1. The Biological Basis of Behavior

2. Neurons: The Messengers
About 100 billion neurons (nerve cells) in the human brain
Neurons have many of the same features as other cells
Nucleus
Cytoplasm
Cell membrane
What makes neurons unique is their shape and function

3. Structure of Neurons Dendrites Cell Body (Soma) Axon Myelin Sheath
Carry information to the cell body from other neurons
Cell Body (Soma)
Contains nucleus
Axon
Carries information to the next cell
Myelin Sheath
Insulates the axon and speeds up the neural impulse

4. Types of Neurons Sensory neurons Motor neurons Interneurons
Carry information from sensory systems to the brain
Also referred to as afferent
Motor neurons
Carry information from the brain to muscles and glands
Also referred to as efferent
Interneurons
Carry information between other neurons

5. Glial Cells Cells that insulate and support neurons
Create the myelin sheath
Remove waste products
Provide nourishment
Prevent harmful substances from entering the brain

6. The Neural Impulse

7. The Neural Impulse Ions Resting Potential Charged molecules
When more negative ions are inside the neuron than outside
Charge is approximately -70mV
Neuron is not transmitting information

8. The Neural Impulse Polarization Depolarization
When the electrical charge of a cell moves away from zero
Depolarization
When the electrical charge of a cell moves toward zero

9. The Neural Impulse Action Potential
Sudden, massive change in charge in the neuron
Occurs when depolarization reaches the threshold of excitation
Ions flow across cell membrane

10. The Neural Impulse Graded Potentials Subthreshold depolarization
Many subthreshold depolarizations are added together to produce an action potential (a process known as summation)

11. The 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

12. The Neural Impulse 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

13. The Synapse Synaptic space (synaptic cleft) Terminal button
Tiny gap between neurons
Terminal button
Enlarged area at the end of an axon
The synapse
Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron

14. Transmission Between Neurons
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

15. Some Well-Known Neurotransmitters
Acetylcholine (ACh)
Released at the neuromuscular junction
Plays an important role in arousal and attention
Loss of ACh producing cells is linked to Alzheimer’s Disease
Dopamine
Affects neurons associated with voluntary movement
Plays a role in learning, memory, and emotions
Loss of dopamine-producing cells causes symptoms of Parkinson’s Disease

16. Some Well-Known Neurotransmitters
Serotonin
Found throughout the brain
Appears to sets an “emotional tone”
Low serotonin levels are implicated in depression
Endorphins
Reduce pain by inhibiting or “turning down” neurons that transmit pain information

17. Neural Plasticity
The brain can be changed, both structurally and chemically, by experience
Rat studies show that an “enriched” environment leads to larger neurons with more connections
Has also been shown in humans
Recent research has uncovered evidence of neurogenesis, or the production of new brain cells, in human brains

18. Nervous System Organization Module 10
Central nervous system (CNS)
Consists of the brain and spinal cord
Peripheral nervous system
Connects the CNS to the rest of the body
Somatic nervous system
Autonomic nervous system

19. Central Nervous System

20. The Peripheral Nervous System

21. The Somatic Nervous System
Consists of neurons that communicate between the body and the brain
Afferent neurons
Neurons that carry messages from sense organs to spinal cord
Efferent neurons
Neurons that carry messages from the spinal cord or brain to muscles and glands

22. The Autonomic Nervous System
Sympathetic division
Most active when you are angry, afraid, or aroused
Fight-or-flight response
Increases heart rate and breathing
Stops digestion

23. The Spinal Cord
The spinal cord controls some protective reflex movements without any input from the brain

24. The Autonomic Nervous System
Parasympathetic division
Calms body
Produces effects opposite to those of the sympathetic division
Reduces heart rate and breathing
Restores digestion

25. The Spinal Cord

26. The Spinal Cord
Complex cable of nerves that connects brain to rest of the body
Carries motor impulses from the brain to internal organs and muscles
Carries sensory information from extremities and internal organs to the brain

27. The Endocrine System
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

28. The Endocrine System Pituitary gland Gonads Adrenal glands
Referred to as the “master gland” because it regulates many other glands
Gonads
Ovaries and testes secrete estrogens and androgens
Adrenal glands
Secretes hormones in reaction to stress

29. The Endocrine System Pineal gland Pancreas
Secretes melatonin which regulates the sleep-wake cycle
Pancreas
Regulates blood-sugar levels
Secretes insulin and glucagon

30. The Endocrine System Thyroid gland Parathyroid glands
Secretes hormones (primarily thyroxin) that control metabolism
Parathyroid glands
Control levels of calcium and phosphate which in turn controls levels of excitability

31. Endocrine System

32. The Brain – The Central Core Module 11
Medulla
Controls breathing, heart rate, and blood pressure
Pons
Maintains the sleep-wake cycle
Cerebellum
Coordinates body’s movements

33. The Brain – The Central Core
Thalamus
Relays information from sensory receptors to the brain
Hypothalamus
Influences motivated behavior
Regulates hunger, thirst, body temperature, and sexual drive.
Directly involved in emotional behavior

34. The Brain – The Central Core
Reticular formation
Network of neurons found throughout the brain
Serves to alert and arouse higher brain in response to incoming information

35. The Brain – The Limbic System
Ring of structures located between the central core and the cerebral hemispheres
Important to learning and emotional behavior
Hippocampus essential in formation of new memories
Amygdala, together with the hippocampus, is important for regulating emotions

36. The Cerebral Cortex Module 12
Occipital lobe
Receives and processes visual information
Temporal lobe
Complex visual tasks such as face recognition
Receives and processed auditory information
Involved in balance, some emotions and motivations
Some language processing

37. The Cerebral Cortex Parietal lobe Frontal lobe
Receives sensory information from body
Involved in spatial abilities
Frontal lobe
Coordinated information from other lobes
Controls voluntary movement, attention, setting goals, and expression of appropriate emotions

38. Brain Hemisphere Module 13
Corpus Callosum
Fibers that connect the two hemispheres
Allow close communication between left and right hemishphere
Each hemisphere appears to specialize in certain functions

39. Split-Brain Research
Much information about functions of each hemisphere has come from studying split-brain patients

40. Genes, Evolution, and Behavior Module 14

41. Genetics Heredity - transmission of trait from one generation to next
Chromosomes
Pairs of thread like bodies that contain genes
Deoxyribonucleic acid (DNA)
Organic molecule arranged in a double-helix
Contains the “code of life”

42. Behavior Genetics Study of behavior from a genetic perspective
Animal behavior genetic studies include:
Strain studies
Selection studies

43. Human Behavior Genetics
Family studies
Assume that close family members share more of a trait than non-relatives
Used to assess the heritability of psychological disorders or traits
Twin studies
Used to determine how heritable a trait or disorder may be
Identical twins would have highest heritability

44. Human Behavior Genetics
Adoption studies
Used to assess the influence of environment
Molecular genetics
Direct study of the genetic code

45. Evolutionary Psychology Module 15
Natural selection
“Survival of the fittest”
Evolutionary psychology looks at the adaptive or survival value of behaviors

46. Social Implications
Study of biological origins of behavior could lead to genocide and eugenics aimed at eliminating certain types of people
Could also be used to create new categories of people, such as people bred to be good soldiers or manual laborers