Are some memory deficits unique to lesions of the mammillary bodies?

The role of the mammillary bodies in human memory is still in debate. A rec ent model of human amnesia proposes similar functions for the mammillary bo dies and the hippocampus. But the main evidence for this model comes from a nimal studies using the delayed non-matching to sample paradigm. We describ e a patient who developed a severe memory impairment after surgical removal of a germinoma. Postsurgical high resolution MRI revealed bilaterally shru nken mammillary bodies and an infarct of the left mammillary body. There we re no other relevant lesions. Neuropsychological testing showed mildly impa ired frontal lobe functions (executive functions, working memory and word f luency), almost intact learning and recognition, but severely impaired free and delayed recall. Experimental investigations revealed a reduced but pre served release of proactive interference and a pronounced impairment of rec ency and source judgments. We conclude that the mammillary bodies do play a prominent role in human memory, although the role differs slightly from th at of the hippocampus.