Final answer:
The case of H.M. suggests that the hippocampus is critical for the storage of new long-term memories, evident from his development of anterograde amnesia following brain surgery that removed his hippocampus and amygdala.
Step-by-step explanation:
H. M., a famous amnesiac, gave researchers solid information that the hippocampus was important in storing new long-term memories. This conclusion came about due to H.M.'s case where, after a bilateral lobectomy to remove the hippocampus and amygdala to control seizures, he developed anterograde amnesia, which is the inability to form new memories. However, H.M. retained the ability to learn new skills (procedural memories) despite not recalling the learning experience itself. His condition highlighted the crucial role of the hippocampus in the consolidation of short-term memories into long-term declarative (explicit) memories, particularly episodic and semantic memories.
Subsequent research on memory and the brain identified that other structures like the medial temporal lobe and the amygdala are also involved in this process, with the hippocampus being key for the encoding of new memories, and the amygdala for determining which memories are stored based on emotional response. The distinction between different types of memories such as short-term, procedural, and episodic implies specific brain areas are responsible for these functions, with the hippocampus being pivotal for long-term episodic memory storage.