News archive

The annual meeting of the International Behavioral Neuroscience Society (IBNS) is coming to Tromsø June 24-29 2025!

We are pleased to announce that the IBNS Program Committee is now accepting proposals to develop an exciting program for the 2025 Annual Meeting, to be held June 24-29, 2025, at the Radisson Blu Hotel, Tromsø in Tromsø, Norway. Symposia play a major role in shaping the IBNS annual meeting by focusing on timely, relevant, and innovative research in the field of Behavioral Neuroscience. More information is provided below, so please share the Call with your friends and colleagues.

October 14, 2024 is the deadline for priority consideration of symposium or satellite proposals. More information can be found here.

Important Dates

In a recent study, published in Psychopharmacology, we aimed to investigate the underlying neurobiological mechanisms that regulate different natural reward seeking behaviors: sexual behavior and sucrose self-administration. Different types of stimuli can have attractive and motivational values that induce approach and consummatory behavior. Food, social interactions, and sexual partners are examples of ‘natural rewards’, because they induce behavior that is needed to survive, or to ensure survival of the species. At the same time, they are examples of ‘intrinsic rewards’, rewards that have an unconditioned, inherently pleasurable value.

Sexual behavior and sucrose consummation are innately motivated and rewarding behaviors and are usually studied separately. It is therefore not fully known whether specific micropatterns of those behaviors overlap and if they are caused by the same mechanisms in the brain.

In this study, the role of a specific type of neurons, the so-called CaMKIIa+ neurons, in the bed nucleus of the stria terminalis (BNST) was explored using chemogenetic silencing and -stimulation. Through detailed behavioral analysis, we demonstrated that these cells play a significant role in the regulation of both sexual behavior and sucrose intake. Although the behavioral outcome measures differed between these two behaviors, the BNST appeared to regulate the modulation of the  tempo of engagement in both these behaviors in male rats. Moreover, our study confirmed that the internal physiological state of the animal (when an animal is socially or food deprived) affects how the BNST modulates these behaviors. These findings suggest that different types of natural rewards may cause a similar brain circuitry to regulate the display of motivated behaviors. Overall, this research provides valuable insights into the neural mechanisms underlying natural reward seeking and sheds light on the interconnected nature of reward-related behaviors in male rats.

The study “CaMKIIa+ neurons in the bed nucleus of the stria terminalis modulate pace of natural reward seeking depending on internal state” was a collaboration between Patty Huijgens, Roy Heijkoop, Louk Vanderschuren, Heidi Lesscher and Eelke Snoeren from UiT The Arctic University of Norway and Utrecht University (The Netherlands). Funding was obtained from the Norwegian Research Council.

Huijgens PT, Heijkoop R, Vanderschuren LJMJ, Lesscher HMB, Snoeren EMS. CaMKIIa+ neurons in the bed nucleus of the stria terminalis modulate pace of natural reward seeking depending on internal state. Psychopharmacology. 2024. doi: 10.1007/s00213-024-06561-5

Excessive consumption of foods rich in sugar and fat, often referred to as “junk” or “fast” foods, plays a central role in the development of obesity. The highly palatable characteristics of these foods activate hedonic and motivational mechanisms to promote food-seeking behavior and overeating, which is largely regulated by the brain reward system. This study, published in Physiology & Behavior, investigated whether consumption junk food for several weeks can change the responses in the brain reward system to food rewards.

In order to study this, we used a female rat animal model that was placed on different diet regimes. While the control group ate healthy normal food pellets, 3 other groups of rats were fed with the so-called Cafeteria (CAF) diet. This diet consists of several unhealthy, often ultraprocessed, but tasty products that humans consume too (e.g. bacon, muffins and cookies). That way it combines the smell and texture properties and palatability of the foodstuffs that promote overconsumption, and mimics a certain pattern of problematic human consumption. We had three junk food groups: one with unlimited access to the junk food, one that only received 30% of their diet with junk food (besides the healthy food) and one group that only received the junk food in the weekend. After having eaten this diet for 6 weeks, the rats were once more exposed to the junk food reward before the brains were collected and the effects on brain activation was studied.

We found that all CAF diet regimes decreased brain cell activation in an important brain reward region, the nucleus accumbens-shell, when presented with a food reward. No changes in neural activation upon the different diet regimes were found in other brain regions, such as the prefrontal cortex and the ventral tegmental area. Just as we hypothesized, our data suggests that long-term junk food exposure can affect the brain reward system, resulting in decreased activity of the nucleus accumbens-shell.

The article “Changes in reward-induced neural activity upon Cafeteria Diet consumption” was a collaboration between Roy Heijkoop, Jaume Lalanza, Montserrat Solanas, A. Álvarez-Monell, A. Subias-Gusils, Rosa Maria Escorihuela, and Eelke Snoeren from UiT The Arctic University of Norway, Norway and Universitat Autònoma de Barcelona (Spain). Financial support was received from Helse Nord.

Every 15th of the month (kl. 12:15-13:00), a different keynote speaker (from different institutes) will present their research, followed by some free coffee, tea and snacks!

(location: MH1 Store Auditorium)

 

This Spring 2024 we present to you the following speakers:

Monday 15th of January

Natasa Skalko-Basnet (IFA)

‘Drug Delivery: why, where and how’

Wednesday 15th of February

Terje Johansen (IMB)

‘Selective autophagy: Waste sorting in our cells promotes healthy aging’

Friday 15th of March

Erik Knutsen (IMB)

‘Using single cell sequencing to study breast cancer metastasis’

Monday 15th of April

James McCutcheon (IPS)

‘Behavioural and neural signatures of protein appetite’

Wednesday 15th of May

Bodil H. Blix (IHO)

‘Changing the conversation about aging’

Friday 14th of June

Kristin B. Borch (ISM)

‘Risk factors for early onset versus late onset colorectal cancer’

We are proud to share that our research group has been awarded with the annual Research Prize of the Faculty of Health Sciences at UiT The Arctic University of Norway.

The committee stated that: "Over the course of several years, the researchers have built up a renowned neuroscience environment at the university. The main focus is on the question of how the brain regulates naturally rewarding behavior. The group has a large international network, which has contributed to success in obtaining external funding. Additionally, they can point to an impressive list of publications with solid research results."

Here a link to the orginal news item.

Are you a passionate researcher at the interface of Machine Learning, Data Science and Neuroscience, whose goal is to advance our understanding of the principles of sociosexual behavior in biological networks?
-> What about applying for a MSCA-PF with us?

UiT The Arctic University of Norway has established «The Arctic MSCA-PF program» (uit.no/project/arcticmsca) to recruit excellent young researchers planning to apply for a Marie Skƚodowska-Curie Postdoctoral Fellowship (MSCA-PF) to pursue a career in research. We invite applications from promising young researchers within the field of Neuroscience, machine learning, data science, systems neuroscience, behavioral neuroscience. The selected candidate will write a proposal for a 24-month MSCA-PF at UiT together with Prof. Eelke Snoeren. This is an opportunity to accelerate your research career while living in the urban research city of Tromsø, uniquely located at the top of the world surrounded by some of Europe’s last pristine wild nature.

We are looking for passionate researchers at the interface of Machine Learning, Data Science and Neuroscience, whose goal is to advance our understanding of the principles of sociosexual behavior in biological networks. 

The research team led by Prof. Dr. Snoeren aims to investigate the neural regulation of natural rewarding behaviors, both in physiological and pathological circumstances. We use sexual behavior as a natural incentive-driven behavior to study the reward system in rats. We are especially interested in the regulation of the transition from an intrinsic motivational state into the execution of copulatory behaviors, and the effect of experience. Our research focuses on circuitries involved in both sexual behavior and reward, including e.g. the hypothalamus, medial amygdala and ventral pallidum. To reach our goals, the team employs a combination of traditional behavioral testing, modern manipulation methods, and advanced imaging.  

For future research aims, we are looking for enthusiastic MSCA-PF funded postdoctoral fellows who would like to spearhead the development of an (open source) automated complex social behavior annotator with (un)supervised machine learning. However, applications from data scientists and/or neuroscientists with good ideas linked to our current research are very welcome as well.  

Please send your CV (max 3 pages) and describe a research project that will strengthen and complement the presented research (max 2 pages) to eelke.snoeren@uit.no by Feb 17th 2023. Mark your application "Arctic MSCA". Successful candidates will be contacted in late March 2023.

Application deadline: Feb 17th 2023

More information: https://euraxess.ec.europa.eu/jobs/65805 

A few months ago, Eelke was challenged to crochet a blanket with the image of a neuron. That challenge had to be accomplished, of course! Now, four months later, the blanket is really here!

The blanket received a lot of attention on Twitter, and several people asked for a pattern. As I am only an amateur, there is no professional pattern available, but here's a description of how the blanket came about.

First, I watched all instruction video’s of Tinna Thorudottir Thorvaldar on how to make a blanket using the mosaic crochet technique (I actually made this Queen Cal blanket first).

Then I used the free online software stitchfiddle and a random image of a neuron available on the internet to make my own pattern.

The end result is a blanket of 150x96cm including the double border. The pattern is based on yarn that gave ca 22 stitches per 10 cm of blanket.

The pattern: (download on the right)

On the pattern you see which color to use (color 1 (e.g. blue) as background and color 2 (e.g. grey) as neuron). As soon as a third color comes in (e.g. white), this is marked next to color 2.

X = double crochet
à or ~ = single crochet
No symbol = double crochet for color 1 and single crochet for color 2
Black = nothing, follow as if it was empty, it just shows how the final image will become

If someone gets inspired, I would love to hear about it!

Enjoy!

Eelke

Are you curious about the effects of food on the brain? Are you interested in psychology and neuroscience? Do you want to know how a biomedical experiment works? If you have answered “yes” to one of these questions, you might like to participate in a study about the effects of food on the brain, being conducting at the Department of Psychology at the Faculty of Health Sciences at UiT The Arctic University of Norway.

Are you curious about the effects of food on the brain? Are you interested in psychology and neuroscience? Do you want to know how a biomedical experiment works? If you have answered “yes” to one of these questions, you might like to participate in a study about the effects of food on the brain, being conducting at the Department of Psychology at the Faculty of Health Sciences at UiT The Arctic University of Norway.

This study is part of a translational project (funded by Helse Nord) aimed to investigate the effects of junk food on the reward system of the brain. This reward system is a collection of structures in the brain and connections between them that regulate how we respond to different stimuli. This reward system works by linking beneficial situations or actions to a feeling of pleasure. Food, drinking, socializing and sex are hardwired in the brains of many animal species, including humans, to be pleasurable. We want to find out if eating junk food for a longer period could change how the reward system works.  

This translational project has two related research lines. In the first one, we test the effects of “cafeteria diet” in rats [you can read more about it in a review published by our research group: link to the review]. The “cafeteria diet” consists of the same unhealthy but tasty and ultra-processed products that humans eat. Looking at the rats’ behavior and the activity of specific parts of the brain at the same time, we are able to measure if and how junk food can change the reward system and behavior.

For the second line, we want to study the effects of food in human volunteers, by using a type of brain scan (functional magnetic resonance imaging, fMRI). 

Are you interested to participate? Do you want to know more about this project? 

Please fill up the form and we will contact you very soon: http://tinyurl.com/uitfoodreward  

The outcome of this project will contribute to explaining the underlying mechanisms of the vulnerability of the reward system by junk food consumption. This will help with more research, and hopefully therapies, for diseases that where the reward system has become unbalanced, such as obesity and addiction.

(picture (CC) by Marco Verch https://flickr.com/photos/30478819@N08/48814061166)

Eelke was interviewed by the radio program EKKO NRK P2. If you are interested in hearing more about our research project on the effects of excessive junk food consumption on the reward system, then listen to Ekko - NRK Radio (around 1:30, in Norwegian)

Eelke was interviewed by the radio program EKKO NRK P2. If you are interested in hearing more about our research project on the effects of excessive junk food consumption on the reward system, then listen to Ekko - NRK Radio (around 1:30, in Norwegian)

Tuesday September 7th marked the end of an era. After years of hard work, Patty Huijgens succesfully defended her PhD thesis entitled "Organization and orchestration of male rat sexual behavior". Professor Juan Dominguez of University of Texas and dr. Susana Lima of the Champalimaud Centre of the Unknown acted as opponents and their engaging discussions allowed then-candidate Patty to show the bredth and depth of her scientific knowledge.For parts of her thesis, Patty traveled to Utrecht in the Netherlands and Minneapolis in the US to perform experiments. Back in Tromsø, she will first stay in our group as postdoc, after which she will start her independent research line as a researcher.

Antidepressant treatment is often used for pregnant women who are depressed. Although the treatment with fluoxetine is generally safe and can be necessary to lessen the effects of depression, the drug could still have damaging long-term effects on the children of these mothers. Previously, we have found that adult rats behave differently when their mothers were given fluoxetine during pregnancy and breastfeeding. Social behavior, coping with stress, but also prosocial behavior are types of behavior that appear to be changed. In the current study, we found that the children also use a different investigation strategies when exploring a novel (and thus stressful) environment. The findings are published in the journal Psychopharmacology.

Fluoxetine is a so-called selective serotonin reuptake inhibitor (SSRI), which increases the concentration of the signal molecule serotonin in the small gaps between brain cells. The mechanism behind the antidepressant effect of SSRIs is still unclear, but elevated levels of serotonin may play a role. A problem, however, is that serotonin also has a role in the development of the brain of a fetus. The elevated serotonin levels during development caused by the SSRI treatment of the mother could thus, in theory, have an unwanted effect on the children.

Previous research with humans showed that children that were exposed to SSRIs can sometimes have a different social-emotional development. Some even suggested that the risk for autism spectrum disorders (ASD) is higher. But pregnant women only use antidepressants because they are depressed, which in itself is known for having effects on the child.

In order to make sure that we only study the effects of the drug, and not the effect of depression, we use animals in our research. Healthy female rats were treated with fluoxetine (or a control substance) during the period of pregnancy and breastfeeding. Their pups were allowed to grow up and then tested (at adult age) in a seminatural environment. This seminatural environment simulates the natural environment, and allows us to study in detail how each animal behaves and interacts with its environment and the other animals. Previously, we found that female rats that were previously exposed to SSRIs via their mothers showed reduced levels of social and prosocial behavior, while male rats struggle with coping with stressful situations. 

In the current study, we were interested in how the fluoxetine exposed animals behave in a situation in a relative stressful situation in which they are exposed to a novel environment with unfamiliar other rats. Therefore, we studied their behavior during the first hour after introduction to this seminatural environment and were interested in what strategy they would use to explore the unfamiliar environment (non-social investigation) and in meeting other rats (social investigation). The results showed that rats that were perinatally exposed to fuoxetine used different aspects of non-social investigation behaviors, while normal social investigation behaviors were used. More specifically, both fluoxetine-exposed males and female rats spent more total time running around the environment than control rats whose mothers did receive the placebo. Furthermore, fluoxetine-exposed females spent less time exploring objects and specific elements in the environment. Altogether, this suggest that SSRIs during pregnancy could lead to changes in behavior in the children later in life. It can lead to a quicker, less detailed investigation strategy in novel environments, especially in female offspring.

This study is part of a collaboration between our group at UiT The Arctic University of Norway and the University of Groningen. It was funded by Helse Nord RHF.

[Summary by Eelke]

Sylte, O.C., Johansen, J.S., Heinla, I., Houwing, D.J., Olivier, J.D.A., Heijkoop, R., Snoeren, E.M.S. (2021). Effects of perinatal fluoxetine exposure on novelty-induced social and non-social investigation behaviors in a seminatural environment. Psychopharmacology.

In Snoerenlab, we are very passionate about studying animal behavior in great depth. In our opinion, a thorough understanding of the patterns and structures of complex behavior, such as sexual behavior, is absolutely necessary for the formation of new hypotheses about how the brain regulates the behavior. In the recent decades, many new methods have been developed to study and manipulate the activity of neurons in specific brain regions. The description and analysis of behavioral results in studies using these techniques are often oversimplified. This leads to many missed opportunities in advancing our understanding of the relation between the brain and behavior. Therefore, we decided it was time to up the game for studies of sexual behavior in male rats, focusing on the behavioral organization of the pauses during sex in our latest paper which is now published in Behavioural Processes.

For this study, we joined forces with Fay Guarraci in the U.S. and Jocelien Olivier in the Netherlands, so that we could test our hypothesis in three different groups of rats. Our results showed that the duration of pauses before and after ejaculation in a sexual encounter are strongly related within each individual rat. In addition, the duration of a pause is longer when the immediately preceding sexual stimulation was stronger. When we look at the second ejaculation, we see that both the pauses before and after ejaculation are longer than those before and after the first ejaculation. Together, these findings lead to the new hypothesis that pauses before and after ejaculation may be regulated by a similar sex inhibition mechanism in the brain. So, our detailed study of behavior has provided pillars for future research that aims to unravel the neuronal mechanisms of sex pauses.

This research was funded by the Research Council of Norway.

[Summary by Patty]

Huijgens PT, Guarraci FA, Olivier JDA, Snoeren EMS. Male rat sexual behavior: Insights from inter-copulatory intervals. Behavioural Processes. 2021. doi: https://doi.org/10.1016/j.beproc.2021.104458

Not getting enough of the macronutrient protein in our diet has severe consequences for health and ultimately can lead to death. It has even been suggested that a low level of dietary protein can cause obesity by leveraging up intake of fat and carbohydrate. However, little is known about how the brain ensures adequate protein intake. In this recent paper published open access in The Journal of Neuroscience , we showed that when rats were protein-restricted a key part of the brain's reward circuity, the VTA, was activated more strongly when rats were drinking protein than carbohydrate. Moreover, after the rats' diet was changed their behavior towards protein shifted quickly even though the VTA activity evoked by protein remained high.Thus, there might be persistent effects of protein deprivation on brain activation.

This work was funded by the Biotechnology and Biological Sciences Research Council [grant # BB / M007391 / 1 to JEM], the European Commission [grant #GA 631404 to JEM], The Leverhulme Trust [grant # RPG-2017-417 to JEM and JA-S.], And Tromsø Research Foundation [grant # 19-SGJMcC to JEM).

[Summary by Jaime]

Chiacchierini G, Naneix F, Peters KZ, Apergis-Schoute J, Snoeren EMS, McCutcheon JE (2021). Protein Appetite Drives Macronutrient-Related Differences in Ventral Tegmental Area Neural Activity. The Journal of Neuroscience ,  41 (23): 5080-5092.  doi: 10.1523 / JNEUROSCI.3082-20.2021.

Babies cry, dogs bark, horses neigh and birds sing. Every animal makes its own sounds which can serve different functions. Babies might cry because they are hungry and want attention from their mothers, dogs bark to communicate they want to play or to warn for intruders, and birds sing to attract a mate partner. Rats also make sounds, and some of these sounds, ultrasonic vocalizations, are sounds that we as humans cannot hear. In our latest study, published in the journal Physiology and Behavior, we investigated the role of these vocalizations in more detail: do silent rats behave differently or similarly to vocalizing rats when we put them in a seminatural environment with multiple unfamiliar rats?

Rat ultrasonic vocalizations, or USVs, occur at two different frequency ranges. The 22-kHz calls are often produced in aversive situation and are believed to act as warning signals, whereas the 50-kHz calls are considered positive calls and are emitted before, during and after pleasurable events such as sexual or social behavior. Whether those vocalizations have any purpose, and if so, which purpose that is, is not yet clear.  Some studies have suggested that the 50-kHz calls have a function in communication, because they found that rats approach the playback of recordings of these calls. In our laboratory, however, we have not been able to replicate these findings.

In our latest study, we hypothesized that if these USVs are indeed used as means of communication in social behavior, it would be most visible during the first encounters with unfamiliar rats. We therefore performed surgery (devocalization) in one group of rats to disable them from making USVs. If USVs are important during social interactions, we expected that the silent rats would behave differently from another group of vocalizing rats. We tested their behavior in a seminatural environment in which rats can freely move around and socially interact with each other in groups of 7 rats consisting of both silent and vocalizing rats.

We found that during the first hour in the seminatural environment, being unable to vocalize did not change their behavior. They were just as quick to meet other rats, showed similar social investigation behavior, passive social behavior or aggressive behavior as their vocalizing group members. Furthermore, the non-social exploratoring behaviors and behaviors reflecting anxiety or stress-like states were also unaffected. These results demonstrated that a disability to vocalize did not result in significant disadvantages (or changes) compared to intact conspecifics regarding social and non-social behaviors. This suggests that USVs might not be very important for communication, and that other (multi)sensory cues (e.g. smell) are more relevant in social interactions than USVs.

This study is part of a collaboration between our group at UiT The Arctic University of Norway and the Norwegian University of Science and Technology.

[Summary by Eelke]

Indrek Heinla, Xi Chu, Anders Ågmo, Eelke Snoeren. (2021) Rat ultrasonic vocalizations and novelty-induced social and non-social investigation behavior in a seminatural environment. Physiology and Behavior. doi: 10.1016/j.physbeh.2021.113450

Why do we sometimes get distracted by things around us and what is happening in the brain when this happens? Distractions are a way of pausing what we are doing to check whether something important is occurring in our environment. In an animal like a rat this might mean being alert to potential threats (eg predators) even while in the middle of a meal.

 In these experiments we explored whether neurons in a brain region called the ventral tegmental area (VTA) were involved in distraction. The VTA is essential for reward (ie responding to good things like food) and learning and we wanted to know if it also responds to distractions. In the Leicester Division of Biomedical Sciences facility we used the cutting edge technique fiber photometry to measure the activity of brain cells in this area. Rats were presented with distracting events (flashing lights, tones etc.) whilst they were already drinking a sweet solution. We found that these distractors caused the rats to pause drinking, and that the VTA responded differently depending on whether the rat was distracted or not distracted. These results show that this important brain area, the VTA, is involved in monitoring the world for interesting or novel events. This may be important in disorders that affect attention such as schizophrenia and post-traumatic stress disorder.

Read the full paper at:  https://onlinelibrary.wiley.com/doi/full/10.1111/ejn.15108

Junk food is both appetizing and consists of high-energy nutrients, which is why the consumption of junk food plays a central role in weight gain, obesity and the associated health risks. To study the effects of junk food on different on different aspects of health, researchers have to use standardized diets, very often in animal models. The Cafeteria (CAF) diet model for animal experiments consists of the same tasty but unhealthy food products that people eat (e.g. hot dogs and muffins), and considers variety, novelty and secondary food features, such as smell and texture. This model, therefore, mimics human eating patterns better than other models.

Even though the features of the CAF model are promising , researchers still don’t completely agree about the exact ingredients and food products that should be included in the diet, as well as how the food should be administered (Barrett et al., 2016; Nilsson et al., 2012). The result is that each research laboratory uses a different CAF protocol. Although cultural and regional differences are relevant for translational approaches, a gold standard of the basic ingredients is necessary for inter-laboratory comparisons.

In our recently published review article, we systematically reviewed studies that have used a CAF diet in behavioral experiments and proposed a standardized protocol for CAF models based on the most used food products and ways of administration. In addition, we summarized the behavioral effects found to be caused by consuming CAF diet.

In the proposed diet, the animal can choose what to eat from different ingredients. The diet  combines different textures, nutrients and tastes, including salty and sweet products, and it is rotated and varied. Our summary of the behavioral effects of CAF diet showed that it alters meal patterns, reduces the hedonic value of other rewards, and tends to reduce stress and spatial memory. So far, no clear effects of CAF diet were found on locomotor activity, impulsivity, coping and social behavior.

[summary by Eelke]

Lalanza JF, Snoeren EMS. The Cafeteria Diet: a standardized protocol and its effects on behavior. Neuroscience & Biobehavioral Reviews. 2020. doi: 10.1016/j.neubiorev.2020.11.003

Sex hormones, such as estrogens and testosterone, are well known to be important for the menstrual cycle, development of sex specific characteristics, and gain of muscle mass. We understand the mechanisms behind these hormonal actions. Still subject to research is how sex hormones in the brain affect sexual behavior, aggression, and even memory. In our latest research project, carried out in Minneapolis with our collaborators, we discovered that in rats, male sex hormones change the structure of neurons in certain brain areas that are involved in the regulation of sexual behavior, motivation, and reward. These findings, published in the Journal of Neuroendocrinology , shine some light on how sex hormones might ultimately influence behavior.

Research on the effect of sex hormones in the brain is often focused on females. This is because the different phases of the menstrual cycle, which is regulated by fluctuations of sex hormone levels, dramatically affect sexual behavior in female rats. Female rats will only participate in sex during one of the menstrual cycle phases, just after levels of estrogens in the blood peaked. Previous research has shown that the high levels of estrogens cause neurons in the hypothalamus to change their structure. Because the hypothalamus is an important brain region for sexual behavior, it is therefore suggested that the structural neuronal changes partly explain why female rats become motivated for sex during the following phase of the menstrual cycle.

The structural neuronal changes in females during the menstrual cycle entail that the neurons become more complex due to estrogens. As shown in the picture, the structure of a neuron consists of a cell body, dendrites, and axons. The axons of a neuron connect with the dendrites of other neurons. More specifically, the contact between axons and dendrites occurs in even smaller structures on the dendrite called spines. When estrogens cause neurons in the hypothalamus of females to become more complex, it means that they increase the number of spines on the dendrites of neurons in the hypothalamus. This enables these neurons to make even more connections with other neurons. This increased connectivity in the hypothalamus caused by estrogens is necessary for female rats to be motivated for sex.

Even though males do not have a menstrual cycle, there are still fluctuations of male sex hormones during life and during certain behaviors such as aggression and sex. Therefore, the aim of our study was to find out whether male sex hormones in males can also cause the same structural changes of neurons that were found in females due to estrogens. To study this, we castrated male rats so that they would not have any sex hormones in their body and then looked at the dendrites of the neurons in different brain regions of those rats. Because neurons and their spines are tiny, we used a microscope that can take pictures of dendrites at a very high magnification and with a very high resolution. An example of such a picture is displayed here. This picture also shows a 3D reconstruction of the dendrite section that we made with the help of a specialized software program. With this 3D reconstruction, we were not only able to count the number of spines on the dendrite section, but also to determine the length and thickness of all of those spines.  

We found that dendrites of neurons in the hypothalamus of the castrated male rats (which did not have any sex hormones) only had about half the number of spines compared to those of males that still had sex hormones. When we treated castrated males with dihydrotestosterone (a “male sex hormone”), the number of spines was no different from non-castrated males. This means that sex hormones are necessary for male rats to maintain the normal architecture of the neurons in the hypothalamus. We also found effects of dihydrotestosterone on neurons in the amygdala, another brain region important for sexual behavior, and in the nucleus accumbens, a brain region in the “reward system” of the brain which responds to all kinds of things that we like, such as sex. Finally, we found some evidence that shows that male sex hormones may use a similar mechanism as female sex hormones through which they affect neuronal structure.

Whether the changing number of spines caused by male sex hormones are also important for sexual motivation in males will be investigated in future research. With this study, however, we have made the first step in finding out how sex hormones might influence behavior in males. It could well be that this is regulated in a similar matter as in females.

This study was conducted in the labs of Professor Robert Meisel and Professor Paul Mermelstein at the University of Minnesota in Minneapolis, USA. The research was funded by the National Institutes of Health and the Norwegian Research Council. Patty received a personal grant from the Norwegian Research Council for her research stay in Minneapolis.

[Summary by Patty]

Huijgens PT, Snoeren EMS, Meisel RL, Mermelstein PG. Effects of gonadectomy and dihydrotestosterone on neuronal pasticity in motivation and reward related brain regions in the male rat. J Neuroendocrinol. 2020. doi: 10.1111/jne.12918

Getting enough protein in our food is crucial for health and development. When we are still growing this protein is especially important. In this study, we looked at how inadequate dietary protein affects brain function both when rats were adults and during their adolescence. We used a recording technique called fast-scan cyclic voltammetry, and saw that low protein diets affected the release of dopamine, an essential neurotransmitter for motivation and learning. Interestingly, the consequence of the low protein diet differed depending on the age of the rats and had stronger effects in adolescent animals than in adults. This research, published as open access in Neuropsychopharmacology , highlights the vulnerability of the brain to dietary deficiencies during development.

Consolation behavior is a type of prosocial behavior that is aimed at an individual in distress. Typically, it involves physical closeness and contact, which has a calming effect on the distressed individual. In our society, it is behavior that we easily recognize, but consolation is not a purely human phenomenon: chimpanzees, dogs, elephants and prairie voles are some of the animals that console each other when the going gets tough. Based on our latest research, published in the journal Physiology and Behavior, we might be able to add rats to the list of animals that are capable of consoling each other.

Comparing types of behavior between species is never straightforward. Types of social behavior for example, are not always expressed exactly the same. It would for example be rare to see human families or other social groups lick each others teeth to greet each other, such as wolves do. On the other hand, sometimes behaviors might look the same, but they mean something quite different. A smiling dog is really just breathing; it expresses joy in a different way. Often we see common types of behavior in many species, but the ways these behaviors are expressed, developed based on the specific needs of the species (food situation, group organisation, location).

If we consider prosocial behavior (helping behavior, consolation) to be a social behavior intended to reduce stress, we should in our study be looking at patterns of behavior following situations that are stressful to the species we work with. Studies with other group animals looked for signs of consolation behavior after stressful fights in the group. Our seminatural environment proved to be the perfect setup to study those spontaneously occuring fights. 

The goal of this study was not solely to determine if rats show prosocial behavior, but also to study whether antidepressant use during pregnancy would have consequences for the child on this kind of behavior. Just as in previous work, we let healthy female rats breed with healthy males and afterwards separated the females into two treatment groups. During pregnancy and breastfeeding we treated these mothers with either the antidepressant fluoxetine or with a control substance. The offspring was thus either exposed or not exposed to fluoxetine during their development. After the 32 pups had grown up, we put them in our seminatural environment for eight days (eight at a time) and observed their behavior. If a fight occurred, we observed what each rat did in the following 15 minutes. In particular we were interested in social behavior (sniffing, grooming) and if witnessing or not had an influence on the behavior.

The first thing we noticed, was that females in the control group who witnessed the fight spent more time (during more episodes) on grooming other animals compared to the control females who did not see the fight happen. If only the animals who see the stressful situation react with this type of behavior, this reaction must be related to an implicit ‘understanding’ of the situation. Interestingly, females that had been exposed to fluoxetine, showed this consolation-like behavior less than control females, and equally when witnessing and not witnessing. This may not be entirely surprising, since fluoxetine exposure was linked to lower levels of active social behavior in our previous paper.

We further analyzed whether the consoling animal consoled the winner of the fight, the loser, or other rats. Even though it looked as if the consolers had more attention for losers of the fights, this did not turn out to be statistically significant.

Maybe surprisingly, both control and fluoxetine-exposed males did not show more active social behavior, or grooming behavior, after a stressful fight. Can we then conclude that male rats do not have the ability to show consolation or procosial behavior? Not quite. Maybe males do not experience this type of fights as so stressful that consolation is necessary. We know from other studies that male rats are capable of helping behavior, which is a form of prosocial behavior too.

Does this research definitively show that female rats are capable of consoling conspecifics? Not exactly. First of all, quantifying the stress levels caused by stressors is possible by measuring stress hormone. In our current setup, that is not possible without disturbing the animals. This means that we don’t really know if the fights did cause significant stress, or if the stress was relieved by being groomed. Still, our results are the first to argue that rats might have to be added to the growing list of species capable of the complex and socially beneficial behavior that is consolation.

This study is part of a collaboration between our group at UiT The Arctic University of Norway and the University of Groningen. It was funded by Helse Nord RHF.

[Summary by Roy]

Heinla, I., Heijkoop, R., Houwing, D.J., Olivier, J.D., Snoeren, E.M.S. (2020). Third-party prosocial behavior in adult female rats is impaired after perinatal fluoxetine exposure. Physiology and Behavior. doi: 10.1016/j.physbeh.2020.112899

We are beyond proud to announce that our postdoc Jaume Ferrer won a very prestigious, EU funded, Marie Curie individual fellowship. With this grant, Jaume will study the effects of junk food on the reward system. In other words, the mechanisms by which unhealthy food modifies our brain in relation to our motivations and rewards

We are beyond proud to announce that our postdoc Jaume Ferrer won a very prestigious, EU funded, Marie Curie individual fellowship.

With this grant, Jaume will study the effects of junk food on the reward system. In other words, the mechanisms by which unhealthy food modifies our brain in relation to our motivations and rewards

As part of a special programme at UiT, Jaume visited our lab in 2018. Brain storm and writing sessions together with supervisor Eelke Snoeren and lab manager Roy Heijkoop led to a first project proposal that sadly did not make the cut. The improvements of this year's version were appreciated by the referees, who gave a high score.

We hadn't even properly introduced the new associate professor of our research group, when Dr. James McCutcheon was awarded a Starting Grant from Tromsø Forskningstiftelse. He will now be able to build his own research team, which will work to find out how animals regulate their intake of protein.

James earned his PhD at University College London, after which his spent a couple of years as a postdoc in Chicago. He returned to England as an associate professor of neuroscience at the University of Leicester, where he gained more experience running his own research team and developed ideas for research projects that ultimately led to this grant proposal.

The new project James will start, is connected to a phenomenon he has long been interested in. What are the mechanisms in the brain that cause animals to get the nutrients that they need, and what happens if something in those mechanisms goes wrong? Animals have a finely tuned sense of procuring the appropriate mixture of nutrients to survive. The intake of protein for example, appears to be regulated in many animal species. To learn more about these the underlying brain mechanisms, the project will use cutting-edge techniques, that enable us to look at the activity and communication of specific groups of brain cells in and between specific brain areas. 

With the new grant, James will purchase the necessary equipment, and set up a specialized research team, which will initially consist of two postdoctoral researchers.

Helsinki formed the stage on which this year's Nordic Neuroscience meeting took place. After Trondheim in 2015 and Stockholm in 2017, this was the third time the biennial conference was organized. We were there to present our latest research.

With only about 400 people, the Nordic Neuroscience conference is relatively small, resulting in a nice athmosphere during lectures and poster sessions.

At these poster sessions, our group was represented by no less than four posters. Indrek, Roy and Jan all presented posters about the influence of perinatal exposure on behavior of the offspring. For Jan, who received an A for his master's thesis the week before, presenting his poster was a nice introduction to scientific conferences. Patty presented a poster about the role of a specific circuit in the brain on the motivation for a food reward.

Another benefit of these smaller conferences is the possibility to network with other researchers in the Nordic region and forge new collaborations. This usually takes place at the fringes of the conference, for example during the commen dinner on Thursday, when even the president of the European Research Council and the president of the Federation of European Neuroscience Societies joined us.

When pregnant women get depressed, they often get treated with the antidepressant fluoxetine. Using this antidepressant is generally safe and can be necessary to lessen the effects of depression. Still, it has been difficult to find out if this drug has damaging long-term effects on the children of these mothers. In our latest work, we have found that adult rats behave differently when their mothers were given fluoxetine during pregnancy and breastfeeding. Social behavior and coping with stress are types of behavior that appear to be changed. The findings are published in the journal Neuropharmacology.

Fluoxetine is a so-called selective serotonin reuptake inhibitor (SSRI), which increases the concentration of the signal molecule serotonin in the small gaps between brain cells. The mechanism behind the antidepressant effect of SSRIs is still unclear, but elevated levels of serotonin may play a role. But serotonin also has a role in the development of the brain of a fetus. So if a fetus is exposed to a drug that elevates serotonin levels, does something happen to the brain, and would we still see these effects when the children are grown up?

Previous research with humans showed that children that were exposed to SSRIs can sometimes have a different social-emotional development. Some even suggested that the risk for autism spectrum disorders (ASD) is higher. But pregnant women only use antidepressants because they are depressed, which in itself is known for having effects on the child.

To make sure that we can separate the possible effects of a depression from those of the antidepressant, animals can be used. Some animal studies show differences in aggression, play behavior and sexual behavior if rats were exposed to SSRIs during development. Very often though, only one type of behavior can be tested at a time, and the time an animal is tested is limited. The results of these tests can indicate that something has gone wrong in isolation, but do not tell us how big the effects are ‘in real life’.

In our experiments, we treated healthy, female rats with fluoxetine (or a control substance) during the period of pregnancy and breastfeeding. We let their pups grow up and put them together (eight at a time) in a seminatural environment for eight days. This seminatural environment is much bigger than a usual test box and is divided in an open area (where it gets light and dark during the day) and a dark ‘burrow’ area that looks similar to the tunnels of rats under the ground. This way we could study in detail how each animal behaved and interacted with its environment and the other animals.

When we analyzed the animals’ behavior at baseline on the fourth day in the seminatural environment, we saw that both fluoxetine (FLX) exposed males and females spent more time on social behavior. More specifically, the animals were resting together and ‘cuddling’ more, compared to the control animals (passive social behavior). On the other hand, FLX-females tended to take less part in active social behavior.

To see if their behavior changed during and immediately after a stressful situation, we played a loud white-noise for 10 minutes. This caused the animals to run around in the burrow area much more. In the open area, it is more difficult to hide: animals that were there, mostly fled to the burrow, but some froze in the open area. The differences we saw earlier disappeared: the social behavior of exposed animals was no longer different from the control animals. However, we saw that the FLX females that liked cuddling with other rats now started to rest more alone, while the control females were instead seeking each other’s company.

Rodents groom themselves very frequently. Besides the obvious purpose of skincare, self-grooming can also be seen more during and after stressful situations. This type of self-grooming has previously been explained as displacement behavior. At baseline, especially the FLX-males behaved differently from the control-males: they self-groomed much less. But after the white noise, they started self-grooming more than before, even more than control-animals. FLX-females also spent more time on self-grooming than before the stressful situation. We believe that this increase in self-grooming is a sign of increased stress levels, and that they use self-grooming as coping mechanism.

This study showed that, in rats, SSRI exposure during and immediately after pregnancy was associated with long-term effects on social behavior and stress-coping. In addition, these differences are not equal between males and females. We also showed that the seminatural environment provides a good experimental setting, in which we can study many different behaviors and their interactions. We do have to be careful to draw big conclusions about the use of SSRIs. Even though we see that social behavior and stress-coping are different after SSRI exposure as fetus, that does not necessarily mean that these animals were worse off. Much more research is needed to map long-term effects of SSRIs on different types of behaviors.

This study is part of a collaboration between our group at UiT The Arctic University of Norway and the University of Groningen. It was funded by Helse Nord RHF.

[Summary by Roy Heijkoop]

Houwing, D. J., Heijkoop, R., Olivier, J. D., & Snoeren, E. M. (2019). Perinatal fluoxetine exposure changes social and stress-coping behavior in adult rats housed in a seminatural environment. Neuropharmacology, 151, 84-97. doi:10.1016/j.neuropharm.2019.03.037

We are pleased to announce that last November, Helse Nord RHF awarded us a sizeable grant (3.25 million Norwegian krone). Starting in september 2019, this money will be used in the project: "The risk of excessive junk food consumption on the brain reward system. A translational study."

Being the northernmost neuroclub in the world is interesting, but every so often it can also be very advantageous to get inspired and strengthen collaborations abroad. Our department has kindly offered to support the scientific development of our group by enabling a stay at a foreign university.

Scientific conferences are a good channel to communicate your research, learn about colleagues’ findings and experiences, get helpful input and forge collaborations. Conferences also can be the perfect backdrop to get together with old colleagues and friends. This year’s Dutch Neuroscience Meeting was all of this!

Eelke was invited to give talks about both our research lines, and to chair a session. This picture was taken during her talk about what we found when we looked into social behavior of offspring that were perinatally exposed to the antidepressant fluoxetine.

PhD student Patty Huijgens is currently overseas, doing research in the lab of Professor Robert Meisel at the University of Minnesota. She sent us a stunning photo she made, showing dendritic spines in different brain areas.

Spines are the tiny, in this case mostly stalk-like, protrusions on the "receiving" end of neurons. Due to the fact that in a short time spines can (dis)appear or change shapes, they play a vital role in connectivity between neurons, and are most likely a key mechanism behind learning and memory.

After a day filled with four thought-provoking lectures and excellent questions from the audience, the only conclusion we were able to draw was: let's do this again!

Our own Eelke Snoeren gave the first lecture, about the neuroanatomical background of motivation for -and execution of- a specific rewarding behavior, sex. Because this behavior is highly stereotypical, we can investigate which environmental cues are involved during specific phases and what the driving or inhibiting brain projections are. Also, what are some of the new instruments in the neurobiologist's toolkit, when it comes to activating or silencing brain cells, brain areas or connections between areas?

The second lecture was provided by Louk Vanderschuren, who is a professor at Utrecht University in The Netherlands. He explored the definition, social necessity and neurobiology of play behavior. At which age do we see play behavior, which relation does it have to aggression and sexual behavior and how much can we find out about the anatomy using an operant chamber and a drug commonly used for the treatment of ADHD?

After a much needed lunch, we reconvened to see the contribution of James McCutcheon, lecturer at the University of Leicester in the UK. James explained how animals select their food and how their physical needs may drive the motivation towards the selection of certain nutrients. Measuring dopamine release in the brain, he researches how nutrients elicit reward, but also how cues that are associated with food can provoke dopamine release, which is of particular relevance in an environment where we are often confronted with commercials or sweet tasting, but sugarless, foods.

The lecture of Oliver Bosch, professor at the University of Regensburg in Germany, concluded the day. His research subjects are the seemingly extremely gregarious prairie voles. These voles display social monogamy, which makes them very interesting to study social bonds. Oliver started out by explaining how these animals maintain bonds, but then focused more on what happens when social bonds break. There appears to be an important role for corticotropin-releasing hormone on the release of oxytocin in the reward-associated nucleus accumbens.

We thank the guest lecturers for their efforts to immerse our university in neurobiology for a day. But we also like to thank our audience for their attention and their role in productive discussions. We noticed that a large part of the audience attended all lectures, which our lectureres really appreciated. We will certainly try to organize this type of seminar more frequently, so stay tuned.

Below, from left to right:

James McCutcheon, Eelke Snoeren, Oliver Bosch, Louk Vanderschuren

Last week UiT became a full partner of the Norwegian Research School of Neuroscience (NRSN). This means new opportunities for both PhD students and Faculty.

This research school offers Norway-based PhD students in all fields of neuroscience interesting courses, summer schools and other events, which aim to provide these young researchers with a strong theoretical background. NRSN is funded by the Norwegian Research Council.

For PhD students: check out the website to see which activities might be interesting for you. Remember that participation is paid for! The annual PhD conference (organized by PhD students), is highly recommended.

Menno Witter honored us with a visit and gave a guest lecture on neurobiological research to a highly interested and enthusiastic audience.

Witter, who works at the Kavli Institute of Systems Neuroscience (NTNU), quickly led us through the past decades of research into the neurobiology of memory and navigation, before showing how this research lead to important pathways towards understanding pathologies of the brain, including Alzheimer's disease.

At first, hilarity ensued when the audience proved to be too numerous to fit inside the lecture room which was booked, but a larger one was quickly found.

We thank Menno for his excellent and very interesting lecture, and we hope to welcome him back sometime in the future.