NEW YORK: Scientists believe they have discovered the gene which controls fear — a discovery which, they say, paves the way for new treatments for anxiety, depression and mental illness.

Researchers at the Howard Hughes Medical Institute at Columbia University, in New York, found the gene which produces a protein inhibiting the part of the brain which learns fear. Two groups of mice — one lacking the protein receptor in the brain — were pitted against each other in tests which involved giving electric shocks.

The normal mice and the receptor-lacking “knockout” group were trained to associate the sound of a tone with a shock. After the training, the researchers compared the degree to which the two strains of mice showed fear when exposed to the same tone alone — by measuring the duration of a characteristic “freezing” response that the animals show when fearful.

“When we compared the mouse strains, we saw a powerful enhancement of learned fear in the knockout mice,” Professor Eric Kandel, of the medical school, told the journal Cell. “The knockout mice showed no increased pain sensitivity,” he said. “So, their defect seemed to be quite specific for the learned aspect of fear.”

The gene, however, appeared only to affect fear which could be learned, rather than that which is instinctive for animals. Kandel added: “While I don’t want to overstate the case, in studies of fear learning we could well have an excellent beginning for animal models of a severe mental illness. We already knew quite a lot about the neural pathways in the brain that are involved in fear learning. And now, we have a way to understand the genetic and biochemical mechanisms underlying those pathways.”—dpa