Executive functioning, planning, and working memoriare functions of which of the following brain structures?

Correct Answer: D

Rationale: Prefrontal cortex . The prefrontal cortex (PFC) governs executive functions (e.g., decision-making), planning, and working memory, per neuroimaging (e.g., Baddeleys model). Choice A (amygdala) regulatemotion. Choice B (hypothalamus) controls homeostasis. Choice C (hippocampus) handllong-term memory. Choice D (precentral gyrus) drivmotor function. truth PFC damage impairs planning (e.g., frontal lobe syndrome) distinguishit from the emotional , regulatory , memory , or motor roles, making it the correct answer.

Correct Answer: B

Rationale: The sense of smell begins to develop in utero, and by the time of birth, a newborns olfactory system is sufficiently mature to detect and respond to odors reliably. Studishow that newborns can distinguish their mothers scent shortly after birth, indicating that smell can be tested reliably at birth . At the 32nd week of gestation , while the olfactory system is forming, the fetus is not yet exposed to air-based odors, and testing is impractical. By three months or six months of age, smell is certainly developed further, but the question asks for the earliest reliable point, which is birth. The ability to test smell at birth is supported by neonatal behavioral responsto olfactory stimuli, making B the correct choice over later developmental stages.

Correct Answer: D

Rationale: Cutaneous lesions over the spine may signal underlying spinal dysraphism, necessitating imaging. A hairy patch , subcutaneous mass or lipoma , and dermal sinus are associated with neural tube defects like spina bifida, requiring MRI or ultrasound to assess for tethered cord or other anomalies. Coccygeal pits , however, are typically benign dimplnear the coccyx, not usually linked to significant spinal pathology unless accompanied by other signs (e.g., infection). Unlike the other options, coccygeal pits alone do not routinely warrant imaging, making D the exception and correct answer. This distinction arisfrom their lower risk profile compared to the more concerning midline lesions in A, B, and C, which have stronger embryologic tito spinal defects.

Correct Answer: D

Rationale: Communicating hydrocephalus results from impaired CSF absorption, often post-inflammatory or hemorrhagic events. Subarachnoid hemorrhage , pneumococcal meningitis , and tuberculous meningitis can cause this by scarring arachnoid villi, blocking CSF uptake. Leukemic infiltratmay similarly obstruct absorption. A vein of Galen malformation , however, is a vascular anomaly causing obstructive (non-communicating) hydrocephalus by compressing the aqueduct or posterior fossa, not a communicating type. Thus, D is the exception and correct answer, as it donot align with the mechanism of nonobstructive hydrocephalus.

Correct Answer: D

Rationale: Predictors of epilepsy after febrile seizurinclude complex seizur, short fever duration , recurrence , and focal complex seizur. Family history also contributes. Focal complex febrile seizurprolonged, multiple, or focal carry the highest risk (up to 30-50% in some studies) due to their association with focal brain injury or underlying pathology (e.g., mesial temporal sclerosis). General complex seizurhave a lower risk (~10-15%), as do recurrent seizuror short fever onset . Thus, D is the correct answer, reflecting the strongest epileptogenic potential among these factors.