Neuroanatomy and Physiology Flashcards
6 cards from real EEG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Neuroanatomy and Physiology flashcards as text
The posterior dominant rhythm (alpha rhythm) in a normal awake adult is generated primarily by which brain structure interaction?
Answer: Thalamocortical circuits involving the thalamus and occipital cortex
The alpha rhythm arises from synchronized oscillations in thalamocortical loops, with the thalamic relay nuclei (particularly the pulvinar and lateral geniculate) pacing cortical neurons in the occipital visual cortex.
Which cortical cell type is the primary generator of EEG signals recorded at the scalp?
Answer: Pyramidal neurons in cortical layers III and V
Pyramidal neurons are the primary generators of scalp EEG because their elongated apical dendrites are oriented perpendicular to the cortical surface, creating open electrical fields that summate and can be detected at the scalp.
The cortical area represented by electrode T3 (T7 in modified nomenclature) overlies which brain region?
Answer: Left mid-temporal region near the Sylvian fissure
T3 (T7) is positioned over the left mid-temporal region, approximately overlying the middle temporal gyrus near the lateral sulcus (Sylvian fissure), a common area for temporal lobe epilepsy discharges.
What minimum area of synchronously active cortex is typically required to produce a detectable signal on scalp EEG?
Answer: 6 cm²
Approximately 6 cm² (some estimates range from 6-10 cm²) of synchronously active cortex is needed to generate sufficient electrical potential to be detected through the skull, meninges, and scalp by surface electrodes.
Delta activity (0.5-4 Hz) in a normal awake adult EEG is considered abnormal because it typically indicates:
Answer: Cortical dysfunction from structural or metabolic causes
In awake adults, delta activity is abnormal and suggests cortical or subcortical dysfunction. Focal delta suggests structural lesion; generalized delta suggests diffuse encephalopathy or deep midline dysfunction.
The mu rhythm, typically recorded over the central regions, is characterized by:
Answer: An arch-shaped 8-13 Hz rhythm that attenuates with contralateral limb movement or movement planning
The mu rhythm is an 8-13 Hz arch-shaped (wicket-like) rhythm over the central (sensorimotor) cortex that blocks with contralateral movement, motor planning, or even observation of movement, reflecting sensorimotor cortex function.