EEG Neuroanatomy and Physiology 5

Question 1

Inhibitory postsynaptic potentials (IPSPs) on apical dendrites of cortical pyramidal neurons generate which polarity at the overlying scalp electrode?

Accepted Answer

Positive deflection

Answer

IPSPs at apical dendrites create a current sink deeper in the cortex and a source near the surface, resulting in a positive polarity at the scalp electrode above.

Question 2

Which ascending arousal pathway originating in the locus coeruleus modulates cortical excitability and EEG background through norepinephrine release?

Accepted Answer

Dorsal noradrenergic bundle

Answer

The dorsal noradrenergic bundle from the locus coeruleus projects widely to cortex, modulating neuronal excitability and promoting EEG desynchronization during alertness.

Question 3

The dentate gyrus, CA fields of the hippocampus, and entorhinal cortex form the primary circuit for memory encoding. EEG theta rhythms (4-8 Hz) recorded over temporal regions are thought to reflect activity in which of these structures?

Accepted Answer

Hippocampus

Answer

Hippocampal theta rhythm (4-8 Hz) is strongly associated with memory encoding and spatial navigation and can be detected with depth or surface EEG over temporal regions.

Question 4

Cortical spreading depression (CSD), associated with migraine aura, is characterized by what EEG finding?

Accepted Answer

Transient high-amplitude slow wave followed by sustained suppression

Answer

CSD produces a brief increase in slow activity followed by prolonged EEG suppression as a wave of depolarization-then-silence propagates across the cortex.

Question 5

The insula, buried within the lateral sulcus, is involved in autonomic regulation. Seizures arising from insular cortex most likely affect which EEG electrode chain?

Accepted Answer

F7-T7-P7-O1

Answer

The insula is accessed via the lateral sulcus and is closest to temporal chain electrodes (F7/T7/P7), making this chain most likely to reflect insular seizure activity.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Neuroanatomy and Physiology 5