Thalamocortical Physiology Flashcards
Absence seizures can be prompted by ______________.
hyperventilating
What is the basic definition of a seizure?
An episode of cerebral dysfunction leading to clinical changes in motor, sensory, or autonomic function
There are two broad categories of seizures: _______________.
partial (involving only a part of the brain) and generalized (involving the entire brain)
Idiopathic generalized epilepsy is a type of generalized absence seizure. There are two subtypes. Describe them.
- A type in which absence seizures are the predominant form (called childhood or juvenile epilepsy)
- A type in which other seizure types are predominant (called myotonic epilepsy)
True or false: absence epilepsy is the most common type of childhood epilepsy.
False. Absence epilepsy accounts for only 10% of childhood epilepsy.
There is a ____________ genetic link to absence epilepsy.
strong (monozygotic concordance roughly 80%)
Simple absence seizures have ____________ motor activity.
minimal (while complex absence seizures have lots)
Simple absence seizures last between ______________.
5 and 15 seconds
Which type of absence seizure (complex or simple) is more common?
Complex
When does childhood absence seizure typically present?
Age 4 to 8
True or false: most childhood absence epilepsy persists to adulthood.
False. 80% resolve
The brand name of valproic acid is ______________.
Depakote
At -85 mV, stimulating the thalamus leads to ______________.
slower action potential frequency due to the presence of T-type calcium channels (that produce the calcium spike)
At -65 mB, stimulating the thalamus leads to _______________.
rapidly oscillating action potentials (1,000 x per second)
Why is there a different effect in stimulating the thalamus at different initial potentials?
Because the T-type calcium channel’s inactivation gate is closed at -65 mV; thus, it does not have the modulating effect that it does at -85 mV.
What anticonvulsants target the T-type calcium channel?
Valproic acid and ethosuximide
Valproic acid functions when people are _________.
asleep
Slow-wave sleep and seizures are characterized by an EEG that fluctuates at _______.
3 Hz
Why is the resting potential of the thalamus -85 when asleep and -55 when awake?
Because GABA channels open during sleep that hyperpolarize the cells
What evidence demonstrates that the T-type calcium channels are necessary to produce seizure?
Mice born without T-type calcium channels cannot be made to have seizures, and there are families with genetic epilepsy that have mutations in T-type channels (allowing the channels to be active when depolarized).
How many seizures do those with simple absence seizures have daily?
100
What is the generic name for keppra?
Levetiracetam
Atypical absence seizures have what EEG pattern?
Less rhythmic than typical, with lots of random squiggles
Absence seizure EEGs resemble those of what stage sleep?
IV
