Brains & Baby Care, Short Stories from the Geaux Girl Fish Power Group!

Hey y’all, it’s Toni here!  Now that the boys Burt and Tyrone are done telling you about their cool news, me and the gals have some even cooler updates for you! The scientists have been pretty busy learning some new things about the brains of us females. Sit back, grab some popcorn, and I’ll tell you 3 different short stories from the Geaux Girl Fish Power group!

Story #1: So you may remember that us females are mouthbrooders and we hold our developing babies inside our mouths for a couple of weeks. It’s kind of a drag because during this time, we can’t eat, because we’re such good mothers and we don’t want to eat our kids!, so we’re essentially in a starvation mode. But how do our brains control these behaviors of feeding and caring for our babies? Well, the researchers did an experiment to identify which regions of our brain were involved in feeding compared to maternal care. To do this, they used a neural activation marker called pS6 (they mentioned what that stood for, but it’s not really important for the story, plus, I forgot!). This marker shows which neurons in our brain were activated or ‘turned on’ when we were in different conditions. They compared groups of us females that were mouthbrooding (so starved and with a brood), ones that were starved without a brood, and ones that were fed without a brood, and then they looked at the patterns of neuron activation in like 16 different regions of the brain (I bet that’s why the paper they wrote about it has so many authors)! What they discovered was that some brain regions were more associated with the female’s energetic status (starved or fed), other regions were associated with maternal care, but the majority of regions showed involvement of both energetics and maternal care. This was pretty cool because it shows how complicated the regulation actually is and how tightly linked our feeding and mouthbrooding activities really are! The researchers say there’s evidence for both distinct and shared brain circuits involved in regulation of our maternal care, food intake, and energy balance. We’re excited about this too because it will help other scientists in the future to better understand the evolution of how the brain controls feeding and parenting, which is important for all animals that take care of their babies in some way!

Story #2: In this story, the researchers wanted to look at specific neurons in our brains called AVT cells. AVT stands for arginine vasotocin, which is a protein hormone that is involved in regulating many different behaviors, responses to stress, and salt and water balance in the body. Humans have this hormone also, but it’s called AVP, or arginine vasopressin (and sometimes also called antidiuretic hormone because it regulates how much water is in your body and how much you pee). We’ve already talked about peeing in the past, so you know that us girls and those boys are constantly peeing at each other, so yeah, we’re pretty much swimming around in a bunch of urine! – thank goodness for our wonderful filtration system! Anyway, back to this story, which is not about peeing. First, the researchers used several different staining techniques to label these AVT neurons in the brain (one method labels the AVT protein in the cell and another method labels the messenger RNA that will be made into the protein) and found them in several cell groups with funny names based on how big the cells are – gigantocellular (these are giant!), magnocellular (these are medium sized), and parvocellular (these are small). They also found another group of cells in a different brain region called the ventral hypothalamus, and these cells are larger in our brains when we are mouthbrooding compared to when we’re ready to mate. This result was pretty cool because it means that these neurons might help us with maternal care and taking care of those wriggly babies in our mouths – they are certainly a lot of work, and we have to starve ourselves while making them happy! Those gigantocellular cells I mentioned earlier are also even more gigantic as we get further into our mouthbrooding stage, so this may help us get ready to take care of our little kids once they’re ready to go out into the world and we let them out of our mouths – this is also lots of work for us mothers since we have to protect them from the hungry mouths of other fish by letting them back into our mouths for protection! Most previous studies on AVT were done in males (what else is new?!), but Wow, this study shows that these AVT neurons are pretty important in us females too!

Story #3: The researchers looked in our brains for a specific enzyme (proteins that help with chemical reactions in the body) called aromatase. Aromatase is important because it takes the hormone testosterone and converts it to estrogen, which is a very useful hormone for lots of body functions, particularly for us ladies. They found aromatase all over our brains!, and this make sense because fishes have the greatest ability to produce estrogen in their brains out of all animals! – pretty cool! And get this, it’s not found in neurons, but in glial cells! Glial cells are important for maintaining healthy neurons and brain function, and actually, there are way more glial cells in our brains (and your brains) than there are neurons! (we girls think that’s especially true for Burt, but that’s another story!). Anyway, the scientists also measured the levels of aromatase in different regions of our brains and found that it changes with our reproductive condition – in other words, my brain aromatase levels are higher when I’m looking for a mate, am gravid, and have large eggs in my ovaries, and then levels are lower when I’m brooding those babies in my mouth! While they saw changes in aromatase levels, there were no changes in the receptors that bind the newly made estrogen (called estrogen receptors).  So, this local production of estrogen in specific regions of our brains may help us females in several ways: improve our ability to sense those crazy courtship displays from the boys, help us make decisions, prepare our brains for when we have to take care of our kids inside our mouths, and potentially lots of other things! Another awesome thing about this project was that there was an undergraduate researcher from another University (University of Louisiana, Monroe) that helped out with it – we love meeting and seeing new faces around the fish room!

Here’s the research papers that explain these experiments and results in detail:

Maruska, K.P., Butler, J.M., Field, K.E., Forester, C., and A. Augustus. 2020. Neural activation patterns related to energetic status and maternal mouthbrooding in an African cichlid fish. Neuroscience. link

Butler, J.M., Anselmo, C., and K.P. Maruska. 2020. Female reproductive state is associated with changes in distinct arginine vasotocin cell types in the preoptic area of Astatotilapia burtoni. J Comp Neurol. link

Maruska, K.P., Butler, J.M., Anselmo, C., and G. Tandukar. 2020. Distribution of aromatase in the brain of African cichlid fish Astatotilapia burtoni: Aromatase expression, but not estrogen receptors, varies with female reproductive state. J Comp Neurol. 528: 2499-2522. link

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Science Comics Anyone?

Hello everyone! Tyrone, here! I’m sure you all love reading Burt’s blog, but what if things got a bit more artsy around here? I’m excited to announce my upcoming masterpiece in the making – a comic book starring myself, Toni, Burt and some friendly new fish faces.

Why a comic book you ask? While Burt uses writing and this blog to share what he and the scientists are up to, I’m more of a visual guy. I LOVE comics!!! But most people assume they’re restricted to superheros or one style of art (although a Superfish sounds pretty awesome). Comics are actually a sequential art where the shape, size, and relationship between panels conveys just as much information as the text itself. They’re really good at portraying abstract concepts in science that are difficult to convey with words – so I thought I’d give it a try!

I’ve turned a big wordy science article published in the Maruska lab into a comic for you readers. I’ve worked really hard storyboarding and sketching a draft for you all. I’ve started the final process of inking everything and once that’s done that’s when the real fun will begin. Like I said, I’m more of a visual guy so not only am I working on this because I love art, but I think I could use it as an educational tool as well! I can use this opportunity to test whether or not readers engage in learning about science more when it’s presented in a traditional format, such as a scientific journal article, or my more untraditional comic book.

I’ll be giving a pre- and post- questionnaire to students chosen to read certain materials to see whether or not there’s a difference in their attitudes towards science and how much they learn! Students will be selected to read either: 1) a scientific journal article, 2) a ‘news-type’ summary of that article, 3) the comic book I’ve created, or 4) nothing (the control group). I’m rooting for my comic to be just as educational as the journal article, but way more fun!


As the star character in this story I don’t want to give too much away about the plot – but like Burt’s blog my goal is to share what fun and exciting discoveries go on in our lab with you all – just in my own unique way. To get everyone excited, here’s a sneak peak at a couple of pages I’ve finished. Only 18 more to go – then on to publication and fun science for the public!

comic-page1 comic-page2

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Model Fish & Model Brains!: Burt’s 3D Printing Adventure

Hello! It’s Burt again. Today, my researcher friends took me outside the lab for a photoshoot. My friends wanted to be able to look at us cichlids outside of the water (why anyone would want to go there, I don’t know). They told us they wanted to make a 3D model of our species, and they chose me to be their study template! We visited LSU’s Communication across the Curriculum (CxC) office and the LSU Engineering Department, where they had me waggle my tailfin for their 3D scanner, and I learned about the 3D scanning and printing process.

3D scanning is the process of using a laser and cameras to analyze an object’s shape, size, and color. As the laser moves over the object, the cameras record the change in distance of the laser. The computer then uses the data to make small triangles or squares in 3D space, in what is called a “point cloud” model. Information from one side isn’t enough, so the scientists asked me to spin around for them so they could take images from lots of angles! After we got all the pictures, I watched as they had to “align” the separate images, putting together a puzzle using the colors and shapes on my body as references. Sometimes, the model is left with holes, so the computer uses a complex algorithm to estimate the shapes of the missing pieces to complete the image.

Guess what else? The researchers also wanted to have a model of my brain!, so they took to a program called Sculptris to digitally “sculpt” a model of my brain so they could print that out too. I heard them say that my brain is pretty similar to theirs in a lot of ways, but since I’m much smaller than they are they needed a bigger version of it to study and teach everyone else how cool our brains are!

Finally, we were ready to print, and my friends and I went back to the CxC office and Engineering department. LSU’s 3D printer is what is called a fused deposition model. The printer is able to deposit, or “extrude”, liquid plastic onto a surface. As soon as the plastic leaves the nozzle, it hardens onto the surface. By depositing this plastic layer by layer, a model is built up. After printing, it takes a soothing dunk in a solution to remove the dissolvable support plastic that held up the Burt model during printing, and then it’s done!  I look even better than I thought I did!


The scientists can then also paint the printed models to look flashy and colorful like me, totally drabby like Tyrone, or even classy like Toni. Now, the scientists in the lab will be able to conduct different types of experiments with a ‘model Burt’ and also teach everyone about us cichlids and how our brains work using their newly-printed models. I can’t wait to show Toni!



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Burt and Tyrone have Different Smelly Brains!

Now that you know we also use pee and olfactory signals to communicate with each other, I want to tell you about another experiment designed to test how the neurons in our brain work to understand these smells.  The scientists put these little needles called electrodes in specific regions of our brain, and then pass water that contains different types of smells (or odors) over our noses to see how our brain responds.  When the neuron they’re recording from gets important information from our olfactory epithelium, it fires what’s called an ‘action potential’ (this is caused by ions like sodium and potassium crossing the cell membrane through channels). The researchers can then compare this firing activity after application of these different smells to determine which ones might be most important to us!

In the first experiments, they’re doing these recordings in us males.  Right now, I’m a dominant male, meaning that I successfully defend my territory, mate with the ladies, and sport this flashy bright coloration. But I wasn’t always dominant, and in fact, most of the other males in my home town, like Tyrone, are subordinate – they don’t have a territory or mate, look pretty faded, and get chased around a lot by dominant guys like me.  Not only do we behave and look differently, but there are also lots of physiological differences between me and Tyrone.  So, the scientists are asking whether the olfactory-sensitive neurons in our brains process smells differently when we’re dominant versus when we’re subordinate.  Some of the smells they’re testing are amino acids (found in food) and steroids (found in urine). But they’re also testing more complex mixtures of chemicals that might actually be released from us fish.  To get these fishy smell solutions, they place either a few ladies that are ready to mate, or a dominant male into some water and let them hang out for a while. Then they collect that water, which contains all of the smells released through the skin, gills, or through peeing!, and put them on our noses while they record from the brain.

Neuron action potential traces in Burt and Tyrone responding to water from females, males, and steroid hormone

What they found out is really cool! – it looks like us dominant males respond really well to lots of different smell types, but especially to the steroids and that water that held the females! When we’re dominant, our brains are more responsive to smells released from females, allowing us to better detect them and stimulate our courtship and mating dances. The subordinate males on the other hand are less responsive overall, but they did show more neurons that were responsive to the odors released from other males. This may help males like Tyrone to better distinguish the dominance status of the other males in the area.  Since Tyrone and the other subordinates are always looking for a chance to get a territory home and become dominant, this olfactory ability may help them better gauge which males are wimpy and which are macho. This is pretty cool and useful because it tells them which males to avoid (so they don’t get beat up) and which they should challenge with a higher probability of winning and getting a territory!

So, my brain and Tyrone’s brain are pretty different, but each one is perfectly-suited to perform all of the tasks we need to do when we’re dominant or subordinate.  This research is important because these types of brain differences may also exist in lots of other animals that also have dominance hierarchies, from bugs to even people!


Here’s the research article that explains the study details and results:

Nikonov, A. and K.P. Maruska. 2019. Male dominance status regulates odor-evoked processing in the forebrain of a cichlid fish. Scientific Reports 9:5083. Link

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I’ve got sickness on my mind…


Hey guys! It’s Burt again back with more fun science for you to explore. Last time I told you a little about smell and how it helps me communicate with Toni and other fish in my environment. We saw how the delivery and reception of chemical odorants dissolved in the water are important in mediating social interactions. Just as it’s important for me to communicate with Toni and other fish, it’s also important that systems throughout my body are able to communicate between each other, particularly the immune and nervous systems.

Just like you, my brain allows me to take in information from my environment, process it, and produce an appropriate response. Although this process takes a lot of energy, I’m able to do this fairly well, which is great because I need to perform a variety of behaviors like finding food, dancing for the ladies, defending my territory, and protecting myself from predators. But recently, I’ve been more concerned with how well I’ll be able to perform these basic functions in the future.


You see, some environmental changes like pollution and climate change, can negatively impact my normal physiology. This includes sustaining the factors that help me maintain homeostasis (keeping a constant & stable body environment) so that I can properly evaluate my surroundings and perform those behaviors I mentioned before. My immune system helps to keep me from getting sick in these changing times, but I worry that this stressful lifestyle may also have negative effects on my brain and body!


Because I’m a dominant macho male, hormones like testosterone circulate throughout my body, allowing me to properly perform crucial behaviors. Smaller, less dominant males have much lower levels of testosterone. So that this makes a little more sense, let me introduce you to my not so good friend, Tyrone. Tyrone is far less colorful than I, much smaller, and not nearly as attractive! I’m able to protect my territory from other males like Tyrone that might try to steal it, but whenever I leave to forage or find mates, Toni tells me that he quickly takes advantage of the opportunity by adapting my phenotype (i.e. bright coloration), but as soon as I return he becomes subordinate again. Pretty deceptive trick, Tyrone!

How might physiological differences between myself and Tyrone mediate different immune responses? I talked to Teisha, another graduate student in the Maruska Lab, about my concerns and she says she is on the move to investigate the interactions between the nervous system and mounting an immune response! She believes that addressing these types of questions would also be helpful in understanding immune interactions in other species, even humans! Fish and humans actually have many similarities in our immune responses, one being inflammation which is common in many diseases impacting humans today like Alzheimer’s, arthritis and even diabetes. I feel better already!

So, stay tuned for more information and if you’re interested in reading more about differences between Tyrone and I, check out these papers from the Maruska lab:

Maruska, K.P.and R.D. Fernald. 2018. Astatotilapia burtoni: A model system for analyzing the neurobiology of behavior. ACS Chemical Neuroscience. 9: 1951-1962. link

Maruska, K.P. 2015. Social transitions cause rapid behavioral and neuroendocrine changes. Integr Comp Biol. 55: 294-306. link

Maruska, K.P.  2014. Social regulation of reproduction in male cichlid fishes. Gen Comp Endocrinol207: 2-12. link

Maruska, K.P. and R.D. Fernald. 2014. Social regulation of gene expression in the African cichlid fish, Astatotilapia burtoni. pp. 52-78. Oxford Handbook of Molecular Psychology (Canli, T., ed). Oxford University Press. link



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OOOooh that smell! Can’t you smell that smell!?

olfactory epitheliumHello everyone! Today I want to tell you about how I smell my world! You see fish live in water (duh!), which means we constantly smell all of the dissolved odorants that are in the water around us while we swim around. In fact, we use smell for almost everything! I use it for finding food, avoiding becoming food (predator avoidance), navigating, and even finding mates or avoiding other males that may want to fight. Fishes have a sensitive “nose” comprised of an olfactory epithelium full of olfactory receptor neurons (ORNs) that detect all kinds of different smells. Each type of neuron detects a certain “type” of smell. For example, ones called ‘crypt neurons’ detect pheromones (which help me find my special friend Toni! ;)). Each of these different types of ORNs sends signals to a specific region in my olfactory bulb at the very front of my brain. You see, my olfactory bulb is a sorting center for all of these different kinds of smells. From there, the signals go on to other parts of my brain that help me decide how to behave. Should I try to eat this smell, should I do a pretty dance for this smell, or should I swim away from this smell??

PeeingNot only can I detect a whole lot of specific smells, but I also send a lot of smells! Especially to Toni, hehe. And Toni sends smells to me, too. You see one way that I communicate with Toni (and other male fish) is through my pee. That’s right! We all pee at each other! Our pee contains lots of molecules that have information on our species, sex, social status, and even reproductive state. So when I see that Toni is ready to spawn, I’ll pee at her more to let her know I am a big strong male with good qualities to pass on to our kids. And Toni pees at me to let me know that she’s ready to spawn. But my pee isn’t just for Toni. If another male wants to try to take over my territory (good luck, buddy!), we will pee at each other to show just how big and strong we are. This helps us assess one another and determine if it’s worth fighting. And Toni pees to other females, too! If she and another female start fighting, she will release pee towards her to show her strength.

So, as you might have gathered, smell is SUPER important for me. In fact, if I can only see Toni, and not smell her, I’m much less likely to dance for her, making her less likely to spawn with me. I need to smell her to be sure she’s ready for my dancing. This whole smelling each other thing is super handy in Lake Tanganyika too. Sometimes hippos or other giant wildlife can walk right through our homes, making things very murky and harder for me to see Toni or other males or even food. So having an excellent sense of smell really helps me out.

I hope you enjoyed learning about my awesome sense of smell and how I pee to communicate! If you want to know more, check out these papers on the lab website:

Field, K.E. and K.P. Maruska. (2017). Context-dependent chemosensory signaling, aggression, and neural activation patterns in reproductively-receptive female African cichlids. J Exp Biol. 220: 4689-4702. link

Nikonov, A.N., Butler, J.M., Field, K.E., Caprio, J., and K.P. Maruska. (2017). Reproductive and metabolic state differences in olfactory responses to amino acids in a mouth brooding African cichlid fish. J Exp Biol. 220: 2980-2992. link

Maruska, K.P. and R.D. Fernald. (2012). Contextual chemosensory urine signaling in an African cichlid fish. J Exp Biol 215: 68-74. link

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Looking on the bright side of a long snowy winter

Greetings from Minnesota! That’s right, Toni and I took a trip to the tundra! Why? Well we’re visiting some friends up here in Dr. Allen Mensinger’s lab at the University of Minnesota at Duluth. They’re helping Julie check our vision using this technique called electroretinograms (but more on that in a minute!).

If you haven’t already noticed, I’m pretty awesome and brightly colored. And I do this little dance for Toni when I’m trying to get her to spawn with me. Like a lot of animals, we primarily use visual signals during reproduction. When I’m ready to mate, orvisualsignals.png around Toni when she’s ready to mate, I produce A LOT more of these visual signals (check out some of them in this picture!). But what my humans are interested in testing is if Toni’s ability to detect my dance and colors changes with her reproductive state. We already know she can probably hear me better when she’s ready to mate (read about that here), but maybe she can see me better too!! How cool would that be?!?!

They’ve done a whole bunch of things to look at this, but the electroretinograms are the final step! We got shipped up here about a week before Julie so that we could acclimate to our new temporary home. And boy is it different! It’s all white outside. I overheard Julie talking excitedly about this thing called “snow”. Apparently, it’s really cold and wet and doesn’t really exist in south Louisiana. We African cichlids don’t know anything about cold. Or snow. Luckily they gave us some heaters so we can stay nice and toasty while the humans freeze.

But anyways, back to the science. So once Julie got here, we got to work! The first step was to make electrodes. They took these teeny tiny wires and soldered them to little metal rods. Once they have the electrodes, they’re ready to start! We get put in this dark room, and the electrodes get inserted into our retina. Then they let is sit in the dark for a long time so we become fully “dark-adapted”. You know how when you go outside to look at the stars it can take a while before your eyes adjust and you can see them? Adjusting to the dark can take a while. So we had to sit there in the dark for at least 30 minutes, but sometimes longer! After that, they flash our eyes with lights of differentquiver.png colors! The electrodes record the response of our retina to each of the wavelengths of light that they’re testing. So they’re comparing the responses of Toni and her friends at different reproductive states. I’m excited to hear about what they find!

We’re heading back to good ole Louisiana soon. While Dr. Mensinger and his lab are great, I miss my friends back in LA. Can’t wait to tell them about this magical thing called snow!

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Balancing Act

Hi everyone! It’s Toni again! Last time I talked about mouth brooding and how I carry my developing young in my mouth. As they develop and grow, they also increase in weight. This affects my buoyancy… Imagine having a weight strapped to just one side of your body! You’d probably walk a little crooked. Luckily, I have a way to fix this so my kids don’t bring me down (literally, and face-first)!

The humans took me on a field trip to the LSU Museum on Natural Science where they got to work with a really cool guy named Prosanta Chakrabarty (he’s an Ichthyologist, or scientist that studies fishes). Once there, they took x-ray images of me and my friends. Some of us were gravid (that means we have big eggs and are ready-to-reproduce). Others were mouth brooding, and some of my friends were in between (or recovering). When they looked at these pictures, they noticed that the swim bladder, an air-filled sac in the body, looked different depending on our reproductive state. The swim bladder helps us regulate buoyancy (or maintain position in the water column), so the humans thought it might change size or shape depending on if we were brooding or not.


After some fancy quantifications and morphometric analyses, they found out that my swim bladder does change size and shape depending on my reproductive state! My swim bladder has two compartments: the front/anterior compartment and the back/posterior compartment. There’s a small membrane separating the two compartments, and that membrane has a small hole that allows for air flow between the chambers.

When I’m holding the babies in my mouth, the front compartment of my swim bladder gets relatively bigger and more round in shape. This allows me to adjust my buoyancy so that I’m not swimming at a downward angle. It’s not easy or fun to swim with your head pointed down the whole time! As the babies grow inside my mouth, that front compartment gets bigger and bigger to compensate for their increasing weight.


Once my brood reaches full development and I release them, my buoyancy gets all messed up again. Immediately after I release the babies, I swim at an upward angle because there’s too much air in the front compartment of my swim bladder. Luckily, this air redistributes to the posterior compartment in ~5 minutes, and I’m able to regulate my buoyancy again.

If you want to know more about this, be sure to check out the article below or its feature in Inside JEB. I know you don’t need a swim bladder, but boy am I happy that I have one!

Butler, J.M., Whitlow, S.M., Gwan, A.P., Chakrabarty, P., and K.P. Maruska. 2017. Swim bladder morphology changes with female reproductive state in the mouth brooding African cichlid Astatotilapia burtoni. J Exp Biol. 220: 4463-4470. Link Here

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Extreme maternal care

Hey Y’ALL! (there’s that Louisiana vocab again!).  It’s Toni here, and in this post I want to share some more about some cool research looking at our maternal care behaviors.  Last time, I told you about how us females are mouth brooders, which means we hold our babies inside our mouths for ~2 weeks until they’re fully developed and can swim out on their own. BrooderNewDuring this time, we can’t really eat, so we’re pretty much starving and lose lots of weight, all to keep our babies happy and healthy! – this is extreme maternal care at its best!  Since we’re pretty hungry, we swim up to the food dropped in our tanks but stop ourselves before eating it when we remember those little guys already in our mouths.  As the babies get bigger, they get heavier too and to keep ourselves from doing a nosedive to the bottom, some adjustments are made in our swim bladders to keep us swimming straight (but that’s a story for another time!).  Anyway, once the babies are grown, we open our mouths and they swim out into the world –so proud!  While they explore their new surroundings, we watch over them for a couple of days, and let them swim back into our mouths if there’s danger like a big bully or predator around. After that, our parental duties are over and they’re on their own!; our new focus is now to eat, eat, eat – diet over!

So here’s the dilemma: how does our brain and body control these switches in motivation between feeding and maternal care? One minute we’re eating, and the next minute after we spawn and the eggs are in our mouth, we stop feeding, cold turkey, and need to start caring for the eggs by churning them around so they grow big and strong! To examine this question, the researchers are looking at which regions of our brain are ‘turned on’ or ‘activated’ in groups of us ladies that are either brooding, or starved or fed for ~ 2 weeks; the same time as a normal brood cycle. By comparing these groups, they can discover which brain regions might be involved in metabolism and feeding, versus those regions involved in our maternal care behaviors.  By doing some staining Stainingexperiments called double-labeling (see picture), they’re also looking at exactly what kind of neurons in the brain are turned on – this gives them insights on their function!  So far, they are unveiling some very interesting differences in brain activation patterns likely due to the starvation aspect of brooding compared to the maternal care aspect; stay tuned for more specific results in the future!  Since maternal care happens in lots of different animals, the researchers are interested in understanding how similar or different the brain mechanisms that help control these parental behaviors are, between, say, a fish like me, a frog, a bird, and a mammal. We love it when the scientists use us to discover new things that can be applied to other animals!

The nice folks at the National Science Foundation gave us some support to study some of these questions related to mouth brooding and maternal care. If you think about it, this research has important relevance to many other animals, including humans!  As fish, we are vertebrates (animals with backbones), as are amphibians, reptiles, birds, and mammals, and we all have very similar brain structures. If the scientists can better understand how the brain controls the conflicting motivations of feeding and maternal care in us fish, it could lead to insights into eating and metabolic disorders even in people!

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the lateral line – my superpower

Hi there! For this post, I want to talk about dancing. That’s right folks, I perform a little dance when I’m trying to get Toni or the other ladies to hang out with me. I also do this move called a “lateral display” where I make myself look really big and shake my body at other males to threaten them. When I fight with other males, we push around a lot of water at each other. If we can’t resolve our fight with these behaviors, then we go to the more dangerous behaviors, like biting each other.

See fish have this thing called the mechanosensory lateralNeuromast line. It’s composed of these little bundles, called neuromasts, that are on my skin or inside canals beneath my skin. These neuromasts have little hair cells on them that are covered by a jelly-like mass called the cupula. When something near me moves in the water, it creates water motion that deflects the cupula over these neuromasts and opens mechanically gated ion channels on the hair cells. This information then gets sent to my brain. This water-movement information helps me orient in a current, find things to eat, avoid things trying to eat me, and even communicate with my friends (and enemies!).

My humans are interested in how I use this sensory system for social communication. To look at my lateral line system, they placed me in a container of orange stuff they called DASPEI. This dye stains the hair cells of my neuromasts and makes them glow in the dark! Here’s a picture…. Think I’ll just use this as my Halloween costume this year!


They can also make my lateral line non-functional. They place me in a beaker of chemicals, either cobalt chloride or aminoglycoside antibiotics, for a few hours. This chemically disables my neuromasts. It’s a weird feeling. I can still feel it if they touch me, but I can’t feel any of the water movements from the other fish around me. Anyways, after this treatment, they let me recover overnight. Then they let me do my thing! I either get to court Toni or defend my territory from another dude. The humans then compare my behaviors when I have an intact functioning lateral line to when they’ve ablated it.

They found that when they knock out my lateral line, I have a hard time assessing the other male. Sure, I can see how big he is, but when we’re closely size-matched, that water movement information also helps me. Because we can’t feel the water we’re trying to push at each other without this functioning lateral line, we also escalate our fights a lot quicker. Man, that’s tiring! I’m happy I normally have use of my lateral line so I don’t have to do that all the time… They even looked in my brain to see where this information is processed!

Now my humans are trying to determine how we use our lateral line during reproduction. As I said, I perform a little dance called a “quiver” when courting Toni. My humans think that Toni uses the water information produced by this dance to help decide which male she wants (obviously I’m the only correct choice!). So they’re knocking out her lateral line system and seeing what it does to her receptiveness to me. I really hope my dancing still impresses her… Check back later to hear from Toni and how this impacts her!

Want to know more about the lateral line? Check out these papers from the Maruska lab:

  • Butler, J.M. and K.P. Maruska. 2016. Mechanosensory signaling as a potential mode of communication during social interactions in fishes. Invited Commentary, J Exp Biol 219: 2781-2789. link
  • Butler, J.M. and K.P. Maruska. 2016. The mechanosensory lateral line system mediates activation of socially-relevant brain regions during territorial interactions. Front Behav Neurosci 10:93. link
  • Butler, J.M. and K.P. Maruska. 2015. The mechanosensory lateral line is used to assess opponents and mediate aggressive behaviors during territorial interactions in an African cichlid fish. J Exp Biol. 218: 3284-3294. link
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