Cerebral EEG Flashcards
What are beta waves?
Smallest amplitude
13-30Hz
Associated with mental activity
Observed during active, alert wakefulness and REM sleep
What are Alpha waves?
Generally associated with relaxed wakefulness
Most prominent over the parietal and occipital lobe
What are theta waves?
More prominent in young
Observed during awake, drowsy and non-REM sleep states
What are delta waves?
Prominent during non-REM sleep
What is a current sink?
transient, local excess of negative charge
Caused by the flow of inward membrane current
What is a current source?
Transient, local excess of positive charge
Return of positive charge to the extracellular space
What are extracellular field potentials?
Changes in extracellular electrical charge
I.e. current sinks and sources
Why are extracellular potentials smaller than intracellular potentials?
Resistance of the extracellular space is much lower than the resistance of the plasma membrane
V = IR
What determines EEG amplitude?
The degree of synchronization within the neuronal population being measured
A very active, but desynchronized population of neurons will yield a small amplitude, high frequency EEG
What does EEG activity primarily reflect?
Synaptic activity due to the fact that these last much longer, allowing better synchronization
Why is the columnar organization of the neocortex important for EEGs?
Functionally related neurons will more likely be activated together
What is a sensory evoked potential?
Specific change in ongoing EEG activity caused by stimulation of a sensory potential
What is epilepsy?
A set of disorders characterized by chronic bouts of abnormal neuronal electrical activity
What are partial seizures?
Seizures that are restricted to one part of the brain
What are generalized seizures?
Seizures that involve abnormal activation of many areas of the brain
Involve loss of consciousness and may trigger falls, loss of muscle tone, or massive muscle spasms
What is a simple partial seizure?
Patients retain consciousness but may experience unusual feelings or sensations and may experience sudden and unexplainable feelings of joy, anger, sadness or nausea
What is a complex partial seizure?
Patient has a change of consciousness, including dreamlike experiences
May be accompanied by repetitious behaviors called automatisms
What are auras?
Sensations warning of an impending seizure
May precede partial seizures
What is secondary generalization?
When a partial seizure spreads to involve other areas
What are absence seizures?
Generalized seizure the patient may appear to be staring into space and/or exhibit muscle jerking or twitching
What are tonic seizures?
Cause stiffening of muscles, generally in the back, legs, and arms
What are clonic seizures?
Generalized seizures that cause repetitive jerking movements of muscles on both sides of the body
What are atonic seizures?
Cause a loss of normal muscle tone, and the patient may fall
What are tonic-clonic seizures?
Involve both tonic and clonic muscle contractions, includes stiffening of the body and repeated jerks of the arms and/or legs
Describe EEG findings in a partial or focal seizure
Show abnormalities initiating in or restricted to only a few EEG channels
Abnormalities may be present during the interictal seizures
Describe EEG findings in a generalized or non-focal seizures
Show essentially simultaneous abnormal on most or all channels of the recording
What is postical depression?
A period depression, with disorientation, drowsiness or confusion and altered EEG may follow a seizure
What are some medications used to control seizures?
Enhance the effectiveness o GABA neurotransmittion
Reduce the ability of neurons to generate repetitive trains of action potentials
What are surgical options for seizure treatment?
Lesionectomy or lobectomy
Temporal love resection is the most common lobectomy
What are some alternative treatments to seizures?
Vagal nerve stimulation
Ketogenic diet
