Free will isn’t free

Posted on December 23, 2016 by cedwardpitt

It’s only two days before Christmas. I know most people in the last forty-eight hours before the Yuletide would be focussing on last minute shopping for presents or foraging for the ingredients for their Christmas feasts, or making their last minute arrangements for their holiday celebrations. So now may not be the right time to post something meaty about the philosophy of free will, but hey, it might just make for a welcome distraction. Come with me, if you’re game, down the rabbit hole of our choices.

Dr Leaf, communication pathologist and self-titled cognitive neuroscientist, posted a quote today from former Regius Professor of Divinity at the University of Oxford, Keith Ward: “Free will is a place where people can decide to do what is right or to do what is wrong and nothing determines their choice – lots of things influence their choice but nothing determines it except them”.

But is it, really? Clearly Professor Ward is a very learned fellow, but what strikes me about Dr Leaf’s quote of the day is Professor Ward’s false moral dichotomy, and his over-simplistic implication that every choice is a fully conscious choice. Perhaps his quote is taken out of context by Dr Leaf and his intended message has been skewed. It wouldn’t be the first time Dr Leaf has cherry-picked and misquoted.

Dr Leaf added in her ‘me too’ comment – “So we are responsible and can be held responsible for our choices – this is confirmed by science and scripture”.

I should say, it’s not that Dr Leaf’s comment is completely wrong – we are held responsible for our choices, but this isn’t confirmed by science or by scripture, it is something that is legal more than it is scientific or scriptural.

As humans, we have a strong feeling of voluntary control over our actions, that everything we do is something that we choose to do. This sense of control is so fundamental to our existence that much of our social system depends on it, such as our laws and the penalties for breaking them [1].

Except that science has proven that our sense of full control is largely an illusion.

I understand this idea might be hard for some people to accept. We’re taught that we have full control over our actions or ideas. We experience this sense of control from the vantage point of our own perception. It’s hard to believe that we’re not really in full control of our actions and choices. The dominant paradigm in the Christian church is the idea of free will. We’re taught that the words we say and things we do are the exclusive product of our will. Cognitive neuroscience paints a different picture.

The modern neuroscience of the will started with Benjamin Libet. Professor Libet was a researcher in physiology at the University of California San Francisco. He was initially studying the electrical properties of different sensations in the brain, but in the early 1980’s, he performed an experiment to look at the electrical readings that take place when a person decides on an action. His subjects would decide to perform a simple movement of their arm or hand, and say when they were aware of the intention to act. Electrodes connected to the subject’s heads measured their brain activity before, during, and after their decision to act.

What was remarkable was that there was a clear spike in electrical activity occurring up to a full second before a test subject was consciously aware of the intention to act [2]. Libet suggested that an unconscious process was responsible for the ‘willed’ action.

Other studies since that time have confirmed Libet’s results. In fact, a study in 2008 showed that predictable brain activity occurred up to eight seconds before a person was aware of their intention to act [3].

This predictable unconscious spike of brain activity prior to awareness of our intention to act has been verified over and over and is beyond doubt, but there’s still lots of debate as to exactly what it means. Defenders of the idea of free will have tried presenting alternative explanations of the pre-awareness unconscious activity, but none of them line up with the proven, repeatable science.

So if we don’t have full conscious control of our actions, what does go on in our brains when we perform an action?

Again, I won’t go into the fine print, but it’s important to understand that our brain does most of its work at a subconscious level, which includes the planning and execution of our actions [4, 5]. The brain takes the information presented to it, as well as information from memories, and makes a prediction of the best course of action. This means that our processing of goals, rewards, and actions can be affected by ‘subliminal priming’ (in other words, information we process below our conscious level can affect the decision about the best course of action [5]).

Even though we’re not aware of every process the brain employs in our subconscious to formulate the best plan of action and to prime our system ready for that action, there is a element of awareness that provides real-time monitoring and a veto function [4]. Like if you were about to complain about your job and then suddenly remembered you were talking to your boss, you could stop yourself from saying something you might later regret.

What does it all mean? The take-away message here is this: We have limited will, not free will.

We still have some capacity to choose, but our conscious choices are dependent on our subconscious brain activity, our experience and knowledge.

We can make choices, or “exercise our will”, if you like, but within the constraints of a number of factors beyond our conscious control. We can “pull the brake”, so to speak, and stop an action that our subconscious brain activity primed us for, but wasn’t such a good idea when a bit more thought was applied. Our brain also uses our experience and knowledge to predict the best action to take, and because some of our knowledge and experience comes from exercising our limited choices, we can also say we have some input into our decisions.

So in this sense, Prof Ward is correct – lots of things influence people’s choices and ultimately, the choice someone makes is their choice. I don’t make your choices for you, they are your choices. Except that it’s inaccurate and misleading to think of our will as being entirely conscious and thought driven. We make a lot of subconscious decisions every day, often based on subconscious priming. Most actions we take, day in and day out, are not influenced by our conscious thought. They may sometimes make it into our subconscious awareness, and if they do, it’s often after the fact.

Have ever had a “Why did I say that” experiences, where your brain is thinking one thing and your mouth says another? These are times that demonstrate the difference in the systems at work in our brains, which are usually co-ordinated, but not always. There are other demonstrations of this as well, like specific brain pathologies leading to conditions such as Alien Hand Syndrome.

These sort of conditions show that intention is not the same as action.

Sure, most of the time they’re aligned, but not always. And this is the key to Dr Leaf’s quote of the day today – the underlying assumption is that all of our choices are reflected in our actions, when really, our choices are better thought of as our intentions (although again, it’s still not that simple … is it morally wrong if you try to hurt someone but you don’t, or is it morally wrong if you try not to hurt someone, but you do?)

Professor Ward’s quote also sets up a false dichotomy of free will into only right or only wrong, and doesn’t take into account the intellectual or developmental capacity of a person to make a choice. Would you expect a two-year-old to judge a complex moral life or death situation? A more practical example is should people with dementia be able to make their own financial and health-related decisions?

Most reasonable people would say, “Well, that depends …” and that’s the correct answer here. Nothing in the real world of human morality and choice is black or white. There is always some subtlety, some nuance.

When put in context, the black-and-white thinking and teaching of Dr Leaf is shown up as shallow and inadequate. Her little quote of the day doesn’t prove that free will is Biblically and scientifically supported, far from it. All it shows is that Dr Leaf’s views are narrow and blinkered, and aren’t reflective of any scientific or scriptural expertise.

Dr Leaf is welcome to her opinion, but until she gains some actual expertise, she should reconsider her choice to share it.

References

[1]        Haggard P. Human volition: towards a neuroscience of will. Nature reviews Neuroscience 2008 Dec;9(4):934-46.
[2]        Libet B, Gleason CA, Wright EW, Pearl DK. Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain : a journal of neurology 1983 Sep;26 (Pt 3):623-42.
[3]        Soon CS, Brass M, Heinze HJ, Haynes JD. Unconscious determinants of free decisions in the human brain. Nature neuroscience 2008 May;3(5):543-5.
[4]        Bonn GB. Re-conceptualizing free will for the 21st century: acting independently with a limited role for consciousness. Frontiers in psychology 205;4:920.
[5]        Horga G, Maia TV. Conscious and unconscious processes in cognitive control: a theoretical perspective and a novel empirical approach. Frontiers in human neuroscience 204;6:199.

Dr Caroline Leaf: Putting thought in the right place

Posted on November 8, 2014 by cedwardpitt

Following hard on the heels of her false assumption that our minds control our health, not our genes, and following the same theme, Dr Leaf had this to say today, “Everything is first a thought; the brain is being controlled with EVERY thought you think!”

Dr Caroline Leaf is a communication pathologist and a self-titled cognitive neuroscientist. Reading back through my blogs, this “thought controls the brain / mind controls matter” is a recurrent theme of hers. It is repeated multiple times in her books, like when she writes, “Thoughts influence every decision, word, action and physical reaction we make.” [1: p13] and “Our mind is designed to control the body, of which the brain is a part, not the other way around. Matter does not control us; we control matter through our thinking and choosing” [2: p33] just as a couple of examples.

So how does thought relate to the grand scheme of our brain and it’s processing? Does our thought really control our brain, or is it the other way around. Through all of the reading that I have done on neuroscience, I propose a model of the place of thought in relation to the rest of our brains information processing. It is based on the LIDA model, dual systems models, and other neuroscientific principles and processes.

We’ve all heard the phrase, “It’s just the tip of the iceberg.” It comes from the fact that icebergs are made of fresh water, which is nine-tenths less dense than seawater. As a result, ten percent of an iceberg sits above the waters surface with most of it hiding beneath.

The information processing of our brains is much the same. We may be aware of our conscious stream of thought, but there is a lot going on under the surface that makes our thoughts what they are, even though we can’t see the process underneath.

What’s going on under the surface is a complex interplay of our genes and their expression which controls the structure and function of our brains, which effects how we perceive information, how we process that information and combine it into our memories of the past, predictions of the future, and even the further perception of the present [3].

Genes, epigenetics and the environment
We start with the most fundamental level of our biological system, which is genetics. It becomes clear from looking at any textbook of biological sciences that genes are fundamental to who we are. From the simplest bacteria, fungi, protozoans and parasites, through to all plants, all animals and all of human kind – EVERY living thing has DNA. DNA is what defines life in the broadest sense.

Proteins are responsible for the size, shape and operation of the cell. They make each tissue structurally and functionally different, but still work together in a highly precise electrochemical synchrony. But ultimately, it’s our genes that hold all of the instructions to make every one of the proteins within our cells. Without our genes, we would be nothing more than a salty soup of random amino acids.

Epigenetics and the environment contribute to the way genes are expressed. Epigenetics are “tags” on the strand of DNA that act to promote or silence the expression of certain genes (I discuss this in more detail in chapter 12 of my book, https://www.smashwords.com/books/view/466848). Environmental factors (the components that make up the world external to our bodies) can influence genes and epigenetic markers. The environment can cause genetic mutations or new epigenetic marks that change the function of a particular gene, and depending on which cell they effect (a very active embryonic cell or a quiet adult cell) will largely determine the eventual outcome. The environment is more influential to our genetic expression than epigenetics.

Still, on average only about 25% of the expression of a complex trait is related to environmental factors. So while the environment is important, it is still outdone 3:1 by our genome.

Yes, epigenetics and the environment are important, but they influence, not control, the genome.

Perception
We live in a sensory world. The five senses are vital in providing the input we need for our brain to understand the world and meaningfully interact with it.

Different organs are needed to translate the optical, chemical or mechanical signals into electrical signals. Different parts of our brain then interpret these signals and their patterns.

Our genes significantly influence this process. For example, if someone is born with red-green colour blindness then how he or she interprets the world will always be subtly different to someone with normal vision. Or a person born with congenital deafness will always interpret his or her environment in a different way to someone with full hearing. I’ve highlighted these two conditions because they provide stark examples to help demonstrate the point, but there are many unique genetic expressions in each of the five senses that subtly alter the way each of us perceives the world around us.

So while we may all have the same photons of light hitting our retinas, or the same pressure waves of sound reaching our ears or touch on our skin, how our brains receive that information is slightly different for every individual. The information from the outside world is received by our sensory organs, but it is perceived by our brain, and even small differences in perception can have a big impact on the rest of the system.

Personality
Personality is “the combination of characteristics or qualities that form an individual’s distinctive character” [4]. Formally speaking, personality is, “defined as constitutionally based tendencies in thoughts, behaviors, and emotions that surface early in life, are relatively stable and follow intrinsic paths of development basically independent of environmental influences.” [5]

Professor Gregg Henriques explained it well in Psychology Today, “Personality traits are longstanding patterns of thoughts, feelings, and actions which tend to stabilize in adulthood and remain relatively fixed. There are five broad trait domains, one of which is labeled Neuroticism, and it generally corresponds to the sensitivity of the negative affect system, where a person high in Neuroticism is someone who is a worrier, easily upset, often down or irritable, and demonstrates high emotional reactivity to stress.” [6] The other four personality types are Extraversion, Agreeableness, Conscientiousness, and Openness to Experience.

Gene x environment studies suggest that personality is highly heritable, with up to 60% of personality influenced by genetics [7], predominantly through genes involved in the serotonin [8] and dopamine systems [9, 10]. The “non-shared environment” (influences outside of the home environment) contributes heavily to the remainder [11, 12].

Personality is like a filter for a camera lens, shaping the awareness of our emotional state for better or worse, thus influencing the flow on to our feelings (the awareness of our emotions), our thoughts, and our actions.

Physiology
Watkins describes physiology as streams of data that are provided from the different parts of your body, like the heart rate, your breathing rate, the oxygen in your blood, the position of your joints, the movement of your joints, even the filling of your bladder telling you that you need a break soon.

All of these signals are constantly being generated, and collated in different parts of the brain. Some researchers consider them positive and negative depending on the data stream and the signal its providing. They coalesce into emotion [13].

Emotion
According to Watkins, “emotion” is the sum of all the data streams of physiology, or what he described as “E-MOTION … Energy in MOTION.” [13] In this context, think of emotion as a bulls-eye spirit-level of our body systems. The different forces of our physiology change the “level” constantly in different directions. Emotion is the bubble that marks the central point, telling us how far out of balance we are.

In the interest of full disclosure, I should mention that although emotion is a familiar concept, the work of literally thousands of brilliant minds has brought us no closer to a scientifically validated definition of the word “emotion”. Some psychologists and researchers consider it vague and unscientific, and would prefer that it not be used altogether [14].

I’ve retained it because I think it’s a well-recognised word that conceptually describes the balance of physiological forces.

Feelings
“Feelings” are the perception of emotion.

I discussed earlier in the chapter that what we perceive is different to what we “see” because the subtle genetic differences in our eyes and brains causes the information to be processed differently between individuals. The same applies to the perception of our emotion.

As I wrote earlier, personality is largely determined by our genetics with contributions from our environment [11, 12]. The emotional signal is filtered by our personality to give rise to our feelings. Classically, an optimistic personality is going to bias the emotional input in a positive, adaptive way while a pessimist or neurotic is going to bias the emotional signal in a maladaptive way

That’s not to say that an optimist can’t have depressed feelings, or a neurotic can’t have happy feelings. In the same way that a coloured lens will allow a lot of light through but filter certain wavelengths out, most of our emotional state of being will come through the filter of our personality but the feelings will be subtly biased one way or another.

Executive Functions
Executive function of the brain is defined as a complex cognitive process requiring the co-ordination of several sub-processes to achieve a particular goal [15]. These sub-processes can be variable but include working memory, attention, goal setting, maintaining and monitoring of goal directed action and action inhibition. In order to achieve these goals, the brain requires flexibility and coordination of a number of networks and lobes, although mainly the prefrontal cortex, parietal cortex, anterior cingulate and basal ganglia, and the while matter tracts that connect them.

Executive functions process the incoming information and decide on what goals are best given the context, then plan the goals, execute them to the motor cortices, and monitor the action. Research work from Marien et al [16] demonstrates that unconscious/implicit goals can divert resources away from conscious goals especially if it is emotionally salient or otherwise strongly related. They also confirm that conscious awareness is not necessary for executive function but that implicit goals can be formed and executed without conscious involvement.

Thoughts
Thoughts are essentially a stream of data projected into our conscious space. Baars [17, 18] noted that the conscious broadcast comes into working memory which then engages a wider area of the cerebral cortex necessary to most efficiently process the information signal. We perceive thought most commonly as either pictures or sounds in our head (“the inner monologue”), which corresponds to the slave systems of working memory. When you “see” an image in your mind, that’s the visuospatial sketchpad. When you listen to your inner monologue, that’s your phonological loop. When a song gets stuck in your head, that’s your phonological loop as well, but on repeat mode.

There is another slave system that Baddeley included in his model of working memory called the episodic buffer, “which binds together complex information from multiple sources and modalities. Together with the ability to create and manipulate novel representations, it creates a mental modeling space that enables the consideration of possible outcomes, hence providing the basis for planning future action.” [19]

Deep thinking is a projection from your brains executive systems (attention or the default mode network) to the central executive of working memory, which then recalls the relevant information from long-term memory and directs the information through the various parts of the slave systems of working memory to process the complex details involved. For example, visualizing a complex scene of a mountain stream in your mind would involve the executive brain directing the central executive of working memory to recall information about mountains and streams and associated details, and project them into the visuospatial sketchpad and phonological loop and combine them via the episodic buffer. The episodic buffer could also manipulate the scene if required to create plans, or think about the scene in new or unexpected ways (like imagining an elephant riding a bicycle along the riverbank).

Even though the scene appears as one continuous episode, it is actually broken up into multiple cognitive cycles, in the same way that images in a movie appear to be moving, but are really just multiple still frames played in sequence.

Action
Action is the final step in the process, the output, our tangible behaviour

Our behaviour is not the direct result of conscious thought, or our will (as considered in the sense of our conscious will).

We discussed this before when we talked about our choices in chapter 1. There are two main pathways that lead from sensory input to tangible behaviour – various automated pathways that take input from the thalamus, deep in the brain, and sent to motor circuits in the supplementary motor area and motor cortex of the brain. These can be anything from evasive “reflex” actions[1] to rehearsed, habituated motor movements, like driving. Then there is the second pathway, coming from the executive areas of our brain, that plan out options for action, which are reviewed by the pre-supplemental motor area and the default mode network.

This second pathway is amenable to conscious awareness. Like thought, the projection of different options for action into our consciousness helps to engage a wider area of cerebral cortex to process the data. Most of the possible plans for action have already been rejected by the implicit processing of our executive brain before consciousness is brought in to help. Once an option has been selected, the action is sent to the pre-supplementary motor area, the supplementary motor area, the basal ganglia and finally the motor cortex.

According to the model proposed by Bonn [20], the conscious network has some feedback from the control network of our brain, providing real time context to actions about to be executed, and a veto function, stopping some actions at the last minute before they are carried out. This is largely a function of the basal ganglia [21], with some assistance from working memory.

So as you can see, according to the CAP model, conscious thoughts are one link of a longer chain of neurological functions between stimulus and action – simply one cog in the machine. Thoughts are dependent on a number of processes that are both genetically and environmentally determined, beyond our conscious control. It’s simply wrong to assume that thoughts control the brain.

Dr Leaf is welcome to her opinion, but it is in contradiction to the overwhelming majority of neuroscientific knowledge

References

Leaf, C., Who Switched Off My Brain? Controlling toxic thoughts and emotions. 2nd ed. 2009, Inprov, Ltd, Southlake, TX, USA:
Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:
Hao, X., et al., Individual differences in brain structure and resting brain function underlie cognitive styles: evidence from the embedded figures test. PLoS One, 2013. 8(12): e78089 doi: 10.1371/journal.pone.0078089
Oxford Dictionary of English – 3rd Edition, 2010, Oxford University Press: Oxford, UK.
De Pauw, S.S., et al., How temperament and personality contribute to the maladjustment of children with autism. J Autism Dev Disord, 2011. 41(2): 196-212 doi: 10.1007/s10803-010-1043-6
Henriques, G. (When) Are You Neurotic? Theory of Knowledge: Psychology Today; 2012, 23 Nov 2012 [cited 2013 23 Nov 2012]; Available from: http://www.psychologytoday.com/blog/theory-knowledge/201211/when-are-you-neurotic.
Vinkhuyzen, A.A., et al., Common SNPs explain some of the variation in the personality dimensions of neuroticism and extraversion. Transl Psychiatry, 2012. 2: e102 doi: 10.1038/tp.2012.27
Caspi, A., et al., Genetic sensitivity to the environment: the case of the serotonin transporter gene and its implications for studying complex diseases and traits. Am J Psychiatry, 2010. 167(5): 509-27 doi: 10.1176/appi.ajp.2010.09101452
Felten, A., et al., Genetically determined dopamine availability predicts disposition for depression. Brain Behav, 2011. 1(2): 109-18 doi: 10.1002/brb3.20
Chen, C., et al., Contributions of dopamine-related genes and environmental factors to highly sensitive personality: a multi-step neuronal system-level approach. PLoS One, 2011. 6(7): e21636 doi: 10.1371/journal.pone.0021636
Krueger, R.F., et al., The heritability of personality is not always 50%: gene-environment interactions and correlations between personality and parenting. J Pers, 2008. 76(6): 1485-522 doi: 10.1111/j.1467-6494.2008.00529.x
Johnson, W., et al., Beyond Heritability: Twin Studies in Behavioral Research. Curr Dir Psychol Sci, 2010. 18(4): 217-20 doi: 10.1111/j.1467-8721.2009.01639.x
Watkins, A. Being brilliant every single day – Part 1. 2012 [cited 2 March 2012]; Available from: http://www.youtube.com/watch?v=q06YIWCR2Js.
Dixon, T., “Emotion”: The History of a Keyword in Crisis. Emot Rev, 2012. 4(4): 338-44 doi: 10.1177/1754073912445814
Elliott, R., Executive functions and their disorders Imaging in clinical neuroscience. British Medical Bulletin, 2003. 65(1): 49-59
Marien, H., et al., Unconscious goal activation and the hijacking of the executive function. J Pers Soc Psychol, 2012. 103(3): 399-415 doi: 10.1037/a0028955
Baars, B.J. and Franklin, S., How conscious experience and working memory interact. Trends Cogn Sci, 2003. 7(4): 166-72 http://www.ncbi.nlm.nih.gov/pubmed/12691765 ; http://bit.ly/1a3ytQT
Baars, B.J., Global workspace theory of consciousness: toward a cognitive neuroscience of human experience. Progress in brain research, 2005. 150: 45-53
Repovs, G. and Baddeley, A., The multi-component model of working memory: explorations in experimental cognitive psychology. Neuroscience, 2006. 139(1): 5-21 doi: 10.1016/j.neuroscience.2005.12.061
Bonn, G.B., Re-conceptualizing free will for the 21st century: acting independently with a limited role for consciousness. Front Psychol, 2013. 4: 920 doi: 10.3389/fpsyg.2013.00920
Beste, C., et al., Response inhibition subprocesses and dopaminergic pathways: basal ganglia disease effects. Neuropsychologia, 2010. 48(2): 366-73 doi: 10.1016/j.neuropsychologia.2009.09.023

[1] We often describe rapid unconscious movements, especially to evade danger or to protect ourselves, as “reflexes”. Medically speaking, a true reflex is a spinal reflex, like the knee-jerk reflex. When a doctor taps the knee with the special hammer, the sudden stretch of the tendon passes a nerve impulse to the spinal cord, which is then passed to the muscle, which makes it contract. A true reflex doesn’t go to the brain at all.

Dr Caroline Leaf and the matter of mind over genes

Posted on November 7, 2014 by cedwardpitt

I think I might have to throw away my genetics textbook.

I was always taught that genes were the main driver behind health and disease, and I always thought it was a pretty good theory.

But not according to Dr Caroline Leaf, communication pathologist and self-titled cognitive neuroscientist, who said on her social media feeds today, “Our health is not controlled by genetics – our health is controlled by our mind.”

Taking her statement at face value, she appears to be saying that genes have nothing to do with our health. Dr Leaf has made some asinine statements in the past, but to suggest that genes are irrelevant to human health seemed so stupid that no one in their right mind would suggest such a thing.

Perhaps I was taking her statement the wrong way? I wanted to make sure I didn’t jump to any rash conclusions about Dr Leaf’s statement, so I pondered it at length. Could she be referring to ‘control’ in the absolute sense? How much control do genes have on our health? What about the mind?

After deliberating for a while, I still came to the conclusion that Dr Leaf’s statement was nonsense.

Unfortunately, Dr Leaf’s statement is, like so many of her previous Facebook memes, so vague as to be misleading. The meaning of ‘health’ and ‘controlled’ could be taken so many ways … which part of our health? How much regulation constitutes ‘control’? What about genetics?

Looking at her statement in more depth, it becomes clear that no matter which way Dr Leaf meant it, it’s still wrong. For example, all of human health is controlled, in part, by genetics. That’s because life itself is controlled by genetics. The human genome provides a blueprint for the construction of all of the proteins in all of the cells in our entire body. The expression of those genes determines exactly how our body will run. If the genes are wrong, if the translation of the gene code into a protein is wrong, or if too much or too little of a protein is made, all determines whether our body is functioning at its optimum level or not.

The stimulus for the expression of our genes is influenced by the environment in which we live. If I go out into the sun a lot, the UV light triggers my skin cells to make the protein melanin, which makes my skin go darker and helps to provide some protection against the damaging effects of the UV light.

While the environment plays a part of the expression of some genes, it’s wrong to say that genetics doesn’t control the process. If I go into the sun too much, I risk developing a melanoma, because the sun damages the genes in some of my skin cells, causing them to grow without control.

Genes are still responsible for the disease itself. Sometimes the trigger is from the environment, sometimes it’s not. There are some people with genes for melanoma who don’t need an environmental trigger, because they develop melanoma on skin that’s exposed to very little UV light, like the genital skin.

So fundamentally, even taking the environment into account, our health is controlled by our genetics.

The other part of Dr Leaf’s meme is also wrong. Our health is not controlled by our mind. Our genes are influenced by “the environment”, which according to the seminal paper by Ottman, “The environmental risk factor can be an exposure, either physical (e.g., radiation, temperature), chemical (e.g., polycyclic aromatic hydrocarbons), or biological (e.g., a virus); a behavior pattern (e.g., late age at first pregnancy); or a “life event” (e.g., job loss, injury). This is not intended as an exhaustive taxonomy of risk factors, but indicates as broad a definition as possible of environmental exposures.” [1]

Even if one considers the mind as part of the sub classification of “a behavior pattern”, it’s still pretty clear that most of the factors that make up our environment are not related to our mind at all but are related to the external world, of which we have minimal or no control over. Sure, we make choices, but our choices aren’t truly free. They’re constrained by the environment in which we find ourselves. In the same way, our mind may have some tiny influence on our health, but only insofar as our environment and our genes will allow.

When it all boils down, this meme of Dr Leaf’s is rested on her foundational presumption that our mind can control matter, a very strong theme throughout her most recent book [2], but which is still preposterous. Our thoughts are simply a function of our brain, which is in turn determined by the function of our nerve cells, which is in turn a function of our genes and their expression.

Our mind doesn’t control matter. Matter controls our mind.

I can keep my genetics textbooks after all.

References

Ottman, R., Gene-environment interaction: definitions and study designs. Prev Med, 1996. 25(6): 764-70 http://www.ncbi.nlm.nih.gov/pubmed/8936580
Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:

Dr Caroline Leaf and the brain control misstatement

Posted on September 30, 2014 by cedwardpitt

“Always give credit where credit’s due.”

Dr Leaf is a communication pathologist, and a self-titled cognitive neuroscientist. Yesterday, Dr Leaf made a couple of carefully worded statements on her social media feeds, which given the quality of her previous couple of neuroscience-based factoids, is a definite improvement.

First, she said that, “Your brain is being continuously rewired throughout your life …”. Yep, I can’t disagree with that one. The brain is a very dynamic tissue, constantly remodelling the synaptic wiring to process the information it receives on a daily basis. That’s why the brain is referred to as ‘plastic’, reflecting the property of plastic to be moulded into any shape.

Her next offering sounds really good too. It’s full of encouragement, positivity and hope … the classic feel-good quote: “You can bring your brain under your control, on the path to a better, healthier, stronger, safer and happier life.” Whether it’s true or not depends on how literally you interpret it.

If you loosely interpret it, then it sounds ok. Sure, we have some control over how we act, and if we live our life in the direction dictated by our values, then we will have a better, healthier, stronger, safer and happier life. Modern psychological theory and therapies confirm this [1].

However, what Dr Leaf actually said was, “You can bring your brain under your control”. Having some control over our actions is entirely different to bringing our brain under our control. We can control some of our actions, but we don’t control our brain any more than we ‘control’ our car.

When we say that we’re ‘controlling’ the car, what we actually mean is that we are controlling the speed and direction of the car. But there are thousands of electrical and mechanical actions that take place each second that are vital for the running of the car, and that we have absolutely no direct control over. It just takes one loose nut or faulty fuse to make the car steer wildly out of control, or stop functioning entirely, and then we’re not in control at all.

In the same way, various diseases or lesions in the brain show that brain is really in control, tic disorders for example. These can range from simple motor tics (sudden involuntary movements) to complex tic disorders, such as Tourette’s (best known for the involuntary tendencies to utter obscenities). Another common example are parasomnias – a group of disorders in which people perform complex behaviours during their sleep – sleep talking, sleep walking, or sleep eating.

The fact we don’t see all of the underlying processes in a fully functional brain simply provides the illusion of control. Our brain is driving, our stream of thought just steers it a little, but it doesn’t take much to upset that veneer of control we think we possess.

Ultimately, our brain is still responsible for our action. We don’t have a separate soul that is able to control our brain. Any decisions that we make are the result of our brain deciding on the most appropriate course of action and enacting it [2] (and see also ‘Dr Caroline Leaf, Dualism, and the Triune Being Hypothesis‘ for a more in-depth discussion on the subject of dualism). Therefore, we can’t ever bring our brain under control.

This is important because if we believe that we can bring our brain under control, then by simple logical extension, we can control everything our brain is responsible for – our emotions, our feelings, our thoughts, our memory, and every single action we make. This is Dr Leaf’s ultimate guiding philosophy, though it’s not how our neurobiology works. If we were to believe that we control our thoughts and feelings, we set up an unwinnable struggle against our very nature, like trying to fight the tides.

We are not in control of all our thoughts, feelings, emotions or all of our actions, and neither do we have to be. We just need to make room for our uncomfortable emotions, feelings and thoughts, and to move in the direction of those things we value.

So if you were to take Dr Leaf at her word, she still missed the mark with her post. It sounds ok in a very general sense, but closer inspection reveals a subtle but significant error.

Giving credit where credit’s due, Dr Leaf has tried to tighten up her social media statements. It’s commendable, but unfortunately she needs to bring her underlying philosophy closer to the accepted scientific position to further improve the quality of her teaching.

References

Harris, R., Embracing Your Demons: an Overview of Acceptance and Commitment Therapy. Psychotherapy In Australia, 2006. 12(6): 1-8 http://www.actmindfully.com.au/upimages/Dr_Russ_Harris_-_A_Non-technical_Overview_of_ACT.pdf
Haggard, P., Human volition: towards a neuroscience of will. Nat Rev Neurosci, 2008. 9(12): 934-46 doi: 10.1038/nrn2497

Dr Caroline Leaf and the genetic fluctuations falsehood

Posted on September 27, 2014 by cedwardpitt

While idling away on Facebook, as is my usual pass time, I came upon Dr Leaf’s Facebook feed. There were her usual self-indulgent holiday happy-snaps and another couple of Pinterest-style fluffy inspirational posts. Then this: “Our genetic makeup fluctuates by the minute based on what we are thinking and choosing”.

Dr Caroline Leaf is a South African born and trained, US based, communication pathologist. She also claims that she’s a cognitive neuroscientist. Given the quality of the posts on her social media pages recently, no one could ever take such a claim seriously.

To make sure we’re all clear about what she just said, I’m going to say it again: “Our genetic makeup fluctuates by the minute based on what we are thinking and choosing”. It was an astonishing, if not bewildering statement, especially coming from someone with a PhD level education. If Dr Leaf were a medical doctor and publically made a statement like that, her registration would be reconsidered.

The core of the statement, which pushes it so far beyond the boundaries of rational scientific thinking, is the phrase “Our genetic makeup fluctuates by the minute.”

DNA in our cells is like an old audio cassette tape. Audio cassette tape is a long magnetic stripe, storing the code which the tape player decodes as sound. DNA is a chemical string which has a sequence of “bases” off to the side. The full DNA molecule is made of two matching strings joined by chemical bonds between the bases (hence the name, “base pairs”). Depending on what the cell needs, it runs the DNA through a decoder to either copy it, or to ‘play’ it (i.e. using the information stored in the code to build new proteins).

Like the tape in an audio cassette, the code of the DNA is incredibly stable. The rate of DNA mutation is about 1 in 30 million base pairs [1]. DNA doesn’t ‘fluctuate’, (“rise and fall irregularly in number or amount” [2]). It’s not the stock market. The number of genes in each cell of my body does not rise or fall depending on whether I’m having a good hair day.

The other part of Dr Leaf’s statement, that our DNA “fluctuates … based on what we are thinking and choosing” is also scientific nonsense. The only way that your thoughts and choices are capable of inducing genetic mutations is if those thoughts or choices involve cigarette smoking or standing next to industrial sources of ionising radiation.

I think Dr Leaf is trying to say that our thoughts and choices can change our gene expression, which is the construction of new proteins from the instructions in the DNA code. However, gene expression has nothing to do with our thoughts and choices. IVF embryos are expressing genes like crazy as they grow from one cell to an embryo in just a petri dish. It doesn’t think or choose.

More often than not, our thoughts and our choices are the result of gene expression, not the cause of it. We don’t have any specific control over the process either. The process of genetic expression is dependant on a complex series of promoters and tags on the DNA, which are controlled by other proteins and DNA within the cell, not thought or choice.

The truth is that gene expression occurs moment-by-moment, regardless of what we think or don’t think, do or don’t do. Gene expression is simply DNA being read. Our genetic makeup, the DNA code, is stable. It does not fluctuate. There is no part of Dr Leaf’s statement that is scientifically accurate.

Ultimately, Dr Leaf continues on her pursuit of pseudoscience, an affront to the people who trust her to tell them the truth, and the God of all truth that she purportedly represents.

References

Xue, Y., et al., Human Y chromosome base-substitution mutation rate measured by direct sequencing in a deep-rooting pedigree. Curr Biol, 2009. 19(17): 1453-7 doi: 10.1016/j.cub.2009.07.032
Oxford Dictionary of English – 3rd Edition, 2010, Oxford University Press: Oxford, UK.

Dr Caroline Leaf and the genetic remodelling myth

Posted on August 29, 2014 by cedwardpitt

We are all slowly mutating!

Yep, it’s true. Not to the same extent as you might see in shows like X-Files or Dr Who, but still, our DNA is slowly accumulating permanent changes to the pattern of the genes that it contains. Thankfully, it’s only in science fiction that the mutations result in zombie apocalypse scenarios.

Dr Caroline Leaf is a Communication Pathologist and a self-titled cognitive neuroscientist. Still glowing from the unquestioning adulation of her faithful followers at the Switch On Your Brain conference last week, Dr Leaf has hit social media again. Most of her posts have been innocuous quotes that look borrowed from Pinterest, but today, Dr Leaf has ventured into the pseudoscientific again by claiming that, “Our genes are constantly being remodeled by our response to life’s experiences.”

Unless your response to life’s experiences is to stand next to an industrial microwave generator or live in a nuclear waste dump, Dr Leaf’s statement is pure fiction. Dr Leaf confuses the mutation of our genes with the expression of our genes.

The only way our genes actually change is through mutation. A mutation is a permanent change in the sequence of the DNA molecule. A genetic mutation is a permanent change in the DNA sequence that encodes a gene. DNA is constantly mutating, because of environmental damage, chemical degradation, genome instability and errors in DNA copying or repair [1: p97]. Still, the actual rate of DNA mutation is about 1 in 30 million base pairs [2]. So DNA is very stable, and changes for a number of reasons, only some of which are related to our external environment. And as I alluded to just before, slightly tongue-in-cheek, our responses are not the main contributor to these environmental influences, unless we deliberately expose ourselves to ionizing radiation or smoke cigarettes. Our DNA does not change because of our thought processes as Dr Leaf advocates [3].

What does change more readily is the expression of those genes. Gene expression is the cell machinery reading the genes and making the proteins that the genes encode. The genes are expressed to make the proteins needed for the cell to maintain its function. Which genes are expressed is dependant on the cell’s stage of development and the environment it finds itself in. For example, when the body encounters a high level of dietary iron, a series of steps activates a gene to promote the production of ferritin, a protein that helps to carry iron in the blood stream [1: p375-6]. Gene expression isn’t solely dependent on our environment though, because an embryo is expressing genes like crazy in order to make the proteins to build a human being, but the gene expression in an embryo is largely following a pre-determined time course, not the environment [4] (and certainly not because of responses to life’s experiences).

In summary, our genes are controlled by a myriad of different factors, nearly all of which have nothing to do with our responses or choices. Our genes are not changed by our choices or our responses. Our genes may be mutating, but God designed our cells with mechanisms to repair them. Our genes are not being remodelled by our responses. That’s the realm of science fiction.

References

Strachan, T. and Read, A., Human Molecular Genetics. 4th ed. 2011, Garland Science, New York, USA:
Xue, Y., et al., Human Y chromosome base-substitution mutation rate measured by direct sequencing in a deep-rooting pedigree. Curr Biol, 2009. 19(17): 1453-7 doi: 10.1016/j.cub.2009.07.032
Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan:
Ralston, A. and Shaw, K. Gene Expression Regulates Cell Differentiation. Nature Education, 2008. 1(1): 127; http://www.nature.com/scitable/topicpage/gene-expression-regulates-cell-differentiation-931

Like to read more about Dr Leaf’s teaching and how it compares to current science? Download the free eBook HOLD THAT THOUGHT, Reappraising The Work Of Dr Caroline Leaf

Dr Caroline Leaf and the Myth of Mind Domination

Posted on May 9, 2014 by cedwardpitt

“You control your brain … your brain does not control you!”

So says Dr Caroline Leaf, Communication Pathologist and self-titled Cognitive Neuroscientist.

You’d hope that Dr Leaf would know. She says on her website that “Since the early 1980‘s she has studied and researched the Mind-Brain connection.” And if you take what she says at face value, it sure sounds right. Of course we’re in control. My brain does what I tell it to do. Except that it actually doesn’t. Our brain has a lot more control over us than we realize.

First of all, our “free” will isn’t actually free at all, but constrained by a number of unseen, subconscious processes that are entirely dependent on our brain. It may seem like we’re in complete control of our choices, but our subconscious brain has already done most of the work for us. Even if we had complete freedom over our choices, our “free” will would still require an intact brain in order to carry out its wishes.

The “control” of our brain is very similar to our “control” when we drive a car. When we say that we’re “controlling” the car, what we actually mean is that we are controlling the speed and direction of the car. But there are thousands of electrical and mechanical actions that take place each second that are vital for the running of the car, and that we have absolutely no direct control over. It just takes one loose nut or faulty fuse to make the car steer wildly out of control, or stop functioning entirely, and then we’re not in control at all.

In the same way, various diseases or lesions in the brain show that brain is really in control. The fact we don’t see all of the underlying processes in a fully functional brain simply provides the illusion of control.

For example, there are a number of lesions of the parietal lobes within the brain that give rise to some unusual but intriguing conditions. One of which is a condition called “Alien Hand Syndrome”. Wegner describes two patients with Alien Hand Syndrome, a lady whose “left hand would tenaciously grope for and grasp any nearby object, pick and pull at her clothes, and even grasp her throat during sleep … She slept with the arm tied to prevent nocturnal misbehavior”, and a man who, “While playing checkers on one occasion, the left hand made a move he did not wish to make, and he corrected the move with the right hand; however, the left hand, to the patient’s frustration, repeated the false move. On other occasions, he turned the pages of the book with one hand while the other tried to close it; he shaved with the right hand while the left one unzipped his jacket” [1]. Alien Hand Syndrome demonstrates that our decision-making and our action sequences are controlled by two separate systems in our brains.

There are other conditions that also show that our brains control us more than we control them. A more common example are the tic disorders, such as simple motor tics (sudden involuntary movements) and complex tic disorders, such as Tourette’s (best known for the involuntary tendencies to utter obscenities). Even more common are parasomnias – a group of disorders in which people perform complex behaviours during their sleep – sleep talking, sleep walking, sleep eating. One of my patients once drove her car while asleep (Honestly, that’s no exaggeration!).

So at best, we only have partial control of our brain. Our brain is driving, our mind just steers it a little, but it doesn’t take much for that veneer of control that we think we possess.

The other way in which we appear to have control over our brain is through free will. Free will has been debated for years on philosophical grounds, but over three decades ago, Libet performed an experiment that demonstrated measurable and predictable brain activity occurring up to a full second before a test subject was consciously aware of the intention to act [2]. More recently, a study by Soon et al showed that predictable brain activity occurred up to eight seconds before a person was aware of their intention to act [3]. As Bonn says, “the gist of these findings is that our feeling of having consciously willed an act is illusory in many ways. It seems that the conscious awareness of intention that we place so much weight upon, that we naively think of as causal, is, in fact, a narrative construction that is formed well after the train of causation has been set in motion.” [4]

The Oracle explained it to Neo, “… you didn’t come here to make the choice. You’ve already made it. You’re here to try to understand why you made it.” (Matrix Reloaded, 2003)

Haggard concludes, “Modern neuroscience rejects the traditional dualist view of volition as a causal chain from the conscious mind or ‘soul’ to the brain and body. Rather, volition involves brain networks making a series of complex, open decisions between alternative actions.” [5]

This does not eliminate our capacity to choose, but frames it in a more realistic fashion. As Bonn points out, “Although we are not consciously aware of what is going on at every stage of the chain of neural events leading to action, there is room for a degree of conscious involvement if only to pull the emergency brake before it is too late. Thus, although it may not be the initial source of motivations and behavioral impulses, the part of the mind that is self-reflective; that can envision the self in causal and narrative contexts, may serve important monitoring and control functions.” [4]

Again, we have less control over our brain than we realize. We feel like we have made a choice, but more often than not, our brain already made the choice for us up to eight seconds beforehand, and the feeling of intention that we have is simply our conscious mind catching up – not making the choice, but finding a reason for why we made the choice.

It’s always nice when people who call themselves neuroscientists tell us what feels intuitively correct. In the cold, hard light of day, actual neuroscientists don’t tell us what’s intuitively correct, but what’s actually correct. It may seem like our mind is in control of our brain, but modern neuroscience confirms that our brain is the dominant force, while our mind just helps to steer a little.

References

Wegner, D.M., Precis of the illusion of conscious will. Behavioral and Brain Sciences, 2004. 27(5): 649-59
Libet, B., et al., Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain, 1983. 106 (Pt 3): 623-42 http://www.ncbi.nlm.nih.gov/pubmed/6640273
Soon, C.S., et al., Unconscious determinants of free decisions in the human brain. Nat Neurosci, 2008. 11(5): 543-5 doi: 10.1038/nn.2112
Bonn, G.B., Re-conceptualizing free will for the 21st century: acting independently with a limited role for consciousness. Front Psychol, 2013. 4: 920 doi: 10.3389/fpsyg.2013.00920
Haggard, P., Human volition: towards a neuroscience of will. Nat Rev Neurosci, 2008. 9(12): 934-46 doi: 10.1038/nrn2497

Bad choices cause brain damage?

Posted on January 25, 2014 by cedwardpitt

“To err is human; to forgive, divine.” Alexander Pope.

I’m not perfect. At least, not the last time I checked. And we’re all the same, aren’t we. We all know through experience that we all stuff things up on a fairly regular basis. We make bad choices. We’re human!

Dr Caroline Leaf, Communication Pathologist and self-titled Cognitive Neuroscientist, believes that these bad choices literally cause brain damage. Her fundamental assumption is that our thoughts control our brain [1: p33]. These thoughts can be healthy or they can be toxic. Toxic thoughts “are thoughts that trigger negative and anxious emotions, which produce biochemicals that cause the body stress.” [2: p19]

Dr Leaf’s assumption is that thoughts and bad choices cause our brain cells to shrivel or die. “Once your body is truly in stress mode and the cortisol is flowing, dendrites start shrinking and even ‘falling off’” [2: p32]. She also says that, “We have two choices, we can let our thoughts become toxic and poisonous or we can detox our negative thoughts which will improve our emotional wholeness and even recover our physical health.” [2: p21]

It sounds a little extreme. We all make bad choices, and we all experience stress. When we’re stressed, do our memories really go missing, or the dendrites of nerve cells shake and fall like tree branches in a storm? If we make a bad choice, do we really get brain damage? Lets see what the scientific literature has to say.

Imagine walking along a path in a forest and you see a snake, only inches in front of you on the path. What do you do? When faced with a high level of acute stress, the brain switches into a binary mode – fight/flight or freeze. Self-preservation has to kick in. The only decision you have to make then and there is whether to run, to try and kill the snake before it kills you, or stop dead still and hope that the snake ignores you and slithers away.

At that point, most memory is redundant, as is a high-level analysis of snake species, or any other cognitive pursuit. The brain doesn’t need them at that precise moment. If they did engage, they would just get in the way. Switching the thinking parts of your brain off focuses your attention on the immediate danger. It’s an adaptive survival response. Meantime, your memories and your theoretical knowledge about snakes don’t disappear. They are still there, unchanged. It is false to suggest that the memories “shrink”.

We’ve all experienced “mental block”. Sometimes when we get into a situation, like an exam or a business meeting, our stress levels are high, and binary mode kicks in again, although this time it can be a hindrance. This phenomenon of mental block under high stress was first proposed in 1908 and is currently known as the Yerkes-Dodson Law, a fundamental principle of the behavioural sciences [3]. Similar to the stress-productivity curve, Yerkes and Dodson proposed a U-shaped curve to represent the relationship between arousal (which could be either level of consciousness or stress) and behavioural performance. At low arousal, there is poor performance. At the mid-point of arousal, there is peak performance, and at high arousal, performance diminishes.

But again, our memories don’t shrink, and our nerve cell branches don’t fall off. Once we reduce our level of arousal, we move away from the fight/flight/freeze mode, and everything is still there (and we perform better, according to Yerkes-Dodson).

Dr Leaf has a favourite analogy of “neurons as trees”. And if neurons are trees, then the branches can “fall off”. But neurons are not trees and dendrites are not tree branches. The dendrites do not ‘fall off’ the neuron. The neurons in the brain have mechanisms for ongoing brain plasticity – the ability of the brain to adapt to the challenges and changes in its internal and external environment that are constantly occurring. If the brain needs to build a new circuit to encode a new piece of information, then it grows new dendrites and creates new synapses. But the brain is limited by the amount of energy it can consume, and therefore the number of synapses it can maintain. So the brain trims unnecessary dendrites, a process called “synaptic pruning”.

Synaptic pruning is a normal process. Chechik and Meilijson confirm that, “Human and animal studies show that mammalian brains undergoes massive synaptic pruning during childhood, removing about half of the synapses until puberty.” [4]

Synaptic pruning is not deleterious, but beneficial. Chechik and Meilijson also note that, “synaptic overgrowth followed by judicial pruning along development improves the performance of an associative memory network with limited synaptic resources.” [4] So synaptic pruning is a normal physiological process, and occurs in all of us for many reasons, predominantly to improve the efficiency of our neural networks. Perhaps synaptic pruning associated with the stress response is also an adaptive process?

Synaptic pruning also occurs in other physiological states that have nothing to do with stress or thought, such as the effects of oestrogen during the menstrual cycle and at menopause [5, 6].

A link between stress and dendrite loss has been discovered, but it is not consistent. Some authors like Kopp and Rethelyi suggest that “severe stress for a prolonged period causes damage in hippocampal pyramidal neurons, especially in the CA3 and CA4 region and reductions in the length and arborization of their dendrites.” [7] However, Chen et al writes, “Whereas hippocampus-mediated memory deficits commonly were associated with—and perhaps result from—loss of synapse-bearing dendrites and dendritic spines, this association has not been universal so that the structure–function relationship underlying the effects of stress on hippocampal neurons has not been resolved.” [8]

It’s more accurate to think that chronic stress causes dendritic remodeling in animals [9], in which some nerve cells prune their synapses, which others grow them, and energy is diverted away from new nerve cell formation to the new synapses that are needed to cope with the stress.

A number of scientists have pointed out that patients with depression or anxiety, who normally have high levels of stress, have a smaller hippocampus and larger amygdala, so stress and depression must cause the smaller brain regions [9]. There may be some reduction in the number of synapses within the hippocampus and the frontal lobes of the brain, which may account for the change in size observed by a number of researchers. But the modern thinking on these changes is that they are associated with depression, not caused by depression [10] (Correlation does not equal causation).

So, stress is associated with depression, but this is because genetic defects in one or multiple genes reduce the ability for the brain cells to produce synaptic branches. It’s this decrease in the number of synapses that contributes to the typical changes in the brain seen at autopsy of patients who suffered from depression or anxiety [11]. The reduced ability of the nerve cells to grow synapses means that new branches can’t grow fast enough to process the stress signals properly [11, 12]. The poor signal transmission leads to a predisposition towards mood disorders like anxiety and depression [10, 11, 13-15], and less synaptic branches means both a smaller volume of the hippocampus, and an inability to process stress signals leads to a larger, overactive amygdala.

In summary, synaptic pruning is not due to toxic thinking or bad choices, unless every one of us engages in nothing but toxic thinking from early childhood to puberty, and menopause causes bad choices and toxic thoughts. Stress doesn’t cause dendrites to fall off, but causes a reorganization of the dendrites to adapt to the new signals. The reduced capacity to form new dendrites makes those prone to mood disorders more vulnerable to stress, and depression or anxiety is the end result.

We are all bound to make bad choices and to have stress. They don’t cause brain damage. Which if you’re not perfect like me, is good news.

References

1. Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan

2. Leaf, C., Who Switched Off My Brain? Controlling toxic thoughts and emotions. 2nd ed. 2009, Inprov, Ltd, Southlake, TX, USA:

3. Cohen, R.A., Yerkes–Dodson Law, in Encyclopedia of Clinical Neuropsychology, Kreutzer, J.S., et al., Editors. 2011, Springer Science+Business Media LLC: New York ; London. p. 2737-8.

4. Chechik, G., et al., Neuronal regulation: A mechanism for synaptic pruning during brain maturation. Neural Comput, 1999. 11(8): 2061-80 http://www.ncbi.nlm.nih.gov/pubmed/10578044

5. Chen, J.R., et al., Gonadal hormones modulate the dendritic spine densities of primary cortical pyramidal neurons in adult female rat. Cereb Cortex, 2009. 19(11): 2719-27 doi: 10.1093/cercor/bhp048

6. Dumitriu, D., et al., Estrogen and the aging brain: an elixir for the weary cortical network. Ann N Y Acad Sci, 2010. 1204: 104-12 doi: 10.1111/j.1749-6632.2010.05529.x

7. Kopp, M.S. and Rethelyi, J., Where psychology meets physiology: chronic stress and premature mortality–the Central-Eastern European health paradox. Brain Res Bull, 2004. 62(5): 351-67 doi: 10.1016/j.brainresbull.2003.12.001

8. Chen, Y., et al., Correlated memory defects and hippocampal dendritic spine loss after acute stress involve corticotropin-releasing hormone signaling. Proc Natl Acad Sci U S A, 2010. 107(29): 13123-8 doi: 10.1073/pnas.1003825107

9. Karatsoreos, I.N. and McEwen, B.S., Psychobiological allostasis: resistance, resilience and vulnerability. Trends Cogn Sci, 2011. 15(12): 576-84 doi: 10.1016/j.tics.2011.10.005

10. Palazidou, E., The neurobiology of depression. Br Med Bull, 2012. 101: 127-45 doi: 10.1093/bmb/lds004

11. Karatsoreos, I.N. and McEwen, B.S., Resilience and vulnerability: a neurobiological perspective. F1000Prime Rep, 2013. 5: 13 doi: 10.12703/P5-13

12. Russo, S.J., et al., Neurobiology of resilience. Nature neuroscience, 2012. 15(11): 1475-84

13. Felten, A., et al., Genetically determined dopamine availability predicts disposition for depression. Brain Behav, 2011. 1(2): 109-18 doi: 10.1002/brb3.20

14. Bradley, R.G., et al., Influence of child abuse on adult depression: moderation by the corticotropin-releasing hormone receptor gene. Arch Gen Psychiatry, 2008. 65(2): 190-200 doi: 10.1001/archgenpsychiatry.2007.26

15. Hauger, R.L., et al., Role of CRF receptor signaling in stress vulnerability, anxiety, and depression. Ann N Y Acad Sci, 2009. 1179: 120-43 doi: 10.1111/j.1749-6632.2009.05011.x

Dr C. Edward Pitt

Faith, Hope, Love, Science.

Tag Archives: choice

Free will isn’t free

Dr Caroline Leaf: Putting thought in the right place

Dr Caroline Leaf and the matter of mind over genes

Dr Caroline Leaf and the genetic fluctuations falsehood

Dr Caroline Leaf and the genetic remodelling myth

Dr Caroline Leaf and the Myth of Mind Domination

Bad choices cause brain damage?