The scans indicated that almost all the damage within Eugene’s skull was limited to a five-centimeter area near the center of his head. The virus had almost entirely destroyed his medial temporal lobe, a sliver of cells which scientists suspected was responsible for all sorts of cognitive tasks such as recall of the past and the regulation of some emotions.
[...]
At the time, no one wondered how a man who couldn’t draw a map of his home was able to find the bathroom without hesitation.
[...]
She asked him to point out which doorway led to the kitchen. Eugene looked around the room. He didn’t know, he said. She asked Eugene what he would do if he were hungry. He stood up, walked into the kitchen, opened a cabinet, and took down a jar of nuts.
[...]
As they rounded the corner near his house, the visitor asked Eugene where he lived. “I don’t know, exactly,” he said. Then he walked up his sidewalk, opened his front door, went into the living room, and turned on the television.
He couldn’t form “real” memories, but he could form habits.
Echoes of the Bicameral Mind here.