Final answer:
The hippocampus does not store long-term memories but is essential for consolidating new ones. Patient H.M.'s case showed he could not form new declarative memories after hippocampal damage, but retained his pre-existing long-term memories. Procedural and implicit memory formation, managed by other brain structures like the cerebellum, remained intact.
Step-by-step explanation:
Damage to the hippocampus does not result in permanent loss of previously-stored long-term memory (LTM). Instead, the hippocampus is crucial for the consolidation of new memories from short-term to long-term storage. The famous case of patient H.M., who underwent bilateral removal of the hippocampus, illustrates this phenomenon: H.M. retained his pre-existing long-term memories but developed anterograde amnesia, preventing him from forming new declarative memories. Procedural and implicit memories, which are processed by other brain areas such as the cerebellum, were unaffected in H.M.'s case.
Moreover, research has shown that the hippocampus is involved in memory functions like normal recognition memory and spatial memory, but after an injury to this area, new declarative memory processing is impaired. Memory consolidation, the process of transferring new learning to long-term memory, highlights the key role of the hippocampus. Nevertheless, other types of memories, including procedural memories and implicit memories, can still be created thanks to brain structures like the cerebellum. Therefore, although hippocampal damage severely disrupts certain aspects of memory, it does not erase existing long-term memories.