Term
| What are some possible applications of EEG? |
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Definition
| diagnosis of sleep disturbances, epilepsy, and determination of coma level and "brain death" |
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Term
| What type of neural activity does EEG reflect? |
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Definition
| the electrical activity of populations of cortical neurons |
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Term
| What is the EEG a measure of? |
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Definition
| difference in electrical potential |
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Term
| What may be used for enhanced detection of activity from the medial temporal lobes when performing EEG? |
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Definition
| nasopharyngeal or sphenoidal electrodes (inserted through the nose or jaw muscle) |
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Term
| What type of EEG activity is typically recorded from the scalp? |
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Definition
| small amplitude (20- 100 microV) and between 1 - 30 Hz (cycles per second) |
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Term
| What types of waves are observed at the amplitude detected by EEG? |
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Definition
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Term
| What characterizes beta waves? |
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Definition
| (13 - 30 Hz). Smallest amplitude EEG. Associated with mental activity. Observed during active, alert wakefulness and REM sleep. |
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Term
| What characterizes alpha waves? |
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Definition
| (8 - 13 Hz). Generally associated with a state of relaxed wakefulness. |
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Term
| Where are alpha waves found to be most prominent? |
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Definition
| Over the parietal and occipital lobes |
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Term
| What characterizes theta waves? |
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Definition
| (4 - 8 Hz). More prominent in young that adult. Observed during awake, drowsy and non- REM sleep states. |
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Term
| What characterizes Delta waves? |
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Definition
| (0.5 - 3.5 Hz). Prominent during non-REM sleep. |
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Term
| What is an electrocorticogram? |
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Definition
| EEGs recorded from the surface of the cerebral cortex |
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Term
| What creates the current sink in EEGs? |
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Definition
| The flow of inward membrane current (movement of positive charge into the intracellular compartment) |
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Term
| What can create current sinks? |
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Definition
| ion channel gating that allows net inward current to flow (i.e., opening of ionotropic glutamate receptors, voltage-gated sodium channels, etc). |
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Term
| What is a sensory evoked potential? |
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Definition
| a specific change in ongoing EEG activity caused by stimulation of a sensory pathway |
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Term
| Which are larger: extracellular field potentials or intracellular synaptic potentials? |
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Definition
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Term
| Which happens first in EEG potential generation: current sink or current source? |
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Definition
| Both happen to some extent while action potentials are happening |
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Term
| What is indicated by low amplitude, high frequency waves in an EEG? |
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Definition
| High activity that is desynchronized |
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Term
| What do high amplitude, low frequency waves in an EEG indicate? |
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Definition
| low activity that is synchronized |
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Term
| Do EEG resadings pick up action potentials or synaptic potentials? |
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Definition
| synaptic potentials, which last longer |
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Term
*What type of activity does EEG primarily represent (i.e., in what kind of cell)?
*What feature of these cells allow for a large dipole? |
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Definition
*population activity in cortical pyramidal neurons
*long apical dendrites allow formation of large dipole |
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Term
What two types of synaptic current flow can create extracellular source that EEG reflect?
Is possible to tell which type of synaptic current flow is generating high frequency, low amplitude EEG waves? |
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Definition
either excitatory or inhibitory synaptic current flow
No |
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Term
| You are recording the alpha waves coming from the occipital lobe of a patient with her eyes closed. What do the waves look like before and after she opens her eyes? |
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Definition
Before: high frequency, low amplitude
After: higher frequency, lower amplitude |
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Term
| Sensory evoked potentials are small. How does a doctor extract them from a reading? |
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Definition
| averaging across many trials |
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Term
*What is the most commonly used sensory evoked potential?
*What are two other kinds? |
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Definition
*auditory evoked potential (AEP)
*somatosensory evoked potential (SSEP) and visual evoked potential (VEP) |
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Term
| What are three things that auditory evoked potentials can be used to detect/assess? |
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Definition
*detect hearing problems in very young children
*assess brain stem integrity (in comatose, unconscious patients)
*assess central conduction velocity |
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Term
*What do the early components of an AEP represent?
*How can they be characterized? |
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Definition
*Cochlear and brain stem events
*far-field and small |
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Term
| *What do the late components of an AEP represent? |
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Definition
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Term
What is a seizure?
How common are they |
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Definition
Abnormal brain activity
Common; about 1 in 10 people have at least one in their lives |
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Term
*What is epilepsy?
*Is it common? |
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Definition
*chronic bouts of abnormal brain activation: recurrent seizures
*no; about 1% of population |
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Term
How many types of seizures are there?
How many epileptic disorders are there? |
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Definition
More than 30
Same number as above |
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Term
| What is a partial seizure? |
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Definition
| A seizure in which the abnormal activity is focal, or limited to or originating in one area of the brain |
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Term
| What are the characteristics of a simple partial seizure? |
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Definition
*remains conscious
*(may experience unusual feelings or sensations; hear, smell, taste, see, or feel things that are not real |
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Term
| What are the characteristics of a complex partial seizure? |
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Definition
*alteration or loss of consciousness
*may show repetitious behaviors such as blinks, twitches, walking in a circle, etc (automatisms). |
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Term
| What are generalized seizures? |
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Definition
| originate simultaneously in multiple areas of both hemispheres; involve loss of consciousness; may cause falls (loss of muscle tone), or massive muscle spasms |
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Term
| What is the difference between a generalized seizure vs. secondary generalization of a seizure? |
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Definition
*generalized: seizures originate simultaneously at multiple locations
*secondary generalization: seizure starts at one point and spreads |
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Term
| How can an EEG be used to diagnose generalized seizures vs. focal/partial seizures? |
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Definition
*Partial seizures: show EEG spikes in only a few specific locations
*Generalized seizures: show abnormal spikes that originate in many different areas at same time |
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Term
| How do medications inhibit seizures? |
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Definition
| Enhancing the action of GABA, an inhibitory neurotransmitter |
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Term
| What are some potential triggers for epilepsy? |
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Definition
| damage from trauma, stroke, or tumors; congenital developmental irregularities; genetic disorders (mutations affecting certain ion channels or neurotransmitter receptors) |
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Term
| What is a commonality underlying many of the different forms of epilepsy? |
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Definition
| imbalance of synaptic excitation over synaptic inhibition |
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Term
| What are the three main types of treatment for epilepsy? |
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Definition
Medication
Sugery
Vagal nerve stimulation/diet (high fat, low carb) |
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