This week in animal research: w/e 5 December
Unlike people, Capuchin monkeys aren't fooled by expensive brands, they don’t assume a higher price tag means better quality. Humans consistently tend to be biased by prices, however, Capuchin monkey can be taught about money and its economic value and still won’t be biased but something’s price. They can understand the differences in price between foods, but won’t necessarily prefer the most expensive one.
“We know that Capuchin monkeys share a number of our own economic biases. Our previous work has shown that monkeys are loss-averse, irrational when it comes to dealing with risk, and even prone to rationalizing their own decisions, just like humans," said Laurie Santos, a psychologist at Yale University and senior author of the study. "But this is one of the first domains we've tested in which monkeys show more rational behavior than humans do. For humans, higher price tags often signal that other people like a particular good. Our richer social experiences with markets might be the very thing that leads us -- and not monkeys -- astray in this case."
A study from the University of Oxford has shown that the HIV virus is evolving into a ‘milder’ form, taking longer to trigger AIDS in patients. Some virologists even suggest that the virus may become almost harmless as it continues to evolve. SIV, the primate version of HIV, is less dangerous for those species than HIV is to us- likely showing this effect in another species:
Prof Jonathan Ball, a virologist at the University of Nottingham, said:
"In theory, if we were to let HIV run its course then we would see a human population emerge that was more resistant to the virus than we collectively are today - HIV infection would eventually become almost harmless. Such events have probably happened throughout history, but we are talking very large timescales."
Male rats prefer females wearing “lingerie”. An unusual study presented virgin male rats with receptive females wearing a tiny jacket. Later, if given a choice, the males will prefer females with a jacket than without. When looking at the brain, males that mated with jacket-wearing females showed more activity in the pleasure centres of the brain - including regions called the ventral tegmental area and the nucleus accubens – than males who mated with jacket-less females. Rats learn to associate sex with a variety of contextual cues, including clothing, this might be the same in humans.
Male rats learn that "each time my partner wears lingerie [a jacket], I'm going to have sex," said study co-author Gonzalo R. Quintana Zunino, a psychologist working in the lab of psychologist Jim Pfaus at Concordia University in Montreal.
A drug that encourages spinal cord nerves to grow and repair injuries has been developed using rats. 21 out of 26 rats showed some degree of improvement following treatment, either in their movement or bladder control. Proteins released by injury scar tissue can act to prevent neurons from growing over a damaged region of the spine. The drug acts to disrupt this “sticky glue” and allow the nerve cells to grow.
Dr Lyn Jakeman, from the US National Institute of Neurological Disorders and Stroke, said: "There are currently no drug therapies available that improve the very limited natural recovery from spinal cord injuries that patients experience. This is a great step towards identifying a novel agent for helping people recover."
Photo: neurons of the rat spinal cord from wikicommons By Zuzanna K. Filutowska
Cells that enable bats to navigate through three dimensional space when flying have been identified in the brain. All mammals have cells in their brains that act as an inbuilt GPS – the 2014 Nobel Laureate John O’Keefe discovered the first component of this system in 1971 – but until now most spatial navigation work was conducted on rats running around on flat surfaces. Scientists at the Weismann Institute of Science in Israel recorded neuronal activity in the brain of fruit bats, identifying a cluster of cells that are responsible for encoding three dimensional space.
The University of Rochester Medical Center in New York have injected human glial cells (the cells in the brain that support neurons) into mouse pups. Within a year the human cells had completely displaced the mouse cells. "We could see the human cells taking over the whole space," says Steve Goldman. "It seemed like the mouse counterparts were fleeing to the margins."
The injected mice were found to have better memory and cognition across a battery of tests. "This does not provide the animals with additional capabilities that could in any way be ascribed or perceived as specifically human," he says. "Rather, the human cells are simply improving the efficiency of the mouse's own neural networks. It's still a mouse."