Question Answer Note/Hint 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? -Hypoglycemia 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? -Positive A positive deflection indicates a (postive/negative) current? - Negative Can interictal spikes fire continuously without a seizure? -Yes they can Ictal discharge is associated with what? -Seizure Is it always possible to know where the deflections from an EEG come from? - No 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. -True 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? - No Is the seizure accompanied by low electrical impluses in the Kindling model lifelong? -Yes 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). -Hyperexcitability What drug can create a model that is microgryic in likeness? -MAM 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)