He could engage in conversation and remember from one moment to
the next the flow of dialogue. He could recall lists of numbers or words
immediately after hearing them recited. He also had decent long-term
memory, at least for some things, and could answer questions involv-
ing information he knew from before the time of his surgery. He could
work crossword puzzles, as long as the clues and words were things he
knew before having had surgery.
Hippocampus
AmygdalaFigure 19.2. Hippocampus and adjacent areas revealed by exposing the medial
temporal lobe region from the side of the brain. The entorhinal region is a fold
of cortex immediately below the hippocampus. To remove H.M.’s medial tem-
poral lobe structures, the surgeon drilled holes into the forehead of his skull
and lifted the frontal lobes to access the underside and interior of the tempo-
ral lobes.
However, Henry was unable to remember, for more than a few
minutes, any new information acquired after his surgery—he suffered
from profound anterograde amnesia. He would read and understand