The hippocampus is a relatively tiny structure in the human brain, and I would guess it’s even proportionally smaller in the mouse brain. I doubt the corresponding decrease in cerebrospinal fluid volume would make any difference in function. There’s already much more variation in cerebrospinal fluid volume in healthy humans than a 20% increase in hippocampal volume could account for.
The hippocampus is a relatively tiny structure in the human brain, and I would guess it’s even proportionally smaller in the mouse brain. I doubt the corresponding decrease in cerebrospinal fluid volume would make any difference in function. There’s already much more variation in cerebrospinal fluid volume in healthy humans than a 20% increase in hippocampal volume could account for.