Women cheat on men for their own needs but superb starling females stray from their mates for the sake of their chicks, according to recent Cornell research. This reasoning includes being able to know if mates are too ‘genetically similar’ for breeding.

That gives ‘doing it for the kids’ a whole new layer of meaning. The study found that superb starling females (Lamprotornis superbus) cheat on their mates based on these factors:

• Superb starlings are cooperative breeders, meaning breeding pairs get help in raising chicks from other family group members. Some females mate with subordinate males when they need help to raise their chicks. This additional male then acquires food and tends to the nestlings, which increases the chicks’ survival rates.
• The subordinate males get something from this also. Females often leave the group when young but most males live their entire lives with their families and, therefore, are usually related to the chicks. By helping the chicks survive, they pass on familial genes.
• Because family males are often around their entire lives, some females cheat with males outside their group if they sense their mates are too genetically similar to themselves. Mating with strangers increases their brood’s genetic diversity even though it does not give them additional help.

How do they know? No one is sure how females detect the genetic similarities between themselves and their mates, though other species of birds appear to adopt similar mating strategies.

Usually, if a female bird (or a human female) is caught cheating, the partner punishes her by doing less work in raising the chicks, or in extreme cases, leaves her to raise the chicks on her own. Not so with these starlings.

Superb starlings of East Africa are cooperative breeders and even if the female is caught cheating, she still may get help from other group members. Still, superb starlings tend to stray much less often than other cooperative breeders, despite the dual potential benefits for females in seeking extra-pair mates.

“In most avian cooperative breeders, 40 to 60 percent of offspring are a result of extra-pair matings, but in superb starlings, only about 14 percent of the offspring are fathered by other males,” said Rubenstein. No one knows why superb starling females have lower rates of cheating, but Rubenstein said it suggests that there may be less conflict between the sexes than in other species. He is currently researching this issue.

While it has long been known that males of many species cheat and mate widely to produce as many offspring as possible to spread their genes, the reasons behind female infidelity appear more complex. With this study and this species, “we can break down the reasons why superb starling females are not faithful to their mates and see that they have different extra-pair mating strategies,” said Rubenstein. “It adds a whole new layer of complexity to the story.”

Source: Cornell

A newly discovered interplay of cells in one of the brain’s memory centers sheds light on how you recall your grocery list, where you laid your keys, and a host of important but fleeting daily tasks.

Scientists at Weill Cornell Medical College say their experiments with common goldfish are uncovering the secrets of a form of short-term recall known as “working memory.”

“We’ve now identified a mechanism that can organize the activity of groups of cells involved in this important form of recall,” says lead researcher Dr. Emre Aksay, assistant professor of computational neuroscience in the HRH Prince Alwaleed Bin Talal Bin Abdulaziz Al-Saud Institute for Computational Biomedicine at Weill Cornell Medical College in New York City.

“Furthermore, because deficits in working memory are often a precursor of schizophrenia, drugs that target this mechanism might someday help fight that debilitating disease,” he says.

The findings have been published in Nature Neuroscience.

Humans rely on their working memory every day to keep track of faces and names, tasks at school or in the workplace, and other important bits of information. “This process is distinct, neurologically speaking, from the storage and retrieval of longer-term memories,” explains Dr. Aksay, who is also assistant professor of physiology and biophysics at Weill Cornell.

Experts in labs around the world have developed theories as to how this process works. “Its basis lies in the ability of specific neurons to maintain a level of activity in the absence of input — a persistent firing rate — that’s finely coordinated across related groups of cells,” Dr. Aksay says.

But how do these brain cells communicate which each other to coordinate this activity”

To find out, Dr. Aksay, along with colleagues Dr. David Tank of Princeton University, and Dr. Mark Goldman of Wellesley College, turned to the common goldfish.

“It’s really quite difficult to test the function of individual brain cells in primates and higher animals during behavior, but the goldfish’s memory centers are much more accessible to research,” Dr. Aksay explains. “We looked specifically at the fishes’ oculomotor system — the neural circuitry that directs the fish to shift its eyes left or right based on stimuli in the local environment.” Because stimuli can be ever-changing and fleeting, the fish relies on its short-term memory to help guide these eye movements.

Two groups of cells are involved in this oculomotor memory, one in each half of the brain. Each group contains two types of neurons — inhibitory cells and excitatory cells, and it is the inhibitory neurons that allow the two groups to interact. “In our experiments, we used pharmacologic means to interrupt either excitatory or inhibitory pathways, and then we watched what happened to persistent firing,” Dr. Aksay says.

When the excitatory pathways were dampened, the persistence was impaired — suggesting that excitation is essential to the sustained firing that working memory requires.

“The real surprise came when we turned off many of the inhibitory pathways,” Dr. Aksay says. In that case, persistent firing remained, but was often present at inappropriate times.

“It appears that the inhibitory cells are not key or even required to generate persistent firing,” the researcher says. “Instead, they send a message from one group to the other that helps coordinate two sides: the role of inhibition in this system is to make sure that only one group is generating persistent activity at a given time. In this way, the goldfish doesn’t get a mixed signal telling it to move its eyes in both directions at once.”

This new finding has big implications for our understanding of the neural processes underlying working memory and the instantaneous decision-making that goes on based on that knowledge.

It might also have broader applications for psychiatric illness, Dr. Aksay notes.

“Many schizophrenic individuals, for example, show severe deficits in working memory, and children with working memory problems are at heightened risk of developing schizophrenia as adults,” he says. Dysfunction in key inhibitory pathways that link brain cells has long been associated with these problems.

“These findings suggest that it is necessary to address not only deficits in excitatory pathways that lead to a lack of persistent firing but also dysfunction in inhibitory pathways that lead to a lack of coordination among groups of cells,” Dr. Aksay explains. “This strategy could provide improved treatment options for people with schizophrenia.”

Source: New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College

Adolescents who are chronically exposed to family turmoil, violence, noise, poor housing or other chronic risk factors show more stress-induced physiological strain on their organs and tissues than other young people.

However, when they have responsive, supportive mothers, they do not experience these negative physiological changes, reports a new study from Cornell.

But the research group also found that the cardiovascular systems of youths who are exposed to chronic and multiple risk factors are compromised, regardless of their mothers’ responsiveness.

The study, led by environmental and developmental psychologist Gary Evans, is published in the March issue of Developmental Psychology. It is the first study to look at how maternal responsiveness may protect against cumulative risk as well as the first, according to the researchers, to look at cardiovascular recovery from stress in children or youths.

Evans said that the findings suggest that the physiological toll of coping with multiple risk factors is significantly greater than with that of coping with a single event, even if that event was rather severe. “Moreover the burden appears to register in physiological systems that help us regulate our responses to stress,” said Evans, the Elizabeth Lee Vincent Professor of Human Ecology and professor of human development and of design and environmental analysis in Cornell’s College of Human Ecology.

To study stress-induced physiological changes in young teens, the researchers — including three students who were undergraduates at the time and a graduate student — used an index called allostatic load. This is a measure of stress-induced changes in neuroendocrine hormonal systems, cardiovascular responses and metabolism that indicate the severity of wear and tear that cumulative strain puts on organs and tissues.

“Allostatic load may very well turn out to be the primary mechanism of how risk, stress and other sources of environmental demands get under the skin and into the body,” said Evans.

In some studies, he noted, high allostatic loads are correlated with a greater incidence of physical, mental and cognitive disorders. The new data, Evans said, may therefore explain, at least in part, “why income and racial inequalities are so pervasive and persistent in our society. Low-income kids and especially low-income kids who are nonwhite bear a disproportionate burden of cumulative risk exposure.”

The researchers also found that when stressed by a mental arithmetic problem, the cardiovascular systems of adolescents who had been exposed to chronic risk factors responded less actively to the stressor and were slower to physiologically recover.

The results are based on surveys, blood pressure measurements and urine samples from 207 seventh- and eighth-grade children in rural upstate New York who had participated in a first wave of the study while they were in elementary school.

“We oversampled low-income children given our interest in risk and poverty,” said Evans. He said they chose a rural, white community “given that the majority of children in America who are poor are white and that rural poverty constitutes greater and more persistent material deprivation than urban poverty.”

The co-authors include graduate student Pilyoung Kim and former undergraduate students Albert Ting ‘98, Harris Tesher ‘03 and Dana Shanis ‘03.