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.

University of Portsmouth scientists have developed a powerful new tool that ‘freezes’ the memory of crime scenes in the minds of witnesses.

The tool - a self-administered interview applied by witnesses at crime scenes - combats natural memory decay by using the latest research in cognitive psychology techniques. It ‘freezes’ images and details of crime scenes and perpetrators in the minds of witnesses, particularly small and seemingly insignificant details that provide major leads for detectives that turn out to be crucial in solving cases.

Tests at simulated crimes scenes were remarkable with witnesses using the tool recalling forensically relevant information 42 percent more accurate than other witnesses who were simply asked to ‘report as much as you can remember’. The tests also revealed the witnesses using the self-administered interview (SAI) were 44 percent more correct with details about people - therefore, possible suspects - who had been involved in the event.

In another test there was a delay of seven days between witnessing the event and providing a full account. Half the participants completed self-administered interviews after witnessing the event while the other participants simply gave their name and contact details - as normally happens to a large number of witnesses at crime incidents. Scientists tested the group after seven days and found participants who had completed the SAI were still reporting almost 30 per cent more correct details than other witnesses.

The SAI protocol tool has been developed by Dr Lorraine Hope from the University of Portsmouth and collaborators Dr Fiona Gabbert (University of Abertay) and Professor Ronald Fisher (Florida International University) with funding from the British Academy. The scientists worked with police forces in England and Scotland to develop the witness ‘recall and report’ tool to record witness memory at the earliest possible opportunity - at the scene of the incident.

Dr Hope said the completeness and accuracy of eyewitness evidence decreases as the delay between witnessing an incident and recalling it increases. In other words, the longer the gap between witnessing the event and fully recalling what was seen under formal interview conditions, the less accurate and less complete a witness report is likely to be.

“Decades of research in cognitive psychology demonstrate that memory decay, or forgetting, occurs rapidly at first. In a witnessing situation, this ‘forgetting’ will occur naturally and within hours of the incident. As the delay between witnessing and formal interview increases to days, memory decay will level off. However, by that time, many useful and forensically relevant details or clues may be lost forever,” she said.

Dr Hope said the SAI tool could play a significant role for law enforcement as the benefits were obvious - witnesses have the opportunity to record their memories before any potentially crucial information is forgotten.

“The forensic implications of these findings for current police practice are considerable. At present witnesses are likely to engage in a very brief initial interview prior to giving a full statement at some later date. This very brief initial interview may actually have a detrimental effect on the ability of a witness to fully recall the incident at a later occasion. In other words, only the memory for the brief outline is strengthened - not the memory for the details, which can sometimes become harder to recall as a result,” Dr Hope said.

“Research has proven, for instance, that recalling an event before any substantial forgetting or memory loss has taken place means that the way the event is represented in memory is strengthened, making it easier to recall in future. In this way, an early recall attempt serves to protect or ‘freeze’ the memory against the course of natural forgetting. There is also some research to suggest that recalling only partial or brief outline information about an event or incident may in fact have a negative impact on ability to recall the incident more fully at a later stage.”

Dr Hope said using the techniques of the cognitive interview, and providing instructions to think carefully about the witnessing environment and report everything no matter how insignificant without resorting to guesswork, the SAI supports the witness in both the recall and reporting of as much information as possible before that information has been lost.

Source: University of Portsmouth.

A unique pattern of gene expression observed in rats may be linked to a conditioned desire for food and excessive food intake, an article published today in BMC Biology suggests.

It’s well known that food-associated cues, such as advertising, can influence food intake. But the underlying neurobiology is far from clear. Craig A. Schiltz and colleagues from the University of Wisconsin Madison School of Medicine and Public Health, USA, created an experimental set up that allowed them to study patterns of gene expression linked to this motivational state - rats conditioned to expect a chocolate-flavoured treat in a particular environment, were subsequently denied their reward.

The research, conducted in the laboratory of Ann E. Kelly showed that expression of a handful of immediate early genes was increased in cortical, striatal, thalamic and hypothalamic brain regions. Food-related cues triggered dramatic changes in the functional connectivity of circuits involved in adaptive behaviour. For example, increased connectivity was seen between the cortex and two other regions - the amygdala and the striatum. Within the latter, there was a shift in activity from the outer shell to the inner core of the nucleus accumbens and an increased expression of the opioid-encoding proenkephalin gene.

Taken together, these results suggest that food-associated cues have a powerful influence on neuronal activity and gene expression in brain areas mediating complicated functions such as cognition and emotion, and more basic abilities such as arousal and energy balance. The pattern of activation differs from that elicited by neutral cues, and may well contribute to a conditioned motivational state that can lead to excessive food intake.

Source: “Food-associated cues alter forebrain functional connectivity as assessed with immediate early gene and proenkephalin expression” Craig A Schiltz, Quentin Z Bremer, Charles F Landry and Ann E Kelley

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.