Human/Rat Mashup-Brain

Wissenschaftler haben menschliches, laborgezüchtetes Hirngewebe in Ratten verpflanzt und die Neuronen haben nicht nur zwei Monate in der Ratte gelebt, sondern verbanden sich mit dem Rattenhirn und die Neuronen feuerten, wenn die Ratte mit Licht angestrahlt wurde.

Stat: Tiny human brain organoids implanted into rodents, triggering ethical concerns
Discover Mag: Human Brain ‘Organoids’ Implanted Into Rats

Dr. Isaac Chen, a neurosurgeon at the University of Pennsylvania, implanted human cerebral organoids into the brains of 11 adult rats, specifically the secondary visual cortex. That structure processes visual signals to, for instance, figure out the color and orientation of something the eye has seen.

The 2-millimeter organoids survived for at least two months, Chen said in an interview, and showed “extensive” growth of human axons into the rat brain. Some of the axons grew as much as 1.5 millimeters, connecting to the corpus callosum, a bundle of neurons connecting the left and right cerebral hemispheres. When the scientists shined light on a rat’s eye, or stimulated brain regions involved in vision, neurons in the implanted organoid fired. That suggested the human brain tissue had become functionally integrated with the rat’s.

Die ethischen Fragen drehen sich nun darum, ob menschliches Hirngewebe in einer Ratte auch menschliches Bewusstsein in einer Ratte wecken kann – nicht in diesem Experiment, aber in zukünftigen. (Das Hirngewebe der hier verwendeten „Organoids“ ist noch nicht komplex genug, um höhere Hirnfunktionen abzubilden.)

Would it feel like a human trapped in a rodent’s body? Because both the Salk and Penn experiments used adult rodents, their brains were no longer developing, unlike the case if implants had been done with fetal rodent brains. “It’s hard to imagine how human-like cognitive capacities, like consciousness, could emerge under such circumstances,” Kimmelman said, referring to implants into an adult rodent brain. Chen agreed: He said his experiment “carries much less risk of creating animals with greater ‘brain power’ than normal” because the human organoid goes into “a specific region of already developed brain.”

Betonung auch „developed brain“. Was passiert, wenn man Hirn-Organoids in eine junge Ratte verpflanzt und ob diese neue, „menschlichere“ Eigenschaften ausbildet, dürfte sich schon sehr bald zeigen.