C HAPTER 2: N EUROSCIENCE Neurons and Neurotransmitters

O RIGINS 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.

B IOLOGY AND B EHAVIOR 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.

N EURAL C OMMUNICATION 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

N EURAL C OMMUNICATION 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.

N EURAL C OMMUNICATION 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.

P ARTS OF A N EURON

A CTION P OTENTIAL 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.

A LL OR N OTHING 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!

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

A CTION P OTENTIAL

N EURON C OMMUNICATION 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

N EURAL C OMMUNICATION LIVE!PsychLIVE!Psych (The Synapse and Neurotransmitters)

N EURON C OMMUNICATION ( 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.

A N EXAMPLE OF R EUPTAKE …

N EUROTRANSMITTERS 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?

A CETYLCHOLINE (AC H ) Enables cognitive skill - learning and memory Undersupply marks Alzheimer’s disease

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

P ARKINSON ’ S D ISEASE AND D OPAMINE Michael J Fox Parkinson's Disease Michael J. Fox has Parkinson's Michael j fox on family guy

S EROTONIN 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.

N OR EPINEPHRINE Influences alertness and arousal Undersupply can depress mood

E NDORPHINS 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

D RUGS AND H OW T HEY A FFECT C OMMUNICATION AT THE S YNAPSE 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

A GONIST V. A NTAGONIST E XAMPLE 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.