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Introductory Psychology Course Interactive Demonstrations

https://www.danblu.com/teaching/demos

Demo Topic: Neuroscience 🡪 Neurotransmission

Remove this slide before you run this demo in class.

This demo requires pre-class setup, please check the Demo 2 Instructions document for more details.

In advance, purchase and prepare all materials. Most items are ready to use after purchase except for these which require some assembly:

Neurotransmitters on actin filaments

Use an awl to poke two small holes on opposite sides of each ping pong ball.

Use the sewing needle to pull the thread through each ping pong ball.

Each ball should be on the thread and be able to slide easily back and forth.

Electrical charges

Cut out small lightening bolts (about 25 cm tall) from the yellow paper. These represent subthreshold electrical charges.

Cut out large lightening bolts (about 75 cm tall) from the yellow paper. These represent an action potential.

Immediately prior to class, use the party streamers to draw out the outline of the presynaptic neuron with dendrites, cell body, axon and synaptic terminus. Tape the streamers to hold them in place on chairs in the classroom or auditorium. Leave a small gap and then use streamers to tape a dendrite of the postsynaptic neuron.

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Learning Outcome:

Understand and explain the key steps in synaptic transmission

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Questions to Consider…

What occurs when a cell reaches its threshold potential?
What role do neurotransmitters play in neurotransmission?
What happens to neurotransmitters remaining in the synaptic cleft?

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Demo

This Photo by Unknown Author is licensed under CC BY-SA-NC

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Setting up the cells

Nucleus

Neurotransmitter

Receptor [activated by NT]

Glial cells

Electrical signal

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Neurotransmitter transport to synapse
Vesicle loaded with neurotransmitters
Inputs at dendrites excite presynaptic cell
With enough input, action potential occurs
Action potential travels down axon to synapse

As you step through each step on this slide, demonstrate the process with the class demo as follows:

1. Neurotransmitter transport to synapse. Have students slide the ping pong ball neurotransmitters from the nucleus to the axon terminus to prepare for release.

2. Vesicle loaded with neurotransmitters. Ping pong balls should be slid off the end of the thread and put in transparent plastic bags.

3. Inputs at dendrites excite presynaptic cell. Ping pong balls (NTs) are put into the plastic cups (receptors) on the presynaptic neuron which triggers the release of a small lightening bolt (excitatory postsynaptic potential) which is passed to the nucleus.

4. With enough input, action potential occurs. Once 3 or 4 lightening bolts have arrived at the nucleus, this triggers the large lightening bolt (action potential) to appear (it is generated when the threshold is crossed). Connect back to initial question 1: What occurs when a cell reaches its threshold potential?

5. Action potential travels down axon to synapse. Students pass the large lightening bolt down the axon to the terminus.

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Neurotransmitter transport to synapse
Vesicle loaded with neurotransmitters
Inputs at dendrites excite presynaptic cell
With enough input, action potential occurs
Action potential travels down axon to synapse
AP stimulates release of neurotransmitter
Activation of receptors on postsynaptic cell

Continue stepping through the last two steps on this slide:

6. AP stimulates release of neurotransmitter. When lightening bolt reaches the axon terminus, the plastic bags are pushed to the cell membrane and opened, releasing the ping pong balls into the synaptic cleft (outside the streamer boundary).

7. Activation of receptors on postsynaptic cell, Ping pong balls bounce around the synaptic cleft but some diffuse to the receptors on the postsynaptic cell. To show this, ping pong balls should be placed in the receptors of the second cell. Connect back to initial question 2: What role do neurotransmitters play in neurotransmission?

The Aftermath. Connect back to initial question 3: What happens to neurotransmitters remaining in the synaptic cleft?

Neurotransmitters left in the synaptic cleft…

Are retrieved by students (reuptake)

Are stepped on by students (enzyme breakdown)

Roll away (diffusion)

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