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Neuroscience Test 1 - Cellular Models of Epilepsy


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What causes the epileptiform spikes in an EEG?
Excessive neuronal discharge; faster or more frequently
What is the change in firing due to in epilepsy?
Changes in the synaptic properties of the cell
Besides abnormal firing, what is another thing that can cause epilepsy?
Abnormal anatomical brain organization
(Hypo/hyperglycemia) can cause seizures?
In normal people, what type of activity (EEG activity) is expressed in the frontal region of the brain(3 descriptors)? What frequency?
1. Low frequency (12-30hz)
2. Low Voltage
3. Beta waves
What type of EEG rhythm is seen in the occiptal region of the brain? What sort of frequency is exhibited? Is it constant?
1. Alpha waves
2. 8-12Hz (closed)
3. No it changes if the eyes are open
What are the anterior and posterior boundries when doing an EEG?
Inion and the Nasion
What actually produces the EEG?
The process of volume conduction and the flow of current through the extracellular space.
Where do you see most of the current drop in a neuron?
Across the highly resistant membrane.
The sink is where current flows (in/out) of the neuron while the source is where the current flows (in/out) of the cell.
1. In
2. Out
At the sink you get a (postive/negative) deflection?
Postive deflection
At the source you get a (postive/negative) deflection?
Negative deflection
A negative deflection indicates a (positive/negative) current?
A positive deflection indicates a (postive/negative) current?
Can interictal spikes fire continuously without a seizure?
Yes they can
Ictal discharge is associated with what?
Is it always possible to know where the deflections from an EEG come from?
What is a more precise way to understand where the spikes in an EEG came from?
Take the EEG with probles actually in the brain
True or false: Seizures in children often do not have a cortical source and cannot be seen by EEG.
Are generalized and absence seizures treatable with drugs?
Very treatable
Absence or petit mal seizures have to do with the connection between what two areas of the brain?
Thalamus and the cortex
what are the three kinds of changes that can induce seizures?
1. Changes in ion channel properties
2. Alterations in inhibition/excitation at synapes
3. Changes in synaptic connections
What drug, in high amounts, when applied directly to the brain induces seizure? How does it work?
Penicillin - it blocks the GABA receptors
During a seizure what would you see at the extracellular probe? The intracellular probe?
1. Extracellular - many AP spikes indicating hyper-excitablity
2. Intracellular - large depolarization currents
What is the depolarization during a interictal spike called?
A giant depolarization or a paroxysmal depolarization shift
If depolarization after an interictal spike lasts longer you can progress to what is called a ?
Ictal event - a seizure
Chronic seizure models mimic what type of seizure in humans?
Complex partial seizures
What are the two methods to induce complex partial seizures?
1. Kainic acid
2. Kindling
What lobular seizures of the brain do Kindling seizures mimic?
Temporal lobe seizures
What areas of the brain are probed in the Kindling model?
Amyglada and Hippocampus
When being Kindled, do the small electrical seizures produce behavior changes?
Is the seizure accompanied by low electrical impluses in the Kindling model lifelong?
The changes in the brain after Kindling can even cause what?
Spontaneous epileptic seizures
What area of the brain changes in response to kindling? What part of this area changes?
Hippocampus - dentate gyrus
What type of fibers sprout in the kindling model?
Mossy fibers
What do mossy fibers innervate?
The CA3 region of the hippocampus
What cells do mossy fibers make connections to in the Kindling model?
Granular cells of the hippocampus
What type of receptors are stimulated by mossy fibers in kindled animals?
NMDA receptors
Activation NMDA receptors causes (hyper/hypoexcitability).
What drug can create a model that is microgryic in likeness?
Seizures that are not responsive to drugs are due to what? Give two examples?
Migration of neurons

1. Heterotopias - cells in the wrong place
2. Cortical dysplasia
What is agyria?
Failure of gyri to form
What is microdisgenesis?
Glial cells but no neurons
What is focal cortical dysplasia?
Small changes in small areas of the brain.
Why are heterotropic cells hyper-excitable?
Abnormal Kv4.2 (K channel)

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