Higher Mental Functions, EEG, Sleep and Limbic System MCQs

Physiology · 51 free questions with answers & explanations.

1. A 35-year-old patient with narcolepsy is found to have markedly low CSF hypocretin-1 (orexin-A) levels. The normal physiological role of orexin in sleep-wake regulation is best described as:
2. During polysomnography, the technician observes K-complexes and sleep spindles (12-14 Hz). This EEG pattern corresponds to which sleep stage, and what is its functional significance?
3. During REM sleep, a healthy person experiences complete skeletal muscle atonia except for extraocular muscles and respiratory muscles. The neuroanatomical substrate generating this REM atonia is:
4. A 66-year-old retired professor develops difficulty naming objects and forming new memories while remote memories remain intact. MRI shows early hippocampal atrophy. Which aspect of hippocampal function is MOST specifically impaired in this clinical presentation?
5. A polysomnography report shows recurrent episodes of loss of skeletal muscle tone (except diaphragm and extraocular muscles) with REMs and desynchronised EEG. This sleep stage is characterised physiologically by:
6. Which EEG rhythm is characteristically SUPPRESSED when a subject opens their eyes and engages in visual processing?
7. A 27-year-old reports sudden episodes of cataplexy (sudden muscle weakness with emotion) and hypnagogic hallucinations. Orexin (hypocretin) levels in CSF are undetectable. Which circuit is disrupted?
8. The Papez circuit, implicated in memory consolidation and emotional processing, includes all of the following EXCEPT:
9. A 35-year-old patient undergoing EEG monitoring shows high-amplitude, low-frequency (1-4 Hz) waves during sleep. This EEG pattern corresponds to:
10. The atonia of skeletal muscles during REM sleep is generated by active inhibition of motor neurons. The neural pathway responsible involves:
11. A patient with bilateral medial temporal lobe damage (Klüver-Bucy syndrome) demonstrates hyperphagia, hypersexuality, and visual agnosia. The structure most critically damaged to produce the core emotional-behavioral features is:
12. In the two-process model of sleep regulation, Process S (homeostatic sleep pressure) is primarily mediated by accumulation of:
13. A 45-year-old patient undergoing polysomnography shows high-amplitude, synchronous, low-frequency EEG waves (0.5–2 Hz) with no eye movements and no muscle atonia. In which sleep stage is this patient MOST likely?
14. A patient taking a monoamine oxidase inhibitor for depression reports total absence of REM sleep on polysomnography over 3 weeks. After the drug is stopped, which phenomenon is expected?
15. During REM sleep, the ascending arousal system shows a specific pattern. Which neurotransmitter system becomes MOST active during REM sleep, driving the characteristic features?
16. A 28-year-old presents with sudden loss of muscle tone when laughing (cataplexy), excessive daytime sleepiness, and hypnagogic hallucinations. Orexin (hypocretin) levels in CSF are undetectable. Which physiological explanation accounts for cataplexy?
17. A 40-year-old woman is found somnolent with her EEG showing high-amplitude, slow-frequency (0.5–2 Hz) waves bilaterally. She is arousable with stimulation, becoming briefly confused before returning to somnolence. Which stage of consciousness does this EEG pattern correspond to, and what is the frequency band involved?
18. In polysomnography, which of the following combinations of findings CORRECTLY identifies REM sleep?
19. The Papez circuit is a limbic system circuit critical for emotional memory formation. Which of the following correctly lists the sequential nodes of the Papez circuit?
20. A researcher gives a healthy volunteer a drug that completely blocks melatonin synthesis. Which of the following effects on sleep architecture would be MOST expected?
21. A 35-year-old man undergoing polysomnography shows episodes of sudden loss of muscle tone precipitated by laughter. His sleep study reveals REM sleep intrusion at sleep onset (sleep-onset REM periods, SOREMPs) on multiple nap tests. Which neurotransmitter deficiency is the PRIMARY neurochemical basis?
22. During which stage of sleep is growth hormone secretion MAXIMAL, and what EEG pattern characterizes this stage?
23. A 55-year-old woman describes vivid, frightening dreams during which her husband reports she shouts and physically acts out the dreams without waking. Her REM sleep shows absence of the normal atonia. This REM sleep behavior disorder is associated with future development of which condition?
24. The Papez circuit, central to emotion and memory, involves which sequence of structures?
25. A 45-year-old shift worker complains of daytime somnolence and has a polysomnography showing frequent transitions from NREM stage N3 to wakefulness without REM sleep. Which neurotransmitter system, when dysfunctional, most specifically explains failure to maintain normal sleep architecture with adequate REM sleep?
26. On EEG recording, sleep spindles and K-complexes are characteristics of which stage of NREM sleep, and what neural structure generates sleep spindles?
27. A 70-year-old man undergoes temporal lobectomy for refractory epilepsy involving the right hippocampus and amygdala. Postoperatively, he develops difficulty forming new declarative memories but retains older memories and procedural skills. This pattern is consistent with damage to which memory system?
28. During REM sleep, the dreaming brain shows vivid hallucinations but the dreamer cannot act them out. Which mechanism specifically suppresses voluntary motor activity during REM sleep?
29. A patient's EEG shows a rhythm of 8–13 Hz over the posterior cerebral regions that disappears when the patient opens their eyes. This rhythm is best described as:
30. During which stage of sleep does the highest threshold for arousal typically occur, and what EEG pattern characterises this stage?
31. The neurotransmitter most responsible for the loss of muscle tone (atonia) during REM sleep is:
32. A 45-year-old man with a unilateral temporal lobe lesion has impaired recognition of familiar faces despite intact visual acuity and limb recognition. The term for this deficit and its most likely localisation is:
33. A patient undergoing polysomnography shows high-amplitude, low-frequency delta waves (0.5–4 Hz) occupying >20% of the recording epoch. This pattern characterizes which sleep stage?
34. Which EEG pattern is characteristically associated with active wakefulness and mental concentration, having a frequency of 14–30 Hz?
35. During REM sleep, which neurotransmitter system is most responsible for the skeletal muscle atonia (paralysis) that prevents dream enactment?
36. Bilateral damage to the hippocampus (as occurred in patient H.M.) results in which specific and lasting memory deficit?
37. A sleep study shows episodes of sudden loss of muscle tone triggered by laughter, with brief REM-like intrusions during wakefulness. Which neurotransmitter system is primarily deficient in this condition?
38. On EEG, which waveform pattern is characteristically seen during the deepest stage of non-REM sleep (Stage N3, slow-wave sleep)?
39. During REM sleep, which of the following physiological events occurs?
40. A 70-year-old patient with Alzheimer's disease has difficulty forming new memories but can still ride a bicycle and play the piano (skills learned decades ago). Which memory systems are selectively affected and preserved, respectively?
41. In the EEG, a 3 Hz spike-and-wave discharge pattern occurring in bursts of 5–20 seconds with abrupt onset and offset, associated with brief staring spells and eyelid fluttering in a child, is most characteristic of which condition?
42. During polysomnography, a patient is noted to have bursts of 12–14 Hz activity lasting 0.5–2 seconds superimposed on a background of K-complexes. Which sleep stage does this pattern represent?
43. Which neurotransmitter system is primarily responsible for the muscle atonia (REM atonia) seen during REM sleep, and what is the clinical consequence of its failure?
44. A 19-year-old man presents with sudden bilateral loss of muscle tone triggered by laughter, excessive daytime sleepiness, and sleep paralysis. Hypocretin-1 (orexin-A) in his CSF is undetectable. Which EEG finding during sleep-onset is characteristic of his condition?
45. The Papez circuit, implicated in emotional memory, consists of which sequence of structures?
46. On an EEG recorded in a relaxed but awake adult with eyes closed, the dominant rhythm is 10 Hz. When the patient opens his eyes, this rhythm is immediately suppressed. What is this EEG phenomenon called?
47. During stage N3 (slow-wave sleep), which EEG pattern predominates, and what is its frequency range?
48. A neuroscience researcher documents that REM sleep is generated by activation of pontine cholinergic neurons (REM-on cells). Which finding is characteristic of REM sleep physiology?
49. A patient with bilateral hippocampal damage (as in severe HSV encephalitis) will typically show which memory deficit?
50. The EEG finding of 3 Hz spike-and-wave discharges in a child who briefly stares blankly and stops activity for ~10 seconds is pathognomonic of:
51. The sleep cycle is approximately 90 minutes in duration. In which part of the night is slow-wave sleep (N3) maximally represented?