It Feels Good When You Sing a Song (In Fall)

A repost of an original article published October 3, 2012.

Most male songbirds will sing when they see a pretty female during the breeding season. But some male songbirds sing even when it’s not the breeding season. Why do so many birds sing in fall at all?

Maybe singing feels good… But how do you ask a bird if it feels good to sing? European starlings are one of those bird species that sing both in spring (the breeding season) and in fall (not the breeding season). Lauren Riters, Cindi Kelm-Nelson, and Sharon Stevenson at the University of Wisconsin at Madison did a series of ingenious experiments to ask starlings if and when it feels good to sing.

A European starling sings his fall-blues away. Photo by Linda Tanner at Wikimedia.

Psychologists have long used a paradigm called conditioned place preference (CPP) to evaluate whether an animal finds something rewarding or pleasurable. CPP is based on the idea that if an animal experiences something meaningless while at the same time experiencing something else that is rewarding, the animal will learn to associate these two things with each other in a phenomenon called conditioning. For example, a puppy that has learned that every time it sits it gets a treat, will find itself sitting more often.

A researcher can also compare how rewarding different types of treats are. If we want to know if puppies like carrots or steak better, we can give one group of puppies a carrot every time they sit and another group of puppies a piece of steak every time they sit. If the group of puppies that are conditioned with steak spend more time sitting, we can conclude that steak is more rewarding to puppies than carrots are.

Lauren and Sharon used this principle to ask starlings if singing is rewarding. They put spring starlings in a cage with a nestbox and a female and let them sing away, while counting how many songs they sang in 30 minutes. Then they immediately put them in another cage that was decorated with yellow materials on one side and green materials on the other, but they restricted each bird to only one of the two colored sides. This is the conditioning phase in which the bird learns to associate the colored cage with the feeling they get from singing.

The next day, they put the starlings in the yellow and green cage without restrictions so they could choose what side they wanted to hang out in. If singing is rewarding, we would expect starlings that sang a lot to spend more time on the side with the color they were placed in the day before.



Do people that sing in the car spend more time in the car?
Photo by freedigitalphotos.net.

That didn’t happen. The spring starlings spent the same amount of time in the yellow or green side of the cage regardless of how much they sang the day before.

But when Lauren and Sharon did the same test with fall starlings singing without a female, there has a huge effect: Males that sang more spent much more time on the colored side of the cage they were placed in the day before. Singing, for a male starling, is apparently rewarding in fall, but not in spring.

This result actually makes a lot of sense. In spring, males sing to attract and court females, so they are rewarded by the feeling they get from the female’s response, not from the act of singing itself. But in fall, males are not attracting females. So why do they sing in fall? Because it feels good.

It looks like Sesame Street got it right with their 1970s song “It Feels Good When You Sing a Song”:

You can't go wrong
when you're singing a song
Sing it loud, sing it strong
It feels good when you sing a song

But why does singing feel good? At least some of the reason, it seems, is opioids. Not quite what Sesame Street had in mind, but hey.

Despite their reputation for being one of the world’s oldest drugs, many opioids are naturally occurring neuropeptides (brain chemicals). They are involved in pain relief and euphoria, commonly combined in the phenomenon of runner’s high. Could opioids be involved in the feel-good sensation created by singing? Maybe.

Cindi, Sharon and Lauren suspect that singing in fall causes male starlings to release opioids in their little brains, which makes singing more rewarding and makes them want to sing more. But how do we know how much opioid an animal has in its brain? Hmmm… Opioids cause analgesia (pain relief). Therefore, if singing a lot in fall releases more opioids, then birds that sing a lot in fall should be more pain-tolerant, right? The researchers let male starlings sing and counted how many songs they produced for 20 minutes. Then they dipped their foot in uncomfortably warm water and timed how long it took for the bird to pull its toes out. Fall males that sang more took longer to pull their feet out of the birdy foot-spa than did the males that sang less.

Interestingly, if you give starlings a drug to enhance opioids, they leave their feet in the foot-spa longer than if you give them a drug to block opioids. So it seems that singing in fall increases pain tolerance in the same way that opioids do, likely because the act of singing in fall causes the brain to release its own opioids. (Although it is also possible that birds that produce more opioids feel like singing more).

And what about singing in spring? When Cindi, Sharon and Lauren repeated the study with spring starlings, these birds did not get pain relief from singing. Again, they are probably rewarded by their interactions with females and not the act of singing.

So if you ever find yourself in pain, just

Sing
Sing a song
Make it simple
To last your whole life long
Don't worry that it's not good enough
For anyone else to hear
Sing
Sing a song
La la la la la la la la la la la
La la la la la la la

Want to know more? Check these out:

1. Riters LV, & Stevenson SA (2012). Reward and vocal production: song-associated place preference in songbirds. Physiology & Behavior, 106 (2), 87-94 PMID: 22285212

2. Kelm-Nelson, C.A., Stevenson, S.A., & Riters, L.V. (2012). Context-dependent links between song production 1 and opioid-mediated analgesia in male European starlings (Sturnus vulgaris) PLOS One, 7 (10)

3. Riters LV, Schroeder MB, Auger CJ, Eens M, Pinxten R, & Ball GF (2005). Evidence for opioid involvement in the regulation of song production in male European starlings (Sturnus vulgaris). Behavioral neuroscience, 119 (1), 245-55 PMID: 15727529

4. Kelm CA, Forbes-Lorman RM, Auger CJ, & Riters LV (2011). Mu-opioid receptor densities are depleted in regions implicated in agonistic and sexual behavior in male European starlings (Sturnus vulgaris) defending nest sites and courting females. Behavioural brain research, 219 (1), 15-22 PMID: 21147175

The Love Chemical Pageant of 2018

A modified repost of an original article from February 15, 2012.

Hello and welcome to the Love Chemical Pageant of 2018! I’m your host, Miss Behavior, and YOU are the judges.

Since the beginning of…well, social animals, many hormones and neurotransmitters have been quietly working in their own ways to fill our world with love. Lately (over the last few decades), some of them have been brought out of the background and into the limelight, credited with every crush, passionate longing, parental hug, embrace among friends, and cuddle between spouses. But who truly deserves the title of The Love Chemical?

Let’s meet our contestants!

Let’s first meet our reining title-holder, Dopamine! Dopamine is a neurotransmitter produced in the brain. Sex increases dopamine levels in both males and females and blocking its effects during sex can prevent prairie voles (a monogamous species often used to test questions on pair bonding) from forming preferences for their own partner. Dopamine also plays a role in maternal and paternal behaviors.

But dopamine is not just involved in love. It has a wide range of known functions in the brain, involved in everything from voluntary movement, mood, motivation, punishment and reward, cognition, memory, learning, aggression, pain perception and sleep. Abnormally high levels of dopamine have been linked to schizophrenia and psychosis. And dopamine is especially well-known for its role in addiction... in fact, many researchers believe that we may even be addicted to our own romantic partners.

Now let’s meet Dopamine’s partner, Opioids! When natural opioids are released in the brain, they can cause a rewarding feeling that often cause us to seek more of it. When prairie voles are given drugs that prevent opioids from acting on a particular opioid receptor type (mu-opioid receptors) in a particular brain region (the caudate-putamen), they do not form pair bonds with sexual partners. Interestingly, people that see the faces of their loved ones experience lots of activity in the caudate-putamen region of the brain, especially if they rate their relationship with that person as very romantic and passionate. The caudate-putamen region of the brain also uses dopamine, so the two chemicals appear to work together there to promote the feelings of romantic love.

Please welcome Oxytocin! Oxytocin is a peptide hormone, most of which is made in the brain. Some of this oxytocin is released into the blood and affects body organs, such as the uterus and cervix during child birth and the mammary glands during breast feeding. But some of it stays in the brain and spinal cord, acting on neurons with oxytocin receptors to affect a number of behaviors. Released during child birth and nursing, oxytocin is important for helping mammalian mothers behave like moms and in species in which both parents raise young, it helps fathers behave like dads. Also released during sex, oxytocin plays an important role in pair bonding in prairie voles (particularly in the female of the pair). In humans, people given oxytocin nasal sprays have been reported to have less fear, more financial trust in strangers, increased generosity, improved memory for faces, improved recognition of social cues, and increased empathy.

But before you fall head-over-heels for oxytocin, you should know a few more things. For one thing, oxytocin isn’t exclusively linked with feel-good emotions; It has also been associated with territoriality, aggressive defense of offspring, and forming racist associations. Also, oxytocin doesn’t work alone. It has been shown to interact with vasopressin, dopamine, adrenaline and corticosterone and all these interactions affect pair bonding.

Next up is Vasopressin! Vasopressin is closely related to oxytocin. Like oxytocin receptors, vasopressin receptors are expressed in different patterns in the brains of monogamous vole species compared to promiscuous vole species. Released during sex, vasopressin plays an important role in pair bonding in monogamous prairie voles (particularly in the male of the pair). If you block vasopressin in the brain of a paired male prairie vole, he will be more likely to prefer spending time around a new female rather than his mate. On the flip side, if you increase vasopressin activity in specific brain regions of an unpaired male prairie vole or even a promiscuous male meadow vole and introduce him to a female, he will prefer spending time with her than other females. Vasopressin may also make male prairie voles more paternal.

But vasopressin does a lot of things. In the body, its primary function is to regulate water retention. In the brain, it plays a role in memory formation and territorial aggression. And even its role in monogamy is not exclusive: Vasopressin interacts with oxytocin and testosterone when working to regulate pair bonding and parental behavior.

Look out for Cortisol! Cortisol is produced by the adrenal glands (on top of the kidneys) and is involved in stress responses in humans and primates. Both men and women have increased cortisol levels when they report that they have recently fallen in love. Many studies have also found relationships between cortisol and maternal behavior in primates, but sometimes they show that cortisol increases maternal behavior and sometimes it prevents it. In rodents, where corticosterone is similar to cortisol, the story is also not very clear. Corticosterone appears to be necessary for male prairie voles to form pair bonds and it plays a role in maintaining pair bonds and promoting paternal behavior. But in female prairie voles, the opposite seems to be true! Corticosterone in females appears to prevent preference for spending time with their partner and pair bond formation.

Put your hands together for Testosterone! Testosterone is a steroid hormone and is primarily secreted from the gonads (testes in males and ovaries in females). Frequently referred to as “the male hormone”, both males and females have it and use it, although maybe a little differently. Testosterone is associated with sex drive in both men and women. But men who have recently fallen in love have lower testosterone levels than do single males, whereas women who have recently fallen in love have higher testosterone than single gals.

This is Estrogen! Estrogen is another steroid hormone, frequently referred to as “the female hormone”, although again, both males and females have it. Estrogen also seems to play a role in sex drive in both men and women. The combination of high estrogen levels and dropping progesterone levels (another steroid hormone) is critical for the development of maternal behavior in primates, sheep and rodents. But look closer and you will find that the activation of estrogen receptors in particular brain regions is associated with less sexual receptivity, parental behavior, and the preference for spending time with the mate.

So let’s have a round of applause for this year’s contenders in The Love Chemical Pageant! Now it is your turn to voice your opinion in the comments section below. Vote for the neurochemical you believe deserves the title The Love Chemical. Or suggest an alternative pageant result!


Want to know more? Check these out:

Burkett, J.P. and Young, L.J. (2012). The behavioral, anatomical and pharmacological parallels between social attachment, love and addiction. Psychopharmacology, 224:1-26.

Fisher, H.E. (1998). Lust, attraction, and attachment in mammalian reproduction. Human Nature, 9(1) 23-52.

Marazziti, D. and Canale, D. (2004). Hormonal changes when falling in love. Psychoneuroendocrinology, 29, 931-936.

Van Anders, S.M. and Watson, N.V. (2006). Social neuroendocrinology: Effects of social contexts and behaviors on sex steroids in humans. Human Nature, 17(2), 212-237.

Young, K.A., Gobrogge, K.L., Liu, Y. and Wang, Z. (2011). The neurobiology of pair bonding: Insights from a socially monogamous rodent. Frontiers in Neuroendocrinology, 32(2011), 53-69.

Why Are Cats Scared of Cucumbers?

Have you seen the video of cats’ terrified responses to cucumbers? No?! Then check this out:

This hilarious video has led many people to try this on their own cats… to varying degrees of success. And it has led to some curious questions: Why are these cats so terrified of a cucumber? And why isn’t my cat?

The fear of something specific (like a cucumber) can either be innate (as in, you’re born with it) or learned. For many animal species, it would make sense to be born with a natural fear of something that can kill you the first time you encounter it, like a steep drop, being submerged under water, or a venomous snake. Some of these things can be so dangerous that an animal with a fear of anything that even resembles it may have a higher chance of surviving long enough to produce its own fearful babies some day. So maybe these cats have an innate fear of snakes that has caused them to respond in this hilarious way to anything that resembles a snake… like a cucumber?

But if cats have an innate fear of snakes, why don’t they all respond to cucumbers this way?

Sometimes fears appear to be innate, when they are actually learned. For example, in 2009, researchers Judy DeLoache and Vanessa LoBue at the University of Virginia explored whether the fear of snakes is innate in human babies with a series of three experiments.

In the first experiment, Judy and Vanessa showed 9- and 10-month old babies silent films of snakes and other animals and they measured how long the babies looked at each type of film. Presumably, a baby will be more vigilant of and spend more time looking at something they are scared of. They found that the babies responded exactly the same towards the snake films than to the films of other animals.

Next, the experimenters showed the babies the films of either a snake or another animal again. However, this time they played the audio of a person sounding either happy or frightened along with the video. The babies looked at the non-snake animal videos the same amount regardless of whether the audio sounded happy or scared. However, the babies looked at the snake videos longer if the audio sounded scared than if the audio sounded happy.

In the third experiment, the experimenters repeated this pairing of audio with visuals, but this time they used still pictures of snakes and non-snake animals instead of videos. This time, the babies did not react differently to the snake or non-snake animal pictures depending on if the audio sounded happy or scared.

This shows that, at least for people, we don’t have an innate fear of snakes, but we do have an innate tendency to develop a fear of snakes if we are exposed to the right combination of hearing someone being afraid and seeing a moving snake. In other words, some fears are more contagious than others. And this isn’t just true for people: a study of rhesus monkeys found that baby monkeys raised by parents that were afraid of snakes only developed a fear of snakes themselves if they observed their parents acting fearful in the presence of a real or toy snake. So perhaps, the cats in this cucumber video saw or heard someone being fearful of something cucumber-like (or snake-like) when they were young... Or maybe they were just surprised by something sneaking up on them while they were eating.

In any case, don’t be too bummed if this hasn’t worked on your cat… Maybe try it on your friends instead!

Want to know more? Check these out:

DeLoache, J., & LoBue, V. (2009). The narrow fellow in the grass: human infants associate snakes and fear Developmental Science, 12 (1), 201-207 DOI: 10.1111/j.1467-7687.2008.00753.x

Mineka, S., Davidson, M., Cook, M., & Keir, R. (1984). Observational conditioning of snake fear in rhesus monkeys. Journal of Abnormal Psychology, 93 (4), 355-372 DOI: 10.1037/0021-843X.93.4.355

The Genetics of Drinking Like a Fish



Image by J. Dncsn at Wikimedia Commons

Among people, drug and alcohol addictions are the most prevalent preventable cause of death in the Western world. But not everyone that tries an addictive substance like alcohol, cigarettes, and addictive drugs becomes addicted to the point that it has a devastating effect on their life and health. People that do struggle with addiction commonly have less control over their impulsive behavior than those that do not, and it is likely that our genes play a role in these differences in both impulsivity and addictive behavior.

Although each animal species has a unique set of traits that defines them as that species, there are also striking similarities between species. It is these similarities and differences that allow comparative physiologists to make inferences about human health based on knowledge of how different animal species function. An animal species that demonstrates an aspect of physiology and/or behavior similar to humans (and can thus provide substantial insight to human health and behavior) is called an animal model. One surprising yet useful model for impulsivity and substance addiction is the zebrafish.

I am coming to get you! Zebrafish photo by Ray Crundwell provided by the Royal Society.

Like humans, zebrafish are vertebrates (animals with backbones). This isn’t just a similarity in structure, but comes from the fact that we share many of the same genes. Not only do zebrafish have many of the same genes that we do, but they show similar variations in behavior, impulsivity, and responses to addictive substances. They can be trained to do tasks that require various levels of impulse control, they can be tested for their likelihood to seek rewarding things, and as a perk, they are transparent as babies and you can see their organs functioning right through them!

If you’ve ever wondered if you’re more impulsive than a fish, now is your chance to find out! Researchers from the School of Biological and Chemical Science at Queen Mary University of London who study the genetics of impulsivity and addiction in zebrafish are showcasing their work at the Royal Society Summer Science Exhibition in London! The Royal Society Summer Science Exhibition is an annual fair of the most cutting-edge science the UK has to offer and it’s running this week from Tuesday the 2nd through Sunday the 7th. No science background is required to attend (exhibits are aimed for anyone over the age of 12) and it’s free!

The Zebrafish Genetics Exhibit focuses on an impulsivity test called the five-choice discrimination task. In this task, a fish learns that a light will turn on in one of five chambers. If it swims to that chamber, it will get a food reward. But if it doesn’t wait for the light and swims to the wrong chamber, it gets nothing. The exhibit features a human-driven version of the task where you can test yourself, your children and your friends. Another way you can test your impulsivity is with the continuous performance task. This task involves continuously hitting a button when you see certain cues appear on a screen, but not hitting the button when an X appears. It may sound easy, but it is deceptively hard. Test yourself and see how you compare to the rest of the population!

The Zebrafish Genetics Exhibit also has a microscope where you can look at the transparent zebrafish babies and see their little hearts beat. They even have some fish with fluorescently labeled proteins which allow you to see neurons (brain cells) with the neurotransmitters dopamine or serotonin. These are among the neurons thought to be involved in addiction. And if you have any questions, you can ask the scientists directly! Researchers Alistair Brock, Matteo Baiamonte, Matt Parker, and Helen Moore (get to know them here) will all be on hand to provide demonstrations and to answer questions.

The Zebrafish Genetics Exhibit is just one of 24 exhibits. Other exhibits include Technology for Nature (a demonstration of how scientists can harness technology from the Information Age to help monitor and respond to environmental change and biodiversity loss), Sports Research (a display of how modern science can help athletes achieve their full potential), and Prehistoric Colours (an exhibit of color-producing fossilized structures that help scientists learn about the role of color in prehistoric animal communication). In addition to exhibits, there are events all week, including talks on cutting-edge science topics; a science cabaret of jokes, songs, demonstrations, videos, poetry and other performances; and hands-on activities and demonstrations.

If you want to attend the Summer Science Exhibition, it is located at 6-9 Carlton House Terrace, London SW1Y 5AG. Directions and other details can be found here. And if you can’t get to London this week, you can still watch the scientist videos, ask the scientists any question you want online, and play the science-based video games. Take advantage of this great opportunity to interact directly with the leading scientists of today!


Want to know more about zebrafish? Check these out:

1. Parker, M.O., & Brennan, C.H. (2012). Zebrafish (Danio rerio) models of substance abuse: harnessing the capabilities Behaviour, 149, 1037-1062 DOI: 10.1163/1568539X-00003010

2. Parker, M.O., Millington, M.E., Combe, F.J., & Brennan, C.H. (2012). Development and implementation of a three-choice serial reaction time task for zebrafish (Danio rerio) Behavioural Brain Research, 277, 73-80 DOI: 10.1016/j.bbr.2011.10.037

3. Parker, M.O., Brock, A.J., Walton, R.T., & Brennan, C.H. (2013). The role of zebrafish (Danio rerio) in dissecting the genetics and neural circuits of executive function Frontiers in Neural Circuits, 7, 1-13 DOI: 10.3389/fncir.2013.00063

It Feels Good When You Sing a Song (In Fall)

Most male songbirds will sing when they see a pretty female during the breeding season. But some male songbirds sing even when it’s not the breeding season. Why do so many birds sing in fall at all?

Maybe singing feels good… But how do you ask a bird if it feels good to sing? European starlings are one of those bird species that sing both in spring (the breeding season) and in fall (not the breeding season). Lauren Riters, Cindi Kelm-Nelson, and Sharon Stevenson at the University of Wisconsin at Madison did a series of ingenious experiments to ask starlings if and when it feels good to sing.

A European starling sings his fall-blues away. Photo by Linda Tanner at Wikimedia.

Psychologists have long used a paradigm called conditioned place preference (CPP) to evaluate whether an animal finds something rewarding or pleasurable. CPP is based on the idea that if an animal experiences something meaningless while at the same time experiencing something else that is rewarding, the animal will learn to associate these two things with each other in a phenomenon called conditioning. For example, a puppy that has learned that every time it sits it gets a treat, will find itself sitting more often.

A researcher can also compare how rewarding different types of treats are. If we want to know if puppies like carrots or steak better, we can give one group of puppies a carrot every time they sit and another group of puppies a piece of steak every time they sit. If the group of puppies that are conditioned with steak spend more time sitting, we can conclude that steak is more rewarding to puppies than carrots are.

Lauren and Sharon used this principle to ask starlings if singing is rewarding. They put spring starlings in a cage with a nestbox and a female and let them sing away, while counting how many songs they sang in 30 minutes. Then they immediately put them in another cage that was decorated with yellow materials on one side and green materials on the other, but they restricted each bird to only one of the two colored sides. This is the conditioning phase in which the bird learns to associate the colored cage with the feeling they get from singing.

The next day, they put the starlings in the yellow and green cage without restrictions so they could choose what side they wanted to hang out in. If singing is rewarding, we would expect starlings that sang a lot to spend more time on the side with the color they were placed in the day before.


Do people that sing in the car spend more time in the car?
Photo by freedigitalphotos.net.

That didn’t happen. The spring starlings spent the same amount of time in the yellow or green side of the cage regardless of how much they sang the day before.

But when Lauren and Sharon did the same test with fall starlings singing without a female, there has a huge effect: Males that sang more spent much more time on the colored side of the cage they were placed in the day before. Singing, for a male starling, is apparently rewarding in fall, but not in spring.

This result actually makes a lot of sense. In spring, males sing to attract and court females, so they are rewarded by the feeling they get from the female’s response, not from the act of singing itself. But in fall, males are not attracting females. So why do they sing in fall? Because it feels good.

It looks like Sesame Street got it right with their 1970s song “It Feels Good When You Sing a Song”:

You can't go wrong
when you're singing a song
Sing it loud, sing it strong
It feels good when you sing a song

But why does singing feel good? At least some of the reason, it seems, is opioids. Not quite what Sesame Street had in mind, but hey.

Despite their reputation for being one of the world’s oldest drugs, many opioids are naturally occurring neuropeptides (brain chemicals). They are involved in pain relief and euphoria, commonly combined in the phenomenon of runner’s high. Could opioids be involved in the feel-good sensation created by singing? Maybe.

Cindi, Sharon and Lauren suspect that singing in fall causes male starlings to release opioids in their little brains, which makes singing more rewarding and makes them want to sing more. But how do we know how much opioid an animal has in its brain? Hmmm… Opioids cause analgesia (pain relief). Therefore, if singing a lot in fall releases more opioids, then birds that sing a lot in fall should be more pain-tolerant, right? The researchers let male starlings sing and counted how many songs they produced for 20 minutes. Then they dipped their foot in uncomfortably warm water and timed how long it took for the bird to pull its toes out. Fall males that sang more took longer to pull their feet out of the birdy foot-spa than did the males that sang less.

Interestingly, if you give starlings a drug to enhance opioids, they leave their feet in the foot-spa longer than if you give them a drug to block opioids. So it seems that singing in fall increases pain tolerance in the same way that opioids do, likely because the act of singing in fall causes the brain to release its own opioids. (Although it is also possible that birds that produce more opioids feel like singing more).

And what about singing in spring? When Cindi, Sharon and Lauren repeated the study with spring starlings, these birds did not get pain relief from singing. Again, they are probably rewarded by their interactions with females and not the act of singing.

So if you ever find yourself in pain, just

Sing
Sing a song
Make it simple
To last your whole life long
Don't worry that it's not good enough
For anyone else to hear
Sing
Sing a song
La la la la la la la la la la la
La la la la la la la

Want to know more? Check these out:

1. Riters LV, & Stevenson SA (2012). Reward and vocal production: song-associated place preference in songbirds. Physiology & Behavior, 106 (2), 87-94 PMID: 22285212

2. Kelm-Nelson, C.A., Stevenson, S.A., & Riters, L.V. (2012). Context-dependent links between song production 1 and opioid-mediated analgesia in male European starlings (Sturnus vulgaris) PLOS One, 7 (10)

3. Riters LV, Schroeder MB, Auger CJ, Eens M, Pinxten R, & Ball GF (2005). Evidence for opioid involvement in the regulation of song production in male European starlings (Sturnus vulgaris). Behavioral neuroscience, 119 (1), 245-55 PMID: 15727529

4. Kelm CA, Forbes-Lorman RM, Auger CJ, & Riters LV (2011). Mu-opioid receptor densities are depleted in regions implicated in agonistic and sexual behavior in male European starlings (Sturnus vulgaris) defending nest sites and courting females. Behavioural brain research, 219 (1), 15-22 PMID: 21147175

Using Science to Train your Pets, Family Members and Friends

If we can train dogs to jump through hoops of
fire,can't we also train our roommates to do the
dishes? Photo by Keith Moseley at Wikimedia.

Living in a social world is difficult. Each individual in the group has his or her own needs, wants and goals and they rarely match what YOU need and want. Wouldn’t it be great if everyone just did what YOU wanted them to do? Imagine a world where your pets sit peacefully at your feet (that is, when they’re not fetching you a cold drink), your brother and sister generously share everything with you, and your best friend spontaneously cleans your room. Is it possible to create such a world? We can certainly try!

The field of psychology provides us with some very useful theoretical tools for shaping the behavior of those around us. Two of them, operant conditioning and classical conditioning, have long been used by animal trainers and science has shown them to be very effective.

Operant conditioning is a learning process in which an animal learns to associate a behavior with a consequence. There are four possible consequences to any behavior:
1) Something good can start or appear
2) Something bad can start or appear
3) Something good can stop or disappear
4) Something bad can stop or disappear

If a consequence immediately and (relatively) consistently follows a specific behavior, the animal will learn to associate the behavior with the consequence and change how frequently it produces the behavior. For example, if you give your dog a treat every time you say “sit” and he sits, he will be more likely to sit whenever you say “sit”. Likewise, if you spray your cat with water every time she jumps on the counter, she will be less likely to jump on the counter when you and the spray bottle are around.

B.F. Skinner, a psychologist at Harvard in the 1960s and 1970s, invented an operant conditioning chamber (also called a Skinner Box), which he used to discover that the predictability with which a consequence is paired with a behavior can influence how quickly an animal learns and how long the training lasts. This is called the schedule of reinforcement. Generally, the more consistently the consequence is paired with the behavior, the faster the animal learns. However, once learned, the consequence can be paired with the behavior very rarely and still maintain the behavior (for example, many slot machine gamblers can play for hours even if they win very rarely).

You can watch a video of Skinner discussing his research here:

For operant conditioning to work, the consequence needs to happen immediately after the behavior. This isn’t always possible. How would a dolphin trainer teach a dolphin to jump through a hoop if she had to give the dolphin a treat right after each jump? In this case, classical conditioning is a helpful tool.

Classical conditioning is a learning process in which an animal learns to associate two stimuli: an unconditioned stimulus that naturally causes the animal to respond and a conditioned stimulus which previously did not elicit a response. Classical conditioning (also called Pavlovian conditioning) is most often associated with Ivan Pavlov, a Russian physiologist and Nobel laureate for his research on digestion. In Pavlov’s famous example of a classical conditioning experiment, he gave a dog a food treat (meat powder) and measured how much the dog salivated. Salivating is a natural response to the food, so in this case, food is an unconditioned stimulus. Pavlov then began to ring a bell immediately before giving the dog the treat. Over time, the dog learns to associate the ringing bell with the treat and will salivate in response to the bell alone. At this point, the ringing bell is the conditioned stimulus.

So how do we put these two theories together to train an animal to show a complex behavior? Generally, simple behaviors are trained by waiting for the behavior to occur and then rewarding it, with something the animal finds naturally rewarding if possible. If that is not possible, a conditioned stimulus can be used by immediately pairing it with the natural reward. This video shows someone training a goldfish to go through a hoop. Notice the timing with which the trainer provides the conditioned reward (the light) and the unconditioned reward (the food).

Once an animal is trained to do a simple behavior, you can build on these behaviors to make them increasingly complex.

Now you can be creative with how you use this knowledge. Train your dog to “read” flash cards. Train your roommate to do the dishes. The possibilities are endless.

Be patient. Training takes time. And remember, the more consistent you are with your rewards, the faster learning and training will happen.


Want to know more? Check these out:

1. Nargeot, R., & Simmers, J. (2010). Neural mechanisms of operant conditioning and learning-induced behavioral plasticity in Aplysia Cellular and Molecular Life Sciences, 68 (5), 803-816 DOI: 10.1007/s00018-010-0570-9

2. Balsam, P., Sanchez-Castillo, H., Taylor, K., Van Volkinburg, H., & Ward, R. (2009). Timing and anticipation: conceptual and methodological approaches European Journal of Neuroscience, 30 (9), 1749-1755 DOI: 10.1111/j.1460-9568.2009.06967.x

Playing “Good Cop, Bad Cop” with Octopuses

Have you ever seen an octopus in an aquarium, or maybe even in the ocean, and thought, “I know you!”? No? Well, they might think that when they see you!

We’ve known for some time that many domestic animals, like dogs, can tell us people apart. It turns out that a lot of animal species can recognize individual people. But how do we humans know that? It’s not like you can walk right up to an animal and say “Hey! Remember me?” ...Well, I guess you could do that, but how would you interpret the answer?

Imagine everything that an animal would have to be capable of to be able to recognize different people: the animal would have to be able to discriminate, learn and remember. Those are pretty complex tasks. Despite our stereotypes of molluscs, octopuses (not “octopi”) are actually quite good at all of these things. They are visual animals that can differentiate between abstract shapes, remember visual patterns, and be conditioned (Conditioning is a process by which an animal learns to associate a behavior with some previously unrelated stimulus). Additionally, many people acknowledge octopuses as the most intelligent (and coolest) of all invertebrates. Furthermore, there have been several anecdotal reports of octopuses recognizing individual people. Some octopuses at aquariums consistently approach the keepers that feed them, even when the keeper is in a crowd of other people. One octopus being trained in a lever-pressing task regularly chose to squirt the researcher in the face rather than press the lever. Another octopus apparently only jetted water at a particular night guard. So octopuses seem like a pretty good species to test individual human recognition (and to test for a sense of humor, but that is for another day).

If you were an octopus, could you tell these two people apart?
Photo by Veronica von Allworden from a figure in the paper
in The Journal of Applied Animal Welfare Science

Roland Anderson and Stephanie Zimsen at the Seattle Aquarium, Jennifer Mather at the University of Lethbridge, and Mathieu Monette at the University of Brussels, set out to do just that. They caught eight giant Pacific octopuses from the wild and took them to the Seattle Aquarium. For 5 days a week over two weeks, they repeated the following process: Two identically-dressed testers played the roles of “good cop” and “bad cop”. Twice a day for each animal, each of the two testers would separately open the tank so they could be seen by the octopus and record its behavior: movements, inking, blowing water, funnel direction, skin color and texture, respiration rate, and the presence or absence of an eyebar (color-changing skin around the eye that may darken due to disturbance). Then, one of them would feed the octopus, and the other would gently poke it with a bristly stick (which was not harmful, but probably pretty irritating). The “good cop” always fed the octopus and the “bad cop” always poked it, although the people that played “good cop” and “bad cop” were different for each animal. The order of the “good cop” and “bad cop” treatments was determined randomly each day. On the last day of the second week, each tester opened the tanks, looked in, and recorded the animals’ behavior.

A giant Pacific octopus displaying his eyebar (shown with the white arrow)
in the wild. Photo by Veronica von Allworden from a figure in the paper in
The Journal of Applied Animal Welfare Science

In the first day or two of testing, octopuses generally moved away from both testers equally, did not have a difference in where their water jets faced or in displaying their eyebars. But in the second week, octopuses generally responded to testers that fed them by moving towards them, aiming their water jets away from them and not displaying eyebars; they generally responded to testers that poked them by displaying their eyebars, aiming their water jets at them, and moving away from them. And some of the octopuses (the larger ones) had faster breathing rates when they saw the testers that poked them than when they saw the testers that fed them.

So octopuses can recognize individual humans, and they treat people differently depending on how they have been treated by the humans. …Hmmm… If octopuses can do it, imagine what other species may be able to do it. Meditate on that the next time you interact with an animal.

Now add individual human recognition to other things we know octopuses can do, like learn and remember skills, play with toys, express personalities, and detect things by vision and smell. And they can do this:

and this:

and this:

I mean really, is there anything octopuses can’t do?

Do you want to get to know the octopuses from this study? Learn to recognize them at the Seattle Aquarium or the Seaside Aquarium, where they are now on exhibit.

Want to know more? Check these out:

1. Anderson RC, Mather JA, Monette MQ, & Zimsen SR (2010). Octopuses (Enteroctopus dofleini) recognize individual humans. Journal of applied animal welfare science : JAAWS, 13 (3), 261-72 PMID: 20563906

2. Mather, J.A., Anderson, R.C and Wood, J.B. (2010). Octopus: The Ocean’s Intelligent Invertebrate. Timber Press, Portland, OR.

3. Octopus Chronicles, a Scientific American blog dedicated to everything fascinating and amazing about octopuses

4. AnimalWise, a blog about animal cognition

The "Love Hormone" of 2012

Hello and welcome to the Love Hormone Pageant Results Show!  You have cast your votes, the results are in, and the “Love Hormone” of 2012 is… (dramatic pause)… Dopamine!

Dopamine is arguably the most exciting of love hormones. A neurotransmitter produced in the brain, dopamine plays a key role in many motivated behaviors (and love, especially falling in love, involves a lot of motivated behavior). It does this mostly through the mesolimbic reward system, which largely consists of dopamine-producing neuron cells in a brain region called the ventral tegmental area and their projections to other brain regions, including the nucleus accumbens. The mesolimbic reward system exists and has been studied in mammals, birds, reptiles and fish, but the story of how dopamine may be involved in “love” has been explored most with one particular mammal species, the prairie vole.

Photo of a prairie vole pair from Young, Gobrogge, Liu
and Wang paper in Frontiers in Neuroendocrinology (2011)

The prairie vole is a small rodent from the grasslands of the central United States. Unlike approximately 97% of mammal species, prairie voles are socially monogamous and form long-term pair bonds. Male and female pairs travel together, nest together and share parenting duties. Pairs tend to stay together for life and when one partner dies, the surviving partner may never re-pair with a new mate. The role that dopamine plays in how these pair bonds are formed between prairie vole couples has been studied extensively over the last 13 years by Zuoxin Wang at Florida State University and over 30 of his colleagues. Kimberly Young, Kyle Gobrogge, Yan Liu and Zuoxin Wang summarize much of this work in a recent review.

Graph showing that prairie voles prefer to
spend time with their partner after 24 hours
of living together and mating:fromYoung,
Gobrogge, Liu and Wang paper in
Frontiers in Neuroendocrinology (2011)

If you put a virgin male and a virgin female prairie vole in an enclosure and let them live together and mate for 24 hours, they will reliably prefer to spend time with each other rather than with a stranger if given that choice – this is called partner preference. If you enhance dopamine action in the brain, this partner preference will happen even sooner and if you block dopamine receptors throughout the brain, it won’t happen at all. This pattern is even true if you change dopamine action only in the nucleus accumbens, showing that dopamine binding in the nucleus accumbens is critical for the formation of partner preference and pair bonds.

The effect of a hormone or neurotransmitter is completely dependent on its receptors: where they are, how many there are, and how well things bind to them. Dopamine receptors can be classified into two main families, called D1-like and D2-like receptors, and they often have opposite effects. For example, in the prairie vole nucleus accumbens, activating D2 receptors or blocking D1 receptors will cause partner preference to form faster, whereas blocking D2 receptors or activating D1 receptors will prevent it from forming at all. Furthermore, male prairie voles develop more D1 receptors in the nucleus accumbens during pair bonding, which likely work to prevent the animal from forming a pair bond with a second female and keeping him faithful to his mate. Interestingly, promiscuous meadow voles generally have more D1-like receptors in the nucleus accumbens than closely related but monogamous prairie voles. So in the prairie vole nucleus accumbens, activation of D2 receptors promotes the formation of pair bonds and activation of D1 receptors prevents the formation of pair bonds.

However, dopamine is not all roses and chocolate hearts. The action of dopamine in the mesolimbic reward system, and especially in the nucleus accumbens, regulates much more than pair bonding; It regulates a whole suite of motivated social behaviors, like sexual, parental, play, and aggressive behaviors, as well as other motivated behaviors, like seeking food and drugs of addiction. Furthermore, mesolimbic dopamine seems to be at the heart of the interactions between drugs of abuse and social behavior. In another recent review by the same research group, Wang and his colleagues point out that brief exposure to any known drug of abuse activates dopamine activity in the nucleus accumbens and repeated drug exposure causes long-lasting or permanent changes to mesolimbic reward brain areas like the nucleus accumbens. For example, repeated exposure to psychostimulants increases the number and sensitivity of D1 receptors in the nucleus accumbens…Wait, what do active D1 receptors in the nucleus accumbens do? Oh yeah, they prevent pair bonding and partner preference formation. And not surprisingly, giving amphetamine (a psychostimulant) to prairie voles prevents them from forming partner preferences and pair bonds. So if you don’t want to hurt your chances of falling in love some day, just say “No” to drugs, mmmkay?

Dopamine is a busy neurohormone: It is not only involved in love and motivated behaviors, but is also involved in everything from voluntary movement, mood, punishment and reward, cognition, memory, learning, aggression, pain perception and sleep. It is also important to keep in mind that dopamine does not work alone. To regulate pair bonding and partner preference, dopamine interacts with oxytocin, vasopressin, glutamate, GABA, and corticotrophin-releasing factor. But then again, love is about as complex a brain function as you can get – we couldn’t expect a single hormone to go it alone!

So put your hands together one last time to celebrate the “Love Hormone” of 2012: Dopamine!

Want to know more? Check these out:

Young, K., Gobrogge, K., Liu, Y., & Wang, Z. (2011). The neurobiology of pair bonding: Insights from a socially monogamous rodent Frontiers in Neuroendocrinology, 32 (1), 53-69 DOI: 10.1016/j.yfrne.2010.07.006

Young, K., Gobrogge, K., & Wang, Z. (2011). The role of mesocorticolimbic dopamine in regulating interactions between drugs of abuse and social behavior Neuroscience & Biobehavioral Reviews, 35 (3), 498-515 DOI: 10.1016/j.neubiorev.2010.06.004