In the absence of the soul, selfhood is located in the brain. But can identity be identified?
“Who am I?” we wonder as teenagers. “Why am I me?” It is the age at which, like St Augustine in his Confessions, each of us becomes “a question to myself”. Many of us never stop wondering. I can be sure, at least, that you are an inquiring reader. There is much more, of course, to your identity — a gender, profession, home town, mother tongue, eye colour, sexual preference — but you don’t need to compile a list to check out your own identity: you are you, the single subject at the centre of your world. Until recently, that single subject could be conveniently located in the soul. But, for the irreligious, this immaterial, invisible, immortal entity has too slim an evidence-base to be a plausible anchor for selfhood. We hunt around, therefore, for an alternative home for the self, reluctant to accept Robert Louis Stevenson’s dark prediction that “man will ultimately be known for a mere polity of multifarious, incongruous and independent denizens”. It seems natural to turn to the brain: this, surely, is the organ of the self. Somewhere within it we will find the key to our identity.
This has been my tacit assumption, working as a neurologist for the past two decades. Occasionally a case has encouraged me in this belief. Some time ago I encountered a patient who insisted that his brain had died: it was his poignant reaction to the profoundly altered experience of a world that depression had emptied of vivacity, pleasure and meaning. All of us say from time to time, “I feel like death,” calling on simile: Graham had been conquered by the corresponding metaphor, like John Donne in his “Nocturnall Upon St Lucy’s Day” — “Love . . . ruin’d me, and I am rebegot/Of absence, darknesse, death; things which are not.” A functional brain scan, remarkably, showed that Graham was not entirely wrong: activity in regions of his brain linked to the sense of self was severely reduced.
More commonly, brain damage, especially damage to the frontal lobes, can cause striking changes in personality, from momentary impulsiveness to pervasive loss of empathy: once again, pathology within the organ of the self transforms identity, reshapes the “person” that we are. But while the importance of the brain in sustaining the human self is unquestionable, the project of locating it there looks to me increasingly problematic. The more eagerly I hunt in the brain for the self, the more puzzled I become: it seems to be both everywhere — and nowhere.
Consider your selves: you are — at least — your body, your mood, your agency, your current thoughts, your memories, your plans, your knowledge of yourself as one among others, as a winner of life’s prizes and a victim of life’s ignominies. This list is not exhaustive, but current research in cognitive neuroscience is gradually running each of these to ground within the brain. Let’s begin where Freud would have wanted us to, with the body.
He recognised that the self was rooted in the body, in our primordial percep-tions of our internal states. Such perceptions turn out to be neurologically complex. The body is mapped over and over again within the brain. The “somatosensory cortex”, just next door to the motor cortex, contains multiple “homunculi”, representations of the body’s surface in which cortical space corresponds to cutaneous sensitivity, with more extensive mapping, for example, of fingertip than palm. Damage to these maps will lead to relatively basic dysfunction — to numbness or to weakness. Not far off, a region in the right parietal lobe helps to allocate attention to both bodily and environmental space. An injury here has a more subtle effect on sensation: you might be able to feel your left hand when touched in isolation, but a simultaneous touch on the right could “extinguish” the left-sided sensation. More extensive damage would cause you to neglect the left side of your body and of the world, failing for example to shave your left cheek. The extreme form of this disorder leads to denial of ownership or “somatoparaphrenia”, disavowal of your intimate connection to your left limbs. Intriguing recent research suggests that the condition of “apotemnophilia”, or body integrity identity disorder, the wish to amputate some part of one’s body, may sometimes be the result of a congenital dysfunction of its sensory representation in the brain. But a quite different region is also implicated in bodily awareness, this time in the awareness of sensations arising within the body. The “insula”, a large island of cortex buried in the Sylvian fissure that divides the frontal from the temporal lobes, receives inputs from our organs, and maps our internal condition: this is where “gut feelings” register. The American neurologist Antonio Damasio has suggested that this area, and the brain stem regions through which signals stream into it from the body, provides the self’s Ground Zero.
As a rule, the signals that inform us about the location and state of our body resonate with the information we are receiving from other senses, like vision and hearing. When discord arises, either at the hands of an ingenious experimenter, or because the parts of the brain that integrate these signals are malfunctioning, bizarre and fascinating disturbances of selfhood can arise: in the Rubber Hand Illusion, you eerily feel the touch of the experimenter’s hand on a visible, lifeless rubber replica of your — concealed — hand; in neurologically based “out of body experiences”, occurring for example as a result of seizures, you have the experience of looking down on your own body because the normal integration of vision and bodily sensation at the junction of temporal and parietal lobes has been disturbed.
Our awareness of our body always has a “feeling tone”, a fringe of contentment or unease. Every so often, this aspect of the self comes to the fore — in moments of high emotion like joy or terror, disgust or empathy. Each of these engages a slightly different network of regions in the brain: disgust, for example, takes us back to the insula, appropriately enough, which maps our gut feelings (“he makes me sick!”); terror is particularly linked with the amygdala, an almond-shaped concentration of neurons in the temporal lobe linked to the recognition, experience, recollection and expression of fear. In sufferers from depersonalisation disorder, in which the world loses its emotional colour and comes to feel unreal, activity in these regions is depressed.
So far we have focused on the possibility that feelings anchor the self. But our sense of ourselves as actors in the world, our sense of “agency”, is another key component of our selfhood. We know something, now, about the neurology that underpins agency: amongst a widespread set of brain regions involved in programming action, one, the supplementary motor area, is especially closely associated with the subjective urge to act. Stimulation of related areas gives rise to mere movement, whereas stimulation here seems to engage the will itself, creating an “urge” to move.
If they are to ground a stable sense of self, feeling and agency presuppose a degree of stability in experience, the possibility of sustaining attention for at least a matter of a second or two, as against the “great blooming, buzzing confusion” William James imagined in an infant’s consciousness. In the adult, sustained attention to a thought calls on our “working memory”, exciting activity in regions towards the front of the brain, involved in organising both behaviour and cognition, and regions elsewhere that represent the thought in question — in language areas, for instance, if the thought is clothed in words.
Our senses of our body, mood, agency and immediate thoughts constitute the central core of our experience of ourselves. But for us humans, this “core consciousness” is immeasurably expanded and enriched by our ability to recollect the past and to anticipate our future. Do we remain ourselves in the absence of this ability? I study patients whose epilepsy has been accompanied by a progressive, sometimes extreme, loss of those vivid, experiential memories that allow us to reinhabit moments from our past. They feel this absence keenly, describing their encounters with diary entries or holiday photos as pretty much like reading someone else’s biography. Lacking the ability to transport themselves mentally into their remembered lives, they lose the pleasures of nostalgia. Intriguingly, the loss of our past also seems to imply some loss of our imagined future — we draw on many of the same mental resources when we anticipate as when we reminisce. Does this “extended consciousness” have an obvious home in the brain? One of the most striking discoveries in recent human neuroscience has been the demonstration of a network of regions that is especially active in the resting brain — this “default mode network” interlinks areas known for half a century to be important for memory with regions more recently associated with self-reflection and imagery. It is engaged particularly by tasks involving the remembrance of the past and the anticipation of the future.
We are of course the heroes, or sometimes the villains, of these adventures in time: as William James put it, our fondest memories have the “warmth and intimacy” of those experiences “appropriated by the thinker as his own”. The brain regions linked to these processes of recollection and anticipation are, not too surprisingly, related to regions involved in self-awareness. I might have a self in the absence of self-awareness, but I would plainly not be writing this article without it. Our ability to think about ourselves and others as subjects of experience, centres of mental life, each of us surveying the world from our peculiar viewpoint, with a particular set of thoughts, beliefs and desires is another quintessentially human capacity. One might describe it as an awareness of awareness: psychologists speak of our “theory of mind”. We can see its glimmerings in some other animals, for example chimps and dolphins, who can, like 18-month-old children, recognise themselves in mirrors, but the full flowering of our “Machiavellian intelligence” has to wait until the grand age of four or five. Lifelong impairment of the ability to deploy mature theory of mind is a cardinal feature of autism. In schizophrenia, theory of mind is over-deployed and the commonly accepted boundary between the mental and the physical breaks down with frightening results: the sufferer’s thoughts are projected as hallucinations or perceived as intrusive insertions. The neuroscience of our theory of mind is young, but several candidate regions with roles in this vital form of “social cognition” have been identified, overlapping with the default mode network of the previous paragraph.
So: when we try to run the self to ground in the brain, we find it — nowhere and everywhere. It is tempting to identify it with just one of its components — with awareness of the body, say, or with our talent for autobiography, but to do so leaves too much out. Perhaps, then, the self can’t be located in a brain region or network but emerges rather from its integrated, interactive activity. Perhaps so, but a recognisable human self, albeit somewhat diminished, can survive considerable losses: loss, for example, of our usual emotional responsiveness in de-personalisation, or of memory in amnesia. The fullness of the typical person is not required for selfhood.
Given the difficulty in locating the self in the brain, it’s tempting to look elsewhere altogether. Roy Baumeister, the American social psychologist, argues that the self is a social construct, existing “at the interface between the animal body and the cultural system”: for Baumeister the self is above all the bearer of reputation, that most crucial possession for members of our pre-eminently social species. There could be no self, on this view, without society, though Baumeister is also an advocate of the idea that we evolved to occupy a social niche: if so, our scrutinised social self, admired or despised, has an evolutionary history and biological basis.
Selfhood, I agree, owes something vital to its social setting, but the social self is one among many — the bodily, affective, effective and reflective selves I have described. Yet Baumeister’s central idea, that the self is a construct, points in the right direction. The religious idea of the soul has left us with a residual sense that the self is a singular entity that must reside somewhere, if not in a ghostly medium congenial to souls, then at least in the body or the brain. But surely the self is not an entity at all — it is an abstraction from all the things we feel and do and are, a useful, imaginative fiction. Likewise, justice exists — but don’t expect to find it lurking in person in any particular law court or parliament building.
Do you, as Robert Louis Stevenson predicted, feel threatened by the suggestion that self is an illusion? This seemingly radical idea does not imply that there are no important continuities in your life: of course there are, and they are crucial. Your personality, your activities, your relationships with friends and family, your memories, your plans all reveal consistent traits and patterns, for better or for worse. But none of these is immutable, nor are they the expression of a mortal or immortal soul. The neuroscience of personhood will not come to the rescue of the self. “Traveller, your footprints are the path, and nothing more; there is no path, the path is made by walking,” wrote Antonio Machado. So it goes with you and me: there is no self, the self is made by living.