Neural CommunicationNeurotransmitters and the Synapse

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

Covering neurotransmitters Activity

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

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What neurotransmitters doNeurotransmitters 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.

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 SystemPERIPHERAL NERVOUS SYSTEM Only two

neurotransmitters Acetylcholine (Ach) Norepinephrine

CENTRAL NERVOUS SYSTEM 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=9

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Examples of Neurotransmission

DrugsMany 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 DrugsInterfere with release of

neurotransmitterOccupy and block neurotransmitter

sitesCause 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