Tag Archives: functional MRI

Scientists chase mystery of how dogs process words

When some dogs hear their owners say “squirrel,” they perk up, become agitated. They may even run to a window and look out of it. But what does the word mean to the dog? Does it mean, “Pay attention, something is happening?” Or does the dog actually picture a small, bushy-tailed rodent in its mind?

scanner_eddie

Eddie, one of the dogs that participated in the study, poses in the fMRI scanner with two of the toys used in the experiments, “Monkey” and “Piggy.” (Photo courtesy Gregory Berns)

Frontiers in Neuroscience published one of the first studies using brain imaging to probe how our canine companions process words they have been taught to associate with objects, conducted by scientists at Emory University. The results suggest that dogs have at least a rudimentary neural representation of meaning for words they have been taught, differentiating words they have heard before from those they have not.

“Many dog owners think that their dogs know what some words mean, but there really isn’t much scientific evidence to support that,” says Ashley Prichard, a PhD candidate in Emory’s Department of Psychology and first author of the study. “We wanted to get data from the dogs themselves — not just owner reports.”

“We know that dogs have the capacity to process at least some aspects of human language since they can learn to follow verbal commands,” adds Emory neuroscientist Gregory Berns, senior author of the study. “Previous research, however, suggests dogs may rely on many other cues to follow a verbal command, such as gaze, gestures and even emotional expressions from their owners.”

The Emory researchers focused on questions surrounding the brain mechanisms dogs use to differentiate between words, or even what constitutes a word to a dog.

Berns is founder of the Dog Project, which is researching evolutionary questions surrounding man’s best, and oldest friend. The project was the first to train dogs to voluntarily enter a functional magnetic resonance imaging (fMRI) scanner and remain motionless during scanning, without restraint or sedation. Studies by the Dog Project have furthered understanding of dogs’ neural response to expected reward, identified specialized areas in the dog brain for processing faces, demonstrated olfactory responses to human and dog odors, and linked prefrontal function to inhibitory control.

For the current study, 12 dogs of varying breeds were trained for months by their owners to retrieve two different objects, based on the objects’ names. Each dog’s pair of objects consisted of one with a soft texture, such as a stuffed animal, and another of a different texture, such as rubber, to facilitate discrimination. Training consisted of instructing the dogs to fetch one of the objects and then rewarding them with food or praise. Training was considered complete when a dog showed that it could discriminate between the two objects by consistently fetching the one requested by the owner when presented with both of the objects.

During one experiment, the trained dog lay in the fMRI scanner while the dog’s owner stood directly in front of the dog at the opening of the machine and said the names of the dog’s toys at set intervals, then showed the dog the corresponding toys.

Eddie, a golden retriever-Labrador mix, for instance, heard his owner say the words “Piggy” or “Monkey,” then his owner held up the matching toy. As a control, the owner then spoke gibberish words, such as “bobbu” and “bodmick,” then held up novel objects like a hat or a doll.

The results showed greater activation in auditory regions of the brain to the novel pseudowords relative to the trained words.

“We expected to see that dogs neurally discriminate between words that they know and words that they don’t,” Prichard says. “What’s surprising is that the result is opposite to that of research on humans — people typically show greater neural activation for known words than novel words.”

The researchers hypothesize that the dogs may show greater neural activation to a novel word because they sense their owners want them to understand what they are saying, and they are trying to do so. “Dogs ultimately want to please their owners, and perhaps also receive praise or food,” Berns says.

Half of the dogs in the experiment showed the increased activation for the novel words in their parietotemporal cortex, an area of the brain that the researchers believe may be analogous to the angular gyrus in humans, where lexical differences are processed.

The other half of the dogs, however, showed heightened activity to novel words in other brain regions, including the other parts of the left temporal cortex and amygdala, caudate nucleus, and the thalamus.

These differences may be related to a limitation of the study — the varying range in breeds and sizes of the dogs, as well as possible variations in their cognitive abilities. A major challenge in mapping the cognitive processes of the canine brain, the researchers acknowledge, is the variety of shapes and sizes of dogs’ brains across breeds.

“Dogs may have varying capacity and motivation for learning and understanding human words,” Berns says, “but they appear to have a neural representation for the meaning of words they have been taught, beyond just a low-level Pavlovian response.”

This conclusion does not mean that spoken words are the most effective way for an owner to communicate with a dog. In fact, other research also led by Prichard and Berns and recently published in Scientific Reports, showed that the neural reward system of dogs is more attuned to visual and to scent cues than to verbal ones.

“When people want to teach their dog a trick, they often use a verbal command because that’s what we humans prefer,” Prichard says. “From the dog’s perspective, however, a visual command might be more effective, helping the dog learn the trick faster.”

Source:  Emory University

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Brain scans of service-dog trainees help sort weaker recruits from the pack

Brain scans of canine candidates to assist people with disabilities can help predict which dogs will fail a rigorous service training program, a study by Emory University finds.

The journal Scientific Reports published the results of the study, involving 43 dogs who underwent service training at Canine Companions for Independence (CCI) in Santa Rosa, California.

Dogs with MRI machine

Some of the service dog trainees that were involved in the study pose with an fMRI scanner. (Photo by Gregory Berns.)

“Data from functional magnetic resonance imaging (fMRI) provided a modest, but significant, improvement in the ability to identify dogs that were poor candidates,” says Emory neuroscientist Gregory Berns, who led the research. “What the brain imaging tells us is not just which dogs are more likely to fail, but why.”

All of the dogs in the study underwent a battery of behavioral tests showing that they had a calm temperament before being selected for training. Despite calm exteriors, however, some of the dogs showed higher activity in the amygdala – an area of the brain associated with excitability. These dogs were more likely to fail the training program.

“The brain scans may be like taking a dog’s mental temperature,” Berns says. “You could think of it as a medical test with a normal range for a service dog. And the heightened neural activity that we see in the amygdala of some dogs may be outside of that range, indicating an abnormal value for a successful service dog.”

The findings are important, he adds, since the cost of training a service dog ranges from $20,000 to $50,000. As many as 70 percent of the animals that start a six-to-nine-month training program have to be released for behavioral reasons.

“There are long waiting lists for service dogs, and the training is lengthy and expensive,” Berns says. “So the goal is to find more accurate ways to eliminate unsuitable dogs earlier in the process.”

The study found that fMRI boosted the ability to identify dogs that would ultimately fail to 67 percent, up from about 47 percent without the use of fMRI.

“This type of approach is not going to be feasible for individual trainers and their dogs because of the expense of fMRI,” Berns says. “It would only be practical for organizations that train large numbers of dogs every year.”

CCI is a non-profit that breeds, raises and trains dogs to assist human partners. Its service dog program, designed for disabled people, provides dogs to do tasks such as turn on lights, pick up dropped keys, open a door and pull a manual wheelchair.

Golden retrievers, Labradors — or crosses between the two — are the usual CCI service dog breeds, due to their generally calm and affable natures. After the puppies are weaned, they are adopted by volunteer puppy raisers for 15 months, before returning to CCI to undergo behavioral tests. Those that pass begin training.

For the Scientific Reports paper, the researchers taught the dogs how to remain still while undergoing an fMRI at the start of the training program.

The Berns’ lab was the first to conduct fMRI experiments on awake, unrestrained dogs, as part of an ongoing project to understand canine cognition and inter-species communication. In an early experiment, dogs were trained to respond to hand signals. One signal meant the dog would receive a food treat, and another signal meant that the dog would not receive one. The caudate region of the brain, associated with rewards in humans, showed activation when the dogs saw the signal for the treat, but not for the non-treat signal.

The researchers adapted this experiment for the current study — the largest yet involving dogs undergoing fMRI. The dogs were taught hand signals for “treat” and “no treat,” but sometimes the signals were given by the dog’s trainer and other times by a stranger.

The results found that dogs with stronger activity in the caudate in response to the treat signal – regardless of who gave the signal – were slightly more likely to successfully complete the service dog training program. However, if a dog had relatively more activity in the amygdala in response to the treat signal – particularly if the signal was given by a stranger – that increased the likelihood that the dog would fail.

“The ideal service dog is one that is highly motivated, but also doesn’t get excessively excited or nervous,” Berns says. “The two neural regions that we focused on – the caudate and the amygdala – seem to distinguish those two traits. Our findings suggest that we may be able to pick up variations in these internal mental states before they get to the level of overt behaviors.”

Berns hopes that the technology may become more refined and have applications for a broader range of working dogs, such as those used to assist the military and police forces.

Source:  Emory University

Praise or food?

Given the choice, many dogs prefer praise from their owners over food, suggests a new study published in the journal Social, Cognitive and Affective Neuroscience. The study is one of the first to combine brain-imaging data with behavioral experiments to explore canine reward preferences.

“We are trying to understand the basis of the dog-human bond and whether it’s mainly about food, or about the relationship itself,” says Gregory Berns, a neuroscientist at Emory University and lead author of the research. “Out of the 13 dogs that completed the study, we found that most of them either preferred praise from their owners over food, or they appeared to like both equally. Only two of the dogs were real chowhounds, showing a strong preference for the food.”

food-or-praise

Praise Pooch: Most of the dogs in the experiments preferred praise over food, or liked them both equally. Kady, a Labrador-golden retriever mix, was the top dog when it came to the strength of her preference for praise.

Dogs were at the center of the most famous experiments of classical conditioning, conducted by Ivan Pavlov in the early 1900s. Pavlov showed that if dogs are trained to associate a particular stimulus with food, the animals salivate in the mere presence of the stimulus, in anticipation of the food.

“One theory about dogs is that they are primarily Pavlovian machines: They just want food and their owners are simply the means to get it,” Berns says. “Another, more current, view of their behavior is that dogs value human contact in and of itself.”

Berns heads up the Dog Project in Emory’s Department of Psychology, which is researching evolutionary questions surrounding man’s best, and oldest friend. The project was the first to train dogs to voluntarily enter a functional magnetic resonance imaging (fMRI) scanner and remain motionless during scanning, without restraint or sedation. In previous research, the Dog Project identified the ventral caudate region of the canine brain as a reward center. It also showed how that region of a dog’s brain responds more strongly to the scents of familiar humans than to the scents of other humans, or even to those of familiar dogs.

chowhound

Chowhound: Ozzie, a shorthaired terrier mix, was the only dog in the experiments that chose food over his owner’s praise 100 percent of the time. “Ozzie was a bit of an outlier,” Berns says, “but Ozzie’s owner understands him and still loves him.”

For the current experiment, the researchers began by training the dogs to associate three different objects with different outcomes. A pink toy truck signaled a food reward; a blue toy knight signaled verbal praise from the owner; and a hairbrush signaled no reward, to serve as a control.
The dogs then were tested on the three objects while in an fMRI machine. Each dog underwent 32 trials for each of the three objects as their neural activity was recorded.

All of the dogs showed a stronger neural activation for the reward stimuli compared to the stimulus that signaled no reward, and their responses covered a broad range. Four of the dogs showed a particularly strong activation for the stimulus that signaled praise from their owners. Nine of the dogs showed similar neural activation for both the praise stimulus and the food stimulus. And two of the dogs consistently showed more activation when shown the stimulus for food.

The dogs then underwent a behavioral experiment. Each dog was familiarized with a room that contained a simple Y-shaped maze constructed from baby gates: One path of the maze led to a bowl of food and the other path to the dog’s owner. The owners sat with their backs toward their dogs. The dog was then repeatedly released into the room and allowed to choose one of the paths. If they came to the owner, the owner praised them.

“We found that the caudate response of each dog in the first experiment correlated with their choices in the second experiment,” Berns says. “Dogs are individuals and their neurological profiles fit the behavioral choices they make. Most of the dogs alternated between food and owner, but the dogs with the strongest neural response to praise chose to go to their owners 80 to 90 percent of the time. It shows the importance of social reward and praise to dogs. It may be analogous to how we humans feel when someone praises us.”

The experiments lay the groundwork for asking more complicated questions about the canine experience of the world. The Berns’ lab is currently exploring the ability of dogs to process and understand human language.

“Dogs are hypersocial with humans,” Berns says, “and their integration into human ecology makes dogs a unique model for studying cross-species social bonding.”

Source:  Emory University media release

Dogs understand both vocabulary and intonation of human speech

Dogs in MRI machine

Trained dogs are around the fMRI scanner. This material relates to a paper that appeared in the Sept. 2, 2016, issue of Science, published by AAAS. The paper, by A. Andics at Eötvös Loránd University in Budapest, Hungary, and colleagues was titled, “Neural mechanisms for lexical processing in dogs.”  Credit:  Enik Kubinyi

Sometimes research about our dogs goes viral which is the case with this latest research.  It’s already done the rounds on Facebook because it has been reported by several major news agencies.

Here is the original media release  from the American Association for the Advance of Science in its entirety:

Dogs have the ability to distinguish vocabulary words and the intonation of human speech through brain regions similar to those that humans use, a new study reports.

Attila Andics et al. note that vocabulary learning “does not appear to be a uniquely human capacity that follows from the emergence of language, but rather a more ancient function that can be exploited to link arbitrary sound sequences to meanings.” Words are the basic building blocks of human languages, but they are hardly ever found in nonhuman vocal communications. Intonation is another way that information is conveyed through speech, where, for example, praises tend to be conveyed with higher and more varying pitch.

Humans understand speech through both vocabulary and intonation. Here, Andics and colleagues explored whether dogs also depend on both mechanisms. Dogs were exposed to recordings of their trainers’ voices as the trainers spoke to them using multiple combinations of vocabulary and intonation, in both praising and neutral ways. For example, trainers spoke praise words with a praising intonation, praise words with a neutral intonation, neutral words with a praising intonation, and neutral words with neutral intonation.

Researchers used fMRI to analyze the dogs’ brain activity as the animals listened to each combination. Their results reveal that, regardless of intonation, dogs process vocabulary, recognizing each word as distinct, and further, that they do so in a way similar to humans, using the left hemisphere of the brain. Also like humans, the researchers found that dogs process intonation separately from vocabulary, in auditory regions in the right hemisphere of the brain. Lastly, and also like humans, the team found that the dogs relied on both word meaning and intonation when processing the reward value of utterances. Thus, dogs seem to understand both human words and intonation.

The authors note that it is possible that selective forces during domestication could have supported the emergence of the brain structure underlying this capability in dogs, but, such rapid evolution of speech-related hemispheric asymmetries is unlikely. Humans, they say, are only unique in their ability to invent words.

Source:  EurekAlert! media release

How our dogs react to faces (vs other objects)

Dogs have a specialized region in their brains for processing faces, a new study finds. PeerJ is publishing the research, which provides the first evidence for a face-selective region in the temporal cortex of dogs.

“Our findings show that dogs have an innate way to process faces in their brains, a quality that has previously only been well-documented in humans and other primates,” says Gregory Berns, a neuroscientist at Emory University and the senior author of the study.

Dog in MRI machine at Emory University

The study involved dogs viewing both static images and video images on a screen while undergoing fMRI. It was a particularly challenging experiment since dogs do not normally interact with two-dimensional images, and they had to undergo training to learn to pay attention to the screen. Photo by Gregory Berns, Emory University

Having neural machinery dedicated to face processing suggests that this ability is hard-wired through cognitive evolution, Berns says, and may help explain dogs’ extreme sensitivity to human social cues.

Berns heads up the Dog Project in Emory’s Department of Psychology, which is researching evolutionary questions surrounding man’s best, and oldest, friend. The project was the first to train dogs to voluntarily enter a functional magnetic resonance imaging (fMRI) scanner and remain motionless during scanning, without restraint or sedation.

For the current study, the researchers focused on how dogs respond to faces versus everyday objects. “Dogs are obviously highly social animals,” Berns says, “so it makes sense that they would respond to faces. We wanted to know whether that response is learned or innate.”

The study involved dogs viewing both static images and video images on a screen while undergoing fMRI. It was a particularly challenging experiment since dogs do not normally interact with two-dimensional images, and they had to undergo training to learn to pay attention to the screen.

A limitation of the study was the small sample size: Only six of the eight dogs enrolled in the study were able to hold a gaze for at least 30 seconds on each of the images to meet the experimental criteria.

The results were clear, however, for the six subjects able to complete the experiment. A region in their temporal lobe responded significantly more to movies of human faces than to movies of everyday objects. This same region responded similarly to still images of human faces and dog faces, yet significantly more to both human and dog faces than to images of everyday objects.

If the dogs’ response to faces was learned – by associating a human face with food, for example – you would expect to see a response in the reward system of their brains, but that was not the case, Berns says.

The researchers have dubbed the canine face-processing region they identified the dog face area, or DFA.

One hypothesis is that distinguishing faces is important for any social creature.

Source:  EurekAlert! media statement


Professor Berns’ group at Emory University is one of the leading research teams in the field of canine cognition.  Previous blog posts about his work include:

New Directions in Canine Behaviour

New directions in canine behavior

The January 2015 special edition of the journal Behavioural Processes is fully online (until January 2016).  This means you can download .pdf copies of fifteen  interesting research articles about dogs and behavior.

In the opening editorial of this journal, Monique A.R. Udell says that research into social development and cognitive evolution of dogs is just beginning to scratch the surface despite the long history of the human-canine relationship.

I am particularly interested in these fields of research (as my many blog postings under the category of ‘research’ show!) because of the work I do with dogs.  Understanding dogs is critical to working with them in a holistic approach to health.

My only criticism of journal articles generally (not just this journal) is the odd and often long names that researchers choose for the title of their articles.  It is just one indication that researchers work in a different world from generalist audiences; they are often judged in peer reviews for language this is technical.  In my experience as a research manager, I have also found that most academic researchers write in a style using long sentences and paragraphs.

Some of these articles are easier to read than others because of this.

The articles in this issue are:

  • Revisiting the concept of behavior patterns in animal behavior with an example from food-caching sequences in Wolves (Canis lupus), Coyotes (Canis latrans), and Red Foxes (Vulpes vulpes)
  • Assessment of attachment behaviour to human caregivers in wolf pups (Canis lupus lupus)
  • Self-regulatory depletion in dogs:  insulin release is not necessary for the replenishment of persistence
  • Dogs and their human companions:  The effect of familiarity on dog-human interactions
  • Scent of the familiar:  An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors
  • Shut up and pet me!  Domestic dogs (Canis lupus familiaris) prefer petting to vocal praise in concurrent and single-alternative choice procedures
  • A comparison of pet and purpose-bred research dog (Canis familiaris) performance on human-guided object-choice tasks
  • Gazing toward humans:  A study on water rescue dogs using the impossible task paradigm
  • Is that fear?  Domestic dogs’ use of social referencing signals from an unfamiliar person
  • Why do adult dogs ‘play’?
  • Down but not out:  Supine postures as facilitators of play in domestic dogs
  • The advent of canine performance science:  Offering a sustainable future for working dogs
  • Do you see what I see?  Can non-experts with minimal training reproduce expert ratings in behavioral assessments of working dogs?
  • Which personality dimensions do puppy tests measure?  A systematic procedure for categorizing behavioral assays
  • Citizen science:  A new direction in canine behavior research

Kathleen Crisley, specialist in dog massage, rehabilitation and nutrition/food therapy, Canine Catering Ltd, Christchurch, New Zealand

 

The human-animal bond using functional MRI

How closely does the relationship between people and their non-human companions mirror the parent-child relationship? Credit: © christingasner / Fotolia

How closely does the relationship between people and their non-human companions mirror the parent-child relationship?
Credit: © christingasner / Fotolia

It has become common for people who have pets to refer to themselves as  “pet parents,” but how closely does the relationship between people and their non-human companions mirror the parent-child relationship?  A small study from a group of Massachusetts General Hospital (MGH) researchers makes a contribution to answering this complex question by investigating differences in how important brain structures are activated when women view images of their children and of their own dogs.  Their report is being published in the open-access journal PLOS ONE.

“Pets hold a special place in many people’s hearts and lives, and there is compelling evidence from clinical and laboratory studies that interacting with pets can be beneficial to the physical, social and emotional wellbeing of humans,” says Lori Palley, DVM, of the MGH Center for Comparative Medicine, co-lead author of the report.  “Several previous studies have found that levels of neurohormones like oxytocin – which is involved in pair-bonding and maternal attachment – rise after interaction with pets, and new brain imaging technologies are helping us begin to understand the neurobiological basis of the relationship, which is exciting.”

In order to compare patterns of brain activation involved with the human-pet bond with those elicited by the maternal-child bond, the study enrolled a group of women with at least one child aged 2 to 10 years old and one pet dog that had been in the household for two years or longer.  Participation consisted of two sessions, the first being a home visit during which participants completed several questionnaires, including ones regarding their relationships with both their child and pet dog. The participants’ dog and child were also photographed in each participants’ home.

The second session took place at the Athinoula A. Martinos Center for Biomedical Imaging at MGH, where functional magnetic resonance imaging (fMRI) – which indicates levels of activation in specific brain structures by detecting changes in blood flow and oxygen levels – was performed as participants lay in a scanner and viewed a series of photographs.  The photos included images of each participant’s own child and own dog alternating with those of an unfamiliar child and dog belonging to another study participant.  After the scanning session, each participant completed additional assessments, including an image recognition test to confirm she had paid close attention to photos presented during scanning, and rated several images from each category shown during the session on factors relating to pleasantness and excitement.

Of 16 women originally enrolled, complete information and MR data was available for 14 participants.  The imaging studies revealed both similarities and differences in the way important brain regions reacted to images of a woman’s own child and own dog.  Areas previously reported as important for functions such as emotion, reward, affiliation, visual processing and social interaction all showed increased activity when participants viewed either their own child or their own dog.  A region known to be important to bond formation – the substantia nigra/ventral tegmental area (SNi/VTA) – was activated only in response to images of a participant’s own child.  The fusiform gyrus, which is involved in facial recognition and other visual processing functions, actually showed greater response to own-dog images than own-child images.

“Although this is a small study that may not apply to other individuals, the results suggest there is a common brain network important for pair-bond formation and maintenance that is activated when mothers viewed images of either their child or their dog,” says Luke Stoeckel, PhD, MGH Department of Psychiatry, co-lead author of the PLOS One report. “We also observed differences in activation of some regions that may reflect variance in the evolutionary course and function of these relationships.  For example, like the SNi/VTA, the nucleus accumbens has been reported to have an important role in pair-bonding in both human and animal studies. But that region showed greater deactivation when mothers viewed their own-dog images instead of greater activation in response to own-child images, as one might expect. We think the greater response of the fusiform gyrus to images of participants’ dogs may reflect the increased reliance on visual than verbal cues in human-animal communications.”

The investigators note that further research is needed to replicate these findings in a larger sample and to see if they are seen in other populations – such as women without children, fathers and parents of adopted children – and in relationships with other animal species.  Combining fMRI studies with additional behavioral and physiological measures could obtain evidence to support a direct relationship between the observed brain activity and the purported functions.

Source:  Massachusetts General Hospital media release