Fisch EEG Primer Chapter 1

Question 1

The EEG is generated by cortical nerve cell…

Answer 1

inhibitory and excitatory postsynpatic potentials or neurons underlying the cortex that lasts over ~100ms. NOTE: not by nerve action potentials which only lasts ~1ms

Question 2

Rythmical cortical EEG activity arises from…

Answer 2

interaction between thalamus and cortex. e.g. sleep spindles generated by thalamic pacemaker cells of the nucleus reticularis, when surgically extracted continue to pace but effected cortical activity ceases

Question 3

Desynchronization of cortical EEG activity results from

Answer 3

• alteration of subcortical pacemaker (e.g. cells of nucleus reticularis)
• alteration of cortical projection fibers (e.g. ascending cholinergic systems)
• direct damage to or suppression of components any component of rythmic cellular networks

Question 4

Scalp electrodes best capture postsynaptic potentials of neurons favoring

Answer 4

slow, SIMULTANEOUS pontentials generated in large cortical areas of pyramidal cells situated 90deg to plane of scalp

Question 5

Tisses that act as a volume conductor to alter recorded EEG activity..

Answer 5

brain parenchyma, dura, CSF, skull, scalp

Question 6

The Operational Definition of the EEG

Answer 6

difference in voltage between two different recording locations plotted over time. These potentials are the result of excitatory and inhibitory postsynaptic potentials

Question 7

What is volume conduction?

Answer 7

current flow through tissues between the electrical generator and recording electrode

Question 8

Describe the inverse problem.

NOTE: related to forward problem

Answer 8

Within scalp recorded EEGs, there are an infinite number of sources within the brain that can explain the recorded potential. It is theoretically IMPOSSIBLE to know EEG gernator location based on scalp recorded EEG.

Question 9

Describe the forward problem.

NOTE: related to inverse problem

Answer 9

If the anatomical source, intensity, and orientation of the electrical generator are known, scalp EEG recordings can be accurately predicted.

Question 10

Resting membrane potential of a neuron

Answer 10

-65mV - results from passive and active transport of ions across cell membranes

Question 11

Excitatory Postsynaptic Potentials (EPSP) results from

Answer 11

transient partial reduction in membrane potential that causes a decreased resting membrane potential (more positive) likely caused by increased permeability to sodium and potassium

Question 12

Inhibitory Postsynaptic Potentials (IPSP) results from

Answer 12

transient increase (more negative) membrane potential caused by opening chloride channels and possible potassium channels

Question 13

Facultative Pacemaker Theory

Answer 13

Thalamocortical cells with corresponding thalamic inhibitory interneurons

Question 14

Scalp EEG tend to filter out

Answer 14

higher frequency potentials and have lower amplitude compared with equivalent cortical recordings (electrocorticogram “ECoG”)

Question 15

Projected Rythyms

Answer 15

Scalp EEG is intended to measure local potential changes, but cortical potential be detected in more widespread distribution (a.k.a. rythmes a distance)

Question 16

The number of scalp electrodes used in standard EEG recordings

Answer 16

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