in causing Alzheimer’s disease.
• What do we still need to know?
– Challenge is to use animal models to develop and test effective
treatments for humans.
Back to Linked ExercisesBack to Techniques for
Studying the Brain
66. 3 | 6
In Class Writing Exercises
• Place one at the start of your presentation.
• Have your students write for a minute or two
about the quote on the slide.
• This will help them center themselves on the
topic to be covered in class.
• You may wish to use their responses to generate
class discussion.
The following slides may be used as advance
organizers for the topics in this unit.
67. 3 |
In Class Writing Exercise::
Human action can be modified to some extent, but
human nature cannot be changed.
Abraham Lincoln
68. 3 |
In Class Writing Exercise::
Every man must do his own growing no matter
how tall his grandfather was.
L.J. Peter
69. 3 |
In Class Writing Exercise::
Brain and brain, what is brain?Brain and brain, what is brain?
——Kara, an EymorgKara, an Eymorg
((Star TrekStar Trek:: SpockSpock’s Brain’s Brain))
Back to Synapses
