This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Guillian Barre syndrome & Alzheimer's disease, Subject name: Medicine
In Wernicke's encephalopathy, the amnestic defect is correlated most closely with inflammation and necrosis of: 
Select and explain. 
A. Mamillary bodies, B. Midline cerebellum, C. Peri-aqueductal gray matter, D. Dorso-medial thalamus
D: Dorso-medial thalamus
Answer: D: Dorso-medial thalamus 
Explanation: Amnestic defect is due to lesions in dorso medial thalamus. Appearance of acute Wernicke encephalopathy on MRI demonstrates abnormal hyperdensity of the dorsomedial thalamus and peri aqueductal gray matter with associated abnormal enhancement on T1-weighted images. Periventricular lesions surround third ventricle, aqueduct, and fouh ventricle, with petechial hemorrhages in acute cases and atrophy of mamillary bodies in most chronic cases. Depending on the location of brain lesion different symptoms are seen: A. Brainstem tegmentum: Ocular pupillary changes, Extraocular muscle palsy: gaze palsy ,nystagmus. B. Hypothalamus, Medulla: Dorsal nucleus of Vagus: Autonomic dysfunction leading to cardio-circulatory and respiratory abnormalities. C. Cerebellum: Ataxia. D. Diffuse cerebral dysfunction: Altered cognition and global confusional state. E. Brain stem -peri aqueductal gray matter: Reduction of consciousness