Updated: Jul 25, 2020


I have a bit of a love-hate relationship with exercise. Well, more of a desire-demotivation-determination-detest-delirious relationship with exercise. Let’s face it, no fitness journey is a linear path of ‘loving it’; despite what some fitness instagrams might imply. (Yeah, they deffo have times when they binge on crisps and don’t want to get up for a 5am workout, but no filter will make that fit with their theme). Most forms of exercise involve pushing ourselves out of our comfort zones and with that comes an array of emotions from deep within your brain. Here is a back-brain pass to the 5 feels of exercise.

1. Desire

This feel is normally at maximum the day before you are planning on working out. You are ready to go get your sweat on and embrace your new lifestyle as a fitness bunny. You have never felt so motivated to exercise in your life and why shouldn’t you? Working out is like, the best thing everrrrr.

Brain Talk: When you decide to book a gym class or get up early to run, your brain sets this as a ‘goal’. Goal-directed behaviour is thought to be mediated by the frontal brain regions, such as the orbitofrontal cortex (OFC) responsible for decision making (read the IOWA gambling test for more on this brain region). These areas are stimulated by neurons which release dopamine; a ‘reward’ neurotransmitter associated with feelings of pleasure. When you set a goal, dopamine is used to predict whether the action is going to pay off with a worthy reward. Dopamine signals before starting a task as a reward-learning technique; teasing your brain with a little taste of the canddyyyy you will get when you reach your goal. This small dopamine hit drives you to set your alarm at silly o’clock to get up and get a sweat on when you’d normally be in cosy bed.

2. Demotivation

Andddddd you can’t be bothered. It is an hour before you are due to put your gym gear on and the last thing you want to do is move. Sitting down and scrolling on your phone is now the most important thing you need to do. If you skip this one workout, you’ll definitely go tomorrow but right now, you aren’t really feeling it, so what is the point right?

Brain Talk: Believe it or not, choosing to stay in bed or sat on the couch is the path ‘hard-wired’ in your brain as this requires the least resistance; costing less to sit still and chill than get up and get going. The brain weighs up the cost of moving with the reward of exercising and current circumstances can massively sway the vote. If it is cold outside and you are warm in bed, your brain states ‘the cost of getting cold is not worth the benefit of exercising’ so tries to convince you to skip the gym. The neuronal mechanisms behind these feelings are still being explored, however, it has been shown that individuals who are generally more apathetic have to over-activate their pre-motor cortex (the movement planning area) before accepting an effortful challenge with a high reward. Therefore, some individuals genuinely need to have someone drag them out of bed to get them to spin in the a.m as their brain cannot muster the effort to push back the covers themselves.

3. Determination

You managed to wiggle into your lycra leggings and this releases a new wave of emotion. You can do this, you are going to do this and you are going to change your life. You are going to push yourself to your limits. The workout has begun, and you feel great. Here we go!

Brain Talk: Determination is a form of intrinsic motivation; describing a behaviour driven by internal (chemical) rather than external (cash-cash-MONEYYY) rewards. This behaviour is also thought to rely on dopamine, as It is common to our ancestral ‘seeking’ behaviour; pivotal to our brains directing us to chase down our target. One study described an increase in dopaminergic (D2) receptors in the striatum (a brain area involved in a circuit which directs voluntary movement), meaning elevated dopamine can readily activate these neurons and increase ‘neuron flow’ – preventing impulsive or distracting behaviours when completing a task. Determination also relies on focus. In the brain, focus is created by increasing neuronal activity in the attention regions (prefrontal cortex) while dampening background neuron signalling from other areas. This creates an in-tune focus to kick-butt on the task at hand.

4. Detest

The novelty has worn off. Mid workout: You are tired, in pain and someone is screaming at you to ‘keep going’. And you hate. Every. Excruciating. Second. Why did you decide to do this again? Burning a few extra calories is not worth this effort. Never again will you put yourself through this ordeal health professionals recommend as being ‘good for you.’

Brain Talk: The absolute desperation you feel mid-workout is your brain’s attempt to get you to give up. It starts telling you how tired you are, and you’ve done enough so you can stop. You brain perceives exercise as your body being under stress as evolutionarily, the only time you would be pegging it would be away from a predator. But as mentioned before, your brain is all about measuring the cost of an action vs the reward you will receive. And mid workout, the reward of ‘completing the workout’ is meagre at best. Your brain thinks you are wasting unnecessary energy running on the spot in a non-threatening, air-conditioned gym so will signal for you to hit ‘stop’ and abruptly end your session.

5. Delirium

Back in the changing rooms after many near-stop moments and you can’t help but feel AMAZING! You are done! Your heart rate has come back down to a semi-normal level and a sensation of clarity washes over your brain. You are buzzing and booking into you next class before you have even hopped in the shower. You swear to go to the gym every day from now on because this is the best feeling EVER.

Brain Talk: Following swinging your kettle bells, you brain experience increases in specific chemicals which make you feel so gooooooode. Endorphins, the brains natural ‘pain-killer’, have been shown to increase in the brain following exercise. These chemicals act on opiate receptors, the same receptors triggered by morphine and other ‘high’ drug, so you are left buzzing after your treadmill slog. Endocanniboids, the chemicals similar to that found in cannabis, are also elevated after exercise. Together, it is thought these chemicals can activate dopaminergic neurons in the ventral tegmental area, leading to stimulation of the pleasure circuit in the frontal lobe. And if your goal was to go to class and workout, you have achieved it, meaning more dopamine is released in frontal regions as a reward for meeting you target. Overall, your brain experiences a huge rush of ‘the good’ chemicals once you have finished exercising, driving motivating behaviours needed to get into an exercise routine.

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Exercising is an emotional rollercoaster for your brain, especially if you are trying to get into a new routine. The more you stick to a plan the easier it becomes as your original goal will be transformed into a habit, making it achievable to win the battle with your alarm clock. Exercise is excellent for your physical and mental health and we should all have some form for active routine to promote your brain health. Try to remember that next time you are experiencing feeling 4 during a class – it may just help you to push through!

Resources used to write this article (Click for linkz)

Mesolimbic dopamine signals the value of work

Individual Differences in Premotor Brain Systems Underlie Behavioural Apathy

Individual differences in the proneness to have flow experiences are linked to dopamine D2-receptor availability in the dorsal striatum

The Emerging Neuroscience of Intrinsic Motivation: A New Frontier in Self-Determination Research

Suppression of Salient Objects Prevents Distraction in Visual Search

What does running do to your brain?

Exercise, pleasure and the brain


Updated: Jul 25, 2020


“Happy New Year! Auld Lang Syne! Hope your 2019 is amazing! What diet plan are you doing?! I am going to get abs this year! I have signed up for a shake diet! I am going to work out every morning, lunch and evening until my summer holiday! So excited to get started!”

… Sound familiar? With the clinking of champagne flutes and popping of party streamers ringing in the new year, so comes the talk of new diets, exercise plans and big changes from almost every human you interact with. Whether it is conversations on your first day back at work or cyber proclamations of change with immediate effect, the ‘new year new me’ chat is unavoidable. The majority of January health kicks often revolve around losing inches off your waistline and getting shredded while forgetting how these changes may alter one of the things vital for a healthy life; your brain. Let’s learn how healthy our new routines really are by exploring the effects cutting calories and muscle building has on our noggins.

Brain-y Pump: The relationship between exercise and brain function

We are all aware of the health benefits of exercise; from reducing obesity and lowering your risk of heart disease to genuinely just making you physically fitter and stronger. Many who maintain long-term exercise routines also experience cognitive improvements such as increased focus and attention and improved memory. It may be obvious, but while you are working out those biceps and triceps, you brain is also going through a workout too, juggling different chemicals and signals before, during and after you train. So whether you love cardio (you super humans), practice high intensity interval training (HIIT) or lift (bro), your brain will be reaping some huge rewards.

Cognitive Function: Attention and Memory

There is nothing like an exercise session to clear the mind and scientifically, it has been reported exercise in young adults improves their ability to learn. This can be seen straight after a session, demonstrated by a study showing an increased ability to learn vocab following running (1), or after prolonged periods of time, witnessed in adults with an average age of 33 undertaking a 3 month aerobic routine (2). The first of these studies showed that changes in cognition correlated to increased cerebral spinal fluid levels of brain derived neurotrophic factor (BDNF); a protein which promotes neuron survival; and catecholamines such as dopamine; a neurotransmitter which stimulates working memory and arousal (1). The effect of the long-term exercise routine performed in the second study revealed a potential increase in the production of new neurons (2). This was shown by a MRI-monitored increase in blood flow to the dentate gyrus; a sub-region connected to the memory-forming hippocampus and one of two brain regions where neurogenesis occurs. Overall, it appears short-term protein and neurotransmitter changes experienced following a workout can improve attention and short-term working memory, and if routines are sustained, these changes can facilitate the production of new neurons and enhance long-term memory (motivation for me to get to the gym tomorrow).

Preventing Brain Degeneration

As we age, many individuals experience problems with memory and learning, which can sometimes be correlated with a decrease in hippocampal volume. However, some studies have reported that increasing physical activity in elderly people promotes their ability to learn and maintain memory. Correlation between cognitive ability and walking level was noted in a study involving around 5000 elderly women over a 6 year period (3). This relationship has since received a bit more of a scientific unpinning by an imaging study revealing the loss of frontal and temporal grey matter, which accompany ageing, is reduced in those who undertake cardio exercise (4). A relationship between exercise and improved cognition in those who carry Alzheimer’s disease risk gene alleles (APOE-e4) has been noted (5). However, much more work needs to go into the fundamental mechanisms underlying all these relationships between exercise and the elderly to see how much therapeutic weight they may hold.

Mechanisms

From the studies mentioned, there does appear to be a relationship between exercise and improved cognition. The potential neuro-mechanisms underlying these changes are still under investigation in animal models (more can be read in reviews (6,7)) but some changes thought to occur are:

  1. Neurogenesis: the production of new neurons in the dentate gyrus

  2. Increased LTP: increased strength between synaptic connections in the hippocampus and up-regulation of genes involved in this process

  3. Increased angiogenesis: formation of new blood vessels in the brain

  4. New dendritic spines (post-synaptic terminals): new connections can be made with existing neurons in hippocampus. New neurons produce mature spines quicker.

  5. Reduced inflammation: increased levels of growth factors and their signalling

A lot of work is still required to pin down how us going to circuits makes us better learners but the is almost certainly a relationship there, so book your next class now!

Calories are King: Dietary Restriction and The Brain

Along with the new workout routine normally comes a ‘healthy eating’ plan too. The majority of these plans work on the basic science of caloric restriction. Your body naturally burns calories (technically defined as the energy needed to raise the temperature of 1 gram of water through 1°C) every day and we eat food to give our body the energy it needs to function. Weight is gained when more calories are consumed than needed, leading them to be stored as fat. All humans need body fat but nowadays, people can easily eat to excess, with one takeaway of a medium ‘veggie volcano’ pizza from Dominos plus a coke and a mars bar racking up a total of about 2000 kcal. Everyone burns different levels of calories per day (see how much you burn here), so the key is to eat slightly under this number added to the calories you burn from exercise to lose weight. So, bin off those shake diets and eat a healthy balanced diet on your specific number of calories. Simples and sustainable.

What does lowering calories do to the brain? The brain, like any other part of your body, requires energy from calories to fuel its actions. Despite its proportionally small size, the brain uses around 20% of the total calories needed to keep your body functioning. A highly debated argument is that small reductions to your required calorie intake, without compromising on nutrients, can have benefits to your cognitive function. This is related to dietary restriction (DR) and improved longevity (8), thought to be caused by reduced cellular inflammation and increased autophagy. An example of such study showed elderly people under DR for 3 months had improved cognition compared to non-DR controls (9). Mechanistically, this could be caused by increased LTP as DR studies have shown that eating fewer calories can enhance synaptic plasticity in tandem with increasing anti-inflammatory mechanisms (10). These improvements are proposed to be mediated by reducing the levels of toxic free radicals in the brain and products from the gut microbiome, however the trigger for these mechanisms remains elusive. The research on DR is responsible for intermittent fasting diets you read about online when you eat about 2 pieces of bread and a grape for 1 day a week. Some rave about these diets, others hate them. It is all a matter of taste (...terrible pun).

Some consequences of DR have also been observed. Recently, a study on long term caloric restriction in monkeys described a 50% increase in lifespan but a huge loss of grey matter (neuron cell bodies) in the brain (11). The monkeys tested didn’t show symptoms of reduced cognition, but grey matter loss is not really something you want to mess with. Also, if calories are cut by over 60%, it can be detrimental to human survival (12). Cognitively, extreme calorie cutting can cause a condition called ‘brain fog’; symptomatically described by tiredness, anxiety and irritability. This condition was characterised under control conditions during world war II, when 36 soldiers volunteered to undergo 6 months of eating half the number of calories they needed while walking 22 miles a week to test if men could recover from long-term lack of nutrients (13). The results of this study found some of the soldiers suffered psychological damage; experiencing lethargy and anxiety while also developing obsessions with food. Upon re-feeding, most of the men stated it took them over a year to fully recover. Brain fog is thought to be caused by a lack of specific nutrients and vitamins (14), such as Vitamin B12, rather than low calories. However, removing high levels of calories from your diet makes it very hard to get the right levels of brain food. Therefore, extreme long-term calorie cutting should be avoided.

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To round up, your new years health and fitness resolutions have a huge impact on your brain. Keeping up exercise routines long term can potentially help your memory and attention, while monitoring what you eat may also have some benefits. However, extreme of either of these activities will lead to excessive calorie loss, which can be super unhealthy. So strike a balance; your brain needs a cheeky piece of cake every once in a while.

References: In case you want more deets

1. Winter B, Breitenstein C, Mooren FC, et al. High impact running improves learning. Neurobiol Learn Mem. 2007;87(4):597-609. doi:10.1016/j.nlm.2006.11.003

2. Pereira AC, Huddleston DE, Brickman AM, et al. An in vivo correlate of exercise-induced neurogenesis ( a traiter). 2007. doi:10.1073/pnas.0611721104

3. Yaffe K, Barnes DE, Nevitt M, Lui L-Y, Covinsky K. A prospective study of physical activity and cognitive decline in elederly women. Am Med Assoc. 2001;161:1703-1708.

4. Colcombe SJ, Erickson KI, Raz N, et al. Aerobic Fitness Reduces Brain Tissue Loss in Aging Humans. Journals Gerontol Ser A Biol Sci Med Sci. 2003;58(2):M176-M180. doi:10.1093/gerona/58.2.M176

5. Etnier JL, Caselli RJ, Reiman EM, et al. Cognitive performance in older women relative to ApoE-ε4 genotype and aerobic fitness. Med Sci Sports Exerc. 2007;39(1):199-207. doi:10.1249/01.mss.0000239399.85955.5e

6. Hillman CH, Erickson KI, Kramer AF. Be smart, exercise your heart: exercise effects on brain and cognition.(SCIENCE AND SOCIETY)(Report). Nat Rev Neurosci. 2008;9(1):58. doi:10.1038/nrn2298

7. van Praag H. Exercise and the brain: something to chew on. Trends Neurosci. 2009;32(5):283-290. doi:10.1016/j.tins.2008.12.007

8. Lee C, Longo V. Dietary restriction with and without caloric restriction for healthy aging. F1000Research. 2016;5(0):1-7. doi:10.12688/f1000research.7136.1

9. Witte A V, Fobker M, Gellner R, Knecht S, Floel A. Caloric restriction improves memory in elderly humans. PNAS. 2009;106(14):1255-1260.

10. Hadem IKH, Majaw T, Kharbuli B, Sharma R. Beneficial effects of dietary restriction in aging brain. J Chem Neuroanat. 2017;95(October 2017):123-133. doi:10.1016/j.jchemneu.2017.10.001

11. Pifferi F, Terrien J, Marchal J, et al. Caloric restriction increases lifespan but affects brain integrity in grey mouse lemur primates. Commun Biol. 2018;1(1):30. doi:10.1038/s42003-018-0024-8

12. Speakman JR, Mitchell SE. Caloric restriction. Mol Aspects Med. 2011;32(3):159-221. doi:10.1016/j.mam.2011.07.001

13. Kalm LM, Semba RD. They Starved So That Others Be Better Fed: Remembering Ancel Keys and the Minnesota Experiment. J Nutr. 2005;135(6):1347-1352. doi:10.1093/jn/135.6.1347

14. Layer AM, Gómez-pinilla F. Brain foods: the effects of nutrients on brain function. Nature. 2008;9:568-576. doi:10.1038/nrn2421

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How physical exercise makes your brain work better

Dieting can make you lose your mind


Updated: Jul 25, 2020


Having a baby is hard work. No sleep, unsolvable crying and demands for attention bring a whole new dimension to the word ‘knackered’. A phenomenon which is experienced by many new parents is a state of mind described as ‘baby brain’. Symptoms include forgetfulness, loss of concentration and altered decision making. While these symptoms can happen to all of us due to tiredness or stress, having cognitive fogginess day to day can be frustrating and debilitating; especially when you have a little human to look after and a life to lead. For many years, baby brain has simply been thought of as an old wives tail, but what physically occurs in the brain during pregnancy is something which has recently been explored. So, how does becoming a new parent alter structures in the brain and how does this explain the common condition of baby brain?

Could you repeat that please: Cognitive Symptoms

Baby brain is thought to start during pregnancy. A cognitive study of pregnant and non-pregnant woman revealed pregnant woman in their third trimester had reduced cognitive function, executive functioning and memory compared to their non-pregnant counterparts [1]. For example, pregnant women were less good at remembering numerical sequences than non-pregnant women, implying their ability to hold novel information and process it is impaired. These symptoms begin in the first trimester of pregnancy, with problems in memory and cognitive function significantly changing between the first and second trimester. However, this decline stabilises in the second trimester until the end of the pregnancy. This study aids the confirmation that baby brain is a real cognitive condition as this impairment is seen across many pregnant women. So, if you are pregnant and feel ridiculous for forgetting to drink that cup of tea you made 4 hours ago, don’t. It seems to be a normal part of growing a human.

We’re goin’ through changes: Pregnancy-Induced Brain Alterations

Symptoms of baby brain are hard to experience and explain to others, but what is causing these alterations to your normal cognitive function? Research has found that pregnancy induces changes to the number of neurons and their connections in your brain; described by alterations to the levels of grey matter. Grey matter describes sections of the brain packed with neurons and throughout pregnancy, the volume of this matter reduces in specific brain regions associated with social cognition [2]. It is believed these changes are adaptive and help prepare a woman for motherhood, as a study found the levels of these changes corresponded to the level of attachment a mother showed towards her child. This loss of grey matter still persists two years after pregnancy, suggesting long-term alterations to social cognition processes. However, a reduction of grey matter does not necessarily equate to a loss of function, but could potentially represent a fine tuning of ‘important’ connections. This is what happens during infant development and adolescence with the aim of keeping only the most important synaptic connections; allowing you to channel your focus. The implications of this study could explain why it is difficult to leave a baby to go on a night out with the girls or go back to work as the focus of your social priorities have shifted massively compared to the days before you were a parent.

Rewiring Circuits: Neuron Changes in Pregnant Rodents

As a cell neurobiologist, I am always interested in the small changes made at the neuron level which lead to these huge shifts in cognitive balance. However, with baby brain, it is somewhat of a challenge to study individual live neurons inside a pregnant woman’s brain. However, we can learn a lot about our own neuron’s experience of baby brain from our furry siblings.

Behaviour wise, many rodent experiments show postpartum mothers have reduced anxiety, improved memory and resistance to stress [3]. But what is going on at the cellular level? During pregnancy, some studies have shown there is reduced activity of neurons in brain regions associated with stress and anxiety, as well as HPA Axis down regulation, which would be important for directing energy normally used for stress into the pregnancy. There is also an increase in synaptic number in the hippocampus; the region associated with memory; as well as an increase in the generation of new neurons in a region called the sub-ventricular zone, meaning novel connections needed for maternal behaviours can be made upon the birth of the pups. The majority of these changes are carried through to initial postpartum stages, however there is a decrease in the production of new neurons in the dentate gyrus (part of the hippocampal formation). Finally, in the stages following weaning, anxiety behaviours are increased and in memory regions, there is a decrease in synaptic connections in first-time mothers but an increase in mother’s who have given birth before. These final changes in rodents are probably important for the mother’s survival and to increase the chance of multiple mating’s.

From studying rodents in a controlled environment during gestation, we can see how complex alterations to the brain during pregnancy and postpartum periods are. Trying to translate these data into a human setting is difficult as human’s do not have large litters of pups or are driven to mate as soon as their offspring is weaned like rodents. Plus, human brains experience different hormone changes during pregnancy and have much more complex, higher-functioning behaviours than rodent brains, which could also be altered while pregnant. However, what the rodent studies do tell us is that pregnancy drives plasticity in the brain, including alterations to synaptic number and new neuron production, and these are mainly in the regions associated with anxiety and memory. In humans, memory and anxiety are two behaviours altered in soon-to-be mothers, so it will be interesting to explore the cellular basis of these behaviours once technology permits.

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Bye-Bye Baby: Concluding Remarks

With pregnancy and being a new mother comes a lot of burdens, alterations to hormones and changes to routine which can undoubtedly lead to huge bouts of stress. However, plasticity experienced in the brain was a process over-looked due to lack of research and understanding. However, the study confirming grey matter changes in pregnant women which last at least 2 years following birth gives the first true evidence for the scientific process of 'baby brain'.

If you are struggling with focus and memory on any tasks other than your new little one, this is completely normal. Your brain has just gone through a huge rewiring job to prepare you for motherhood. This most likely makes trying to act like you were ‘before’ a challenge, so don’t be hard on yourself if you are struggling to get back into routine. In the future, it will be interesting to explore the molecular basis of these alterations in order to provide a deeper explanation for pregnant women as to why they feel ‘brain foggy’ and also develop successful coping mechanisms. Studying if any of these changes occur in new dad's will also be interesting as different hormones and environmental influences would also have to be researched. But for now, if you forget to go to an appointment or accidentally dunk a piece of lego in your tea, relax; it's completely normal behaviour after growing a new human.

References

1. Davies et al (2018), Cognitive impairment during pregnancy: a meta-analysis, Med J Aust, 208 (1): 35-40

2. Hoekzema et al (2017). Pregnancy leads to long-lasting changes in human brain structure. Nature Neuroscience 20: 287–296.

3. MacBeth A.H & Luine V. N. (2010) Changes in anxiety and cognition due to reproductive experience: A review of data from rodent and human mothers. Neuroscience & Biobehavioral Reviews. 34(3): 452-467


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