W8L2 - Glutamate and GABA Flashcards
List down some properties of Glutamate and Gaba: (1) Evolution (2) Commonality (3) “True”
Glutamate and GABA
- Believed to be the first to evolve and are found in very simple organisms
- Most common neurotransmitters in the CNS
- “True” neurotransmitters – directly affecting the likelihood of the post-synaptic neuron firing
What is the main excitatory NT? What does the excitation NT do in terms of firing
Glutamate
Increase likelihood of post-synaptic neuron firing
How many of the brain synapse release glutamate
Estimated over half of all brain synapses.
What is the acid associated with glutamate
Glutamic Acid
Must glutamate be synthesized? Why?
- Glutamate = Glutamic Acid
- Glutamate is an amino acid that acts as a neurotransmitter in its “original” form but this amino acid does not pass the blood brain barrier so it still needs to be synthesized in the brain
- Glutamate is synthesized from glutamine which is released by cells neighbouring the neurons
Glutamate > Glutamine >(Synthesised by neighbouring cells) > Glutamate
Where is glutamate found
In most long projection neurons throughout cortex
What are the connection points like for excitatory connections”. Do they have general functions?
“Point-to-Point”. Direct.
No, there are many region-specific functions (e.g. vision)
How many types of glutamate receptors are here?
- 3 Ion channels
- NMDA Receptor
- AMPA Receptor
- Kainate Receptor
- 1 G-protein coupled receptors
- Metabotropic Glutamate Receptor
NMDA Receptor: How many binding sites are there. What are some conditions for glutamate to be attached
6 Different Binding Sites.
- Glycine Molecule attached
- Magnesium ion not bound
- Or else it won’t open
Other binding cites modulate receptor function.
What are some drugs discussed in Week 8 Lecture 2 that affects NMDA. What do they have in common.
Alcohol, PCP, Ketamine
- NMDA antagonists (inhibit)
- But they all have different impacts on the mind
How does alcohol related to NMDA receptor. What does this explain
- NMDA antagonist (inhibit)
- Reduce glutamate
- GABA agnoist (excite)
- Increase GABA
- Explains general sedative effects and brain inhibition
What does PCP and Ketamine cause. Are they safe?
PCP = “Angel Dust”
Ketamine = “Special K”
- PCP and Ketamine are NMDA antagonists (Reduce glutamate)
-
Dissociative hallucinations
- Feel disconnected rather than perceiving visions
- Risk of suicidal behaviour
- Though Ketamine is very safe
-
Dissociative hallucinations
What is the association between glutamate and psychosis?
What is psychosis?
What changes are there in individuals with psychosis?
- Some have suggested a link between glutamate and psychosis but it is controversial and likely to involve others NTs like DA.
- Psychosis
- Symptom cluster, not diagnosis
- SZ = 1% (Diagnosis)
- Psychosis = 3% (Symptom Cluster)
- Widespread disruption & lack of coherent integration of sensory information
- No major structural impairment in psychosis
- Likely reflect chemical inbalances
- Symptom cluster, not diagnosis
Genetic studies and psychosis. What is the role of NMDA? Conclusion?
Genetic studies on Psychosis
- NMDA receptor activity
- Critical for learning, memory, perception and synaptic plasticity in general.
- Genetic studies identify NMDA receptor genes as likely being relevant in schizophrenia, but also relevant to general function and IQ
- Large number of genes that all may each contribute to a small amount of risk for psychosis.
- Picture remains unclear and may simply reflect altered synaptic activity in psychosis
What is GABA and what does it do in to the post-synaptic neuron?
Main inhibitory NT - Decreasing likelihood of the post-synaptic neuron firing
How does GABA help in neural tuning. Are they perfect?
- Delicate coordination of neurons to signal very specific information
- “Keeping signal sharp”
- Selective, not perfect
- Reduce likelihood of neurons firing for non-preferred stimulus (Dosen’t stop firing for non-preferred stimulus)
- Explains tuning curve
Explain the study on high fever and vaccinations.
High fever and Vaccinations.
- Vaccinations cause high fevers in some children and the fevers can trigger the first epileptic event
- Some children with epilepsy genes without vaccinations still ended up getting epilepsy
- Some children with epilepsy gene had seizures before vaccinations
