December 12, 2002
Gene Influences Learned Fear In Mice

Mice that do not have the gastrin-releasing peptide (GRP) gene show enhanced learning of fear.

The researchers next explored whether eliminating GRP's activity could affect the ability to learn fear by studying a strain of knockout mice that lacked the receptor for GRP in the brain.

In behavioral experiments, they first trained both the knockout mice and normal mice to associate an initially neutral tone with a subsequent unpleasant electric shock. As a result of the training, the mouse learns that the neutral tone now predicts danger. 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 exhibit when fearful.

"When we compared the mouse strains, we saw a powerful enhancement of learned fear in the knockout mice," said Kandel. Also, he said, the knockout mice showed an enhancement in the learning-related cellular process known as long-term potentiation.

"It is interesting that we saw no other disturbances in these mice," he said. "They showed no increased pain sensitivity; nor did they exhibit increased instinctive fear in other behavioral studies. So, their defect seemed to be quite specific for the learned aspect of fear," he said. Tests of instinctive fear included comparing how both normal and knockout mice behaved in mazes that exposed them to anxiety-provoking environments such as open or lighted areas.

"These findings reveal a biological basis for what had only been previously inferred from psychological studies that instinctive fear, chronic anxiety, is different from acquired fear," said Kandel.

In additional behavioral studies, the researchers found that the normal and knockout mice did not differ in spatial learning abilities involving the hippocampus, but not the amygdala, thus genetically demonstrating that these two anatomical structures are different in their function.

The regulation of the expression of a large variety of genes in the brain varies from person to person because there are genetic variations in genes and regulatory areas that govern how much each gene makes its resulting protein product(s). Personality types will eventually be shown to have genetic causes. This will of course lead to a desire on the part of prospective parents to exercise some control over which personality-related genetic variations their offspring will get. Genetic engineering of personality will become a hotly debated topic when it becomes clear to the general public that this will be technically possible.

Share |      Randall Parker, 2002 December 12 02:57 PM  Brain Genetics

James said at March 29, 2006 9:50 PM:

Perhaps this soft of biotechnology would actually not only make mice not as afraid on humans, or even cure out phobia in humans, it may actually be a new tool in domesticating new livestock or even manipulating traits in species.

Traditionally, it took years into domesticating of animals and some even can't be domesticated at all, especially monkeys. But with new tools, we can bring even new and bigger cattle, quite namily the bison, to our ranch and our plates.

There is domestic bison, but it has the genes of cattle in the bison, so it's not 100% bison. But thankfully, with this technology, it can be implanted into bison, so that it can be safe to stand right next to the 500 lb. bison without being trampled on! Therefore, we can have a whole new set of cattle...all heart healthy 100% pure-bred bison, ostriches, and...well...chickens pigs will be still in our barns. After all, bison ranches are more sustanable...and cleaner...than the beef cattle that we have today. But I do allow it to be still concidered a pure-bred as long as it is more than 95% bison, and no other animal genes other than the "change" in genetics are on there. I am in full support of replacing all that fatty beef away to all buffalo, including the meat, and even bison milk!

But this transistion takes time. First, we move cattle out in favor of beefalo, which is, cattle with the genes of the bison. Than finally, purebred bison will replace beefalo and one hundred years from now, the bison went from our staple, to the brink of extinction in 1900, back to our plates by 2100!

And this may work on monkeys, so that we can have monkeys as pets that don't bite and can even be trained for handicaped people.

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