1

CHAPTER TWO: NEUROSCIENCE AND BEHAVIOR

2

Neurons: The Basic Units of the Nervous System

• Why do psychologists study the brain and nervous system?

• What are the basic elements of the nervous system?

• How does the nervous system communicate electrical and chemical messages from one part to another?

3

Structure of the Neuron

• Neurons (Nerve cells)– Basic elements of the

nervous system– As many as 1 trillion

Figure 1 of Chapter 2

4

The Structure of the Neuron

• Dendrites– Clusters of fibers that receive messages from other

neurons

• Axon– Carries messages received by the dendrites to other

neurons– Terminal buttons-send messages to other neurons

• Myelin sheath– A protective coating of fat and protein that wraps around

the axon like links of sausage

5

How Neurons Fire

• Transmits an electrical impulse along the axon– All-or-none law– Resting state– Action potential – Mirror neurons

Figures 2 and 3 of Chapter 2

6

Where Neurons Meet: Bridging the Gap

• Synapse– The space between two

neurons where the axon of a sending neuron communicates with the dendrites of a receiving neuron by using chemical messages

Figure 4 of Chapter 2

7

Where Neurons Meet: Bridging the Gap

• Neurotransmitters– Chemicals that carry messages across the synapse

to a dendrite of a receiving neuron• Excitatory messages

– Increase the likelihood that neurons will fire

• Inhibitory messages – Decrease the likelihood that neurons will fire

• Reuptake– Reabsorption by the terminal button

8

Neurotransmitters: Chemical Couriers

• Acetylcholine (ACh)• Dopamine (DA)• Serotonin• Endorphins

Figure 5 of Chapter 2

9

Parts of the Nervous System

Figure 6 of Chapter 2

10

The Nervous System: Linking Neurons

• Central and Peripheral Nervous Systems– Central nervous system• Brain• Spinal cord

– Reflex» Sensory (afferent) neurons» Motor (efferent) neurons» Interneurons

11

The Nervous System: Linking Neurons

• Central and Peripheral Nervous Systems– Peripheral Nervous System• Somatic division

– Voluntary movements

• Autonomic division– Controls organs that function automatically

12

The Central Nervous System & the Peripheral Nervous System

Figure 7 of Chapter 2

13

Activating the Divisions of the Autonomic Nervous System

• Sympathetic Division– Acts to prepare the body for action in stressful

situations by engaging all of the organism’s resources to run away or confront the threat• “Fight or flight”

• Parasympathetic Division – Calms the body after emergency ends

14

Major Functions of the Autonomic Nervous System

Figure 8 of Chapter 2

15

The Evolutionary Foundations of the Nervous System

• Evolutionary Psychology– The branch of psychology that seeks to identify

how behavior is influenced and produced by our genetic inheritance from our ancestors

Behavioral Genetics Studies the effects of heredity on behavior

Behavioral genetics, gene therapy, and genetic counseling

16

The Endocrine System: Hormones and Glands

• The chemical communication network that sends messages throughout the body via the bloodstream– Hormones– Pituitary gland

• “Master gland”

Figure 9 of Chapter 2

17

The Brain

• How do researchers identify the major parts and functions of the brain?

• What are the major parts of the brain, and for what behaviors is each part responsible? How do the two halves of the brain operate interdependently?

• How can an understanding of the nervous system help us find ways to alleviate disease and pain?

18

Techniques for Spying on the Brain

• Electroencephalogram (EEG)

• Functional Magnetic Resonance Imaging (fMRI)

• Positron Emission Tomography (PET)

• Transcranial Magnetic Stimulation (TMS)

19

Brain Scans Produced by Different Techniques

Figures 10A, 10B,10C, and 10Dof Chapter 2

20

Major Structures in the Brain in Cross-section

Figure 12 of Chapter 2

21

The Central Core: Our “Old Brain”

• Central Core– Hindbrain• Medulla

– Breathing and heartbeat

• Pons – Transmitter of motor information

• Cerebellum – Balance Reticular formation

• Reticular Formation– Passes through the midbrain and into the forebrain– Activates other parts of the brain to produce bodily arousal

22

The Central Core: Our “Old Brain”

• Central Core– Thalamus• Relay station for information about the senses

– Hypothalamus• Maintains a steady internal environment for the body

23

The Central Core: Our “Old Brain”

• The Limbic System: Beyond the Central Core– Controls a variety of functions relating to emotions and self-

preservation, like eating, aggression, and reproduction

– Includes: • Amygdala• Hippocampus

Figure 13 of Chapter 2

24

The Cerebral Cortex: Our “New Brain”

• Cerebral Cortex– Provides the ability to

think, evaluate, and make complex judgments• Lobes

– Frontal – Parietal – Temporal – Occipital

Figure 14 of Chapter 2

25

The Cerebral Cortex: Our “New Brain”

• The Motor Area of the Cortex– Largely responsible for the body’s voluntary movement

• The Sensory Area of the Cortex– Corresponds to body sensations

• Somatosensory area– Touch – Pressure – The greater the amount of brain tissue devoted to a specific area of

the body, the more sensitive that area of the body

26

The Cerebral Cortex: Our “New Brain”

• The Association Areas of the Cortex– Executive functions• Higher mental processes such as thinking, language,

memory, and speech

27

The Adaptable Brain

• Neuroplasticity– The brain continually reorganizing itself

• Neurogenesis – New neurons created in certain areas of the brain

during adulthood

28

Specialization of the Hemispheres: Two Brains or One?

• Left and right symmetrical halves– Lateralized • Left

– Verbal competence– Processes information sequentially

• Right– Spatial relationships– Recognition of patterns and drawings– Music – Emotional expression – Processes information globally

29

The Split Brain: Exploring the Two Hemispheres

• Split-brain patients– The corpus callosum is

surgically cut – The two hemispheres of

the brain no longer communicate with each other

– The patient cannot combine the information of both hemispheres

Figure 16 of Chapter 2