Nothing to fear but ghosts and leopards

There's a house in my neighborhood that puts on a giant show every Halloween, with graves, ghosts, and horror-show music. We call it the "Halloween house", and it has everything you would need for a haunted house except jello brains. A few years ago, my daughter Sophie was thrilled by the Halloween house, talking about it all the way up to October 30.

Then, the excitement turned to fear. All around the neighborhood Halloween night, she was clearly in denial. She managed to put the house out of her mind up to the end of the sidewalk leading up to the house, where the combination of the imminent creepiness and the slasher music had her quaking in her shoes.

We didn't get treats at the Halloween house that year, or the next.

This is the season for thinking of fear -- I was briefly quoted in our student newspaper about the evolution of fear. But Mo of Neurophilosophy does a much better job of describing the related neural circuitry.

They key region is the amygdala, and memory is intimately involved. There is some new progress on the genetics of the mechanisms:

Recently, however, Gleb Shumyatsky and his colleagues at Rutgers University in New Jersey discovered several genes that are highly expressed in the amygdala, and which appear to be involved in this process. One of these encodes a protein called stathmin (also known as oncoprotein 18), which is now known to be involved in mediating the formation of memories of both conditioned and unconditioned fear. There is a high level of expression of the stathmin gene, and a corresponding high concentration of stathmin protein, in the amygdala, but not in the adjacent hippocampus.
Mutant mice lacking the stathmin gene were unable to learn new fears or to act instinctively in a fearful situation, i.e. they had weaker memories of fearful experiences. The stathmin knockout mice also showed less anxiety when presented with new mazes to explore or with potentially dangerous situations. Upon further examination, it was observed that mice lacking the stathmin gene had a less dynamic microtubule network than wild type (normal) mice.

This year, we got treats from the Halloween house, even my 2-year-old. I think the younger ones were mainly influenced by the bravery of the eldest. Also, they cut out the spooky slasher-movie music. No Michael Myers hiding in the bushes.