A frame at the left of the illustration is titled, Forming New Memories. The text reads, In an attempt to control the disabling seizures of a man named Henry Molaison, H.M., doctors surgically removed portions of his brain, including the hippocampus. The surgery affected H.M.’s memory. He had profound anterograde amnesia; He could tap into old memories, but he could no longer make new explicit memories. However, he could still create implicit memories. Using information gathered about H.M.’s brain, scientists have been able to directly connect the hippocampus to the creation of new explicit memories.
An image shows several slices of a brain arranged before a researcher. A callout to the image reads, After his death, H.M.’s brain was cut into over 2,000 slices that were preserved and digitized for research.
A frame at the bottom is titled, Storing Memories. The text reads as follows;
Through his experiments slicing the cortices of rats that had learned to navigate mazes, Karl Lashley concluded that complex memories are not localized to a particular region in the cortex, but are instead widely distributed. Later research has established the interrelated roles of specific structures in the process of encoding, storing and retrieving memories.
In a process called memory consolidation, which occurs in the hippocampus, memories are moved to other parts of the cerebral cortex for long-term storage, Genzel et al., 2017. Research on this topic is ongoing, but some evidence suggests that REM sleep plays a crucial role in memory consolidation, Li, Ma, Yang, & Gan, 2017.
The graphic shows three sketches of a rat brain with areas marked at the back and bottom of the sketches. A callout reads, Lashley kept a careful record of the sizes and locations of lesions made in each rat as part of his experiments.
An illustration of the brain shows callouts to different areas. Three callouts are to areas involved in memory creation, and include the following;
Amygdala—implicit memory formation, emotional memory formation. Hippocampus—explicit memory formation. Cerebellum—implicit memory formation.
Six callouts are to areas involved in memory storage, and include the following;
Visual cortex—visual memory storage, Temporal lobes—spatial memory storage, Prefrontal cortex—working memory essential for retrieval, Hippocampus—memory consolidation, Cerebral cortex—memory storage distributed throughout, Auditory cortex—, mostly hidden from view auditory memory storage.