Remember Daniel Keyes fabulous short story/novel/play/movie Flowers for Algernon? The title character was a mouse with surgically enhanced intelligence.
It seems that this part of the future has already arrived.
What would Stuart Little make of it? Mice have been created whose brains are half human. As a result, the animals are smarter than their siblings.
Goldman's team extracted immature glial cells from donated human fetuses. They injected them into mouse pups where they developed into astrocytes, a star-shaped type of glial cell.
Within a year, the mouse glial cells had been completely usurped by the human interlopers. The 300,000 human cells each mouse received multiplied until they numbered 12 million, displacing the native cells.
"We could see the human cells taking over the whole space," says Goldman. "It seemed like the mouse counterparts were fleeing to the margins."
Astrocytes are vital for conscious thought, because they help to strengthen the connections between neurons, called synapses. Their tendrils (see image) are involved in coordinating the transmission of electrical signals across synapses.
Human astrocytes are 10 to 20 times the size of mouse astrocytes and carry 100 times as many tendrils. This means they can coordinate all the neural signals in an area far more adeptly than mouse astrocytes can. "It's like ramping up the power of your computer," says Goldman.
A battery of standard tests for mouse memory and cognition showed that the mice with human astrocytes are much smarter than their mousy peers.
Although creepy, the work has some obvious implications for understanding some kinds of metal retardation, and, conceivably, treatments.
According to the lead investigator, Steve Goldman of Rochester University:
"This does not provide the animals with additional capabilities that could in any way be ascribed or perceived as specifically human," he says. "Rather, the human cells are simply improving the efficiency of the mouse's own neural networks. It's still a mouse."
However, the team decided not to try putting human cells into monkeys. "We briefly considered it but decided not to because of all the potential ethical issues," Goldman says.