Archive for January 13, 2010

Dog Science News

From Proceedings of the National Academy of Sciences:  Dogs have been subjected to artificial selection pressure that, unfortunately, has often focused on creating and preserving exaggerated traits, like flat faces, curly coats, short legs or wrinkly skin. Researchers performed a genome-wide analysis of ten breeds looking for breed-specific mutations that could be related to the expression of these exaggerated traits. They found genes linked to curly coats in poodles and wrinkles in shar-peis.

Genomic data was collected from 275 dogs of ten different breeds. They identified 155 distinct genetic loci that may be important in controlling breed-specific traits. These included genes related to size, coat color, coat texture, behavior and physiology. The group plans to follow up with studies focused on identifying loci related to behavioral differences in dog breeds.

Tufts University reports that researchers have found a gene that appears to be associated with canine compulsive disorder (CCD). reports:

The chromosome 7 location most significantly associated with CCD is located within the neural cadherin-2 gene, CDH2. CDH2 is widely expressed, mediating synaptic activity-calcium flux related neuronal adhesion. Dogs showing multiple compulsive behaviors had a higher frequency of the “risk” associated DNA sequence than dogs with a less severe phenotype (60 and 43%, respectively, compared with 22% in unaffected dogs). This highly significant association of CCD with the CDH2 gene region on chromosome 7 is the first genetic locus identified for any animal compulsive disorder, and raises the intriguing possibility that CDH2 and other neuronal adhesion proteins are involved in human compulsive behaviors, including those observed in autism spectrum disorder. The neural cadherin-2 gene, CDH2, is an especially attractive candidate disease gene as it is involved in mediating presynaptic to postsynaptic neuronal junction adhesion, neuronal axon outgrowth and guidance in the central nervous system during development when critical brain nerve networks are established.

This may be another case where dogs and humans help each other through comparative medicine. Insights gained from studies on dogs with CCD may someday help treat or prevent similar disorders in humans. Most of the dog-related buzz I’ve read on this has focused on the idea that the gene may help identify dogs that would benefit from behavioral medication. I hope it leads to a tool breeders can use to produce mentally healthy puppies.

There’s an interesting article in Nature on extinction. During a mental process referred to as reconsolidation, stored memories become open to change for a short period after they are retrieved. The group has taken advantage of better knowledge on how reconsolidation functions to develop a non-invasive technique to extinguish fear memories in humans. They found evidence that old fear memories can be updated with non-fearful information provided during the reconsolidation window.

Timing and re-exposure to the fearful stimulus were the key factors identified. People who were given extinction training without being re-exposed to the stimulus retained their fear of it. Extinction training also needed to be conducted within hours of exposure. There appears to be a limited window of opportunity when we can edit a retrieved a memory trace. If training happens outside this window, the brain creates two memory traces, and the fearful one isn’t overwritten.

As a dog trainer, this makes perfect sense to me that you need to be exposed to a frightening or stress-inducing thing to learn that it isn’t dangerous. I hope that information on the size of the effective window of memory reconsolidation will help dog trainers to rehabilitate fearful dogs more efficiently.

Last, but most definitely not least, from PhD Comics, a brilliant explanation of typical mainstream media science coverage (click here for enlarged size at the source):

January 13, 2010 at 1:11 pm 2 comments

Because A Dog’s Mind is a Terrible Thing to Waste


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January 2010