The site of lesion in korsakoff psychosis is

Wernicke-Korsakoff syndrome is associated with periventricular lesions surround the third ventricle, aqueduct, and fouh ventricle, with petechial haemorrhages in occasional acute cases and atrophy of the mammillary bodies in most chronic cases. There is frequently endothelial proliferation, demyelination, and some neuronal loss. These changes may be detected by MRI scanning. The amnestic defect is related to lesions in the dorsalmedial nuclei of the thalamus. Reference: Harrison19e pg: 1783