Reviewed by Robert Charman
Dr Eagleman directs the Laboratory for Perception and Action and the Initiative on Neuroscience and Law at Baylor College of Medicine, Houston. His research interests are neuroplasticity, time perception, synaesthesia, visual illusions and the developing field of neurolaw (the implications of neuroscientific findings for the basis on which we make laws, punish criminals and formulate methods of rehabilitation). He has published over 90 research papers, is the author of Incognito: the Secret Lives of the Brain (2011), co-athor with Dr Richard Cytowic, Clinical Associate Professor of Neurology, George Washington University Medical Centre, of Wednesday is Blue: Discovering the Brain of Synesthesia, co-author with Dr Jonathan Downar, Assistant Professor, Department of Psychiatry, University of Toronto, of Brain and Behaviour: A Cognitive Neuroscience Perspective (2016) and was the writer and presenter of the six hour television series The Brain with David Eagleman.
This book, which includes numerous neurological case histories, is a model of lucid writing accompanied by excellent illustrations. It is referenced by chapter end notes and ends with a glossary of terms that does not include an entry concerning spirituality, parapsychology, life after death or any related heading. Why, then, does it merit a review in the Network Review? The answer is that if Dr Eagleman is representative of the neuroscience community as a whole it presents the latest consensual thinking across the neurosciences concerning the relationship between brain and mind or, to be more accurate, between brain activity and mental activity including consciousness and sense of self. Whatever theories are formulated concerning the nature of psi, soul or spirituality we must start from what we know, or can reasonably infer, concerning the brain-mind relationship. From the standpoint of a neuroscientist Dr Eagleman synthesises our present knowledge of this relationship in six chapters headed Who am I? What is reality? Who’s in control? How do I decide? Do I need you? And Who will we be? If these fundamental questions do not attract your immediate interest I’m at a loss to think what will.
According to Eagleman the basic premise of the neurosciences including neuropsychology is that each human mind (taken here as a collective noun including all forms of mental activity from the subconscious through everyday consciousness to whatever exalted state of meditative, spiritual, or transcendental experience one can aspire to) is an emergent property arising from the coordinated activity of billions upon billions of densely packed nerve cells, their trillions upon trillions of interconnecting circuitries carrying billions of bioelectrical impulses across a range of frequencies from 1-100Hz+ throughout the brain and cerebellum without cease. Feed into this mix incoming impulses from all our sense organs, outgoing motor impulses activating our muscles to move our bodies, sensory return impulses from skin, joints and tissues saying what is happening to our body ‘out there’ together with the sympathetic and parasympathetic nervous systems controlling all our viscera, and one can obtain an impressionistic glimpse of our brains ‘humming’ with bioelectrical activity.
The premise that mind is an emergent property of brain and therefore dependent upon brain is an inference based upon the vast banks of data accumulated over the last two hundred or so years from worldwide clinical investigations and laboratory research findings. We do not know how our conscious awareness and sense of self arises from apparently non-aware physical brain processes but, the neurosciences say with one voice, the fact that, as yet, we do not know how does not alter the fact that it does. In support of this position Dr Eagleman emphasises the fact is that for every mental experience there is a corresponding correlate of brain activity without any known exception. Correlation of an A with a B does not, in itself, provide evidence of A→B causation or vice versa because causation requires a specific relationship between the two correlations. The premise of neuroscience is that this causal requirement is fulfilled because if the latter does not happen then the former does not happen and it never ever happens the other way round. The mental properties of mind must, therefore, emerge from the physical properties of the brain as there is no other credible interpretation of their relationship.
Dr Eagleman offers the analogy of a leaf cutter ant colony in which the coordinated activity of hundreds of thousands of individual ants results in the emergence of a super-organism with collective behavioural properties far more sophisticated and problem solving that any of its individual parts. Each ant, taken as analogous to each individual neuron, is programmed to follows simple rules of behaviour with no awareness of the whole but the organisational properties of the whole emerge from the continuously active sum of its myriad parts.
In his chapter on Who am I? Dr Eagleman says that when he holds a brain in his hands he remains in awe that this soft, dense, jelly like, structure weighing some 3 lbs with its deeply wrinkled surface seems so completely at odds with the mental processes it creates. ‘Our thoughts and our dreams, our memories and experiences all arise from this strange neural material. Who we are is found within the intricate firing patterns of electrochemical impulses. When that activity stops, so do you. When that activity changes character due to injury or drugs you change character in lockstep. Unlike any other part of your body if you damage a small piece of the brain, who you are is likely to change radically’. From birth onwards the brain endlessly reshapes its synaptic connections and therefore our mental processes and who we are by forming new circuitries joining different parts of the brain together in ever changing functional unities. Commencing with the basic genetic programming that built the brain and how it functions the major determinants for our subsequent development as human beings are our physical and our social environments from babyhood onwards, resulting in concurrent changes to our neuronal circuitry and therefore our emergent selves.
Eagleman quotes as an example of these determinants how many adoptive parents found that children brought up from birth in the regimented, emotionally empty, sensorily deprived and communicatively barren world of Romanian orphanages were unable to understand their new world of loving parenthood. Tests indicated IQs in the sixties and seventies and EEGs showed ‘dramatically reduced neural activity’. Encouragingly, neuroplasticity in response to new experiences enabled various degrees of recovery, with children under the age of two recovering best but with older children showing prolonged developmental deficits into adulthood. Their emergent self was permanently damaged. Teenage brains differ in the wiring of their connections from adult brains with the resultant differences in impulsive behaviour and attitudes that are the despair of parents. Finding our way round our surroundings, which seem so obviously ‘out there’, depends upon the two midbrain hippocampal nuclei that store geographically correlated neural maps. These subcortical nuclei are substantially larger and their neural wiring is far more intricate in the brains of London cabbies who have successfully taken some four years to learn ‘The Knowledge’ of London streets, hotels, shops, theatres, sports grounds and so on involving thousands of interconnected geographical locations than those of us who have not. Presumably, the hippocampal nuclei of those unable to complete the course may not have been up to the task. If they are damaged, then so is our conscious spatial memory. This is just one example amongst dozens of our unaware mental dependence upon our brains for our everyday reality.
Our personalities and resulting behaviour can be dramatically affected by brain pathology. Consider the following case discussed by Eagleman. On August 1, 1966, twenty-five year old Charles Whitman took an elevator to the observation deck of the University of Texas Tower in Austin. He then fired down at random into the crowd killing thirteen and wounding thirty-three others before the police killed him. They later found that he had killed his wife and mother the night before. Nothing about his everyday life and social relationships as observed by family, friends and colleagues indicated that he could possible become a mass murderer. He was an Eagle Scout and was working as a responsible bank teller to fund his engineering course with a bright future ahead. When they searched his home the police found the following typed note ‘I don’t really understand myself these days. I am supposed to be an average reasonable and intelligent young man. However, lately (I cannot recall when it started) I have been a victim of many unusual and irrational thoughts……After my death I wish that an autopsy be performed on me to see if there is any visible physical disorder’. When the autopsy was performed the pathologist found a small tumour pressing against the amygdala nuclei that carry neural correlates of fear, anger and aggression. As Dr Eagleman describes it ‘this small amount of pressure on the amygdala led to a cascade of consequences in Whitman’s brain, resulting in him taking actions that would otherwise have been completely out of character. His brain matter had been changing and who he was changed with it’. What, one wonders, would have been the verdict if he had been brought to trial without any knowledge concerning that small tumour.
The answer to ‘Who am I?’ is that there is no ‘I’ that remains unchanged over successive days and years. It changes everyday throughout life in parallel with correlated changes in our brain in response to changing circumstances even although, through the uncertain thread of memory, we retain the continuity of feeling that we are the same person as before but just a little bit older. If, says Eagleman, you were able to sit on a park bench alongside a series of yourself as a six year old, a mid teenager, in your mid twenties, thirties, forties, fifties and sixties to yourself in your mid seventies you would be meeting very different people in physical energy, outlook, emotions, relationships, ambitions and understanding of life. Our memories of who we think we were at any given age are very different to who we actually were at that time. Even our familiar ‘I’ has only a limited daily existence. Neurologically speaking, our conscious ‘I’ only arises as an emergent property when our billions of neurons are engaged in patterns of synaptic exchange across the whole brain whose collective purpose is to create our daily ‘I-ness’. When we become non-conscious as in deep sleep our brain still remains active but in more discrete areas and our brain waves fall into frequencies of around 4Hz. The daytime ‘I’ no longer exists and only returns when our brain ‘fires up’ again next morning into a familiar pattern of cortical activity including activation of memories of yesterday’s ‘I’. Today’s newly conscious ‘I’ seamlessly reconnects with the conscious ‘I’ of yesterday in apparent continuity of being as if the intervening eight hour period of non-existent ‘I’ had never happened. If your brain does not wake up again, then nor does the emergent ‘I’ of you that is dependent upon it.
The answer to What is Reality? is that as far as your experiential reality is concerned it is a construct of the brain that, from babyhood onwards, has been genetically programmed to use its huge computational capacity to interpret the messages pouring in from its senses to create a psychologically emergent picture of the outside world and your experiential body moving within it. This applies to all species according to their survival needs. As Eagleman describes it the inferred physical reality as explored by physics is ‘colourless, odourless, tasteless and silent. Outside your brain there is just energy and matter. Over millions of years of evolution the human brain has become adept at turning this energy and matter into a rich sensory experience of being’ and later ‘All of your sensory experiences are taking place in storms of activity within the computational material of your brain’ which ‘has no access to the world outside. Sealed within the dark, silent chamber of your skull, your brain has never directly experienced the external world and it never will’. The brain translates all incoming sensory impulses into a common currency of electrochemical signals, passes them through intermediate stages of incredibly complex computation that is completed by the cerebral cortex to create an emergent mental reality of experiencing. But in neurological reality Eagleman says that ‘Everything you experience – every sight, sound, smell – rather than being a direct experience, is an electrochemical rendition in a dark theater’.
The apparently effortless immediacy of experiencing the ‘out there-ness’ of our three dimensional world of vision requires the computational power of a third of our brain to create and sustain. Eagleman illustrated this point by discussing the experience of Mike May. Aged three and a half he was blinded by a chemical explosion that scarred both corneas. Despite this handicap he became a successful business man and a champion paralympic skier, navigating the slopes by sound markers. In his late forties he underwent a new treatment that restored corneal transparency so his retinas could again supply his brain with accurate visual information. The result was not what he or anyone had expected. It was terrifying. Every visual experience was a discordant jumble of colours, shapes and movement without depth or coherence causing him great distress. Although this partially improved with time some fifteen years later Mike still had difficulty in reading, recognising faces and facial expressions and still relied on his other senses for emotional security. His adult brain had lost the computational power of childhood necessary to convert his retinal signals into the mental creation of an outside world we take as an objective given. Somehow, our visual brain working in concert with all of our other bodily senses including movement and touch constructs an experiential reality of ‘out-there-ness’ that somehow invests the spatial features and properties of a pre-existing physical world out there in a species specific way for survival. All animals share the same public space that exists out there and envision it according to their needs.
What happens, then, to the mind when all incoming streams of visual and auditory stimuli are removed? When Alcatraz was a prison disruptive prisoners were locked in a cell called The Hole for days or weeks. Pitch black and in complete silence prisoners in The Hole lost all sense of time and everyday reality. Many became totally disoriented, banging their heads on the walls in despair. One ex-prisoner spent 29 days in The Hole for smashing up his cell. He told Eagleman that his mind replayed inner memories of family trips. He relived flying a kite as if he was back in that moment. Another inmate said that he saw an inner spot that expanded into a television screen on which he watched programmes. These experiences were not a form of daydreaming, they saw these pictures as completely real. In the absence of incoming sensory stimuli their active brains had created emergent inner realities as real as everyday reality.
Our experience of the rate of time flow has a rather elastic relationship with clock time. An interesting example is when in retrospect we recall the dramatic slowing down of time and rate of observed events as in the moments before a life threatening car crash or falling from a considerable height. What happened in a few seconds of clock time seemed to take for ages. To test whether perceptual time really did slow down during such a situation Dr Eagleman devised a wrist worn chronometer with numerals that alternated their pattern slightly faster than can be seen to change in normal time but should be seen if time slowed down. He and some very brave students then dropped 150 feet in terrifying free fall while looking at their chronometers, but despite post-fall certainty that time really had dramatically slowed down during the fall they were unable to see any alternation in number change. Neurologically, what happens in such life threatening circumstances is that our amygdala nuclei activate an incredibly fast incident observation and memorisation system that stores a vast amount of data for later review. As this review takes place at our normal, much slower everyday processing rate it takes much longer to download so much dense detail, creating a post experience certainty of recall that time really had had slowed down.
So ‘Who’s in control? As you will have guessed by now the first answer is our brain. You are totally dependent in everything you do from ‘standing, walking, driving a car, recognising a friend, getting a joke, feeling hungry or thirsty’ on ‘vast computations happening below your conscious awareness. At this moment, just like in every moment of your life, networks in your brain are buzzing with activity, billions of electrical signals are racing along cells, triggering chemical impulses at trillions of connections between neurons. Simple acts are underpinned by a massive labour force of neuron activity. You remain blissfully unaware of all this activity but your life is shaped and coloured by what is happening under the hood: how you act, what matters to you, your reactions, your loves and desires, what you believe to be true and false. Your experience is the final output of these hidden networks’. Having said that Dr Eagleman then asks rather surprisingly ‘So who exactly is steering the ship?’ In brief, and sticking with this nautical analogy, the emergent consciousness of you is the captain and steersman who decides on your course, based upon the outcome of interacting variables of emergent emotions, memories, imagined future scenarios, desired goals and logical thinking as to how to get there. In that sense the main function of the brain is to create an effective, practical emergent you as without a daily you and your awareness and response to the world around you it cannot survive. An alternative analogy is that the emergent you acts as a cerebral CEO in charge of competing sub departments, deciding upon overall strategy but not needing to know detail.
How Do I Decide? Dr Eagleman takes the line that the brain is a battleground of competing neural networks linked to the emergent you of likes and dislikes and decisions as to whether, for example, your love of ice cream is greater than your desire to cut down on sugar for the sake of your health and waist line. An emotional desire to come to a decision after weighing up the alternatives is essential as without it you remain in a state of indefinite indecision. This depends upon an intact relationship between your orbitofrontal cortex (just above your eyes) that contain the frontal lobe neural correlates of intellectual assessment and creation of possible future scenarios of what must be decided and the midbrain emotional centres feeding information on the emotional pros and cons. Eagleman quotes the case of Tammy Myers who sustained damage to part of her orbitofrontal cortex that connected to her emotional centres following a motorbike accident. Her intelligence remained unimpaired but she now finds making a decision almost impossible as although she can weigh up the pros and cons in intellectual abstract the drive to come to a decision has disappeared. In consequence, she often spends whole days of indecisive reflection on the sofa. This is a long chapter discussing, in part, how knowledge of the brain through brain imaging is being used to assist criminals to control their antisocial impulses and drug addicts to overcome their drug dependency by retraining brain circuitry.
Do I Need You? The short answer is ‘Yes’. It seems that ‘Normal brain function depends upon the social web around us. Our neurons require other people’s neurons to survive.’ ‘We are social creatures and an enormous amount of brain circuitry has to do with other brains’. This chapter provides numerous examples to illustrate this point and the personal and social problems created when your brain has not got, or has not been able to activate, the necessary empathic social circuitry as in the spectrum from Asperger’s Syndrome to severe autism. This section includes an intriguing example where, using transcranial magnetic stimulation (TMS) researchers applied a series of strong magnetic pulses to the dorsolateral frontal cortex of a participant who suffered from Asperger’s Syndrome. Although a member of a rock band he was unable to understand and interpret social interactions so he retreated into a world of audiovisual technology. To the complete surprise of the researchers these pulses somehow ‘unlocked’ his ability to enter the normal social world. A whole emergent new self opened up as he suddenly felt part of society. He could now emotionally ‘read’ conversational meanings, bodily gestures and facial expressions. It was a complete revelation to him and, again to the surprise of the researchers, this change into a new, socially aware ‘I’ appears permanent.
Who Will We Be? Eagleman discusses recent advances in digital technology as in cochlear and retinal implants, patterns of sensory stimuli on the body or tongue based on spectacle mounted cameras that allow the brains of the blind to ‘see’ in in emergent 3D and many other such advances. He discusses the big question as to whether an emergent ‘I’ could ever be transferred from the brain by brain-digital interface and run on a comparable computational platform other than neurons. What if, in some future time, we do not have to die? ‘ Eagleman’s frustration concerning the transitory nature of our emergent I’ is summed up in the following quote ‘When my friend and mentor Francis Crick was cremated I spent some time thinking about what a shame it was that all his neural matter was going up in flames. That brain contained all the knowledge, wisdom and intellect of one of the heavyweight champions of twentieth-century biology. All the archives of his life – his memories, his capacity for insight, his sense of humour – were stored in the physical structure of his brain, and simply because his heart had stopped everyone was content to throw away the hard-drive’.
This very readable book, which contains so much more of fascinating interest than can be presented in a review, raises questions about our true nature in an acute form. Is Dr Eagleman’s interpretative standpoint concerning the relationship between brain and mind one that can be dismissed as ‘neuroscientific hubris’? Or, based as it is findings from ever increasing research concerning this relationship, is his neuroscientific interpretation closer to reality as to our true nature? Is the ‘I’ of conscious thought, emotion and awareness an emergent phenomenon entirely dependent upon our brain reaching some critical threshold of cortical activity for us to emerge into daily temporary existence?
This way of thinking about ourselves and all animals as temporary brain-mind organisms based upon the input from our known sensory systems may well become common currency in society as a whole as more books, more websites, more blogs and more television programmes such as Horizon promote this point of view. If so, how will anyone be able to account in any creditable way for the claim of extrasensory phenomena such as telepathy, clairvoyance and precognition, apparitions and ghosts, let alone psycho-kinesis and psychic healing? What of NDEs and the implication that they are a portal into an afterlife? Does Dr Jimo Borigin’s unexpected discovery of a period of intense brain activity in dying rat brains imply a possible neural correlate for human NDEs if all brains follow the same final trajectory unless resuscitated? This would be in line with Dr Eagleman’s picture that allows for two-way interaction between the brain and the emergent ‘I’ of consciousness and underlying neural mechanisms. If this is the case then all talk of souls, spirituality and life after death is redundant.
This apparent two-way brain-mind interaction raises the unanswered question as to the nature of the emergent ‘I’. For any such interaction to occur the usual requirement is that the two agents concerned must be of the same nature. That is, they must be different in degree but not in kind as in energy conversions. So is the emergent ‘I’ of ‘consciousness’ a physical property of the same bioelectrical nature as our brain impulses and synapses? Does it, for example, consist of a daily emergent field of physico-mental energy, different in degree from its related brain activity but definitely not different in kind? Alternatively, is the ‘I’ of ‘consciousness’ and sense of ‘self’ a mental phenomenon only whose nature and properties are different in kind to the brain? If so, this leaves the problem of brain/mind interaction unsolved and possibly unsolvable. Either way the social and philosophical implications of neuroscientific research as to the relationship of brain and mind are profound.