Which of the following are true regarding the thalamus?
I. Located deep in the cortex.
II. It processes all sensory signals.
III. Important for sleep and consciousness.

• A. I & II only.
• B. I & III only.
• C. II & III only.
• D. I, II, & III.

Answer: (B)

Verified step by step guidance

1. Understand the role of the thalamus in the brain: The thalamus is a small structure within the brain located just above the brainstem between the cerebral cortex and the midbrain. It is involved in several functions, including relaying sensory and motor signals to the cerebral cortex and regulating consciousness, sleep, and alertness.
2. Evaluate statement I: 'Located deep in the cortex.' The thalamus is indeed located deep within the brain, but it is not part of the cortex itself. It is situated beneath the cerebral cortex, making this statement partially true.
3. Evaluate statement II: 'It processes all sensory signals.' The thalamus is known for processing most sensory signals, such as visual, auditory, and somatosensory information, before they reach the cortex. However, it does not process olfactory (smell) signals, which bypass the thalamus.
4. Evaluate statement III: 'Important for sleep and consciousness.' The thalamus plays a crucial role in regulating sleep and consciousness, as it is involved in the sleep-wake cycle and helps maintain alertness.
5. Determine which statements are true: Based on the evaluations, statement I is partially true, statement II is not entirely true, and statement III is true. Therefore, the correct answer is I & III only.