Cerebral EEG

Question 1

What are beta waves?

Answer 1

Smallest amplitude

13-30Hz

Associated with mental activity

Observed during active, alert wakefulness and REM sleep

Question 2

What are Alpha waves?

Answer 2

Generally associated with relaxed wakefulness

Most prominent over the parietal and occipital lobe

Question 3

What are theta waves?

Answer 3

More prominent in young

Observed during awake, drowsy and non-REM sleep states

Question 4

What are delta waves?

Answer 4

Prominent during non-REM sleep

Question 5

What is a current sink?

Answer 5

transient, local excess of negative charge

Caused by the flow of inward membrane current

Question 6

What is a current source?

Answer 6

Transient, local excess of positive charge

Return of positive charge to the extracellular space

Question 7

What are extracellular field potentials?

Answer 7

Changes in extracellular electrical charge

I.e. current sinks and sources

Question 8

Why are extracellular potentials smaller than intracellular potentials?

Answer 8

Resistance of the extracellular space is much lower than the resistance of the plasma membrane

V = IR

Question 9

What determines EEG amplitude?

Answer 9

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

Question 10

What does EEG activity primarily reflect?

Answer 10

Synaptic activity due to the fact that these last much longer, allowing better synchronization

Question 11

Why is the columnar organization of the neocortex important for EEGs?

Answer 11

Functionally related neurons will more likely be activated together

Question 12

What is a sensory evoked potential?

Answer 12

Specific change in ongoing EEG activity caused by stimulation of a sensory potential

Question 13

What is epilepsy?

Answer 13

A set of disorders characterized by chronic bouts of abnormal neuronal electrical activity

Question 14

What are partial seizures?

Answer 14

Seizures that are restricted to one part of the brain

Question 15

What are generalized seizures?

Answer 15

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

Question 16

What is a simple partial seizure?

Answer 16

Patients retain consciousness but may experience unusual feelings or sensations and may experience sudden and unexplainable feelings of joy, anger, sadness or nausea

Question 17

What is a complex partial seizure?

Answer 17

Patient has a change of consciousness, including dreamlike experiences

May be accompanied by repetitious behaviors called automatisms

Question 18

What are auras?

Answer 18

Sensations warning of an impending seizure

May precede partial seizures

Question 19

What is secondary generalization?

Answer 19

When a partial seizure spreads to involve other areas

Question 20

What are absence seizures?

Answer 20

Generalized seizure the patient may appear to be staring into space and/or exhibit muscle jerking or twitching

Question 21

What are tonic seizures?

Answer 21

Cause stiffening of muscles, generally in the back, legs, and arms

Question 22

What are clonic seizures?

Answer 22

Generalized seizures that cause repetitive jerking movements of muscles on both sides of the body

Question 23

What are atonic seizures?

Answer 23

Cause a loss of normal muscle tone, and the patient may fall

Question 24

What are tonic-clonic seizures?

Answer 24

Involve both tonic and clonic muscle contractions, includes stiffening of the body and repeated jerks of the arms and/or legs

Question 25

Describe EEG findings in a partial or focal seizure

Answer 25

Show abnormalities initiating in or restricted to only a few EEG channels

Abnormalities may be present during the interictal seizures

Question 26

Describe EEG findings in a generalized or non-focal seizures

Answer 26

Show essentially simultaneous abnormal on most or all channels of the recording

Question 27

What is postical depression?

Answer 27

A period depression, with disorientation, drowsiness or confusion and altered EEG may follow a seizure

Question 28

What are some medications used to control seizures?

Answer 28

Enhance the effectiveness o GABA neurotransmittion

Reduce the ability of neurons to generate repetitive trains of action potentials

Question 29

What are surgical options for seizure treatment?

Answer 29

Lesionectomy or lobectomy

Temporal love resection is the most common lobectomy

Question 30

What are some alternative treatments to seizures?

Answer 30

Vagal nerve stimulation

Ketogenic diet