General Psychology Neurology

Sarah Rach-Sovich

A quick review…

• Neural communication– Build from billions of interconnected cells– Name this cell

Neuron

???

What is my name?

Dendrites

Axon

Myel in Sheath

Terminal Branches

of Axon

Cell Body

Parts of a Neuron

• Cell Body: life support center of the neuron.• Dendrites: branching extensions at the cell body.– Receive messages from other neurons.

• Axon: long single extension of a neuron• Myelin sheath: covers the axon to insulate and

speed up messages through the neurons• Terminal Branches of axon: branched endings of

an axon that transmit messages to other neurons.

Synapse

• Junction between the axon tip of the sending neuron and the dendrite

• Tiny gap is called the synaptic gap or cleft

Neurotransmitters (NT)

• Released from the sending neuron

• Travel across the synapse and bind to receptor sites on the receiving neuron

• This influences it to generate an action potential

Reuptake

• NT in the synapse are reabsorbed into the sending neurons through this process

• Applying the brakes

How do they influence us?

• Serotonin pathways are involved with mood regulation

• Can I bum at neurotransmitter?

If only it were that simple…

•NTs do affect mood

•Utilization of drugs

Dopamine Pathways

• Involved with diseases such as schizophrenia & Parkinson’s disease

NTs and their functions

Lock & Key Mechanism

NTs bind to the receptors of thereceiving neuron in a key lock mechanism.‐

Agonist

Antagonist

How about an example?

•Marijuana (and others such as nicotine and cocaine) primarily affect the brain’s limbic system (also called the ‘reward system’)•Under normal circumstances pleasurable experiences are followed by the release of the NT dopamine which creates feelings of pleasure

How do you feel when something good happens?

• Your limbic system at work• Natural pleasures are necessary for survival– Food, water, sex

• Limbic system creates an appetite that drives you to seek those things

First time use of a drug

– Unnaturally intense feelings of pleasure– Limbic system is flooded with dopamine– The brain starts changing• There is more than enough dopamine• Neurons begin to reduce the number of dopamine

receptors• Neurons may make less dopamine in the brain (down

regulation)• Some neurons may even die

What if a person keeps using?• How many times can a person use

drugs without changing his or her brain and becoming addicted?

• Addicted limbic system craves the drug (made worse because of down regulation)

• Without the drug, the dopamine levels in the brain are low– Feels flat, lifeless, depressed,

joyless• Larger amounts of the drug are

needed (tolerance)

Questions?

A little advice to leave you with…