Neuro Exam 4: Eeg And Erp

Front 1

What do EEG waves primarily represent?

Back 1

Summated postsynaptic potentials (both excitatory and inhibitory) generated by vertically oriented pyramidal neurons of the cerebral cortex
-synchronization of these potentials into waves depends on interactions between cortical, brain stem, and diencephalic structures (esp. RAS and thalamic nuclei)

Front 2

What are the 4 bands of EEG frequencies?

Back 2

Delta waves: less than 4 Hz
Theta waves: 4 to just under 8 Hz
Alpha waves: 8 to 13 Hz
Beta waves: more than 13 Hz

Front 3

Which rhythm does the normal waking adult characteristically display?

Back 3

-Alpha rhythm over the posterior regions of the head (with mental activity alpha goes away; rest/relax alpha comes back)
-Some beta activity especially over the fronto-central regions
-Minimal, if any, theta waves over the temporal areas
-Delta waves are not observed in EEGs of normal adults during wakefulness

Front 4

How can disease change the EEG brain wave patterns?

Back 4

1) Epileptiform abnormality: spike or spike & slow wave and sharp wave
2) Distorted or suppressed normal rhythms: slow waves in the theta or delta bands

Front 5

What are the two types of topography of abnormalities?

Back 5

1) Diffuse abnormalities
2) Focal abnormalities

Front 6

What does ictal activity refer to?

Back 6

If epileptiform activity during EEG occurs during convulsions or abnormal behavior

Front 7

What does interictal activity refer to?

Back 7

Epileptiform activity during EEG without any accompanying convulsions or abnormal behavior (e.g., between seizures)

Front 8

What are some special techniques for brining out abnormalities on the EEG?

Back 8

Hyperventilation, photic stimulation, sleep deprivation

Front 9

What EEG findings do focal lesions of the cerebral hemisphere tend to produce (at the area overlying the site of pathology)?

Back 9

-Slower frequency, decreaesd voltage
-Abnormal waves, usually of delta or theta frequency
-Manifestation of epileptiform discharges

Front 10

What EEG findings do lesions of the brainstem tend to produce?

Back 10

-May result in comatose states associated with major EEG changes most commonly prominent bilateral generalized slow activity

Front 11

What EEG findings do diffuse lesions tend to produce?

Back 11

Widespread slow activity in the EEG

Front 12

What are evoked potentials?

Back 12

Changes in electrical activity of the nervous system elicited by sensory stimulation
(Amplitudes are very low, detection made possible by averaging responses to a large number of stimuli)