Lesion in Wernicke's encephalopathy occurs in -
In thiamine deficiency, hemorrhages into the mamillary bodies cause Wernicke-korsakof syndrome.
Other regions of CNS involved in thiamine deficiency are periventricular regions of the thalamus, the floor of the fourth ventricle and the anterior region of the cerebellum.
Mamillary body
Cerebellum
Motor cortex
Substantia nigra