Neurotransmitters and the Synapse Neural Communication

Question for Thought What are ways in which you communicate with your friends? Neurotransmitters are the means of communication for neurons. However, they can illicit action or stop all communication.

Question for Thought How are neurotransmitters and the neuron linked to psychology? What is their importance?

Outline of Lesson Quick review of the Neuron parts Lecture Activity Covering neurotransmitters Activity

Film-Neural Communication http://www.youtube.com/watch?v=HXx9qlJetSU

What neurotransmitters do Neurotransmitters are central to memory, learning, mood, behavior, sleep, pain perception and sexual urge. They operate at the junctions between neurons, allowing communication between cells.

Acetylcholine involved in voluntary movement, learning, memory, and sleep Too much acetylcholine is associated with depression, and too little in the hippocampus has been associated with dementia.

GABA (Gamma-Amino Butyric Acid) inhibits excitation and anxiety Major inhibitory neurotransmitter in Brain Too little GABA is associated with anxiety and anxiety disorders. Some anti-anxiety medication increases GABA at the receptor sites.

Glutamate Common neurotransmitter in the brain Always excitatory and driven by the Sodium-Potassium pump Receptors concentrated in the Cerebral Cortex especially the hippocampus Reabsorption of Glutamate is affected during mercury poisoning

Seratonin plays a role in mood, sleep, appetite, and impulsive and aggressive behavior Too little serotonin is associated with depression and some anxiety disorders, especially obsessive-compulsive disorder. Some antidepressant medications increase the availability of serotonin at the receptor sites.

involved in energy, and glucose metabolism Epinephrine involved in energy, and glucose metabolism Too little epinephrine has been associated with depression.

Norepinephrine associated with eating, alertness § Too little norepinephrine has been associated with depression, while an excess has been associated with schizophrenia.

Dopamine correlated with movement, attention, and learning Too much dopamine has been associated with schizophrenia, and too little is associated with some forms of depression as well as the muscular rigidity and tremors found in Parkinson’s disease.

Endorphins involved in pain relief and feelings of pleasure and contentedness

Role of Neurotransmitters in the Nervous System Peripheral Nervous system Central Nervous system Only two neurotransmitters Acetylcholine (Ach) Norepinephrine Many Neurotransmitters Why? Brain functions are not as uniformed Many neurotransmitters to perform many different tasks

Film– 3D example of Neurotransmission http://www.youtube.com/watch?v=90cj4NX87Yk

Examples of Neurotransmission

Drugs Many drugs and chemicals influence synaptic transmission Drugs can be agonistic or antagonistic But not all drugs increase dopamine levels in the brain in the same way.

Drugs cont. Some substances imitate natural neuromediators and take their place on their receptors. Morphine, for example, binds to the receptors for endorphin (a natural "morphine" produced by the brain), while nicotine binds to the receptors for acetylcholine. Other substances increase the secretion of natural neuromediators. Cocaine, for example, mainly increases the amount of dopamine in the synapses, while ecstasy mainly increases the amount of serotonin. Still other substances block a natural neuromediator. Alcohol, for example, blocks the NMDA receptors.

Agonistic Drugs Increase synthesis of neurotransmitter Increase release of neurotransmitter Activate receptors, mimic neurotransmitter Inhibit reuptake of neurotransmitter

Antagonistic Drugs Interfere with release of neurotransmitter Occupy and block neurotransmitter sites Cause neurotransmitter loss from vesicles.

Psychotropic drugs Agonists mimic the neurotransmitter by binding to the receptor sites just as the neurotransmitters do and having the same effect on the receiving neuron. Agonists are used when it is believed that there is not enough neurotransmitter Antagonists BLOCK the neurotransmitter by binding to the receptor sites without affecting the receiving neuron in the same way. Because they “fill” the receptor sites, the neurotransmitters can’t bind to the neuron. Antagonists are used when it is believed that there is TOO much of the neurotransmitter in the body.

Psychotropic drugs When there is TOO LITTLE neurotransmitter in the body, drugs may also help by blocking reuptake and thus increasing the amount of neurotransmitter that remains in the synapse Prozac is an example of this sort of drug. Prozac falls in a class of drugs called SSRI’s (Selective Serotonin Reuptake Inhibitor) and by inhibiting reuptake of serotonin, they increase the levels of this neurotransmitter in the brain.

Activity