How is the Nervous System Organized?

1. How is the Nervous System Organized? Chapter 2-Neuroscience: The Brain and Behavior

2. Module Objectives: • Identify and define the structures of the neuron • Identify and discuss the role of neurotransmitters on behavior

3. Ancient cultures believed the heart was the center of all thoughts and emotions. But we now know that the brain and the rest of the nervous system are the power behind our psychological life and much of our physical being.

4. This chapter introduces you to the field of neuroscience and biopsychology the scientific study of the biology of behavior and mental processes

5. This amazingly complex nervous system controls some of our most sophisticated psychological behaviors We will begin by examining the most basic elements of the human nervous system. Let’s look at our foundation!

6. The Neuron • The neuron is the basic building block of the nervous system • Each one is a tiny information-processing system with thousands of connections for receiving and sending electrochemical signals to other neurons. • Each human body may have as many as one trillion neurons.

7. Look at the following pictures and make a list of words that best describe the picture Pretend that you’re describing the picture to a friend who cannot see it.

11. Did you notice a web-like appearance in those neurons? We will see that neurons do create a neural network crucial to communication…what you will also learn is that as much as they look like a web, neurons do not actually touch

12. 4 parts of the neuron • Dendrites are specialized to receive signals from neighboring neurons and carry them back to the cell body • Thin, bushy-like structures that receive information from outside the neuron • Relays the information into the cell body

13. The Neuron • The Cell body contains the cell nucleus • The cell body relays the information down to the axon

14. The structure of a neuron • Axon: A thin, long structure that transmits signals from the cell body to the axon terminal. • Axon Terminal is the last step for the relay of information inside the neuron. Axon

15. The cell body is covered with Axon Terminals

16. Once the information hits the terminal, it is transmitted outside the cell by neurotransmitters, which reside in the axon terminal.

17. -Electrical Communication-Chemical Communication How do Neurons Communicate?

19. The Electrical Part • Action potential is an electrical current sent down the axon. • The activity within the neurons is electrical. This current causes the neuron to “fire” • This is an “all-or-none” process…a neuron never firs half way. It either fires or it doesn’t.

20. Action potentials travel down the axon like a wave of energy

21. Synaptic transmission • The Synapse is the space between neurons -The synaptic gap or cleft • Information must be transmitted across the synapse to other neurons via the neurotransmitters. • This is an electrochemical process

22. Notice how the neurons don’t physically touch

23. Let’s Review!

24. Presynaptic Neuron

25. Neurotransmitters • Neurotransmitters are chemical substances that reside in the axon terminals • They communicate to other neurons by binding to receptors on neighboring neurons -The communication between neurons is chemical

26. Chemical Communication

27. Synaptic Transmission • The neurotransmitters are released from the vesicles and then attach to receptors located on the postsynaptic neuron. • These neurotransmitters are in contact with the dendrite of the postsynaptic neuron only briefly. • The chemical is almost immediately destroyed or reabsorbed (reuptake)

28. Neurotransmitters • At least 50 different types of neurotransmitters have been identified • Acetylcholine • GABA • Serotonin • Dopamine • Norepinephrine • Endorphins

29. Acetylcholine • Activates motor neurons controlling skeletal muscles • Contributes to the regulation of attention, arousal and memory

30. Examples of Neurotransmitters • Gamma-aminobutyric acid (GABA) is involved in experiences of anxiety, alcohol abuse, seizure disorders, and sleep disorders • Serotonin is involved in sleep and mood regulation, eating and aggression • Abnormal levels may contribute to depression and OCD

31. Dopamine • Contributes to control of voluntary movements, feelings of reward and pleasure • Too much dopamine has been associated with schizophrenia • Too little dopamine has been associated with ADD and Parkinson’s Disease

32. Norepinephrine • Involved in arousal reactions, especially important for vigilance • A heightened sensitivity to your surroundings

33. How do drugs effect behavior?

34. Drugs Impact on the Brain • Common drugs can alter the amount of a neurotransmitter released at the synapses • Some drugs can mimic/facilitate the action of the neurotransmitters while others can block the action of the neurotransmitter.

35. Agonists versus Antagonists • Agonists mimic or facilitate the actions of a neurotransmitter • Antagonists oppose/block the actions of a neurotransmitter Agonist Antagonist

38. What’s Next? The Brain • How do the neurons work together? • The Central Nervous System • The Peripheral Nervous System