Answer: Henry Molaison was a patient with profound memory deficits as a result of a bilateral temporal lobectomy.
Born in 1926, Henry Molaison was an American man who is best known for how he has informed the world about memory learning. Henry suffered from intractable seizures from early childhood, experiencing several severe tonic-clonic seizures when he was a teenager. He took several medications to try to decrease his seizures, but the seizures prevented him from living a normal life.As a desperate measure to improve the quality of his life, surgeons removed large parts of both temporal lobes in 1953.
Following the surgery, he experienced an inability to create new memories (anterograde amnesia) as well as a loss of some memories up to two years before the surgery (retrograde amnesia). He remembered several moments from his childhood, so it was a surprise that these older memories were still intact. It demonstrated that the temporal lobes were an important brain structure that contributed to the consolidation of memories, implying that a memory is held in the temporal lobes for a short time before that memory becomes permanent.
Scientists have learned a lot about implicit and explicit memories through studying his condition. He could not remember a short series of numbers or perform well on a Corsi block tapping task, indicating that one aspect of these memories were impaired. He could not learn about the changing world around him, despite watching the news every night. He was unable to identify the president, or any famous celebrities beyond the ones he knew prior to surgery.
He was able to perform well on motor tasks. He was asked to trace the inside of a star while watching his hand in the mirror, a challenging task. As anyone else, he would improve at this task over time, moving quicker and making fewer mistakes. However, when asked about this behavioral test, he would have no recollection of ever doing the tasks. This disparity indicates that the hippocampus and temporal lobes serve to preserve discrete memories, but not procedural memories.
Henry lived a long life and died in 2008.