LIFESCI 15 Lecture Notes - Lecture 16: 5-Ht Receptor, Axon Terminal, Fluvoxamine
3/6/18
I. The Synapse
II. Do it again centers in the brain
III. Drugs can hijack pleasure pathways
The Synapse
The Big Picture: nervous system functioning
1. Signal – initiates action potential in response to external stimuli: a sound, smell, sight, etc
2. Travels from dendrite down axon
3. Synapses with another cell – a muscle, gland, or another neuron; causing a response/reaction
Typical Synapse Functioning (look at picture)
1. Action potential arrives at terminal button
2. Calcium channels open and calcium rushes in
3. Vesicles fuse with terminal button membrane
4. Neurotransmitter dumped into synapse
a. Acetylcholine is the neurotransmitter for muscles
5. NT binds with post-synaptic receptors, causes:
a. Muscle contraction OR
b. Action potential
6. Re-uptake/enzymatic breakdown of NT
THM1: at the synapse, an action potential is converted to a chemical signal, releasing neurotransmitters to
stimulate tissue or another neuron
Do-it-again Centers in the Brain
There are pleasure centers in animal brains
- 1954: James Olds put electrodes in the mesolii aea of ats’ ais
o Rats loved the sensation and would do anything to get it
▪ Would navigate complex mazes
▪ Would self-stimulate to the point of death from starvation! (more than 700x per hour!)
- It is one of several pleasure centers in the brain. Called do-it-agai etes
Q: What good does it do an animal to have a set of neurons that makes them feel real good?
- They want us to do things they want
- Can train us
- Ex: exercise, food, achieving status
What is going on in the pleasure centers? (look at picture)
1. Neuron is stimulated (in response to your behavior)
2. Dopamine is released into the synapse
3. Receptors on adjacent ell bind dopamine and fire
4. Happiness ensues
An interesting aside (that is relevant)
- Cocaine binds to re-uptake receptors, blocking them
- Dopamine remains in synapse
- Pleasure is intensified
- The essage soethig good is goig o is ot teiated
- Rats will self-administer until death from starvation
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Thm1: at the synapse, an action potential is converted to a chemical signal, releasing neurotransmitters to stimulate tissue or another neuron. It is one of several pleasure centers in the brain. They want us to do things they want. What is going on in the pleasure centers? (look at picture: neuron is stimulated (in response to your behavior, dopamine is released into the synapse, receptors on adjacent ell bind dopamine and fire, happiness ensues. Cocaine binds to re-uptake receptors, blocking them. The (cid:373)essage (cid:862)so(cid:373)ethi(cid:374)g good is goi(cid:374)g o(cid:374)(cid:863) is (cid:374)ot te(cid:396)(cid:373)i(cid:374)ated. Rats will self-administer until death from starvation. Thm2: our brains are built with pleasure centers. Stimulating them is so pleasurable we want to behave in ways that repeat and maximize the stimulation. What if you block serotonin re-uptake transporter protein: no more depression, prozac; ssri (selective serotonin receptor inhibitor, zoloft, paxil, luvox, celexa. Adenosine is a chemical produced as a by-product of cellular metabolism.
