New research reveals how elephants ‘see’ the world

Think Elephants International, a not-for-profit organization that strives to promote elephant conservation through scientific research, education programming and international collaborations, today announced its latest study, “Visual Cues Given by Humans are Not Sufficient for Asian Elephants (Elephas Maximus) to Find Hidden Food.”

This study has been published in the April 17, 2013 issue of PLOS ONE, an international publication that reports original research from all disciplines within science and medicine. Designed in collaboration with and co-authored by 12-14 year old students from East Side Middle School in NYC, the study revealed that elephants were not able to recognize visual cues provided by humans, although they were more responsive to vocal commands. These findings may directly impact protocols for future efforts to conserve elephants, which are in danger of extinction in this century due to increased poaching and human/elephant conflict.

The publication of this paper is the climax of a three-year endeavor to create a comprehensive middle school curriculum that brings elephants into classrooms as a way to educate young people about conservation by getting them directly involved in work with endangered species. This research tested whether elephants could follow visual, social cues (pointing and gazing) to find food hidden in one of two buckets. The elephants failed at this task, but were able to follow vocal commands telling them which bucket contained the food. These results suggest that elephants may navigate their physical world in ways that primates and dogs, prior subjects of animal cognition studies, do not.

"Dogs have a great sense of smell, but appear to be able to follow human pointing as a way of finding food," said Joshua Plotnik, PhD, founder and CEO of Think Elephants. "Perhaps elephants’ sense of smell is one of their primary sensory modalities, meaning that they may use it preferentially when navigating their physical worlds."

In the field of animal cognition, there has been considerable attention focused on how animals interact with each other and humans. Particularly, there is a lot of interest in how dogs are able to read social cues to understand what people see, know or want. Remarkably, non-human primates such as chimpanzees are not good at this, suggesting it may be that through domestication or long-term human contact, dogs have developed a capacity for following social cues provided by people. Think Elephants aimed to test elephants on this because they are a wild, non-domesticated species that, in captivity in Thailand, are in relatively constant contact with humans.

The study’s findings have important implications for future protection protocols for wild elephants.

According to Dr. Plotnik, “If elephants are not primarily using sight to navigate their natural environment, human-elephant conflict mitigation techniques must consider what elephants’ main sensory modalities are and how elephants think so that they might be attracted or deterred effectively as a situation requires. The loss of natural habitat, poaching for ivory, and human-elephant conflict are serious threats to the sustainability of elephants in the wild. Put simply, we will be without elephants, and many other species in the wild, in less than 50 years if the world does not act.”

To mitigate this, Dr. Plotnik suggests further attention to research on elephant behavior and an increase in educational programming are needed, particularly in Asia where the market for ivory is so strong. Think Elephants’ education program in NYC is a pilot that will be expanding to Thai schools later in 2013.

The students were integrally involved in the development of this study, even helping to design some of the experimental control conditions. The study was carried out at Think Elephants’ field site in northern Thailand, and students participated via webcam conversation and direct web-links to the elephant camp.

This shows that collaborations that include both academics and young students can be productive, informative and exciting.

According to Jen Pokorny, PhD, Think Elephants’ head of education programs, “We are so proud of our pilot program with East Side Middle School and hope to use this as a model for other schools throughout the state and country. This wonderful group of students had an opportunity that very few young people have and, as a result, are now published co-authors on a significant piece of animal behavior research. They were integrally involved in the development of the study, even helping to design some of the experimental control conditions. Think Elephants is committed to showcasing these productive, informative and exciting student collaborations, and we believe similar studies can help to change the way in which young people observe and appreciate their global environment.”

Negative Thoughts Can Be Contagious

The way the people around us respond to stressful events — whether those people react negatively or positively — may be contagious when we are in the midst of a major life transition, a new study says.

What’s more, the increased risk of depression that comes with negative thinking also seems to rub off during these times, the study found.

For the study, researchers looked at 103 pairs of college-freshmen roommates’ “cognitive vulnerability,” which is the tendency to think that negative events are a reflection of a person’s own deficiency or that they will lead to more negative events. Those with high cognitive vulnerability are at an increased risk of depression, studies have found.

"We found that participants’ level of cognitive vulnerability was significantly influenced by their roommates’ level of cognitive vulnerability, and vice versa," the researchers wrote. All roommates in the study were selected randomly; students did not choose their roommates. Only three months of living together was needed for this contagiousness to be seen.

The researchers also found that those who experienced an increase in cognitive vulnerability during the first three months of college had nearly twice the level of depressive symptoms at six months, compared with those who did not experience an increase in cognitive vulnerability, according to the study. The effect was particularly strong when participants were under high-stress conditions.

Prior to this study, it was thought that cognitive vulnerability didn’t change much once a person passed early adolescence. However, the new findings suggest that during big transitions in life — when a person is continually exposed to a new social situation — cognitive vulnerability can be altered, the researchers said.

They noted that genetic, biological and environmental factors all likely play a role in a person’s level of cognitive vulnerability.

Further research is needed to determine whether cognitive vulnerability may change over time, the researchers said, noting that college freshmen are in a unique social environment. 

"Our findings are consistent with a growing number of studies that have found that many psychological and biological factors previously thought to be set in stone by adulthood continue to be malleable,” the researchers said.

The study was published online April 16 in the journal Clinical Psychological Science.

Learned helplessness in flies and the roots of depression

When faced with impossible circumstances beyond their control, animals, including humans, often hunker down as they develop sleep or eating disorders, ulcers, and other physical manifestations of depression. Now, researchers reporting in the Cell Press journal Current Biology on April 18 show that the same kind of thing happens to flies.

The study is a step toward understanding the biological basis for depression and presents a new way for testing antidepressant drugs, the researchers say. The discovery of such symptoms in an insect shows that the roots of depression are very deep indeed.

"Depressions are so devastating because they go back to such a basic property of behavior," says Martin Heisenberg of the Rudolf Virchow Center in Würzburg, Germany.

Heisenberg says that the idea for the study came out of a lengthy discussion with a colleague about how to ask whether flies can feel fear. Franco Bertolucci, a coauthor on the study, had found that flies can rapidly learn to suppress innate behaviors, a phenomenon that is part of learned helplessness.

The researchers now show that flies experiencing uncomfortable levels of heat will walk to escape it. But if the flies realize that the heat is beyond their control and can’t be avoided, they will stop responding, walking more slowly and taking longer and more frequent rests, as if they were “depressed.”

Intriguingly, female flies slow down more under those stressful circumstances than males do. It’s not clear exactly what that means, but Heisenberg explains, “if we realize that the fly trapped in a strange, dark box, unable to get rid of the dangerous heat pulses, has to find a compromise between saving energy and not missing any chance of escape, we can understand that such a compromise may come out differently for males and females, as their resources and goals in life are different.”

Heisenberg’s team now intends to explore other questions, such as: How long does the flies’ depression-like state last? How does it affect other behaviors, like courtship and aggression? What is happening in their brain? And more.

Heisenberg says that the findings are a reminder of a lesson that children’s books are often best at showing: “Animals have lots in common with us humans. They breathe the same air, share many of the same resources, actively explore space, and have distinct social roles. Their brains serve the same purpose, too: they help them to do the right thing.”

Brain Activation in Motor Sequence Learning Is Related to the Level of Native Cortical Excitability

Cortical excitability may be subject to changes through training and learning. Motor training can increase cortical excitability in motor cortex, and facilitation of motor cortical excitability has been shown to be positively correlated with improvements in performance in simple motor tasks. Thus cortical excitability may tentatively be considered as a marker of learning and use-dependent plasticity. Previous studies focused on changes in cortical excitability brought about by learning processes, however, the relation between native levels of cortical excitability on the one hand and brain activation and behavioral parameters on the other is as yet unknown. In the present study we investigated the role of differential native motor cortical excitability for learning a motor sequencing task with regard to post-training changes in excitability, behavioral performance and involvement of brain regions. Our motor task required our participants to reproduce and improvise over a pre-learned motor sequence. Over both task conditions, participants with low cortical excitability (CElo) showed significantly higher BOLD activation in task-relevant brain regions than participants with high cortical excitability (CEhi). In contrast, CElo and CEhi groups did not exhibit differences in percentage of correct responses and improvisation level. Moreover, cortical excitability did not change significantly after learning and training in either group, with the exception of a significant decrease in facilitatory excitability in the CEhi group. The present data suggest that the native, unmanipulated level of cortical excitability is related to brain activation intensity, but not to performance quality. The higher BOLD mean signal intensity during the motor task might reflect a compensatory mechanism in CElo participants.

New understanding of hearing loss

A major breakthrough in the understanding of hearing and noise-induced hearing loss has been made by hearing scientists from three Pacific Rim universities.

Scientists from The University of Auckland, the University of New South Wales in Sydney, and the University of California in San Diego have collaborated for nearly 20 years on this research.

“This work represents a paradigm shift in understanding how our ears respond to noise exposure,” says Professor Peter Thorne from The University of Auckland, who is one of the co-authors of two papers published recently in the prestigious journal, the Proceedings of the National Academy of Sciences (PNAS) [1, 2].

“We demonstrate that what we traditionally regard as a temporary hearing loss from noise exposure is in fact the cochlea of the inner ear adapting to the noisy environment, turning itself down in order to be able to detect new signals that appear in the noise,” he says.

After the noise is turned off, hearing remains temporarily dull for some time while it readjusts to the lack of noise.

“Clinically, this is what we measure as a temporary hearing loss,” says Professor Thorne. “This has always been regarded as an indication of noise damage rather than, in our new view, a normal physiological process.”

The researchers show that this is due to a molecular signalling pathway in the cochlea, mediated by a chemical compound called ATP, released by the cochlear tissue with noise and activating specific ATP receptors in the cochlear cells.

“Interestingly, if the pathway is removed, such as by genetic manipulations, this adaptive mechanism doesn’t occur and the ear becomes very vulnerable to longer term noise exposure and the effects of age, eventually resulting in permanent hearing loss.”

“In other words the adaptive mechanism also protects the ear,” says Professor Thorne.

The second paper, done in collaboration with United States colleagues, reveals a new genetic cause of deafness in humans which involves exactly the same mechanism.

People (two families in China) who had a mutation in the ATP receptor showed a rapidly progressing hearing loss which was accelerated if they worked in noisy environments.

“This work is important because it shows that our ears naturally adapt to their environment, a bit like pupils of the eye which dilate or constrict with light, but over a longer time course,” Professor Thorne says.

This inherent adaptive process also provides protection to the ear from noise and age-related wear and tear. If people don’t have the genes that produce this protection, then they are more likely susceptible to developing hearing loss.

“This may go some way to explaining why some people are very vulnerable to noise or develop hearing loss with age and others don’t,” he says.

“Our research demonstrates that what we have always thought was temporary noise damage (i.e. the temporary hearing loss experienced in night clubs or a day’s work in factories), may not be this, but instead, is the ear regulating its sensitivity in background noise”.

“Although our research suggests that our hearing adapts in some noise environments, this has limits,” says Professor Thorne. “If we exceed the safe dose of noise, our ears can still be damaged permanently despite this apparent protective mechanism.”

“People need to protect their ears from constant noise exposure to prevent hearing loss and this is particularly important in the workplace and with personal music devices which can deliver high sound levels for long periods of time,” he says.

The motivation to move: Study finds rats calculate ‘average’ of reward across several tests

Suppose you had $1,000 to invest in the stock market. How would you decide to pick one stock over another? Scientists have made great progress in understanding the neuroscience behind how people choose between similar options.

But what happens when neither choice is right?

During an economic downturn, for instance, your best option might be not to invest at all, but to wait for market conditions to improve.

Using an unusual decision-making study, Harvard researchers exploring the question of motivation found that rats will perform a task faster or slower depending on the size of the benefit they receive, suggesting that they maintain a long-term estimate of whether it’s worth it to them to invest energy in a task.

As described in an April 14 paper in Nature Neuroscience, a research team led by Naoshige Uchida, associate professor of molecular and cellular biology, found that rats averaged how much benefit they received over as many as five trials. When their brains were impaired in one region, however, the rats based their actions solely on the prior trial.

“This is a new framework to think about decision-making,” Uchida said. “There have been many studies that focused on action selection or choices, but the question of the overall pace or rate of performance has been largely ignored.”

To get at those decision-making questions, Uchida and his team designed the experiment.

In each trial, rats were presented with an apparatus that had three holes. Based on whether a sweet or sour odor was delivered through the middle hole, rats went either left or right to receive a water reward. On one side they received a large reward; the other side delivered a smaller reward.

“What we measured was, after getting the reward, how quickly they went back to initiate the next trial,” Uchida said.

What researchers found, Uchida said, was surprising. When rats received, on average, a larger reward, they were more likely to quickly initiate the next trial, which suggested that they weren’t reacting merely to the prior result, but were “averaging the size of the reward from several previous trials.”

“They essentially calculate the average over the previous five or six trials, and adjust their performance accordingly,” Uchida said. “They’re making a calculation to determine whether they’re getting something out of the task or not. If it’s worth it for them, they go faster. If not, they go slower.”

When researchers impaired part of the striatum, a brain structure that is part of the basal ganglia and is thought to be involved with associative thinking, in the rats’ brains, however, that calculation changed. Rather than considering the average of multiple trials, the rats chose whether to go slower or faster based solely on the prior result.

“They still go faster or slower depending on the size of the reward, but they base that decision only on the size of the reward they just got,” Uchida said. “So the rat becomes very myopic. They only care about what just happened, and they don’t take other trials into account.”

In addition to shedding new light on how decision-making happens, the study may also offer some hope for people suffering from Parkinson’s disease.

“This part of the striatum receives a great deal of inputs from dopamine neurons, so it may be related to Parkinson’s disease,” Uchida said. “Some people now think Parkinson’s may actually be related to the motivation, or ‘vigor’ to perform some movement. So if we can identify brain regions that are involved in the regulation of general motivation, it’s possible that it could be contributing to the symptoms of Parkinson’s disease.”

Going forward, Uchida said, he hopes to study the role dopamine plays in regulating motivation and decision making, as well as working to understand what role other areas of the striatum might play in the process.

“There are some interesting similarities between this part of the striatum in rats and in humans,” he said. “One is that this area receives very heavy inputs from the prefrontal cortex. That’s an area that may be important in integrating information over a longer period of time. Deconstructing this process is a critical step to understanding our behavior, and this could go a long way toward that.”

Fight Control: Researchers link individual neurons to regulation of aggressive behavior in flies

Scientists have long pondered the roots of aggression—and ways to temper it. Now, new research is beginning to illuminate the cellular-level circuitry responsible for modulating aggression in fruit flies, with the hope of someday translating the findings to humans.

Researchers at Harvard Medical School have identified two pairs of dopamine-producing neurons, also called dopaminergic neurons, and traced their aggression-modulating action to a common structure in the fly brain called the central complex, suggesting that important components of aggression-related behaviors may be processed there.

“This is the first research to identify single dopaminergic neurons that modulate a complex behavior—aggression—in fruit flies,” said Edward Kravitz, George Packer Berry Professor of Neurobiology at HMS and lead author of the study.

“We don’t know how complex this modulatory circuit is, but we now have a key element of it. If we eliminate or increase the function of that dopaminergic neuron, it affects the circuit of the brain responsible for controlling aggression,” Kravitz said.

The findings were published last week in PNAS.

Flies are an ideal animal model for neurological research because genetic methods allow scientists to manipulate neurons and simultaneously observe the resulting behaviors. Many fundamental nervous system mechanisms in flies are similar to those in humans. In fact, both flies and humans share the same neurohormones.

Dopamine is one such neurohormone, and across species it affects a range of behaviors, from learning and memory to motivation and movement. In humans, neurohormones are associated with conditions such as Parkinson’s disease and psychiatric disorders.

Dopaminergic neurons are found in small numbers in particular parts of nervous systems. In humans, there are about 200,000 to 400,000 of these neurons; in fruit flies there are about 100. While their numbers are few, these neurons influence a vast array of behaviors.

Kravitz, along with Olga Alekseyenko, a postdoctoral fellow in the Kravitz lab and first author on the paper, set out to discover how these few dopaminergic neurons can influence such a wide range of behaviors.

To do this, study co-first author, Yick-Bun Chan, HMS research associate in neurobiology, genetically engineered 200 lines of fruit flies. He then used them to target select dopaminergic neurons that could be activated or silenced while the flies engaged in various behaviors.

The team detected two pairs of dopaminergic neurons that affected aggressive behavior in the flies. Interestingly, aggression was increased in the flies either by augmenting the function of these cells or by deactivating them.

In fruit flies, males fight for territory and form stable hierarchical relationships. Using previous observations and analysis of more than 20,000 interactions in fly fights, the team established quantitative measures of aggressive behavior, such as lunging, that allowed them to compare aggression levels in different fly attacks.

“When we turned off the pairs of dopaminergic neurons, the flies fought with more lunging; when we turned them on, they also fought at higher intensity levels. Apparently normal levels of aggression require a precise amount of dopamine released at a specific time and place in the nervous system. These results suggest that these neurons ordinarily hold aggression in check,” said Alekseyenko.

Also significant was the finding that while the two sets of dopaminergic neurons modulated aggression, they did not influence other behaviors.

The first pair of neurons are found in the PPM3 cluster of neurons in the fly brain and the second are within the T1 cluster. Both pairs innervate different parts of the central complex, an important structure in the fly brain.

“We already knew that dopamine receptors are present in the central complex, but we didn’t know which dopamine neurons connected to the receptors or what behaviors those neurons affected,” said Alekseyenko.

“Now we know that two pairs of aggression-mediating dopaminergic neurons terminate in different regions of the central complex, and we know that those regions have different types of dopamine receptors. Our study shows that aggression is one of the behaviors coordinated in these regions of the brain, but we still don’t fully understand the process,” he said.

In a third group of flies, a neuron pair that projected into a different part of the brain was identified. These neurons affected locomotion and sleep, but did not influence aggression.

Kravitz said the next phase of the research will be to use genetic tools to allow his team to identify the subsequent steps in the brain circuitry—which neurons are pre- and post-synaptic to the T1 and PPM3 neurons and how that affects neuronal network function.

The goal will be to establish fundamental principles for how dopaminergic neurons work in the fruit fly system, with the hope that the research will one day translate to how these neurons work in higher species. This may ultimately aid in the development of new dopamine-targeted medications for humans.

“We can now relate these two pairs of neurons specifically to one behavior, and that is aggression,” Kravitz said. “That means we have one piece of the puzzle.”

Babies develop conscious perception from five months of age

Infants develop the ability to consciously process their environment as early as five months of age, according to a study published in the journal Science.

The team of French and Danish researchers, led by neuroscientist Sid Kouider, discovered a signal in the nervous system of infants that reliably identifies the beginning of visual consciousness, or the ability to see something and recall that you have seen it.

The team set out believing infants had the capacity for conscious reflection, but they had to overcome the barrier that babies could not report their thoughts.

They used electroencephalography (EEG) to record electrical activity in the brains of 80 infants aged five, 12 and 15 months while they were shown pictures of faces and random patterns for a fraction of a second.

When adults are aware of a stimulus, their brains show a two-stage pattern of activity. When they see a moving object, the sensors in the vision centre of the brain activate with a spike of activity.

The signal then moves from the back of the brain to the prefrontal cortex, which deals with higher-level cognition. This is known as the late slow wave.

Conscious awareness begins after the second stage of neural activity reaches a specific threshold.

The new study found this two-stage pattern of brain activity was present in the three groups of infants, though it was weaker and more drawn out in the five-month-olds.

The researchers say neurological markers of visual consciousness may help paediatricians better manage infant pain and anaesthesia.

But they note the research does not provide direct proof of consciousness. “Indeed, it is a genuine philosophical problem whether such a proof can ever be obtained from purely neurophsysiological data,” the paper said.

Professor Louise Newman, Director of the Centre for Developmental Psychiatry & Psychology at Monash University, said the study was novel in its ability to measure the way very young brains register stimuli.

But five months should not be seen as a fixed point at which infants start to process information, she said.

“Although this group has studied five months and up, my suspicion would be that if we had different techniques, young infants – from birth on – would show the capacity of registering these sorts of stimuli.

“Infants are born with quite sophisticated capacities to observe, respond to and interact with the environment, particularly the social environment,” she said.

“Very soon after birth, infants will maintain gaze with their parents or parent: they’ve got quite sophisticated visual tracking capacity from an early age.”

Professor Newman, who has undertaken behavioural studies in two- to four-month olds, said young infant brains were extremely sensitive to their mother’s emotional reaction.

“They learn that ‘if I do this, or if I smile or signal in this way, this is what usually happens’. If you manipulate that so they don’t get that response, they’re very sensitive to that and they show signs that it’s very aversive to them.”