A considerable amount of the human brain is devoted to speech and to fine motor control. A large proportion of the lateral regions of the brain (including the temporal lobe and lateral motor and premotor areas) are required for functional speech perception and generation. These areas include the vast memory stores that allow us to understand and ascribe meaning to the tens of thousands of words we call on to describe the objects in our world, their interrelations, our reactions to them, our stories and our predictions for the future.

Although speech is wonderful for naming objects, whether real or imagined, and talking about them in various undeniably useful ways, there are large domains of our understanding of the world for which speech simply does not do the job. Colloquial English abounds with phrases such as ‘A picture is worth a thousand words’ or ‘When all else fails, read the instructions’. Neuroscientific discoveries over the last twenty years have provided a strong explanation for this phenomenon.

A very large portion of our brain is devoted to processing the spatial properties of the objects in the world together with our ability to manipulate them with our hands. These areas (including most of the parietal lobe and much of frontal lobe) in a very real sense embody our physical experience of the world: the shapes of objects, their textures, their weights, their spatial relations to each other. Surprisingly, this spatio-motor information about the world is stored and accessed independently of our verbal knowledge of the world. Hence, we can easily show someone how to sew a button onto a shirt or make a cappuccino or do a somersault, but to try to learn such a skill from written instructions alone is very difficult, or even impossible, especially if you have never actually seen the action done before.

Our non-verbal sense of spatio-motor properties of the world is so ingrained in us that we tend to take it for granted. Once again, however, colloquial English provides us with a clue to the central importance of this knowledge. At a fundamental level, spatial relations are embedded in language via prepositions, adverbs, adjectives, verbs and so on. But as pointed out by many contemporary philosophers and linguists, most notably George Lakoff (George Lakoff and Mark Johnson, Philosophy in the Flesh, 1999), our language is replete with motor metaphors that explain or verbalise or embody diverse aspects of abstract thinking. Thus, we grasp an idea, catch the drift of an argument, consider the merits of hard facts compared with soft logic, we fashion turns of phrase or figures of speech. Of course, if taken literally, one could only really know if facts were ‘hard’ by handling them.

Communication as motor activity

Despite its limitations, speech is not unreasonably considered as our primary mode of communication. This is what takes our conscious attention when we are talking with and about each other and our places in the world. However, motor activity is critical to communication as well.

Speech itself is a highly complex motor activity involving dozens of muscles in our face and lips, tongue, throat, larynx, neck and chest. Not only must we use our larynx to generate the raw pitched sounds for speech, we must use our throat, tongue, palate and lips to shape and form the harmonics of vowels and the filtered noise of consonants. All the while, we must control our breathing to generate speech phrasing appropriate to the demands of grammar, prosody and the physiological requirements for keeping sufficient oxygen supplied to our brain and body.

In addition to the motor components of speech, several modes of non-verbal communication require both generation and recognition of structured motor activity. The most obvious of these are facial expressions, hand signals or gestures, and body language.

The recognition of facial expressions can be very quick, employing subconscious pathways of the brain (usually involving the amygdala) that circumvent conscious information processing by higher cortical centres. For example, we recognise fear, anger or disgust in another person’s face before we try to understand why the person may be feeling that way. This response occurs in the absence of specific recognition of whose face it is: you do not need to know the name or social background of someone to know that he or she is threatening you, although such knowledge may colour your reaction to the apparent threat. Such relatively low-level processing is inherent to our brain connectivity. Consequently, facial expressions representing deep emotional states are shared by all cultures. In contrast, facial expressions that carry less direct emotional content, such as winking, may be understood differently within different cultural contexts. Similarly, hand signals such as ‘thumbs up’ or the ‘V for Victory’ sign carry only culturally acquired meaning. Nevertheless, they can have critical survival value, as when divers signal to each other underwater.

Over the last ten years or so, combinations of sophisticated experimental and imaging techniques have revealed the brain pathways that are specifically involved in the recognition and interpretation of hand gestures, body language and, ultimately, the intent of another person’s action. Central to the function of these pathways are the aptly named ‘mirror neurons’, originally discovered by Giacomo Rizzolatti and his colleagues.

When we observe someone moving, information from the visual system is processed more or less sequentially through a series of parallel circuits. Although we usually develop a unitary visual experience of someone whom we are watching, different parts of the visual system selectively process specific elements of the visual scene, such as colour, contrast, direction of movement, the nature of the object, and, if it is human, who it is, what the person is doing, and so on. Key elements of these circuits run through areas of the brain that are physically close to those processing language. Indeed, the logic of processing language perception (hearing, understanding, replying) is isomorphic with interpreting body signs (seeing, understanding, responding). The validity of such a comparison has been reinforced by recent data showing that Broca’s Area (in the lateral frontal cortex), long known to be required for many aspects of speech production, such as grammatical structure, prosody and the accurate use of verbs, is also required for responding appropriately to meaningful gestures and body language.

Mirror neurons occur in several locations involved in processing visual information about the movements of others. Those in and near Broca’s Area are especially adapted to recognising skilled motor movements in the context of the predicted end point of the other person’s action. When stimulated in this way, many components of the observer’s motor pathways are activated, as if the observer is actually carrying out the action. Consequently, it is now widely accepted that the pathways containing mirror neurons provide the basic mechanism for learning a motor skill simply by watching someone else do it. Furthermore, mirror neurons provide the basis for interpreting and predicting the outcome of another person’s actions. As such, they almost certainly form a core element in the neural structures required for generating a ‘theory of mind’: that is, the feeling that others perceive the world in a way comparable to our own perceptions. As argued recently by French neuroscientist Marc Jeannerrod (Motor Cognition, 2006), an awareness of the output of these circuits may well be essential for our experience of consciousness.

Actions without thought

One of the most significant challenges facing modern neuroscience is to understand how we generate continuous sequences of skilled motor activity. Imagine doing some intense motor activity, such as surfing a giant Hawaiian wave. Assuming you are an experienced surfer and you have done something like this before, what would you be thinking about? What would your perception of time be as you accelerate down the face of a ten metre-high wave? Almost certainly, you would not be thinking about exactly where your feet are on the board, nor the angles of your elbows nor the positions of your fingers. If asked afterwards about any of those things, you could not answer (at least, not without reference to a video of your ride). Nevertheless, the whole time you were on the wave, you would have been carrying out a sequence of fine adjustments to all of these parts of your body, and more. Without a conscious thought. Instead, your attention would have been focused almost entirely on trying to predict what the wave will do next and, as a consequence, what your next move will be. As you carry out your manoeuvres, your board will feel as though it’s a part of you. So, how long did your ride last: did it feel ‘all over in a flash’ or did it seem to ‘last a lifetime’?

You do not need to be a big-wave surfer to understand this type of experience. It happens all the time to us, most notoriously during that drive home from work when you cannot actually remember any details of negotiating the busy intersections along the way. Skilled motor activity (which includes driving a car) commonly has three characteristic features. First, if you are using a tool or instrument of some sort, it feels like it is an extension of the body. There is now good neuroscientific evidence that we do indeed process information about familiar implements as though they are part of our own body. Next, the perception of time is distorted. Generating our unified conscious experience of the world takes time, typically between about 0.3 and 0.5 seconds. This means that the ‘feeling of now’ is already running a bit late. But what our brains are really good at is predicting the immediate future; most neuroscientists would say this is the primary purpose of our cerebral processing power (e.g., Rodolfo Llinas, I of the Vortex: From Neurons to Self, 2001). So, in carrying out skilled motor activity, we are generating anticipatory motor responses adapted in almost real time from a well-learned repertoire. In other words, the ‘feeling of now’ is the net result of living a little in the past, whilst looking a little into the future. Finally, you usually cannot recall the details of the skilled motor activity you have just completed.

If speech is considered not in terms of the meaning of its words, but as a flow of motor activity, what kinds of things must the brain do? First, the motor activity (i.e. the sequence of sounds you generate) needs to be streamed correctly in terms of the sequence of words, their timing and their context. The underlying units of motor activity (the phonemes and words) need to be well rehearsed: you need to know your pronunciation and grammar. If your speech is to make any sense to the listener, you also need to keep in mind the underlying target of your attention, the topic you are trying to talk about. Finally, you must do all of this within a series of environmental restraints: in this case, the rules of grammar and syntax that apply to the language you happen to have learned, as well as the social and physical environment within which you are attempting to speak.

Now let us consider using your hands to carry out a skilled motor activity, such as untying your shoelaces. Just like speaking, you must stream and sequence your movements, those actions need to be well practised, you need to target your attention to the end point of the task at hand, and what you can actually do is limited by the environment. Here, this includes the interaction between the physical nature of your body (what movements are available at each joint in your back, shoulders, arms and hands) and the physical nature of the external world (the thickness of your laces and the style of your shoes).

On the basis of this comparison, it seems reasonable to suggest that there is a ‘grammar of movement’ that underlies most, if not all, skilled motor activity. Such a grammar has three primary functions: (1) it sets rules for sequencing and timing the order of the action; (2) it selects a subset of all possible movements you could do; and (3) it is constrained by the target of your attention and the immediate physical environment. Nearly all of this is done subconsciously by the brain.

How then, can we generate a grammar of movement without a conscious thought? The critical regions of the brain almost certainly lie within a complex series of structures located deep within the cerebral hemispheres, known collectively as the ‘basal ganglia’. The basal ganglia have many functions, but most important in this context is their ability to initiate motor programmes and time sequences of motor activity (Llinas calls them ‘fixed action patterns’). Much insight into these functions of the basal ganglia come from the study of patients in whom some aspect of basal ganglion function has failed.

Tourettes’ Syndrome (George Gilles de la Tourette, 1859–1904) is a defect of basal ganglia in which patients generate spontaneous gestures and vocalisations, that often include swearing, curses and oaths. These are small skilled motor programmes that normal people often utter before they realise what they’ve said (e.g. swearing in polite company when you spill a drink). This syndrome presumably releases the context-dependent inhibition of such motor programs. A more extreme abnormality of the basal ganglia is Huntington’s Disease (George Huntington, 1850–1916) which produces spontaneous ‘dance-like’ movements of the limbs, hence the earlier names for this condition: St Vitus Dance or Huntington’s Chorea. The opposite phenomenon is seen in Parkinson’s Disease (James Parkinson, 1755–1824), an abnormality of the basal ganglia in which the ability to sequence and time skilled movements is reduced or lost.

The automaticity of subconscious movement generation is most easily seen during talking, not in the speech production itself, but in what we do with our hands. As extensively documented by David McNeill (Hand and Mind, 1992), during speech we incorporate a whole range of hand gestures to emphasise the rhythm of speech, to indicate points of attention, to embody relations between abstract or difficult ideas, and so on. On the whole, such gestures are devoid of intrinsic meaning: they only make sense in the context of the concurrent speech. Most of the time, we have no conscious awareness that we are making them. They are so embedded in our behaviour that even when our other conversant is out of view, as on a telephone, we still employ hand gestures while we speak. Critically, though, these are not random movements of our hands: of all the possible hand gestures we could make, we use a surprisingly limited subset.

One fascinating consequence of the use of hand gestures, especially during explanatory speech, is that abstract ideas are brought into a spatio-motor domain that is unavoidably translated into a human body scale within an approachable personal space. Whether you are talking about the structure of the solar system or the interactions between an enzyme and its chemical substrate, whether you are trying to describe how to make a cake or change the gearbox on your car, you use subconscious hand gestures to help explain your ideas on a scale that is immediately familiar to others.

The concept that motor activity through gestures somehow facilitates verbal description suggests that, even though verbal and motor knowledge is largely incommensurable, there are, nonetheless, critical links between these two domains. Indeed, it has been known for centuries that verbal learning can be reinforced by appropriate patterns of spatio-motor activity. In other words, well-learned spatio-motor sequences can act as mnemonics for complex arrays of verbal knowledge. To pursue this proposition further, let us move out of the realm of modern neuroscience and briefly visit the medieval practitioners of the Art of Memory.

The Art of Memory

How can you organise your memory when you have a vast array of material to learn, especially if the order of things matters? This was a problem facing orators in classical times, but it became a serious issue in the Middle Ages with the flowering of scholarship and enquiry into all aspects of the spiritual and material world. As revealed by the ground-breaking work of France Yates (The Art of Memory, 1966), Paolo Rossi (Logic and the Art of Memory, 1983, 2006) and Mary Carruthers (The Book of Memory, 1990), the fundamental process in ‘mnemotechnics’, the Art of Memory, was to link movement through space with movement through information.

Originally derived from texts and ideas of Aristotle, Cicero and the anonymous author of Rhetorica ad Herennium among others, the Art of Memory reached its zenith via Ramon Lull (1232–1316) to the works of Giulio Camillo (1480–1544), Giordano Bruno (1548–1600) and Robert Fludd (1574–1637). Much of the Art of Memory involved creating imaginary buildings or other ordered structures into which one ‘placed’ various pieces of information, such that the structure of the building (which was easy to remember) triggered recall of knowledge with a corresponding structural arrangement (which could be difficult to remember). There were two basic ways of using these schemes. One could develop a memory for ‘things’ (memoria rerum), in this context meaning ideas and concepts, with each concept being assigned a place in the mnemonic structure. Alternatively, one could develop a memory for ‘words’ (memoria verborum), by which one learned specific facts or, in the extreme, whole texts word-perfect, with the text being arranged in an ordered way around the walls of the mnemonic structures.

Whilst the relative merits of various approaches to the Art of Memory were vigorously debated, the basic techniques were embedded within a wide range of educational approaches ranging from formal schooling to the teaching of biblical lessons to the faithful. An outstanding example of the latter can be seen in the Collegiate Church of San Gimignano in Tuscany.

The spectacularly banded arches supporting the roof of this church create a series of frames for the viewer looking towards a magnificent series of frescoes. One wall, probably painted from 1333–41 by a student of Simone Martini, portrays scenes from the life of Christ. The other wall, painted by Bartolo di Fredi in 1367, depicts a series of Old Testament stories. In each case, the stories are arranged chronologically following the architectural constraints of the building itself. Moreover, in some of the larger frescoes, such as Taddeo di Bartolo’s The Tortures of Hell (1393), the image itself is subdivided into a series of highly ordered smaller sections, giving the strong visual impression of a sequence of rooms or chambers within which each episode of the story occurs. Finally, di Fredi’s Creation of the World, is arranged as a set of concentric circles divided into segments by radiating lines, thus replicating the mnemonic device of the ‘rotor’ (hence ‘learn by rote’) that was in widespread use for learning systems of relational information such as prayer cycles, rhetoric, and arithmetic. It is easy to imagine an illiterate member of the San Gimignano congregation mentally walking through these beautifully arranged scenes to help trigger recall of the articles of faith as needs required.

Practitioners of the Art of Memory moved on from real structures to abstract structures designed to facilitate the recall of specific interrelated sets of information, ranging from musical scales and harmonies to vast arrays of magical and astrological knowledge such as Camillo’s ‘Memory Theatre’. This approach to organising knowledge systems almost certainly underpinned the development of the New Scientific Method by Francis Bacon (1561–1626), René Descartes (1596–1650), Gottfried von Leibnitz (1646–1716) and Isaac Newton (1642–1727), all of whom were familiar with aspects of the Art of Memory.

At a more practical and personal scale, there was an alternative to using complex imaginary buildings as the spatio-motor mnemonic: the human body itself. For example, various methods of recalling the Gospel stories relied on assigning significant events to particular parts of the body. But it is in music that we find our way back to the neuroscience of spatio-motor learning, the role of gesture and the link to language. As argued by Anna Maria Busse Berger (Medieval Music and the Art of Memory, 2005) and Penelope Gouk (Music, Science and Natural Magic in Seventeenth Century England, 1999), at a time when most musicians could not read, and, indeed, there was little in the way of musical notation anyway, choristers needed a way to keep track of a thousand or more pieces of music, with their melodies and correct harmonisations.

Even with the development of increasingly sophisticated musical notation, largely arising from the work of Guido of Arezzo (995–1050), the Art of Memory was applied to music in many ways, including identifying parts of the body as components of a spatial mnemonic. Probably the best known was the use of the hand to graphically represent the steps of the musical scale (the ‘gamut’), as well as a way of working through the various modes and their harmonisation rules. Once again, it is easy to imagine a medieval music class with the choirboys and instructor using a series of stylised gestures to work through the scales until each and every one of them could instantly recall the required pattern of notes, with barely a single intervening thought.

Music and the value of poetry

Music provides us with a link between speech, the motor activity of communication and that strange intermediate territory: poetry. First and foremost, music can be regarded as a motor language: to perform music, you must sing or whistle or play some kind of instrument, all of which require considerable motor skills. The appreciation and performance of music activates areas of the brain that are similar to, but different from, those used for speech. Music itself is processed by a highly distributed set of parallel pathways in the brain, so that melody and rhythm, for example, are recognised in by quite different regions (see Daniel Levitan, This Is Your Brain on Music, 2006; Oliver Sacks, Musicophilia: Tales of Music and the Brain, 2007). As with speech and other skilled motor activity, it is possible to make music without thinking consciously about the details, but this only works if you have practised the material intensively. Consider a professional rock musician prancing around a stage, waving his guitar around, singing at the top of his lungs, all the while managing to stay in tune and in time. You may not like this style of the music, but at a neural level this is a truly remarkable feat of parallel processing.

Such a performance reveals another aspect of music. Having mastered the elements of melody and rhythm, the music can become a scaffold for other activity. Songs can carry valuable social, cultural and historical information, while dancing can contribute to a strengthened sense of community bonding. Speech that has been converted into a learned song somehow acquires a different character. We know this intuitively (after all, this is why we have a special word for songs). Moreover, some patients with brain damage lose the ability to speak, without necessarily affecting their capacity to sing, suggesting that the key information required for recalling and performing songs is stored in an area of the brain different from that required for spontaneous speech. Some such patients can still recite previously learned poems, even though they cannot generate coherent normal speech.

Which brings us to poetry. Why do we have poetry? Why does good poetry affect us the way it does? What might poetry tell us about the science of communication? In the context of the preceding discussion, we can propose that there are two main functions for poetry (which, I hasten to add, are not mutually exclusive).

First, poetry can act as a scaffold for organising and recalling useful verbal information, in a way similar to a song. In this mode, poetry can be considered a form of ‘embodiment of knowledge’. The very act of recitation – with its rhythm, metre, rhyme, versification, and the clever use of language to encapsulate key ideas – forms a bridge between verbal and motor knowledge domains. Memorising the motor activity required for recitation collaborates with the structure of the poem to strengthen the memory for content, thereby forming a kind of short cut into the Art of Memory. Once learned, these poems are recognised and recalled rapidly, like familiar tunes or faces. This mnemonic function of poetry (and related forms of musical expression) is especially important in oral cultures, but is still a feature of many aspects of contemporary Western culture (How many days hath September ...?).

A second function of poetry is something altogether more elusive to define. This is ‘poetry as the art of elegant movement’. We often refer to an expert dancer or an athlete as representing ‘poetry in motion’. As is often the case, there may be considerable insight embedded within this metaphor, especially if we consider real poetry as real motion, as real motor activity. Poetry of any style often incorporates highly compressed and stylised use of words, which can generate layers of meaning beyond those encountered (or even tolerated) in day-to-day speech. This way of using language increases the chance of triggering new associations and meanings in the listener or reader of the poem. When this occurs, the poet has tapped into the human predilection for seeking novel experience, the human art of recognising an experience as representing something unexpected, unique, special.

But ultimately, the deep power of a poem may be its ability to generate a response that is genuinely akin to the awe we feel when a dancer or athlete successfully carries off a spectacular move. The pathways containing our mirror neurons would be highly activated as we watch, as we listen: what is going to happen next? An expectant pause, and then, how did they do that? In this way of thinking about poetry, it is the finely tuned economy of expression, the physical sound of the language, the beauty of the bodily movements we barely detect, that give the poem its special power.

In the end, some form of the Art of Memory must be embedded in all oral culture. It must allow links to be established between the visual and verbal, the motor and abstract. Mostly, we take it for granted: after all, making these connections is a lot of what our brain is doing, whether we are aware of it or not. From time to time, these connections emerge as poems, songs, paintings. And through them all, there is movement, there is language, each embedded in the other, each entwined with the other. This is surely what links people together as a community. This is surely what embeds a community in its country, in its world.

Epilogue

hand to hand
       we stroll along boulevards and riverbanks
       we waltz among swirling chorus lines
hand to mouth
       we pass our stories, our delicious histories
       another, another, beyond unfamiliar horizons
mouth to mouth
       we kiss, we intermingle, we breathe
            life into this, our common land