Scientists build parts of human brain

STANFORD, California — Scientists have grown and assembled parts of a human brain in a dish.

The mini-brain forms mental circuitry — and cells converse with each other.

“There is cross-talk,” said lead researcher Dr. Sergiu Pasca, assistant professor of psychiatry and behavioural sciences at Stanford University School of Medicine, whose study was published in the journal Nature.

Researchers did not build an entire brain, the stuff of sciencefiction fantasy. It doesn’t think and is not self-aware. That is a far more complex and, most likely, unattainable goal.

Instead, they made a tiny, but powerful, model of the cerebral cortex for the study of such devastating human conditions as schizophrenia, epilepsy and autism — impairments not easily studied in people.

The mini-brain reveals how networks of our mind can grow, behave and communicate, giving scientists an unprecedented view of our most mysterious organ.

The researchers hope to learn what goes wrong with the mental circuitry of people with disease or disorders.

Their brain also can be used to test potential drugs, essential for improving the pharmaceuticals used by psychiatrists.

“It’s the first example of assembling, in a 3-D culture, this brain region,” Pasca said. “Essentially, we get a small cerebral cortex in a dish.”

Understanding the neurobiology of the brain remains one of the great challenges of modern medicine because we haven’t had direct views of the brain’s cellular behaviour. While we can watch mental function through tools such as magnetic resonance imaging, that doesn’t show us what is happening at the most basic level.

Brain development has not been observed in the lab because it happens during the second and third trimester of pregnancy.

Researching other diseases, such as cancer, don’t have this problem because doctors can sample tumour cells and look at them under a microscope. The sampling and study of brain cells is much harder.

Stanford researchers started with longstanding tried-and-true techniques.

They took skin cells and turned them into stem cells. Then they used chemical prods to turn them into two different types of brain cells.

In one dish, they grew cells called glutamatergic neurons, because they secrete the chemical glutamate, responsible for sending excitatory messages in the brain.

Too much cellular excitement is thought to underlie disorders such as epilepsy.

In a second dish, they grew cells that secrete a different chemical, called GABA, which sends inhibitory messages in the brain. Their job is to apply the brakes.

Then they were introduced to each other.

Within three days, the two cell types fused into one big sphere — and started organizing.