Time: 3 Hours Total Marks: 80 --- SECTION A: MULTIPLE CHOICE QUESTIONS (40 MARKS) Choose the best answer for each question. Each question carries 1 mark. 1. Wh
Time: 3 Hours Total Marks: 80 --- SECTION A: MULTIPLE CHOICE QUESTIONS (40 MARKS) Choose the best answer for each question. Each question carries 1 mark. 1. Which thalamic nucleus is primarily responsible for relaying visual information to the cortex? A) Medial geniculate body B) Lateral geniculate body C) VPL nucleus D) Anterior nucleus Answer: B) Lateral geniculate body Explanation: The lateral geniculate body specifically relays visual information from the retina to the visual cortex, while the medial geniculate body handles auditory information. 2. The neurotransmitter primarily released by the locus coeruleus that promotes wakefulness is: A) Serotonin B) GABA C) Norepinephrine D) Acetylcholine Answer: C) Norepinephrine Explanation: The locus coeruleus is the primary source of norepinephrine in the brain and is a key component of the ascending arousal system. 3. Sleep spindles are characteristic of which stage of NREM sleep? A) Stage 1 B) Stage 2 C) Stage 3 D) REM sleep Answer: B) Stage 2 Explanation: Sleep spindles (10-14 Hz bursts) are the defining feature of Stage 2 NREM sleep, generated by the thalamic reticular nucleus. 4. The master circadian pacemaker is located in the: A) Pineal gland B) Suprachiasmatic nucleus C) Locus coeruleus D) Raphe nuclei Answer: B) Suprachiasmatic nucleus Explanation: The SCN receives direct input from the retina via the retinohypothalamic tract and coordinates all circadian rhythms. 5. PGO spikes during REM sleep originate from: A) Pons → Geniculate → Occipital cortex B) Parietal → Geniculate → Occipital cortex C) Pons → Globus pallidus → Occipital cortex D) Pineal → Geniculate → Occipital cortex Answer: A) Pons → Geniculate → Occipital cortex Explanation: PGO spikes are generated in the pons and travel through the lateral geniculate nucleus to the occipital cortex, marking REM sleep onset. 6. The EEG frequency range for alpha rhythm is: A) 4-7 Hz B) 8-13 Hz C) 13-30 Hz D) 30-100 Hz Answer: B) 8-13 Hz Explanation: Alpha rhythm (8-13 Hz) is seen in awake, resting adults with eyes closed and indicates a relaxed, low-attention state. 7. Which neurotransmitter is inhibitory and promotes sleep when released from the preoptic area? A) Glutamate B) Histamine C) GABA D) Orexin Answer: C) GABA Explanation: GABA neurons in the preoptic area of the hypothalamus are sleep-promoting and inhibit arousal systems. 8. The approximate duration of a complete sleep cycle is: A) 60 minutes B) 90 minutes C) 120 minutes D) 150 minutes Answer: B) 90 minutes Explanation: Sleep cycles average 90 minutes, with 4-6 cycles occurring during a typical 8-hour sleep period. 9. Delta waves are most prominent during: A) REM sleep B) Stage 1 NREM C) Stage 2 NREM D) Stage 3 NREM Answer: D) Stage 3 NREM Explanation: Delta waves (0.5-4 Hz) are the slowest, highest amplitude waves and define Stage 3 NREM (slow-wave sleep). 10. Melatonin is synthesized in the: A) Hypothalamus B) Pineal gland C) Thalamus D) Brainstem Answer: B) Pineal gland Explanation: The pineal gland produces melatonin in response to darkness, regulated by the SCN via sympathetic innervation. 11. Which of the following is characteristic of REM sleep? A) High muscle tone B) Slow eye movements C) Muscle atonia D) High-amplitude EEG waves Answer: C) Muscle atonia Explanation: REM sleep is characterized by muscle atonia (except respiratory and eye muscles) to prevent acting out dreams. 12. The percentage of REM sleep in full-term neonates is approximately: A) 25% B) 50% C) 75% D) 80% Answer: B) 50% Explanation: Full-term neonates spend about 50% of sleep time in REM, which decreases to about 25% in adults. 13. Beta rhythm is associated with: A) Deep sleep B) Drowsiness C) Alert wakefulness D) Coma Answer: C) Alert wakefulness Explanation: Beta rhythm (13-30 Hz) appears during focused attention and mental tasks, representing the alert/awake state. 14. Orexin neurons are located in the: A) Brainstem B) Thalamus C) Lateral hypothalamus D) Cortex Answer: C) Lateral hypothalamus Explanation: Orexin (hypocretin) neurons in the lateral hypothalamus stabilize sleep-wake transitions and promote wakefulness. 15. The EEG in REM sleep shows: A) High-voltage, slow waves B) Sleep spindles C) Low-voltage, fast activity D) Delta waves Answer: C) Low-voltage, fast activity Explanation: REM sleep EEG resembles waking EEG with low-voltage, high-frequency activity, hence "paradoxical sleep." 16. Chandelier cells in the cortex: A) Release glutamate B) Target pyramidal cell axon initial segments C) Promote excitation D) Are located in deep cortical layers Answer: B) Target pyramidal cell axon initial segments Explanation: Chandelier cells are inhibitory interneurons that form synapses on axon initial segments, providing powerful inhibition. 17. The bulboreticular facilitatory area is most active during: A) REM sleep B) Deep NREM sleep C) Morning awakening D) Dream states Answer: C) Morning awakening Explanation: The bulboreticular facilitatory area becomes maximally active in the morning, overcoming sleep-promoting influences. 18. Which nucleus produces serotonin? A) Locus coeruleus B) Raphe nuclei C) Tuberomammillary nucleus D) Suprachiasmatic nucleus Answer: B) Raphe nuclei Explanation: The raphe nuclei in the brainstem are the primary source of serotonin, which has complex roles in sleep regulation. 19. K-complexes are seen in: A) Stage 1 NREM B) Stage 2 NREM C) Stage 3 NREM D) REM sleep Answer: B) Stage 2 NREM Explanation: K-complexes are large, slow waves that appear along with sleep spindles in Stage 2 NREM sleep. 20. The retinohypothalamic tract carries information about: A) Visual images B) Light-dark cycles C) Color perception D) Visual motion Answer: B) Light-dark cycles Explanation: This tract carries non-visual light information from specialized retinal ganglion cells to the SCN for circadian regulation. 21. Histamine promotes wakefulness and is released from: A) Locus coeruleus B) Raphe nuclei C) Tuberomammillary nucleus D) Pedunculopontine nucleus Answer: C) Tuberomammillary nucleus Explanation: The tuberomammillary nucleus in the posterior hypothalamus releases histamine, a key wake-promoting neurotransmitter. 22. Which sleep stage is most restorative? A) Stage 1 NREM B) Stage 2 NREM C) Stage 3 NREM D) REM sleep Answer: C) Stage 3 NREM Explanation: Stage 3 NREM (slow-wave sleep) is the most restorative, particularly after sleep deprivation. 23. The ascending arousal system is primarily: A) Monosynaptic B) Polysynaptic C) Inhibitory D) Cortical Answer: B) Polysynaptic Explanation: The ascending arousal system involves multiple synaptic connections from brainstem and hypothalamus to cortex. 24. Dreams are most vivid and memorable during: A) Stage 1 NREM B) Stage 2 NREM C) Stage 3 NREM D) REM sleep Answer: D) REM sleep Explanation: REM sleep is associated with vivid, memorable dreams, unlike the less memorable dreams of NREM sleep. 25. Light exposure suppresses melatonin by affecting: A) Pineal gland directly B) Suprachiasmatic nucleus C) Hypothalamus generally D) Retina only Answer: B) Suprachiasmatic nucleus Explanation: Light activates the SCN, which then inhibits melatonin synthesis via sympathetic pathways to the pineal gland. 26. The thalamic reticular nucleus releases: A) Glutamate B) GABA C) Acetylcholine D) Dopamine Answer: B) GABA Explanation: The thalamic reticular nucleus is GABAergic and plays a crucial role in generating sleep spindles and regulating thalamic activity. 27. As the night progresses, there is typically: A) Increased Stage 3 sleep B) Decreased REM sleep C) Increased REM sleep D) Constant sleep stage distribution Answer: C) Increased REM sleep Explanation: REM episodes become longer and more frequent toward morning, while deep NREM sleep decreases. 28. The EEG reflects: A) Action potentials B) Postsynaptic potentials C) Intracellular potentials D) Resting potentials Answer: B) Postsynaptic potentials Explanation: EEG records summated postsynaptic potentials from dendrite