Electrical Synapses

Where were electrical synapses first studied?

First studied inside the Giant Synapse of the motor neuron inside the Crayfish.

The motor neuron is responsible for the cray fish’s escape response (this is why its so massive)

studied bc the synapse is massive and accessible

How do we know that electrical synapses are Gap Junctions?

There is an overlap between the presynaptic AP and the Gap potential in postsynaptic neuron

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the darker areas on the electronmicrograph shows that there are alot of proteins in the area

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this is the space between Gap electrical synapses → the two membranes get pushed together and thus have smaller gap than other cell synapses.

Whis is it called a “gap potential”?

it passes through the gap junction and is slightly smaller than the AP

What are the 4 characteristics of chemical synapses?

1. unidirectional communication
2. not always reliable
3. metabolically expensive
4. speed can vary widely

What are the 4 characteristics of electrical synapses?

1. bidirectional communication
2. very reliable
3. metabollically inexpensive
4. extrememly fast

What is a nonrectifying electrical synapse?

the responses to the stimulation are equal in both directions

What is a rectiifying electrical synapse?

A stimulus applied to both cells will show that the responses are unequal, one direction has bigger response than the other.

What determines if a synapse is rectifying or nonrectifying?

depends on the exaxt combination of hemiconexxons

heterotopic→ more likely to be rectifying

HOw do you modulate the strength of electrical synapses?

1. how many open/closed channels
2. in general to open/close channels
3. density of electrical synapses in an area

Electrical synapses can coordinate…

activity among groups of neurons

(can link function and cause synchronized activity)

Neurotransmitter release can…

modulate connectivity of electrical synapses/gat junctions

→ ie in dim light, electrically coupled amacrine cells are greater in amount compared to darkness or brightness.

How are gap junctions important for development of cortical columns?

They coordinate the activity of the neurons within the cortical column.