In adult monkeys, an antidepressant treatment has induced new nerve cell growth in the hippocampus, a brain area responsible for learning and memory. A similar process may occur in humans, the research suggests, and may help explain the effectiveness of antidepressant treatments.The results, the first from nonhuman primates, are similar to those previously seen in rodents. They suggest that creation of new nerve cells, a process known as neurogenesis, is an important part of antidepressant therapy. Researcher Tarique Perera, MD, at Columbia University, and colleagues observed changes in the number of brain cells in the dentate gyrus region of the hippocampus. The study is published in the May 2 issue of The Journal of Neuroscience.

The growth of new nerve cells in the hippocampus has been suggested as the way antidepressants work in rodents, says Eric Nestler, MD, PhD, of the University of Texas Southwestern Medical Center. “However, the clinical relevance of this action has remained controversial, in part, because of uncertainty as to whether similar neurogenesis occurs in humans,” he says. “This finding further supports the potential clinical relevance of changes in neurogenesis seen in rodent models.”

Perera and the team treated a group of monkeys with electroconvulsive shock (ECS), an animal version of the highly effective clinical antidepressant electroconvulsive therapy. They saw an increase in new nerve cells in the hippocampus. Over four weeks, a majority of these cells became mature neurons.

These brain changes were not a response to tissue damage, Perera says, because no evidence of increased cell death was found in the ECS treated animals. In fact, the researchers found that the ECS treatments increased production of a protein (BCL2) that protects neurons from damage.

“These findings support the hypothesis that induction of neurogenesis is a necessary component in the mechanism of action of antidepressant treatments,” Perera says.

What a person says is not necessarily an indication of what that person knows because speech is motivated by social circumstances and the desire to influence the listener. Two researchers at the University of Missouri-Columbia have applied this principle to local environmental knowledge by indigenous peoples and are urging other scientists to incorporate more observation and skepticism into their studies.

“We need to treat talk for what it is,” said Craig Palmer, assistant professor of anthropology in MU’s College of Arts and Science. “Talk influences people. It’s used as a social and political tool, and it may or may not reflect actual knowledge. People’s answers to questions may have more to do with social relationships than with their knowledge.”

Palmer and Reed Wadley, also an MU assistant professor of anthropology, wrote a paper on this subject that has been published electronically and will appear in October in the journal Human Ecology. The paper argued that because scientists often study local environmental knowledge by asking questions, it is important to recognize that answers to such questions may not reflect true knowledge. Revealing true local environmental knowledge is important because it gives people in other parts of the world another possible way to deal with environmental change, Wadley said.

“One of the keys to responding well to environmental change of whatever kind is having a diverse toolkit from which to draw. Local environmental knowledge represents such toolkits that people have developed over the generations, based on local responses to environmental change,” Wadley said.

The concept that talk may be different from knowledge has been largely overlooked in studies of local environmental knowledge, Palmer said. To illustrate the importance of this concept, the researchers used as an example the residents of small fishing villages on the Great Northern Peninsula (GNP) of Newfoundland. According to Palmer, these people are traditionally reluctant to talk about their knowledge or to disagree with what others say about the environment. It also is popular to tell “cuffers,” exaggerations that are used to make talk more interesting.

The fishing industry has historically been a major source of income in the GNP, but a decline in cod stock in recent decades has caused economic problems and resulted in social stratification and blame in the communities. As a result, nearly all conversation about the environment is highly politicized, Palmer said. Local residents are acutely aware of this and attempt to influence the listener when they talk about the environment. Regular accusations for the reduction of the cod stock against one group or another have resulted in what Palmer called “an almost ritualized reference to the possibility that talk would not be equivalent to knowledge.”

Palmer and Wadley recommend that scientists recognize and make use of this skepticism, as well as observation of non-verbal behavior, rather than relying solely on verbal answers to questions. Palmer said they do not encourage researchers to ignore what local residents say, but to take into consideration the entire knowledge of local peoples, both social and environmental, and how that knowledge can affect talk about the environment.

“To filter out the social talk about ecological things from the knowledge that might be ecologically useful, we need to go beyond the talk and study non-verbal behavior and how it matches with local environmental talk: what do people talk about that they actually use in dealing with the local environment? That sort of study is a good deal harder than asking folks questions and recording what they say they know,” Wadley said.

Source: University of Missouri-Columbia.

New research from Columbia’s Primate Cognition Laboratory has demonstrated for the first time that monkeys could acquire meta-cognitive skills: the ability to reflect about their thoughts and to assess their performance.

The study was a collaborative effort between Herbert Terrace, Columbia professor of psychology & psychiatry, and director of its Primate Cognition Laboratory, and two graduate students, Lisa Son — now professor of psychology at Barnard College — and UCLA postdoctoral researcher Nate Kornell.

The test used touch-screen technology and a multiple-choice format. Six novel photographs were presented at the beginning of each trial, one at a time. One photograph was selected at random and then displayed simultaneously with EIGHT novel photographs. The monkey’s task was to select the photograph that appeared at the beginning of the trial. The monkey then evaluated the accuracy of its choice by selecting a high and a low-risk icon presented on the screen. It earned a large reward if it selected the high-risk icon after a correct response (THREE tokens dropped into a bank displayed on the video monitor) Credit: Herbert Terrace-Columbia University

The study, which appears in the January issue of Psychological Science, a journal of the Association for Psychological Science, was designed to show that a monkey could express its confidence in its answers to multiple-choice questions about its memory based on the amount of imaginary currency it was willing to wager. Their experiment was derived from the observation that children often make pretend bets to assert that they know the answer to some question. According to Son, “the ability to reflect on one’s knowledge has always been thought of as exclusively human. We designed a task to determine if a non-human primate could similarly learn to express its confidence about its knowledge by making large or small wagers.”

In the experiment, two monkeys were trained to play a video game that would test their ability to remember a particular photograph while also allowing them to make a large or a small bet. Ultimately, this wager would reflect the monkey’s perception of their memory accuracy.

The test used touch-screen technology and a multiple-choice format. Six novel photographs were presented at the beginning of each trial, one at a time. One photograph was selected at random and then displayed simultaneously with 8 novel photographs. The monkey’s task was to select the photograph that appeared at the beginning of the trial. The monkey then evaluated the accuracy of its choice by selecting a high and a low-risk icon presented on the screen. It earned a large reward if it selected the high-risk icon after a correct response (3 tokens dropped into a bank displayed on the video monitor).

Choosing the high-risk icon following an incorrect response resulted in the loss of 3 tokens. Low risk bets were always followed by a small reward (a gain of 1 token). When the monkey accumulated enough tokens, it was rewarded with food. The results demonstrated that with the monkeys, there was a strong correlation between high-risk bets and correct responses and between low-risk bets and incorrect responses.

Terrace argues that, “the pattern of the monkeys’ bets provided clear evidence of their ability to engage in meta-cognition, an ability that is all the more remarkable because monkeys lack language.” But the results may have further reaching implications as well. Terrace notes “our results are of general interest because non-verbal tests of the type used in this and other experiments on animal cognition can be adapted to study cognitive abilities of infants and autistic children.”

Source: Association for Psychological Science.

New research from Columbia University Medical Center may explain why people who are able to easily and accurately recall historical dates or long-ago events, may have a harder time with word recall or remembering the day’s current events. They may have too much memory –making it harder to filter out information and increasing the time it takes for new short-term memories to be processed and stored. Published in the Proceedings of the National Academy of Sciences (March 13, 2007 issue), the research reinforces the old adage that too much of anything –even something good for you– can actually be detrimental.

Sounds to me like Aristotle’s Nicomachean Ethics as well.