W2 L3 (Fast Synaptic Transmission)

Question 1

FAQ : What is the difference between an action potential and a graded potential? Why is this difference caused?

Answer 1

APs are all or none, while graded potentials are not. This is because if an AP reaches threshold it leads to a feed-forward (positive feedback) loop until the channels are deactivated. With a graded potential, the change is caused by ligand-gated channels which don’t respond to stimulus and rather slowly have their neurotransmitters removed which leads to these channels slowly closing as they are unable to self-renew

Question 2

FAQ: Are EPSP and IPSP graded potentials since they are influenced by the amount of a neurotransmitter that is released into the synaptic cleft?

Answer 2

They are graded because their activity is determined by the number of neurotransmitters and therefore the amount of ligand-gated ion channels (typically ionotropic) that are activated

Question 3

Are PSPs boosted or enhanced as they travel down the axon?

Answer 3

No

Question 4

FAQ: Do inhibitory neurons act much quicker than excitatory neurons?

Answer 4

Depending on what needs to be done one may act slower or faster than the other. ex. Need to inhibit something then the inhibitory neurons will fire much quicker

Question 5

FAQ: What does amine and peptide neurotransmitters as “messengers” mean in terms of
neurotransmission?

Answer 5

These are 1st messengers and they bind metabotropic receptors which cause 2nd messengers to be generated

Question 6

FAQ: In synaptic transmission, what signal triggers the neurotransmitter molecules to dissociate from
the receptor, enter the glial/terminal of the presynaptic neuron, and be repackaged?

Answer 6

A neurotransmitter dissociates from the receptor because of diffusion and the fact that all systems will go towards chemical equilibrium. Transmitters are released into the cleft to keep the concentration balance as some transmitters are being readily taken up and brought back to the

Question 7

FAQ: What triggers the switch of releasing excitatory neurotransmitter molecules to inhibitory
transmitter molecules?

Answer 7

Most neurons don’t switch between the neurotransmitters that they release. Most neurons stick to a certain molecule or a few at their synapses.

Question 8

FAQ: Do acetylcholine and glutamate work the same way? Is there different functions for these two
molecules or are they just neurotransmitters which cause EPSPs? Same with GABA and glycine?

Answer 8

The mechanisms and outcomes of different excitatory transmitters (Ach, glutamate) or inhibitory transmitters (GABA, glycine) binding to their respective ionotropic receptors are often similar. However, the exact amount and ratio of ions that pass when Ach binds an Ach receptors vs glutamate binding a glutamate receptor is often different. Also, the rate at which the Ach binds and mediates an effect can often be different from a glutamate response, despite both molecules causing EPSPs. While GABA and
glycine both open Cl-selective channels, again the kinetics and affinities are often different. These subtleties allow for fine tuning of a response or a particular EPSP or IPSP.

Question 9

FAQ: Do EPSPs and IPSPs apply to complex thought processes?

Answer 9

Yes, All aspects of brain function, from volitional or autonomic motor control, hormonal output, and
feedback, sensory perception and processing, emotion, cognition, and memory involve synaptic input and integration, as well as modulation of the way a synapse impacts a given neuron. It appears to be a combination of many synapses working on many neurons to achieve the emergent properties of complex thought

Question 10

FAQ: How much does the emotional context behind the thought contribute to the IPSP/EPSP?

Answer 10

It is the other way around. The context would be coded for by neurons which are receiving
IPSPs and EPSPs, as well as causing IPSPs and EPSPs on other neurons. The simplest way to approach this subject is to first realize that all aspects of what psychologists call “mind” is really the work of neurons signally one another (with action potentials, fast synaptic potentials, slow transmission, and electrical transmission). The particular aspect in question (emotion, reasoning, memory) will depend on a particular combination of neurons and how the three types of synaptic transmission are used.