Your humble reporter lives on a horse farm, and many of our equine friends compete on a regular basis, so we are always interested in anything to keep them fit, healthy and happy.

I was interested to see a report of some research done in Finland. The main carbohydrate store in muscle is called glycogen, and Seppo Hyyppä, from MTT Agrifood Research Finland, looked at the way in which muscle glycogen stores are rebuilt after exercise. This is an important question, and not only for horses: glycogen is the most important nutrient during exercise and if glycogen stores are depleted the horse breaks down the protein in its own muscles to provide energy. So if the horse is chronically over-exercised it can hurt him.

The two most important factors in rebuilding muscle glycogen were:

• Sufficient recovery time between intense training periods, and
• Hydration

Giving horses an isotonic glucose-electrolyte rehydration solution soon after exercise helps to overcome dehydration significantly better than providing them with plain water.

The research also showed that weighing the horse before and after exercise gave a reasonably accurate estimate of the rate at which glycogen was being replenished. If you don’t have a set of weighing scales handy, you can measure the horse’s chest circumference.

The research also confirmed what every horse owner knows: you can tell a lot by looking at a horse: his general alertness and, for example, suppleness and appetite, indicate that he is in good condition.

“A canter is the cure for every evil.”
–Benjamin Disraeli, 1st Earl of Beaconsfield (English Statesman, Novelist and, in 1868 and from 1874-1880, British Prime Minister, 1804-1881)

“A man on a horse is spiritually as well as physically bigger than a man on foot.”
–John Steinbeck (American Writer and, in 1962, Winner of the Nobel Prize in Literature, 1902-1968)

It is almost forty years since Fernando Nottebohm first began to describe some of the dynamic changes that occur in the brains of songbirds as the seasons change. Every year some regions of the brain grow in response to changes in ambient light levels and others regress. There are marked seasonal changes in the brains of fish, reptiles, amphibians, birds and even some mammals such as gerbils, mice and perhaps even in humans. But the magnitude of the changes in birds far outweighs any other species. It is hoped that that understanding the mechanism controlling that change may help us to develop treatments for age-related degenerative diseases of the brain such as Parkinson’s and dementia.

Researchers from the University of Washington and the University of California, Berkeley, have published some interesting new data in the Proceedings of the National Academy of Sciences. They report a striking shrinkage in the size of the brain regions that control singing behavior of Gambel’s white-crowned sparrows. This transformation is triggered by the withdrawal of testosterone and can be seen within 12 hours. The study is the first to report such rapid regression of brain nuclei caused by the withdrawal of a hormone and a change in daylight conditions in adult animals.

The research protocol was designed to mimic the natural seasonal changes that occur in the brains of the sparrows. Their song-control regions expand in the spring and summer leading up to the breeding season, as they use songs to establish territories and attract mates in Alaska. Later in the summer, as the birds get ready to migrate back to California, the same brain regions shrink.

To better understand what happens in the sparrows’ brain, the researchers received federal and state permits to capture 25 of the migrating male birds in Eastern Washington. They then housed the birds for 12 weeks before exposing them to 20 days of long-day conditions comparable to the natural lighting the sparrows would experience in Alaska during the breeding season. The birds were also implanted with testosterone.

At the end of 20 days, six of the birds were euthanized and the remaining 19 were castrated and testosterone implants were removed so there would not be any circulating testosterone in their systems. After 12 hours five more birds were euthanized and the remainder were euthanized at 2, 4, 7 and 20 days.

The researchers found that the size of the high vocal center (HVC) region decreased 22 percent within 12 hours after the withdrawal of testosterone and that the number of neurons in this song-control region fell by 26 percent after four days. In addition, the size of two other song-control regions called Area X and the RA significantly regressed after 7 and 20 days.

Much as I dislike animal experiments of any kind, it is invaluable to have an animal model system in which we can observe predictable neurodegeneration. As men age, circulating levels of testosterone decrease, and other research has shown that this decline may contribute to cognitive impairment.

This is an important new approach to understanding the interplay between nerve cell degeneration and hormones.

I have commented before on my longstanding interest in handedness and laterality, as well as gender differences in the brain. A recurrent question when we look at both of them is whether culture has any role in the development of either. Are some of the differences in male and female brains driven by educational opportunities and cultural expectations, or is there something innate about them?

A recently published paper in PLoS ONE reports finding both sex and handedness influences on the relative size of the corpus callosum in Capuchin monkeys.

Capuchin monkeys are playful, inquisitive primates best known as the “Organ Grinder” monkeys. They have great manual dexterity, complex social behavior, and cognitive abilities. The new research now shows that just like humans, they display a fundamental sex difference in the organization of the brain, specifically in the corpus callosum, the band of white matter that connects the two hemispheres of the brain.

In the study, thirteen adult capuchins underwent magnetic resonance imaging of the brain to determine the size of their corpus callosum. The monkeys were later given a task to determine hand preference. The authors’ results led them to conclude that, as in humans, male capuchins have a smaller relative size of the corpus callosum than females, and right-handed individuals have a smaller relative size of the corpus callosum than left-handed individuals.

As the two hemispheres show greater independence of function, the relative size of the corpus callosum is expected to be smaller. This has been documented in humans, and same pattern was found in capuchins.

This finding may be related to hemispheric specialization for complex foraging tasks that require the integration of motor actions and visuospatial information. In the wild, capuchin monkeys live in trees as well as on the ground, and they are known to be very good at capturing small swift prey such as birds, lizards, and squirrels.

Shortly after the earth cooled, I was given a book with the arresting title of the Dieter’s Guide to Weight Loss During Sex.

I have no idea why. Nothing in the title seemed at all relevant to me.

So now I learn that sex makes you fat.

But only if you’re a female tick.

I would like to share with you that after mating, the weight of the female African ixodid tick balloons until she is 100 times her original size. That is truley astonishing.

This observation has lead a researcher from the Department of Biological Sciences at the University of Alberta to investigate what it is about copulation that triggers such a massive weight gain.

In a new paper published in the Journal of Insect Physiology, Dr. Reuben Kaufman suggests that there are several differences between the ixodid tick and other blood-sucking beasties - mosquitoes, tsetse flies, bedbugs and kissing bugs – that may help explain the weight gain. None of them has anything like this kind of weight gain: it seems to be unique to the female African tick.

Kaufman suggests that the ixodid tick displays a significant difference in lifestyle from the other insects and that it is adaptive for the virgin to remain small before mating: she wants to stay below the host’s radar.

This species of tick remains on the host for a number of days, rather than minutes. As Kaufman says,

“In this family of ticks, mating takes place on the host. Most other insects mate before or after their brief blood meal - the two acts are totally separate, but not with these ticks.”

Female ticks require six to 10 days to engorge fully. First, she attaches herself to the skin. Then she feeds to 10 times her unfed weight and finally, after copulation, she increases her weight a further tenfold.

On the other hand, the virgin tick rarely exceeds the critical weight necessary for laying eggs. She will hang on to the host for weeks waiting for a male to find her. If the virgin gains too much weight and is groomed off the host, she will not be able to reattach herself to another host and continue feeding. If she remains small she still has a chance to reattach itself to another host, which hopefully will be infested with some feeding males. Then she cannot only continue feeding, but may also have the chance of meeting a mate.

As Kaufman says,

“If a male eventually copulates with her, she will engorge normally and then be able to lay eggs. This is one reason why it might be adaptive for the virgin to remain small until mated.”

In terms of what causes the female to become so engorged, it seems to have something to do with the exchange of bodily fluids. The male fluids contain two engorgement factor proteins that together act as a signal to tell her to complete engorgement.

This work may sound as if it is a bit out of left field, but it is actually very important. Ticks can be a real problem in many parts of the world: even in Georgia, it is a daily ritual to check the dog, cats and horses for ticks.

This work is part of a research program to produce an anti-tick vaccine. Some experiments have already suggested that normal, mated ticks are unable to fully engorge when feeding on a host that has been immunized against the engorgement factor proteins. If these observations can be confirmed and extended, an effective anti-tick vaccine to protect livestock and pets could be on the horizon.

Human beings have a remarkable ability to be able to understand the goals and intentions of others. This ability develops gradually during infancy and early childhood and is known as the theory of mind. This ability seems often to go wrong in people with autism spectrum disorders and schizophrenia. Psychologists have tended to think that this is a purely human ability, yet every one who spends a lot of time with animals is sure that they have a similar ability.

New research from the University of Vienna and the University of Budapest, have found striking similarities between humans and dogs in the way they imitate the actions of others.

The researchers were examining a phenomenon known as “selective imitation.” Dogs were given the task of opening a food container by pulling a rod. Normally dogs prefer to use their mouths for this kind of task, but a female dog was trained to open the box with her paw. When the other dogs watched how she did it, they imitated her to get the food. But the dogs only imitated selectively.

When the “training dog” used her paw while holding a ball in her mouth, they used their mouths instead of their paws for manipulating the rod. But when the demonstrating dog’s mouth was free, the dogs once again imitated her and used their paws. This implies that they assumed that she was only using her paw because her mouth was otherwise occupied.

It also indicates that dogs are like human infants in that they do not simply copy an action that they observe, but they adjust the extent to which they imitate depending on the situation. Neither dogs nor humans blindly copy what another creature is doing: they copy what is appropriate for the task at hand. The research has just appeared online in the journal Current Biology.

After their millennia of association with humans, dogs may be a special case. But I doubt it: this is yet more evidence that the gap between animals and humans is shrinking much more rapidly than many of us realize.