Author Archives: The Physiological Society

About The Physiological Society

The Physiological Society brings together over 3,500 scientists from over 60 countries. Since its foundation in 1876, its Members have made significant contributions to our knowledge of biological systems and the treatment of disease. We promote physiology and support those working in the field by organising world-class scientific meetings, offering grants for research, collaboration and international travel, and by publishing the latest developments in our leading scientific journals, The Journal of Physiology, Experimental Physiology and Physiological Reports.

Shark Diary, Episode II: Meet the team

The main goal of our Greenland shark research mission was to gather physiological and biological information about the sharks. We tagged every shark we caught with an identification tag, in case they were caught in the future. We measured body and fin length in all sharks and took a small sample of tissue from each animal for DNA analysis. To further our understanding of how these sharks use their environment, we tagged some with satellite bio-loggers, which track their location as they move about in the depths. We also wanted to understand more about the way they swim – as Greenland sharks are considered among the slowest swimmers in the sea.  We employed a different kind of tag for this called an accelerometry tag.

Some of the sharks were injured on the line – either by being bitten by other Greenland sharks or by swallowing hooks. These sharks were humanely euthanized and brought aboard the vessel so that we could study their internal anatomy. We studied the reproductive organs of both male and female sharks. We also studied their skeletal muscle to link how the muscles contract with their slow swimming speed.  Lastly, we wanted to study their hearts and blood circulation. We wanted to learn about heart rate, about blood pressure about how the heart muscle contracts and how much blood it pumps, and about blood chemistry.

John Fleng Steffensen, University of Copenhagen

The Greenland Shark first caught my attention back in 2001 when the captain of our research vessel told me he’d heard that the creatures live to be very old. When I searched for past research on this creature, I only found one reference to their age, from back in the 1960s, when P.M. Hansen found that one shark had grown only 8 cm in 16 years. Such slow growth seemed to suggest they might live very long. It was our work in finding a way to calculate the age of these sharks that eventually determined that they could indeed live for centuries! Our cruises to southwestern Greenland have taught us much more than just the sharks’ longevity: on our latest mission, we looked at heart muscles, properties of the circulatory system (heart rate and blood pressure), where and how fast they swim, and filming their feeding at depths of 200 to 600 meters.

Takuji Noda, The Institute of Statistical Mathematics

I am an interdisciplinary scientist working between biology and informatics. My main interests are locomotion, behaviour and physiology of fish in their natural environment and how to measure that information in various types and sizes of fish. Therefore, I am developing customized animal-attached data loggers, composed of a variety of sensors (the technique is called bio-logging). With colleagues, I have established a company called Biologging Solutions Inc. to support the creation of customized data loggers and solutions for improving data recovery.

I am interested in the swimming ability and behaviour of Greenland sharks, which live in deep and cold waters. In the fjord of Greenland during the expedition, we attached multiple-sensor data loggers to Greenland sharks. The loggers automatically detached from the sharks and popped up to the surface of the water, where we could find and recover them using radio telemetry. Using a high-resolution accelerometer and speedometer, we measured swimming patterns such as tail-beat frequency and speed to understand how slowly they move and if they exhibit bursting movement when feeding.

Although it was difficult to measure bursting moment during the recording period, the data showed the sharks generally swims at very slow tail-beat frequency (at about 6 seconds per beat). This supports the measurements from physiological experiments in the lab.

Julius Nielsen, University of Copenhagen

I am a PhD student from the University of Copenhagen and have been working on the #GreenlandSharkProject since 2012. This project investigates many aspects of the biology of Greenland sharks including longevity, feeding ecology, migration patterns and population genetics.

I first started studying sharks caught as bycatch by the Greenland Institute of Natural Resources during fish monitoring surveys. These sharks gave unique insights into this poorly studied species, for example revealing their extreme longevity. The oldest shark we analysed was at least 272 years old, making the Greenland shark the longest-living vertebrate known. We also learned that they catch fast-swimming prey like Atlantic cod and seals, an unexpected finding given their seemingly sluggish nature. How they do this is still a mystery; I expect they might be ambush predators, who catch prey by being stealthy rather than speedy, as well as opportunistic feeders, scavenging carcasses from the ocean floor.

On this expedition, my main focus is to deploy satellite tags on the sharks to learn more about their movement patterns. We especially want to tag sexually mature animals to learn about mating areas and pupping grounds. I will also take samples from any sharks too injured to release, to inform my ongoing investigations about feeding, longevity, and reproductive biology.

John, Peter, Diego and Emil

L-R: John Steffensen, Peter Bushnell, Diego Bernal and Emil Christensen aboard the research vessel.

Diego Bernal, University of Massachusetts Dartmouth

I’m a comparative physiologist who studies how temperature affects the swimming muscles of fish who are elite swimmers. These quick fish, such as the tuna and mako shark, keep their bodies warm. The Greenland shark is the opposite of the fish I usually study, it’s slow and cold. I was curious to learn how its muscles function in its cold environment and how it manages to catch its prey. On our last expedition to study these sharks, the equipment we brought to study the muscles was too small for the huge muscle fibres. We also learned that we needed a way to keep the samples at 1-2 degrees Celsius, to mimic the water temperature where the sharks live.

Peter G Bushnell, Indiana University South Bend

I am a comparative physiologist: I’m interested in how different animals adapt their bodily functions to meet their needs. I focus on the circulatory and respiratory systems of marine animals, and have been studying polar animals in the Arctic and Antarctic for more than 25 years. When my colleague John Steffensen and I discovered how little was known about Greenland sharks, we decided to look at various aspects of their biology such as their swimming ability, migratory movements, diet, metabolism, and reproduction.

On this particular trip I was interested in how their hearts work, as this will impact their cardiovascular system, metabolism, and swimming ability. To do that, I cut out little strips of heart muscle and stretched them between clips. Every time a strip was stimulated by a small electric current, as happens in a normal heart to cause it to beat, the strip would briefly contract (shorten) and then relax: this is called a twitch. By measuring various aspects of the twitch, like strength and duration, we can learn a lot about how the heart might operate in an intact animal.

Making this technique work in Greenland sharks proved very challenging. However, I have managed to conclude that a twitch takes about 3-5 seconds, putting maximum heart rate somewhere between 12-20 beats/min. To put that in perspective, your normal resting heart rate is about 60-70 beats a minute with a maximum heart rate around 180 beats/min. Heart function is temperature sensitive, so it is not surprising that Greenland sharks swimming in very cold and deep water have much lower heart rates. However, I believe their heart contracts very slowly, which is in keeping with the idea that they don’t do anything quickly.

Robert Shadwick, University of British Columbia

I am a physiologist who studies animal form and function, also known as biomechanics. I am interested in the structure and mechanics of the heart and blood vessels in a variety of animals. Blood pressure is an important indicator in an animal. In fish, it reflects the level of activity of a species. Tuna for example are fast, continuous swimmers and have relatively high blood pressure compared to slower fish such as carps.

Activity levels vary greatly among shark species. The Greenland shark is generally considered very sluggish, but may swim fast to capture and eat seals. The purpose of my study was to estimate average blood pressure in the Greenland shark, to understand how these large sharks compare to other species.

To do this, we used the aorta, a large blood vessel that carries blood to the gills. The aorta is very elastic at low blood pressure, but when blood pressure is high the aorta wall becomes stiff. This transition between elastic and stiff typically occurs around the average blood pressure of the animal. By measuring the flexibility of Greenland shark aortas at different pressures, we can estimate the average blood pressure of these animals.

Our preliminary results show that the Greenland shark aorta is very flexible at pressures below 3 kilopascals (kPa, a measurement of pressure), but becomes very stiff with further increase in pressure. Therefore, we can tentatively estimate the average blood pressure to be around 2-3kPa. Our own blood pressure, in comparison, is about five times more (13 kPa), and the slow-moving dogfish shark’s is 4kPa. These results support the idea that Greenland sharks are indeed a sluggish and likely a slow-moving species.

the team in Narsaq, Captial of south Greenland

The team enjoy an evening on land in Narsaq, south Greenland. L-R: Julius Nielsen, Takuji Noda, Bob Shadwick, John Steffensen, Diego Bernal, Peter Bushnell.

Holly Shiels, University of Manchester

As a fish cardiovascular scientist I am interested in the mechanisms that maintain or adjust heart function in a changing environment. Such knowledge has application to cardiac health and disease and in predicting how organisms, populations, ecosystems and natural resources respond to environmental change and stressors.

Investigating cardiovascular function in the Greenland shark is very exciting, because these animals are long-lived and thrive in cold environments.  Several of their cardiac features make them particularly interesting. The first is their very slow heartbeat. Although not surprising for an animal living at 1-2⁰C, it takes a long time for their hearts to fill with blood between one beat and the next. This affects how much the heart stretches out and how strongly it then contracts to push out the blood. We suspect stretch regulation of force is particularly important in this shark.

We are also interested in the Greenland shark’s longevity.  In humans, age is associated with many cardiovascular problems, such as fibrosis (the aged heart becoming stiffer). A key question for us is whether the Greenland shark heart stiffens with age. And if it does, how does that affect its ability to fill will large blood volumes between heart beats?

Both stretch and fibrosis of the heart muscle create an environment for arrhythmia – irregular heart-beats.  Arrhythmias are dangerous in humans, but what about sharks?

During the expedition, we used echocardiography to measure heart rate before releasing the sharks. In animals too injured to release, we collected the hearts and measured pressure and flow relationships. We then preserved the hearts to study their structure, including fibrosis, in the lab.

Emil Aputsiaq Flindt Christensen, University of Copenhagen

I am a biologist with special interest in the interaction between ecology and physiology, the so-called ecophysiology, of fishes. I work both in the field, fitting animals with tags to study their behavior in the wild, and in the lab studying physiology through both animal behavior and biochemical analyses of tissues.

My research has focused a lot on the salt and water balance in fish. In that regard, sharks and similar species are “osmo-conformers”, meaning that they maintain water balance by producing organic molecules such as urea and a chemical called TMAO.

TMAO is an especially interesting compound to me, because it stabilizes chemical reactions that happen in the body, which is helpful under the high pressure conditions found in the deep sea. Thus, analyzing TMAO levels in the Greenland shark might tell us something about how deep it swims.

On a side note, Greenlandic hunters feed their dogs with Greenland shark, but sometimes the dogs get poisoned. This might be because TMAO degrades to a poisonous compound called TMA.

Follow #SharkDiary on Twitter to see all the updates about the expedition.

This expedition was made possible by funding from the Danish Centre for Marine Research, the Greenland Institute of Natural Resources, The Danish Natural Science Research Council and the Carlsberg Foundation.

Shark Diary, Episode I: On the trails of the Greenland Shark

By Holly Shiels, University of Manchester

The Greenland shark was one of the lesser-known species of sharks up until last year when their extreme longevity was uncovered. The finding that they live in the deep, dark Arctic waters for hundreds of years captured the imagination of the world and the attention of scientists. How does an animal born in Shakespeare’s time still patrol the deep today? What do they eat? When do they breed? What features distinguish males from females?

There are many open questions about these enigmatic animals.  The purpose of our #GreenlandSharkProject expedition was to use physiology – the science of how living things work – to help us find answers.

The Greenland shark can live for over 400 years.

The Greenland shark is listed by the International Union for Conservation of Nature (IUCN) as data-deficient and near-threatened. While we know the species is under pressure to survive, we need more information about its biology to form an effective conservation plan.

To gather this information, John Fleng Steffensen, Professor in Fish Physiology at the University of Copenhagen, brought together an international group of eight physiologists. Our team includes experts in swimming and locomotion (kinematics), skeletal muscle and cardiac muscle, osmoregulation (the regulation of water, salt and other ions in the body) and eco-physiology (how an organism’s body adapts to its environment).

Researchers Diego Bernal, Bob Shadwick and Takuji Noda aboard the ship.

In the broadest sense, our mission was to gather data on the physiology of these mysterious animals – their hearts, their movements, their diet, and their reproduction. We were also interested in whether their body’s adaptation to cold water is related to their longevity. Clarifying how the Greenland sharks age without developing diseases associated with human ageing, like cancer and heart disease, could lead to new therapies down the line. Not only can we find clues about aging and disease, but also, understanding shark physiology is important for their conservation.

1,856 miles from Manchester to Nuuk

Before boarding the ocean-going research vessel to spend two weeks off the coast of southern Greenland, we gather in Nuuk, Greenland’s capital. The journey from Manchester to the world’s largest Island proves to be an adventure in itself.

After a hectic day in the lab in Manchester, I head to the airport for my flight to Copenhagen. I’m travelling light: a hoodie, woolen socks and the rest of the bag filled with electronics, glassware, and chemicals to make up the 15 kilograms I’m allowed to carry. A few weeks ago, I sent three large boxes of equipment and clothes to be put on a cargo ship to Nuuk.

Fast forward to a few hours later. I’ve reached my hotel l in Copenhagen and head out on the town for some Danish beer with three of the other scientists, as our flight to Nuuk isn’t until the morning. Drinking now is important, as the research vessel is dry. Too much heavy equipment on the rough sea to have alcohol blurring judgement!

When I arrive back to my hotel room, I remember that I’ll need to keep my scientific chemicals cool during the night. There’s no fridge in my room, so out the window suspended on a string they go. It’s about 5 degrees Celsius outside so they should be fine, as long as there are no mischievous Danish squirrels about.

The team prepares to board the Dash-8 to Nuuk.

By the morning, two more team members have arrived. The five of us board our Greenland Air flight to Kangerlussuaq, Greenland. The plan is to connect there on a small plane to Nuuk, where we will join the rest of the team. The weather, however, has different plans. A large and unseasonal snowstorm is brewing above Nuuk.

Our small Dash-8 tries to find a clearing in the snow that will let us land. After circling and circling, we attempt a landing twice but the wind and snow are fierce. The pilot has no other choice but to abort. The altimeter shows that one of our landing attempts brings us just 110 metres above the runway! Finally, the captain comes over the radio with the bad news that we need to head back to Kangerlussuaq. We are running out of fuel and there was no sign of the storm lifting. This is a problem, as our ship is meant to be leaving Nuuk that night.

Luckily, the storm eventually lets up and we are able to join the rest of the team at the ship. In the end, our departure is pushed back to the next morning because of a radar issue. This gives us a final restful night at the dock before the adventure at sea!

The team finally reaches the snow-covered research ship.

Follow #SharkDiary on Twitter to see all the updates about the expedition.

This expedition was made possible by funding from the Danish Centre for Marine Research, the Greenland Institute of Natural Resources, The Danish Natural Science Research Council and the Carlsberg Foundation.

Spinning Out of Control? Public Engagement at SPIN Cycle Festival

By Daniel Brayson, @drdanbrayson

SPIN cycling festival, a celebration of all things cycling, took place on the weekend of 12 May 2017 at the Olympia in Kensington, London. Here at The Physiological Society, we thought it would be the perfect opportunity to showcase the wonders of physiology, using funding from The Society’s Public Engagement Grants.

Banner pe grants 2017_extended deadline June

The premise of our activity was to find some anecdotal dogma, which is prevalent in sports like cycling, and disprove it. Put simply, we went on a myth-busting mission.

A popular assumption among amateur cycling enthusiasts is that it is good to cycle at a high cadence. Discarding the jargon, this essentially means pedalling really fast. Many people think this because successful professional athletes such as Chris Froome, and previously Lance Armstrong, cycled at very high cadences when they were racing in huge competitions such as the Tour de France, the most famous cycling race in the world.

We based our experiment on a paper in one of The Society’s journals, Physiological Reports, from 2015 by Formenti and colleagues titled Pedalling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer. What the paper essentially showed is that the faster you pedal for a given work rate, the more energy you use.

Bike like the wind

With this in mind, we set out to perform some live experiments on festival-goers. We set up a bike on a smart turbo trainer with a computer that we could use to read measurements. We recruited many willing volunteers over the course of the weekend, fitting them with a device to measure heart rate, and setting them up on the bike.

Using the smart turbo trainer, we set the amount of work that the volunteers would do to 150 watts of power and placed headphones on them. They then sat for 1 minute before beginning to cycle in time with a metronome, or a clicking sound, that was playing through the headphones. We changed the speed of the click at set intervals which meant that the volunteer would change their cadence accordingly. At each cadence, we recorded the heart rate of the volunteer twice, 30 seconds apart.

Pedalling faster, beating faster

We found that as pedalling rate increased, so did heart rate. This can be seen on the left-hand graph below by the line which goes up in diagonal from bottom left to top right. This suggests that faster pedalling did indeed require more energy, even though the power output remained constant.


Our graph, on the left, comes to a similar conclusion as Formenti and his colleagues on the right. As pedalling rate goes up, so does work rate and energy expenditure. Where Formenti measured oxygen uptake, which requires unwieldy equipment unsuitable for our event, we used heart rate as an easily obtainable proxy measurement, and it agrees nicely with Formenti’s findings.

What does it mean, really?

The real world meaning here is that cycling along the road in lower gears than necessary with high pedalling rate uses more energy than cycling in slightly higher gears but pedalling at a slower rate.

So what’s the deal with Chris Froome?

Chris Froome, and other pro cyclists are not your average human beings from a physiological perspective, so it’s probably a bad idea for us to copy them! The science does show that pedalling quickly at sustained power outputs up to 400 watts, achievable mostly by elite athletes, is far less wasteful. This is because most of the energy gets transferred to the bike in this scenario.


It was especially dynamic and rewarding to engage with a diverse mix of people and preach the gospel of physiology. I would like to thank all the visitors who staked their reputations by joining our experiment! I would also like to thank The Physiological Society for financial support and especially Anisha Tailor for all of her sage advice. A big thanks to Louis Passfield for his generous support and loan of equipment. Finally, I would especially like to thank all of my wonderful volunteer scientists without whom the whole event would surely have been a disaster Elizabeth Halton, Chris Fullerton, Ozama Ismail, Fulye Argunhan, Elena Wilde, Svetlana Mastitskaya, Xiao Xiao Han, and Nick Beazley-Long.



Five Pillars of Public Engagement

By Lewis Hou, @fiddlebrain, @leithlabs

For up to £5000 for innovative public engagement projects about any aspect of physiology (available to both members and non-members), apply by 14 June. This grant has funded exciting projects, including the project Lewis tells us about below, Leith Labs.


Ocean Terminal is a shopping centre down in Leith, a proudly independent district of Edinburgh next to the coast of the Firth of Forth. Far from a purely commercial ecosystem of shops, cinema, and gym, there exists community spaces, social enterprises, pop-up art galleries, design exchanges, living museums and as of June 2016, a long-term science programme, Leith Labs.

Leith Labs is not the first use of science in malls, but is unique in that it is a long-term science residency involving both university researchers and professional science communicators, with regular, monthly, free events for both passing shoppers, families, and the adult communities who use the space.

On a given Saturday, there are simple drop-in activities exploring the Leith Lab’s theme (be it the science of the North Pole for Christmas, or fireworks for Bonfire Night) or explaining local research with scientists from the four universities in Edinburgh. We also have Science Buskers, both professional from Eureka Edinburgh and trained from the university, who perform short shows drawing in crowds around our hacked Leith Lab unit that was very kindly donated by the shopping centre. Finally, we also have informal discussions over tea and biscuits with researchers and community members at the Living Memory Association, a living reminiscent centre.

Leith Lab’s strengths as a project are based on principles that are vital for any science communication or education project that wants to meaningfully engage with communities.

Reaching out to new audiences:

Too often in science communication, we are not critical enough about who we are reaching with our events, and whether we are reaching beyond the “already converted” to science. Only 2% of the UK population have attended a science festival in the last year (Wellcome Trust Monitor, 2015) & up to 20% do not engage in science at all. If we want to reach the other community members, we can’t expect them to come to us. We, as science communicators, need to reach out to these communities in spaces where people go, be it libraries, arts/music festivals, pubs, cafes or shopping centres. This is an important principle guiding Leith labs, and our evaluation data is primarily looking at who is coming to our events, and filling our postcards.



Reaching out to new audiences is not enough if this is just a one-off. Whilst there is definitely a place in science communication for high-quality events that happen once, or even annually, such as science festivals, the lack of regular, long-term engagement opportunities can be a real barrier to audiences and attitude change generally.

Our current plan is to ensure Leith Labs runs in the long-term, at least once a month. The hope is that with more collaboration from research groups, we can eventually hold events even more regularly. There have been many occasions where conversations start with “I’ve seen you guys a few times before…”, indicating it was only after a few times that they came and engaged with the activities. We already have a few returning families who come to Ocean Terminal especially for the activities and arrive even before we’ve set up!  We’re definitely interested in trying to evaluate how long it takes for people to come and visit.


For this project, we want it to be as community-led as possible. Over time, we want the questions collated from the post-cards to actually determine the themes of Leith Labs. If we get lots of questions based on space for example, there is obviously community interest in this, and this gives us an opportunity to reach out to the universities’ astrophysicists to help us provide content. We have been keen to reach out and collaborate with the community groups and projects that are already in Ocean Terminal, and this allows us to ensure that our talks are of interest.

Our close relationship with the Living Memory Association has been very important. Beyond providing a venue and support for the tea, science, and biscuits talks, we’ve had some success engaging their older audiences in some of the talks. This is still developing, and not quite there yet, but based on one community that use this space, Care for Carers, we’ve had several very successful talks discussing dementia and the role of music and language (including a session involving singing together).


From the outset, Leith Labs is trying to be as collaborative as possible, integrating with many different projects with overlapping goals. The planned programme built up towards being a major part of the university-led “Explorathon” project (EU Researchers Night) on the 30th of September and then continued as part of the Fun Palaces programme on the 1st of October (a nice tie to the origins of the project). Collaborating with Beltane, this provided mutual benefit, allowing the university to provide training for researchers and a venue out in the community (and new audiences).

On a similar note, we already have plans to integrate Leith Labs with other projects across the year (Edinburgh International Science Festival, Voluntary Arts Festival, Audacious Women Festival and Leith Festivals), and form partnerships with more university departments and life-long organisations such as Ragged University and People Know How. This is an important part of our sustainability plan for Leith Labs. We are all trying to do similar things when it comes to community engagement (science, further education, arts). The more we collaborate, pool resources and knowledge, and build relationships, the more we can achieve.


Evaluating of audience numbers and monitoring background: This can be very difficult and lots of different methods have been tried. Ideally, a project would have someone dedicated to evaluation. This of course depends on having a big enough team to dedicate someone to this task. During the Explorathon weekend, we were actually able to provide evaluation training beforehand for the volunteers.

Small audiences: For our tea, science, and biscuit discussions, it can sometimes be hard to get audiences even when community members usually use that space. Sometimes even too scientific a title can be intimidating, so we tried to have more broad titles, and to link each science talk with a more general discussion about art or society. However, our deepest engagement tends to happen with smaller audiences, so don’t neglect quality for quantity.

Thank You: A massive thank you to The Physiological Society for funding the project through their public engagement fund. Additional financial and in-kind support came from Edinburgh Beltane and Explorathon. A big thank you to Ocean Terminal for their support of the project and for providing both unit and space, including Alison Bancroft. We couldn’t do it without our partners and communities at Living Memory Association, People Know How, Eureka Edinburgh, guest partners including Haemophilia Scotland, ASCUS, all the science communicators (especially Ross and Craig) and all the researchers from the University of Edinburgh, Napier University, Heriot Watt and Queen Margaret University.

If you have any questions or comments, get in touch with Lewis at, and learn more about his projects at, or

Running away from stress…literally

By Molly Campbell, University of Leeds, @mollyrcampbell

Exercise – for some, it’s a hobby, for others, a burden. We all know exercise is good for us. Yet, ironically, many people feel too busy or stressed to exercise regularly. Particularly during exam time, who wants to swap an hour of revision for an hour of tiring yourself out?

Research actually suggests that committing to exercise when you are experiencing stress can lower your stress response both now, and in the future. Regular exercise can be particularly helpful in boosting your mood, and thus your motivation to do work. Scientific research suggests that exercise elevates molecules in the body associated with the feeling of joy, whilst decreasing those that cause stress.

Post-exercise feelings of bliss

The term ‘runner’s high’ was coined in the 1970’s following an apparent worldwide increase in the number of people running long distance. This feeling of elation was attributed to the increased levels of endorphins in runners’ blood after exercise. Since then, many studies have been conducted that expand on this work to clarify exactly how exercise produces this ‘feel good’ effect.

Exercise also increases the release of endocannabinoids in the body. These are a type of cannabinoid that are endogenous, meaning they are made within our body. Endocannabinoids serve as a message between cells. Cells receive the message when the endocannabinoid attaches to another molecule, called a receptor, on the outside of a receiver cell. The receiver cells for endocannabinoids are in the central nervous system (brain and spinal cord) as well as other parts of the body. This elicits a wide range of beneficial effects.

The chemical anandamide, one type of endocannabinoid, gets its name from the Sanskrit word ‘ananda’ meaning joy. It is created in areas of the brain involved in motivation, memory, and higher cognitive function. Whilst its exact function has not been clarified, increased levels of anandamide are associated with states of heightened happiness. Anandamide can enter the brain through the so-called blood-brain barrier. This means that an increase of anandamide in the blood is followed by an increase of the chemical in the brain.

An experiment by Elsa Heyman and her colleagues demonstrated that, following a period of intense exercise, cyclists have increased levels of anandamide in their blood (1). This increase in anandamide was correlated with the increase of a molecule that is extremely important for the growth and maintenance of neurons in the brain, called brain-derived neurotrophic factor (BDNF).

Johannes Fuss and his colleagues used mouse models to demonstrate that exercising on a running wheel produced a significant increase in anandamide levels, which was correlated with a substantial reduction in anxious behaviours (2). When the researchers gave the mice a drug to block the cannabinoid receptors, to which anandamide binds, this reduction in anxiety was reversed.

Together, these findings therefore suggest an emerging role for the endocannabinoid system in producing the feeling of well-being and stress relief people experience after exercise. However, anandamide is broken down in the body very rapidly, possibly explaining why exercise is most beneficial when done regularly.

Sweat away your stress

Susanne Droste and her colleagues investigated the short-term effects of exercise on stress hormones in mice (3). Adult male mice were provided access to a running wheel for four weeks before undergoing a series of behavioural tests. Exercising mice were found to exhibit a significant decrease in corticosterone (the equivalent of the stress hormone, cortisol, in rodents) responses to a novel environment compared to control animals that had not exercised. These animals were also found to be less anxious in behavioural tests.

Researchers have also found long-term changes in the stress response after repeated exercise. Mindfulness experts suggest exercise, such as running or yoga, can indeed be a meditation practice carried out ‘on the go’. By placing focus on the repetitive movement of our joints and the increase in our heart rate, and the general effects exercise exerts on our body, we are distracted from the thoughts circling through our mind. Repeatedly applying this focus, particularly when high levels of stress cause us to be entangled in our thoughts, can produce long-term changes in the bodily tools we rely on to calm down. Ann Kennedy and her colleagues found that several studies show that this improves breathing rate and depth, lowers heart rate, and increases our ‘rest and digest’ response, or the so-called parasympathetic nervous system (4).

Although it may seem a chore to take time out of the day to get your body in motion, research about our physiology suggests that your brain (and therefore your grades) will benefit from doing so!


  1. Heyman, E. Gamelin, F.X., Goekint, M., Piscitelli, F., Roelands, B., Leclair, E., Di Marzo, V. and Meeusen, R. 2012. Intense exercise increases circulating endocannabinoid and BDNF levels in humans—possible implications for reward and depression. 37(6), pp. 844-851.
  2. Fuss, J. Steinle, J., Bindila, L., Auer, M., Kirchherr, H., Lutz, B. and Gass, P. Runners high depends on cannabinoid receptors in mice. PNAS. 112(42).
  3. Droste, S.K., Gesing, A., Ulbricht, S., Muller, M.B., Linthorst, A.C and Reul, J.M. 2003. Effects of long-term voluntary exercise on the mouse hypothalamic-pituitary-adrenocortical axis. Endocrinology. 144(7), pp. 3012-3023.
  4. Kennedy, A. and Resnick, P. 2015. Mindfulness and Physical Activity. American Journal of Lifestyle Medicine. 9(13), pp. 221-223.


The Glastonbury of Neuroscience

By Anjanette Harris, University of Edinburgh, @anjiefitch

I have been to many music festivals in my time, but last month I went to my first Neuroscience Festival. Every two years, the British Neuroscience Association holds the Festival of Neuroscience, which boasts a jam-packed program of research talks from experts across many disciplines within neuroscience, as well as workshops and discussion forums. It is quite simply the national celebration of neuroscience.

Last month, nestled amongst the canals of Birmingham, the International Conference Center provided the perfect backdrop for over 1500 scientists from around the world to get together, share their latest data, and enthuse one another. This year, The Physiological Society hosted a strand running through the festival called The Neurobiology of Stress as part of their annual theme Making Sense of Stress. One of the symposia, organised by Professor Megan Holmes, brought together researchers from around the world, including myself, to present our work on imaging the emotional brain.

What puts us at risk of depression?


Dr Stella Chan, a lecturer in clinical psychology from the University of Edinburgh, kicked off with the staggering statistic that half of all cases of depression first occur in adolescence. Stella reminded us that adolescence is a tricky time in which teenagers struggle with intense emotions on the road to self-discovery. But why do some youngsters develop depression while others don’t?

To answer this question, Stella studies how young people perceive themselves and the world around them. One startling finding is that those at risk of depression find it harder to see joy in other people’s faces. Because Stella uses teenagers at risk of, but not yet suffering from, depression she is able to see if there are changes in perception that may flag up that a youngster is likely to develop depression. If Stella can untangle whether a negative self-opinion is the cause or consequence of depression, she may be able to develop mind-training techniques to prevent depression in those at risk.

Untangling cause and effect using mice


Dr Marloes Henckens, a post-doctoral researcher from the Donders Institute at Radboud University, presented her work on the effects of stress on brain function. She uses both human and mouse subjects to help her distinguish between cause and effect. Marloes began by setting her work in context; she highlighted that the brain is a collection of networks and that brain disorders are probably caused by disorders of the connections between different networks.

With that in mind, Marloes showed that stressing humans or giving them stress hormones caused the connections that make up the fear network to become stronger. While this is useful for priming a person to tackle danger, it may lead to an anxiety disorder, such as post traumatic stress disorder (PTSD) in which suffers are haunted by intense unpleasant memories. Marloes takes pictures of the brains of mice with PTSD-like symptoms and has shown that reduced activity at the front of the brain (important for reducing unpleasant memories) is a consequence and not the cause of PTSD. It remains to be seen how connections between different networks are affected in mice with PTSD.

Hormonal influences on brain activity in rats

The following speaker, Professor Craig Ferris of Northeastern University, is the pioneer of imaging rats’ brains while they are awake. Craig began with a whistle-stop tour of the groundbreaking technology that he and his team have developed. His special scanning technology allows researchers to monitor brain activity while the rats are responding to things. For example, Craig showed changes in brain activity in mother rats as their pups start to suckle. It comes as no surprise that the brain areas involved in reward and motivation are active with breast-feeding. In fact, in these rats, breast-feeding is more rewarding than cocaine!

Craig then presented images of brain activity involved in aggression. To observe this, he first took pictures of the brain of a male rat that was happily lying in the scanner with its girlfriend, and then introduced an unfamiliar male rat and observed the changes in the first rat’s brain. The abrupt change in brain activity that was seen in the male rat’s brain might be described as blind rage, as it is similar to that observed with the onset of a seizure. Craig’s ambition knows no bounds: he finished his talk with musing on whether he could fit a killer whale into his brain scanner!

The impact of stress on emotional memory in rats


The final speaker was me, Dr Anjanette Harris. I’m a post-doctoral researcher from the laboratory of Megan Holmes at the University of Edinburgh. I want to understand how stress affects brain function. This is particularly tricky to study in humans, especially if we want to look at the effects of early life stress on the brain, so we use rats (read more on the importance of using rodents in psychiatric research in my previous blog post). The work that I presented uses the technology of Craig Ferris coupled with memory exercises for rats that we specialize in designing. We have shown that rats that experience stress in early life form stronger memories of unpleasant experiences. These rats also have stronger activity in brain areas involved in fear when recalling unpleasant experiences in adulthood. This mirrors what is found in humans and means that we may be able to test potential therapies for human memory disorders on rats, ensuring that the treatments target appropriate areas in the brain.

Practical Innovations in Life Science Education

By Nick Freestone, Kingston University

On 27- 28 April, The Physiological Society held a workshop under the auspices of the Education and Teaching Theme. The workshop was held at The Society’s HQ, Hodgkin Huxley House, and in somewhat of a departure for such an event, extended an invite to those unsung heroes of the Higher Education environment – technical support staff.  Thus, in the weeks leading up to the event, to encourage participation from this under-represented group (in The Physiological Society participation terms anyway) various inducements were proffered to our technical colleagues. Primary amongst these was the offer of an all-expenses paid trip to London contingent upon the submission of an abstract as a prelude to a poster presentation at the event itself. Who could refuse such a generous offer?

Equally heartening from the point of view of your cynical correspondent was the presence of a number of new faces to the physiological pedagogical arena. This served to greatly enliven the proceedings and ensured that the event wasn’t merely an echo chamber reverberating to the well-worn axioms of the usual suspects.

Happily the event kicked off with lunch, which served as a great prompt for punctuality. This was followed by Session 1 chaired with great aplomb by Sarah Hall (Cardiff University) where the audience was blown away by fantastic contributions from Iain Rowe (Robert Gordon University) on teaching pharmacokinetics, Viv Rolfe (University of the West of England) on Open Educational Resources, Michelle Sweeney (Newcastle University) on the use of LabTutor and our very own Derek Scott (Aberdeen) on developing a renal physiology practical for large groups – no urine required!.

This left the audience so energised that a refreshment break was necessary to recover. After this much-needed pause, Session 2 included contributions from Frances Macmillan (University of Bristol), on developing experimental design skills in first and second year students and Rachel Ashworth (Queen Mary University of London) on using technology to teach respiratory physiology from a clinical perspective.

Given so much food for thought it was an opportune time for the participants to form smaller discussion groups facilitated by the Education and Teaching Theme Leads and tireless organisers to discuss a variety of questions posed by The Physiological Society around the general question of “how can The Society help?”. Having set the world to rights in this format, and having provided The Physiological Society with an extensive to-do list, heroically noted down in real time by Chrissy Stokes, the formal part of the day was rounded off by a message from our sponsors, ADInstruments, who reported on upcoming initiatives involving their widely used educational wares. Rather more informal was a wine and poster session which melded seamlessly into a later gathering at a local hostelry.

Day 2 kicked off with a plenary lecture by Peter Alston of Liverpool University. While Peter is not a physiologist, his talk, “Technology-informed curriculum design” was received with rapt attention by an appreciative audience. At this stage of the proceedings, Professor Judy Harris (Bristol University) exerted her considerable crowd control skills and marshalled the next batch of contributions expertly and smoothly. These included talks from Dave Lewis (University of Leeds) on Open Educational Resources, Hannah Moir (Kingston University) who did a livestream of her lecture to us to her own students via an app called Periscope (Think about that for a while! Hannah lectured to us, whilst showing students that she was lecturing to us whilst giving us a demonstration of a technique to enhance student engagement. There’s too many layers there for me to unpack into a coherent story!), Louise Robinson (Derby University) and our very own Sheila Amici-Dargan on how online tools can be used to enhance the learning and teaching environment. Louise Robinson’s talk deserves a special mention here covering as it did a topic close to my own heart, lecturing using gamification techniques. This caused an appreciative hubbub from the assembled throng.

Now if you thought gamification was a bit outré in the august setting of The Physiological Society HQ then you would have been astonished by the contribution of Emma Hodson-Tole (Manchester Metropolitan University) who gave a talk on teaching physiology through the medium of interpretative dance!

I told you this was a different kind of conference. This presentation, in the batch of talks after refreshments, focussed on motor neurone disease and provided evidence on how learning can be facilitated across different groups using unconventional teaching techniques. Other talks in this section included my own (Kingston University) on Outreach and Public Engagement by the use of a “Lab in a Lorry”-initiative funded by HEFCE, and Dawn Davies (Bristol University) who talked about her work using patient simulators in public arenas such as shopping centres. This looked fantastic, if rather daunting fun!

Now I started off talking about how this wasn’t your usual run-of-the-mill academic event, with the old hands nodding sagely while trying not to fall asleep after lunch. No! This event included actual live students! These were Patrick Evans and Elodie Cox also of Bristol University (Judy’s enthusiasm for learning and teaching is obviously infectious). Their talk “Engaging the public with final year undergraduate projects” definitely proved one thing once and for all. Our students are a FANTASTIC resource, capable of giving much better talks than even the most seasoned academic. Suitably humbled and chastened by this demonstration of youthful excellence, the excited crowd networked over lunch whilst perusing some of the items of equipment one can put on the road in a “Lab in a Lorry”.

Feedback from the event was uniformly and overwhelmingly positive. Ideas are being gestated as we speak as a result of this inspirational event. Watch this space for more positive, energising educational stuff in the near future.