Lec7: Studying synapses Flashcards
What is the name of the process used to measure synaptic activity?
Electrophysiology
What is another name for extracellular recordings?
Field recordings
Draw a schematic showing how a field recording is taken, and describe what each of the two electrodes do.
Stimulatory electrode = stimulates axons to fire APs
Recording electrode = recorded current flow through ion channels
Field recordings measure from a large population of neurons. What is the advantage and disadvantage of this?
- Advantage = technique is easy to learn
2. Disadvantage = Only gives general info about synaptic activity
Draw a voltage-time graph showing a field recording. What is the name of the downward deflection and why is it negative?
- Field EPSP (Field Excitatory Post-synaptic potential)
2. There is a loss of positive ions (Na+) extracellularly
What is another name for whole cell recording? Where is the recording electrode attached?
- Patch-clamping.
2. To the cell, essentially becoming a part of it.
Draw a voltage-time graph showing a whole cell recording. What is the name of the downward deflection and why is it negative?
- AMPAR EPSP (AMPA receptor excitatory post-synaptic potential)
- When patch-clamping, inward current is always recorded as a negative deflection, regardless of whether the inflowing ions are positive or negative.
What three aspects of setup are important when performing patch-clamping?
1 . Antivibration table = even small movements will completely disturb recording
- Faradays cage = Electrically isolated
- Inflow line = Supply neurons with glucose to keep them healthy
What is the name for synaptic strength increase and decrease respectively?
- Long Term Potentiation (LTP)
2. Long Term Depression (LDP)
Where is the hippocampus located?
Temporal Lobe.
Synapse plasticity underlies the formation of what “type” of memories? Where in the brain are these memories formed?
Declarative/Explicit memories formed in the hippocampus
Why are Hippocampal slice preparations very advantageous?
Because the neurons can survive for many hours, allowing time to make dissections, then to make slices, from which you can take recordings.
What is the purpose of making and examining hippocampal slices?
To understand the simple architecture of the brain.
What is the simple architecture of the brain referring to in terms of hippocampal slices?
It has very specific axonal pathways and post-synaptic neurons that are easy to stimulate and record from. (ie. The Trisynaptic loop)
Draw the trisynaptic loop in the hippocampus, making sure to label all the relevant areas and where electrodes can be placed.
Entorhinal cortex - Perforant Pathway - Dentate Gyrus - Mossy Fibres - Area CA3 - Schaffer’s Collaterals - Area CA1
