Chapter 2: Neuroscience

1. Chapter 2: Neuroscience Neurons and Neurotransmitters

2. Origins of studying the brain • Plato believed that the mind was located in the spherical head • Aristotle believed that the mind was located in the heart • Phrenology – Studying bumps on the head to reveal a person’s mental abilities and character traits, • Franz Gall invented phrenology • Gall was correct to conclude parts of the brain have specific functions. VIDEO: Racing and the brain.

3. Biology and Behavior • Biology is the foundation for our behavior and mental processes • Biological Psychologists – study links between biology and behavior • Neuroscience – interdisciplinary field studying how biological processes relate to behavioral and mental processes.

4. Neural Communication • Neuron – nerve cell, the building block of the nervous system • Each neuron consists of a cell body (sometimes called the soma) and branching fibers • Neurons send out electrochemical communications to the brain and the rest of the body • Dendrite – receives information coming from the neuron

5. Neural Communication • Axon – Passes information to other neurons, muscles and glands • Axons can be very long (unlike the dendrite which is very short) • Myelin Sheath – insulates the axon • Helps impulses travel quickly • Importance of the myelin sheath is seen in Multiple Sclerosis. • Consider MS – the myelin sheath breaks down and results in slow communication to the muscles.

6. Neural Communication • Axon Terminal Buttons ( aka end buttons / branches, synaptic vessicles) –the branched end of the axon that contains the neurotransmitters. Reaches right up to another neuron, muscle, organ.

7. Parts of a Neuron

8. Action Potential • Neural impulses are called action potential • Action Potential is a brief electrical charge that travels down an axon • Where does an electrical charge come from? • During the resting potential axon gates are closed and do not allow positively charged ions in. negatively charged ions are on the inside. • Electrical activity must get past the threshold to fire.

9. All or Nothing • Neuron fires (aka Action Potential) --- + charged ion comes into axon. Negative ions rush out.(this depolarizes the axon) --- depolarizing causes the next gate to open and then the next… etc. (like dominoes) • Neuron’s Action Potential • An “all or nothing response” • Like a gun firing or camera taking a picture… it does not go halfway • Refractory Period- • When the positive ions are pumped outside of the axon. During the phase the neuron can’t re-fire as in needs to recharge. FIELD TRIP TIME. YEAH!

10. FIELD TRIP • When you come back from our very brief field trip answer how the flushing of a toilet is analogous to the firing of a neuron. During which part of the demonstration did the following occur? • “all or nothing” principle • Resting potential • Threshold • Action Potential (neural impulse) • Refractory Period

11. Action Potential

12. Neuron Communication • Individual neurons function as independent agents within the nervous system • Synapse – junction between the axon tip of the sending neuron and the dendrite of the receiving neuron (junction is called the synaptic gap) • From the axon terminal buttons, neurotransmitters travel across the synapse • ACTIVITY: Neural Network

13. Neural Communication • LIVE!Psych (The Synapse and Neurotransmitters)

14. Neuron Communication (cont.) • When the action potential reaches the end of the axon, it triggers the release of neurotransmitters (chemical messengers) • Neurotransmitters cross the synaptic gap and binds to the receptor sites on the receiving neuron • Excess neurotransmitters are reabsorbed by the sending neuron – this is called reuptake • Many drugs today block the reuptake of neurotransmitters. Ex Zoloft, prozac, Paxil for Serotonin.

15. An example of Reuptake …

16. Neurotransmitters • Neurotransmitters – chemicals produced by neurons that travel across the synaptic gap and are then used for communication between neurons for the performance of mental and physical activities. • Q ANY EXAMPLES?

17. Acetylcholine (ACh) • Enables cognitive skill - learning and memory • Undersupply marks Alzheimer’s disease

18. Dopamine • Motor Movement • Oversupply is linked to schizophrenia. • Undersupply is linked to tremors and decreased mobility (ex. Parkinson’s disease) Stem cell m Cell Reading

19. Parkinson’s Disease and Dopamine • Michael J Fox Parkinson's Disease • Michael J. Fox has Parkinson's • Michael j fox on family guy

20. Serotonin • Mood Control • Undersupply is linked to clinical depression • Selective Serotonin Reuptake Inhibitors (SSRI) are a frequently used drug for depression (ex. Prozac, Paxil, Lexapro, Zoloft) These drugs increase the activity of Serotonin. • Anti-depressants and Placebo effect. VIDEO- Penn and Teller, Korea, college students and alcohol, talking to one person you can fully trust.

21. Nor epinephrine • Influences alertness and arousal • Undersupply can depress mood

22. Endorphins • Released in response to pain and vigorous exercise – linked to pain and pleasure. Ex.- Donovan McNabb, Jack Youngblood. • “morphine within”. Runner’s high, exercisaholics • Involved in addictions – Ex. Heroine

23. Drugs and How They Affect Communication at the Synapse • Agonist v. Antagonist Drugs • Agonist – mimic neurotransmitters (Excite) • Blocks reuptake of neurotransmitters • Fits into the receptor site and function as neurotransmitters • Antagonist– blocks neurotransmitters (Inhibit) • Inhibit neurotransmitters from releasing • Block receptor sites • LIVE!Psych

24. Agonist V. Antagonist Example • Ex. Dopamine • Undersupply (Parkinson’s) – Agonist Drug. Overdosage and hallucinations (grandfather) • Oversupply (Schizophrenia) – Antagonist. • dyskenesia • Drugs such as heroine and morphine can take the place of natural neurotransmission • Brain stops producing natural opiates • Body is in pain until the natural production of endorphins begins again.