Palming off unsustainability

9090154930_c5e1eb08c6_kWhen I first landed in Singapore last October I expected to be greeted by clear skies and sunshine but, in reality, I couldn’t even see the famous skyline in front of me.  Welcome to the reality of living in South East Asia during the dry season. While most people will remember the news stories about the ‘haze crisis of 2015’, what many don’t realize is that this was not an isolated event, in fact haze is a persistent problem in this part of the world.

What causes the Haze?
Haze arises from the burning of forest areas for agriculture in the neighboring regions of Indonesia, normally through illegal ‘slash and burn’ practices of land clearing. Although slash and burn is not a new farming technique, increasing requirement of land for the growing of palm oil and paper production now results in larger and often uncontrolled fires. In addition, the land which is cleared is often peatland which, when burnt, leads to denser and longer lasting fires. The resulting ash and debris is carried to neighboring countries leading to dense smog – think of the foggiest day in the UK, then remember that fog is just caused by water whereas the haze in SE Asia is formed of ash and debris.

During the dry season this makes it hard to see and, for some, hard to breath and carry out daily tasks like walking upstairs or going to the shops. Already the PSI (pollutant standard index) here in Singapore is on the rise, reaching moderate levels while I’m writing this article.

6373026485_dc8f75e253_zWhile here in the city we think mostly of the effect the haze and land burning has on us but it’s not just people that are affected. Indonesia is one of the most bio-diverse countries on the planet, most famously home to Orangutans. Destruction of the forests doesn’t just pollute their air, it also destroys their homes. According to online sources, up to 5000 already endangered Orangutans are killed every year through the destruction of their habitat for palm oil productions

The palm oil problem
Palm oil is a type of vegetable oil and a highly concentrated form of fat found in many household products from cosmetics to junk food. Over 80% of the world’s palm oil is produced in the Indonesian regions of Borneo (Sumatra and Kalimantan), with the majority of this traded through companies right here in Singapore. Many people have not heard of palm oil due to frequent product mislabeling: note that it is often mislabeled as kernel oil or vegetable oil.

However, it is important to recognise that palm oil itself is not technically the problem.  The main issue lies with the unsustainability of current palm oil farming practices. Specifically the process of cut and burnt farming, failure to replace felled trees and the over-exploitation of land as the demand for palm oil overtakes tree growth. Even ‘so called’ sustainable methods of palm oil agriculture have come under scrutiny by environmentalists.

The crux of this issue is that, until the demand for palm oil products decreases, or better farming methods are devised the haze will continue in a futile cycle – food for thought as we tuck into ice cream on a hot day.

Post by: Stephanie Macdonald

For more information of products made using sustainable palm oil see here:

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Ovarian cancer: early diagnosis is the best treatment

The 8th of May was world ovarian cancer day. Ovarian cancer is considered to be the most lethal gynaecological malignancy, being the  fourth most common cause of cancer death in women in the developed world (1). Early stage misdiagnosis is common, especially since symptoms (such as feeling bloating, abdominal pain, difficulty eating or constipation) can be incorrectly attributed to common stomach and digestive complaints. Indeed, of the approximately 7000 new cases diagnosed in the UK each year, only a small percentage of diagnoses (around 20%) (2) will be early stage where the survival rate is over 90%. The key to successful early diagnosis lies in the frequency and the number of symptoms a woman suffers.

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Risk factors and diagnosis:

Common risk factors include: menopause (this being the most significant risk), mutations in genes associated with DNA repair like BRCA1 and BRCA2 genes, family history, infertility or having fertility treatment, endometriosis or being overweight.

There is unfortunately no accurate screening to diagnose ovarian cancer. Current screening practices rely upon CA125 (a tumor marker that can be detected in the blood) screening, alongside abdominal and transvaginal ultrasound (3). However, CA125 screening lacks both specificity and sensitivity. Specifically, CA125 can be detected in a range of cancers and in benign conditions in premenopausal women like endometriosis, pelvic inflammatory disease or even pregnancy, it is also more accurate for late stage diagnosis.

Treatment:

The standard of care for patients with advanced disease involves surgical tumour debulking followed by chemotherapy but sadly most patients will relapse within 18 months and eventually will die from the disease. Over the years clinical trials have been set up to explore combinations of drugs which could improve the prognosis for ovarian cancer patients. One of these therapies is called targeted cancer therapy or biological therapy and involves stopping tumour growth through interfering with tumour biology. Tumours need to spread out to find oxygen and nutrients, a process called angiogenesis (this being crucial for tumour growth and proliferation). Several anti-angiogenic drugs have been developed and are now being tested in preclinical and clinical settings. The aim is to target not the tumour but the surrounding structures (blood vessels) necessary for tumour growth. VEGF is a molecule which is overexpressed in most solid tumours including ovarian cancer and is crucial in tumour angiogenesis. So this molecule represents a good drug target, the rationale being that inhibition of VEGF may eliminate or delay tumour growth. Bevacizumab (Avastin) is a monoclonal antibody that binds VEGF and sequesters it, causing blood vessels growth to stop, thus making it more difficult for the tumour to grow. It is the only anti-angiogenic drug licenced to be used in women with advanced ovarian cancer alongside chemotherapy. However, despite promising results in initial studies it has so far not proved beneficial to overall survival rates and some people consider it not to be cost-effective (4).

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Another targeted cancer therapy used to treat ovarian cancer is inhibition of PARP1 (a molecule involved in DNA repair). This drug is called olaparib and is offered to patients with deficient tumour suppressor proteins BRCA1 and BRCA2 since cells deficient in BRCA1/2 are more sensitive to PARP1 inhibitors. PARP1 and BRCA1/2 are involved in repairing broken DNA, in patients carrying BRCA mutations, inhibition of PARP1 results in cumulative DNA damage and tumor cell death.

There are also a range of antivascular agents (drugs which attacks the blood supply of a tumor) now entering clinical trials (5). We are also making advances in immunologic therapies and in drugs targeting relevant gene mutations but, in some cases, toxic side effects make these treatments unfeasible.

The future:

Despite advances in drug research, early-stage detection is still believed to be the key to improved survival. Therefore continued research into biological markers for early detection and diagnosis is vital. It is hoped that such research, alongside work into finding biomarkers that predict disease progression, drug response and allow us to select patients who benefit the most from a specific treatment option will give us a fighting chance against ovarian cancer.

References

  1. Paik ES, Lee Y-Y, Lee E-J, Choi CH, Kim T-J, Lee J-W, et al. Survival analysis of revised 2013 FIGO staging classification of epithelial ovarian cancer and comparison with previous FIGO staging classification. Obstetrics & Gynecology Science. 2015 ;58(2):124-34.
  2.         Hennesy BT, Coleman RL, Markman M. Ovarian cancer. Lancet 2009. 17;374:1371-82
  3.         Jayson GC, Khon EC, Kitchener HC, Ledermann JA. Ovarian Cancer. Lancet 2014. 2014;384:1376-88.
  4.     Robert H. Carlson. Antiangiogenic Therapy’s Value in Ovarian Cancer Questioned. Oncology Times 12/25/14
  5.        Bell-McGuinn K, Konner J, Tew W, Springgs DR. New drugs for ovarian cancer. Ann Oncol. 2011 Dec;22 Suppl 8:viii77-viii82. doi: 10.1093/annonc/mdr531.

Links of interest:

UK CR. Ovarian Cancer incidence by UK region 2015 [cited 2016 07.01]. Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/ovarian-cancer/incidence#ref-0.
Post By: Cristina Ferreras

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Yoga for health: uniting body and mind

Yoga is an eastern tradition which is becoming increasingly popular in Western societies. Although the spiritual elements of this ancient Indian practice have partially disappeared in its westernised form, the practice still remains a holistic and multi-dimensional approach to maintaining good health and wellbeing (de Manincor et al., 2015). This is reflected in the meaning of its Sanskrit name: ‘to unite’ or ‘to attain what is previously unattainable’ (Uebelacker et al., 2010). Its main elements include physical postures (asanas), breathing techniques (pranayama) and meditation (dhyana) (Uebelacker et al., 2010). The emphasis on these elements differs between styles, e.g. Iyengar yoga focuses on the alignment of the body in asanas, whilst vinyasa teaches to link breath with movement. In addition, yogis promote positive values and attitudes, as well as lifestyle. Research has shown that it can help with health problems ranging from mental health difficulties to musculoskeletal ailments.

So, is yoga really effective and beneficial for our health and if so, what is its secret?

Meditation is one of the core elements of yoga.

Meditation is one of the core elements of yoga.

Randomised controlled studies of yoga have shown that it can reduce pain and improve functional outcomes for individuals with physical problems such as lower back pain and fibromyalgia (Ward et al., 2013). Some evidence indicates that yoga can not only manage, but also reduce some musculoskeletal problems such as scoliosis – a condition in which the spine curves laterally (Fishman et al., 2014). Scoliosis patients who performed a pose known as the ‘side plank’ for an average of  90 seconds a day, most days of the week for seven months, showed a decrease in the lateral spine curvature by around 32%. The more conscientiously the patients practiced the side plank, the more their spine improved. The authors of the study emphasise the importance of performing the pose on the convex side of the spine only (do not try this without a consultation with a specialist). Such asymmetry of the exercise might achieve its effect by strengthening the weaker side of the vertebral column. The results of this study are very encouraging, however randomized controlled trials with a longer follow-up period are needed to substantiate these findings.

Although other forms of physical activity, such as stretching, can be equally effective in improving daily functioning, in some cases yoga has been shown to be superior to physical therapy. Specifically, when it come to improving quality of life and reducing depression, which often accompanies physical illness (Ward et al., 2013). Indeed, yoga has been shown to help those with mood disorders, including women with postnatal depression (Buttner et al., 2015).

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It can however be difficult to draw clear conclusions from research which examines yoga for health. Specifically because the type of yoga, the intensity and length of practice vary greatly among studies.  Is it possible to formulate a ‘prescription’ yoga practice that would provide clear evidence of its effectiveness? Some yoga experts suggest that, in order to help reduce depression and anxiety, yoga practice not only needs to include certain key elements, but also avoid some of other components (de Manincor et al., 2015). For example, both depression and anxiety might be alleviated with breath regulation, however depressed individuals benefit more from the focus on the inhalation, whilst those with anxiety from lengthening the exhale and ‘humming bee’ (bhramari) technique. Anxious yoga students should avoid rapid breathing techniques, as well as heated and crowded yoga rooms. It is suggested that students with mental health problems should practice for 30-40 minutes 5 times a week for 6 weeks. However, frequency of practice is more controversial among teachers of yoga for musculoskeletal conditions, predominantly because unsupervised yoga sessions can be harmful to those with no previous yoga experience (Ward et al., 2014). However, experts in both areas agree that yoga practice that aims to help with specific problems should be integrated, personalized and taught by those with sufficient experience and training, specifically relating to the condition of their students.

The active ingredients of yoga are thought be mindfulness and physical activity (Uebelacker et al., 2010). Both of these elements are important in other approaches to treating health problems. One of the advantages of yoga, however, is its holistic focus on reaching one’s full potential rather than reducing the symptoms of illness, as well as its emphasis on uniting the mind and body and building self acceptance (Uebelacker et al., 2010). Although it can be difficult to meet the exact requirements for yoga as a treatment for physical and mental health problems, i.e. frequency of practice and structured personlised classes, it still remains a promising adjunct therapy. So, let us hope that the growing popularity of ‘attaining what is previously unattainable’ might increase the access and diversity of classes.

Post by: Jadwiga Nazimek

References:

Buttner, M. M., R. L. Brock, M. W. O’Hara, and S. Stuart, 2015, Efficacy of yoga for depressed postpartum women: A randomized controlled trial: Complement Ther Clin Pract, v. 21, p. 94-100.

de Manincor, M., A. Bensoussan, C. Smith, P. Fahey, and S. Bourchier, 2015, Establishing key components of yoga interventions for reducing depression and anxiety, and improving well-being: a Delphi method study: BMC Complement Altern Med, v. 15, p. 85.

Fishman, L. M., E. J. Groessl, and K. J. Sherman, 2014, Serial case reporting yoga for idiopathic and degenerative scoliosis: Glob Adv Health Med, v. 3, p. 16-21.

Uebelacker, L. A., G. Epstein-Lubow, B. A. Gaudiano, G. Tremont, C. L. Battle, and I. W. Miller, 2010, Hatha yoga for depression: critical review of the evidence for efficacy, plausible mechanisms of action, and directions for future research: J Psychiatr Pract, v. 16, p. 22-33.

Ward, L., S. Stebbings, D. Cherkin, and G. D. Baxter, 2013, Yoga for functional ability, pain and psychosocial outcomes in musculoskeletal conditions: a systematic review and meta-analysis: Musculoskeletal Care, v. 11, p. 203-17.

Ward, L., S. Stebbings, K. J. Sherman, D. Cherkin, and G. D. Baxter, 2014, Establishing key components of yoga interventions for musculoskeletal conditions: a Delphi survey: BMC Complement Altern Med, v. 14, p. 196.

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Understanding cosmetic testing in the UK.

If we were to ask you which of the following high street brands use animals to test the cosmetic products they sell in their UK stores (Tesco, Sainsbury’s, Boots, The Body Shop, Lush or none of these); what would your answer be?

Many of us will have seen Lush’s bag which boldly expresses the store’s dedication towards the fight against animal testing but what about the other four?

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You may be surprised to learn that none of these high street brands currently use animals to test their cosmetic products. In fact it has been illegal to test cosmetic products or any of their ingredients on animals in the UK since 1998 and an EU-wide ban has been in place since 2013. This means that no cosmetic product sold anywhere in the EU should include new ingredients tested on animals. Although many ingredients will have been tested at some point in the past before these legislations came into play.

If you didn’t already know this don’t feel bad, a recent survey carried out by ‘Understanding Animal Research’ found that only 38% of respondents were aware of these legislations. And, advertising in many stores can perpetuate the belief that some UK cosmetics are still tested on animals. Specifically, products marketed as ‘cruelty free’ or ‘not tested on animals’ may not technically be examples of false advertising but they do perpetuate the incorrect belief that some product sold in UK stores are still tested on animals.

Wendy Jarrett, CEO of Understanding Animal Research, said:

“The proliferation of ‘Not tested on animals’ or ‘Cruelty-Free’ logos has led many to believe that other cosmetic products sold on the UK market are tested on animals – something which has not been the case for 18 years. While animals continue to play a small but key role in medical developments, the UK has successfully eliminated such testing for cosmetics and, more recently, household products.”

This is undoubtedly a huge step forward and we are also heartened to know that the UK government is currently working with a number of non-EU countries supporting them to move away from cosmetic animal testing towards non-animal alternatives.

So, the next time you are out shopping for cosmetics or household products you can shop with the confidence that none of the products you see on the shelves will be tested on animals!

Post by: Sarah Fox

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Gifts for the science lover in your life.

It’s been a long day. The PCR machine broke (again), your buffer solution may be contaminated and you’ve just realised that your data is all non-parametric so your statistics could be totally off. Although the gods of scientific endeavour may not be smiling on you today, you know deep down that you’re still a grade A science nerd and you just need a little ‘pick-me-up’. So, as a favour to your inner geek, we at the brain bank have compiled a list of some of our favourite science-themed gifts

Go ahead, give your brain a treat!

1: Giant microbes.

If, like me, you are a sucker for anything cute, fluffy and quirky you’ll most likely love Giant microbes. From Cholera to the Common Cold, these fuzzy oddities somehow brain-cellsucceed in making microbes mesmerisingly cute. As a neuroscientist my personal favorite has to be the brain cell. But, putting my serious science hat on, I did notice a problem with the product description online. Specifically, the website states that ‘the more brain cells you have the smarter you are’ – this is not necessarily true. Note that studies of Einstein’s brain did not find any significant differences in the number of brain cells coiled in the genius’s cortex. Instead there was some speculation that Einstein’s brain contained more glial cells than neurons – these specialised cells support brain cell function, fixing them in place, keeping them supplied with oxygen and nutrients alongside many other important functions. So, perhaps we should petition Giant Microbes to make Bobby Brain Cell a new friend… Glenda Glia perhaps?

2: Euler’s Identity Romantic Geek Art

Screen Shot 2016-04-24 at 12.51.15A few years ago my partner bought this for me as a valentines present and there is nothing I don’t love about it. The text is the perfect mix of geeky and cute, plus the disclaimer he gave me when I ripped open the wrapping was so beautifully him….On opening the gift he looked at me and, with a serious expression on his face, said “I’m glad you like it but of course you do know that nothing is actually more beautiful than Euler’s Identity…and if that upsets you, you obviously don’t understand maths”. Somehow this comment made me love him more and we are now married…so, there’s another win for the geeks. If you want to check out this and similar products they can be found here.

3: Serotonin Necklace.

Screen Shot 2016-04-24 at 12.52.34For days when you need a little boost, how about wearing a little piece of happiness around your neck? This white metal neurotransmitter necklace is just the right balance of quirky and cute and will certainly get noticed – I do love wearing it around the lab! Check out this website for more products – personally I think the Dopamine necklace may also be quite rewarding (boom boom)…

4: Try Science.

Screen Shot 2016-04-24 at 12.54.02For academics and fans of the amazing xkcd this may be just the t-shirt for you. My brother-in-law bought me this for Christmas and it never fails to put a smile on my face. Actually, I’m going to admit to a bit of a crazy biologist trade secret here. Biology is one branch of science which many lament does not always follow logic… It’s not unusual to run two identical experiments on successive days and get very different results (dam you complex biological variability). This means that many biologists harbor a bit of a superstitious streak…For me I find that wearing this t-shirt always seems to bring me luck in the lab. So, if you’re having a run of bad luck, this may just be the outfit choice for you.

5: Brain specimen coasters.

Screen Shot 2016-04-24 at 12.54.48OK so I don’t currently own these, but I very much would like to – hint hint ;). I have spent many long days painstakingly mounting sections of brain tissue onto glass microscope slides with a paintbrush (no I’m not kidding this is actually how we do this) and the results always amaze me. Looking at the intricate structure of these brain slices is absolutely inspirational and I’ve often wished I could take my slides home. Sadly, knowing the cocktail of chemicals used to mount and fix these samples, I’ve always decided it was too risky to remove them from the lab. But, these coasters may be the perfect solution to this problem – put some serious thought into your morning cuppa and rest it on a slice of brain!

Post by: Sarah Fox

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Dian Fossey and the ‘Gorillas in the Mist’

Dian Fossey is one of those rare biologists in that her name and work are known by a vast proportion of the general public. Nearly everybody knows of her work, perhaps by the title of the book she wrote describing her scientific career, “Gorillas in the Mist“.

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Dian Fossey. Image provided via CC BY-SA 2.0 by Flickr user mary-lynn. Originally provided by ‘danisolas’

Fossey’s incredible 18-year study of Rwandan mountain gorillas and her conservation work are testament to the passion she had for her work. However, it isn’t just the work for which Fossey is best known that I wanted to draw people’s attention to in this post. Fossey’s early career also featured defining moments that many of us will recognise from our own lives and lessons from which we can learn.

Career Choices

Like many young people, Fossey took a rather meandering route to finding her ideal job. She was encouraged by her stepfather to study business at college but, after one year, she decided to foster her love of animals by switching to a pre-veterinary course. Somewhat surprisingly, given her famous career, Fossey shortly changed courses once more thanks to struggles with her Physics and Chemistry modules. After eventually completing a course in Occupational Therapy, Fossey began a career working with tuberculosis patients and then crippled children.

It wasn’t until she was 31 years old that Dian Fossey discovered her real passion. In 1963 she fulfilled a long-held dream and went travelling around Africa. There she met a pair of wildlife photographers – Joan and Alan Root – in Uganda who were photographing mountain gorillas in the Virunga mountains. It was at this point that she began to transform into the Dian Fossey we are familiar with. The Roots took her with them to watch the gorillas and, when it came time to leave, Fossey had resolved to return and learn more about the species that had so captivated her during her time there.

Many young professionals worry that they don’t know what to do with their lives. I see Fossey’s life as an encouraging reminder that even some of our most celebrated individuals only worked out what they wanted to do at a relatively late age.

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Gorillas in the Virunga Mountains. Image provided via CC BY-SA 3.0 by Cai Tjeenk Willink.

Enthusiasm

During her time in Africa, Dian Fossey met archaeologist and naturalist Louis Leakey, who was funding research into the great apes at the time. When she returned home, Fossey wrote three articles about her time in Africa, which she had published in local newspaper, ‘The Courier-Journal’. Her eagerness to tell the world about this subject that so fascinated her would turn out to be a great aid in achieving her goal.

In 1966, Leakey gave a series of lectures that brought him to Fossey’s home of Louisville. Upon speaking to her again and being impressed by the articles she’d had published, Leakey invited Fossey to lead a long-term field project in Africa to study the gorillas; the only stipulation being that she would have to have her appendix removed first. Fossey willingly went ahead with the operation only the find out that Leakey had just been trying to see how enthusiastic she was about the project!

This goes to show just how much fervour for one’s work can pave the way for even greater success. Had Dian Fossey not spent her free time writing about her trip to Africa and had she not being willing to go ahead with the appendectomy, she might not have been given this life-changing opportunity. Now, I wouldn’t encourage anyone to go around offering up bodily organs in exchange for research grants, but Fossey is a prime example of how pushing yourself that bit further than other people can pay dividends in a big way.

Gorillas in the Mist

Dian Fossey was finally able to begin her studies into the mountain gorillas in early 1967. Based in the Kabara meadow in the Congo, Fossey would venture into the forests to track and observe the gorillas. Through careful study and considerable patience, she identified three distinct social groups of gorillas in the region, which she was able to get close to by mimicking their grooming, grunting and eating habits so they were more accepting of her presence.

When Fossey’s work was disrupted by a civil war in the Congo, she relocated to a national park on the Rwandan side of the mountains in September 1967. There she established the ‘Karisoke Research Centre’, naming the camp after the two volcanoes in-between which it was nestled. This move to Rwanda would eventually inspire Fossey’s famed conservation work as the gorillas in this region were under constant threat from poachers.

Laws prohibiting poaching were rarely enforced in the park, with bribery of conservation staff rife. Given her love of, and fascination with, the gorillas, it is easy to understand how Fossey was affected when she came across areas in which the apes had been slaughtered. Consequently, she financed her own team to destroy poachers’ traps and assisted in several arrests.

Fossey’s efforts protected the gorillas in her study area for a decade, whilst those outside of her protection suffered extensive poaching. Having been able to interact with some of the apes in her area, again by mimicking their actions, Fossey also grew rather attached to them; forming a particularly strong bond with a male she named Digit. Tragically, on New Year’s Eve in 1977, Digit’s group was attacked by poachers and he died protecting the other gorillas. Digit was decapitated and his hands were severed so they could be sold as ashtrays.

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The Dian Fossey Gorilla Fund International. Image provided via CC BY-SA 4.0 by ‘azurfrog

In the wake of Digit’s death, Fossey set up the ‘Digit Fund’ to finance anti-poaching patrols. Now renamed in some countries, this fund still works to protect mountain gorillas and operate Fossey’s Karisoke Research Centre. In its formative years, Fossey used the fund to great effect, destroying nearly 1,000 traps in one 4 month period. The fund acts as her legacy since her untimely death in December 1985, when she was found murdered in her mountain   cabin in a case that has never been solved…

Post by: Ian Wilson

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How to build a brain

4155648600_67c6ecc258_zI will always remember the moment which first sparked my interest in neuroscience. It was a rainy day in Oxford – it poured as we stepped off the bus. We had arrived at the University Department for Neuroscience. After being introduced to a group of researchers we were given an extensive tour of the facilities. As an A-level student, the visit was my first encounter with a fully functioning research lab. At its close, the visit left a resounding impression on many of us, and personally I remember becoming immediately interested in the prospect of studying neuroscience at university.

The lab was at least 15 strong, yet they continually reminded us that they were investigating a tiny piece of a puzzle which has been studied by generations of brilliant minds. The interconnection issue; how does the structure of our brain, from single neurones to complex circuits, relate to function. It was their enthusiasm for such a complex question that sparked my own interest. Whether you’re a member of the general public or an active researcher, it’s easy to forget just how amazing the brain is, either because you’re unaware of the dizzying numbers or, like me, you’ve become transfixed on understanding a small part of brain infrastructure from a very specific angle. I write this post to briefly introduce the structure of the brain to those unfamiliar with it, and to serve as a source of motivation for fellow neuroscientists who spend huge amounts of times with their heads buried in the vast sands of the field.

Let’s start with the building blocks. The human brain has about 100 billion individual neurones with an estimated 200 trillion contacts between them. Remarkably this staggering number of neurones are arranged in such a way that we can effortlessly transition from a walk to a run, respond to sensory stimuli, perceive emotions and learn complex skills such as playing an instrument.

A human neocortical pyramidal neuron stained via Golgi technique. Notice the apical dendrite extending vertically above the soma and the numerous basal dendrites radiating laterally from the base of the cell body.

A human neocortical pyramidal neuron stained via Golgi technique. Notice the apical dendrite extending vertically above the soma and the numerous basal dendrites radiating laterally from the base of the cell body.

To complicate things further, each neurone is a complex device in its own right; perhaps the most intricate cell type nature has created. Neurones are tree like cells with branching appendages that maximise the receptive surface area for connections from other neurones. To increase the cells receptive area these branched appendages, called dendrites, are covered by many spines. Yes that’s right, branches on branches. The spines accommodate between thousands and tens of thousands of postsynaptic receptors which listen for signals from other neurones.

Dendrites are the targets of thin and long processes from other neurones, called axon collaterals, which typically emerge from the cell body and take a long, convoluted journey to reach a dozen or tens of thousands of nearby and distant neurones. Terminating in close proximity to the cell body and dendrites of other neurones, axons release chemicals that modulate the postsynaptic receptors, evoking a response. This is the basis of neurone to
neurone communication.

Fluorescent micrograph showing the cerebellar network of purkinje neurons from a mouse imaged using 2-photon microscopy. The neurons are visualised by labelling the cells with green fluorescent protein (GFP). Purkinje cells are specialised neurons found in layers within the cerebellum (at the back of the brain). In humans they are one of the longest types of neurons in the brain and are involved in transmitting motor output from the cerebellum.

Fluorescent micrograph showing the cerebellar network of purkinje neurons from a mouse imaged using 2-photon microscopy. The neurons are visualised by labelling the cells with green fluorescent protein (GFP). Purkinje cells are specialised neurons found in layers within the cerebellum (at the back of the brain). In humans they are one of the longest types of neurons in the brain and are involved in transmitting motor output from the cerebellum.

Now we have met the basic structural characteristics that permit neurones to communicate with one another, let’s consider how these change between neurones. We know from detailed imaging studies that the shape and dimensions of a neurone are tailored to fit its role in the brain’s circuitry. Furthermore, different neuronal types are more strongly localised to specific areas of the brain. For example, the cerebellar Purkinje cell epitomises the link between structure and the broader function. Named after their discoverer, Czech anatomist Johann Evangelist Purkinje, these cells are amongst the largest in the brain. Their elaborate tree of dendrites makes them ideally suited to receive input from many other neurones. This is an important feature for a cell which needs a lot of incoming information to effectively coordinate the fine movement of our limbs.

Finally, I want to put aside the physical components and touch briefly on how information is encoded in the brain. Neurones produce single electro-chemical spikes, called action potentials. These electrical discharges result from rapid and well-timed ion movements across the neuronal membrane. Action potentials typically last 2-5ms however they can stretch or compress depending on the amalgamation of ion channels that are incorporated into the membrane. Neurones can repeatedly fire action potentials; the firing frequency depends on postsynaptic inputs and cascades of processes occurring within the cell.  Any given neurone may fire just one action potential per second in its resting state. However, when receiving a stimulus from another can increase this firing rate . Neurones can also produce elaborate bursting patterns of action potentials, or can be completely silent.

The brain is complex at every level of its architecture. The billions of neurones, trillions of synapses, an unimaginable number of action potentials and many flavours of ion channel all add layers to its computational capacity. Perhaps even more staggering is that all these components occupy less than a 1 litre volume inside the skull, and are somehow wired together as circuits to convert tiny fluxes of ions to organism-wide behaviours. Now a PhD student, deeply entrenched in a specific research question, I try not to lose sight of the reason I chose to study neuroscience. For me it all comes back to that rainy day in Oxford.

Post by: Adam Watson

References:

‘Ion Channels of Excitable Membranes’ Third Edition- Bertil Hille.
‘Rhythms of the brain’- Gyӧrgy Buzsáki

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