In a recent research, human brain cells were implanted inside baby mice and it was reported that the leaning ability of the mice improved.

Astrocytes, a type of glial cells, were initially thought to be mere support cells without transporting signals. However, later it was reported that astrocytes in humans perform a more complex and are highly efficient in transmitting signals than those found in the brain of mice.
Maiken Nedergaard and Steve Goldman of the University of Rochester Medical Centre in New York in their experiment had incorporated astrocytes generating stem cells into the brains of baby mice. When the mice matured, the researchers tested the learning ability of the mice by conducting various experiments. The mice learnt to clear a maze, find objects and avoid mild electric shock at a much quicker pace.
Scientists opine that same technique could be used to explore human brain diseases by grafting glial progenitor cells taken from a person with the disorder.
Source-Medindia