Daniel Bor enjoys a sophisticated study of how the meat in our skulls generates the self.
The Brain: The Story of You
- David Eagleman
In my bolder moments, I consider neuroscience to be one of the most fundamental scientific fields. The brain is, after all, the location of our experiences and identities, and our main tool for understanding every facet of the Universe. The Brain by neuroscientist David Eagleman ambitiously promotes this view. Built around a series of fundamental questions, such as “what is reality?”, it calls on a wide range of classic and recent findings, including innovative experiments by Eagleman himself, to demonstrate how brain science is optimally placed to answer those questions.
Eagleman begins by arguing that the brain determines who we are, and how we change. He illustrates just how dramatic such changes can be through the case of Charles Whitman, who in the 1960s switched from mild-mannered bank clerk to violent murderer because of a small tumour pressing on his amygdala, an area of the brain linked to aggression and fear.
Although the brain's development has a disproportionate role in human identity, with synaptic pruning in infancy a key shaping factor, our brains remain plastic throughout our lives. Eagleman demonstrates this with the well-known example of London taxi drivers found to have enlarged hippocampi — key to memory consolidation — after memorizing thousands of the capital's streets. Memory is the bedrock of our identities, but Eagleman highlights how the past is very much a reconstruction bordering on mythology. A case in point is the relative ease with which false memories can be implanted. The emerging picture is far removed from one in which we have a single personal identity. Instead, he notes, “from cradle to grave, we are works in progress”.
Everyone's world view, then, is fallible. Eagleman extends that idea by focusing on perception. We tend to assume that we have a direct connection to what is out there, and that all that we experience is all there is, but the truth is very different. He writes how “every sight, sound, smell — rather than being a direct experience, is an electrochemical rendition in a dark theater”. But we are not experiencing a continuous flow of sight and sensation. We sample the world through saccades — jumping visual snapshots. From these, the brain constructs a continuous narrative heavily biased by expectations. We believe this narrative implicitly, even when it goes horribly wrong, such as in schizophrenic delusions.
In light of the idea that our view of our own minds is also deeply skewed, Eagleman challenges the primacy of consciousness. With most forms of expertise, such as driving, the conscious mind merely gets in the way. Furthermore, unconscious influences on our decisions are pervasive. For instance, judges deciding whether to award parole to prison inmates are more likely to do so if they have eaten beforehand. Decisions are little more than the product of unconscious neural battles between competing drives. Eagleman uses this stance to argue for an end to the catastrophic US war on drugs that began in the 1970s, and to call for more sympathy for, and (neuroscientific) understanding of, the plight of people addicted to drugs. He is helping addicts to reduce cravings by getting them to retrain their brain activity through neurofeedback in a functional magnetic resonance imaging scanner. They can view real-time summaries of the relative activities of their “craving” and “suppression” brain networks, and can practise strategies to discover the most effective way of suppressing cravings.
What of our relationships with others? Here, Eagleman notes that “what we demarcate as you is simply a network in a larger network”. He describes how social exclusion can, like physical harm, activate pain centres in the brain such as the insula. Empathy, neurally speaking, invokes emotions as if we were experiencing for ourselves the events that we see others experience. However, when we consider members of “outgroups” to which we have no social ties, our empathic and social neural responses are flattened — as if we were dehumanizing them. This, Eagleman argues, is the neural mechanism that allows us to switch from being friendly to neighbours to wanting to wipe out their entire ethnic group, as for instance happened in the Bosnian war of the 1990s. Eagleman suggests that education about the neural underpinnings of our responses to outsiders is key to reducing the chance of genocides.
Eagleman ends by considering the future of humanity, and how neuroscience can technologically reshape almost every aspect of our lives. Although by far the most speculative part of the book, this is also the most fascinating. Eagleman describes the senses as flexible “peripheral plug-and-play” devices, with the brain not caring what input it receives as long as it is useful. We already exploit this feature with cochlear and retinal implants for people who have hearing or visual impairments. How much further can we take it?
Eagleman and his graduate student Scott Novich have developed an electronic vest that provides tactile feedback to the torso through arrays of small vibrating motors, and are testing it on people with impaired hearing, to allow them to 'hear' through touch. The vest could be used for almost any real-time information stream, such as weather, stocks or altitude readouts in plane cockpits. And enhancing senses is only half the story: if we can control a robot arm through motor-cortex activity (see Nature 497, 176–178; 2013), could someone check their e-mails while their brain–computer interface manages a vacuum cleaner?
Throughout, Eagleman provides multiple, varied explanations for what consciousness is and what it is for; he settles on neuroscientist Guilio Tononi's integrated information theory. This equates high levels of consciousness with information that is widespread throughout a network capable of supporting many different information states. Tononi's theory is consistent with the possibility of uploading our minds into computers. Without being limited by our fragile biology, we might feasibly travel to extrasolar worlds, “pausing” the computer simulation of our minds on the bulk of the journey to avoid boredom. Although such ideas are immensely fun to imagine, to computationally capture our brains we would have to be able to read every cellular detail of this incredibly complex organ — a feat that is centuries away, if it will ever be possible.
With such exciting themes, The Brain — a companion book to Eagleman's upcoming six-part television series of the same name on the US Public Broadcasting Service — is an ideal introduction to how biology generates the mind. Readers familiar with this field will be revisiting a range of classic research, and might feel frustrated that more depth is not given in places. The science, however, is structured around crucial and wide-ranging questions, saturated with personal and social relevance. And Eagleman's answers are consistently clear, engaging and thought-provoking.
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Neuroscience: My brain made me do it
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Bor, D. Neuroscience: The mechanics of mind. Nature 526, 41–42 (2015). https://doi.org/10.1038/526041a