Final answer:
The hippocampus is the part of the brain that, when damaged or removed, leads to anterograde amnesia, as exemplified by the case study of H.M. who suffered from this condition after brain surgery.
Step-by-step explanation:
When a person's hippocampus is damaged or removed, as was the case for H.M., anterograde amnesia, or the inability to form new memories, results. Henry Molaison, known as H.M., underwent surgery to remove both of his left and right medial temporal lobes in an attempt to control his seizures, which included the hippocampus and amygdala. This profound brain surgery led to his anterograde amnesia. While H.M. retained the capacity to remember past events or what's called retrograde memory, he could not form new episodic or semantic memories post-surgery. However, his ability to develop new procedural memories remained intact, evidenced by his increasing proficiency with puzzles despite not recalling having seen them before.