The Sea Gypsies

The Sea Gypsies

The Sea Gypsies are nomadic people who live in a cluster of tropical islands in the Burmese archipelago and off the west coast of Thailand. A wandering water tribe, they learn to swim before they learn to walk, and live over half their lives in boats on the open sea, where they are often born and die. They survive by harvesting clams and sea chambers. Their children dive down, often thirty feet beneath the water's surface, and pluck up their food, including small morsels of marine life, and have done so for centuries. By learning to lower their heart rate, they can stay under water twice as long as most swimmers. They do this without any diving equipment. One tribe, the Sulu, dive over seventy-five feet for pearls.

But what distinguishes these children, for our purposes, is that they can see clearly at these great depths, without goggles. Most human beings cannot see clearly under water because as sunlight passes through water, it is bent, or “refracted,” so that light doesn't land where it should on the retina.

Anna Gislén, a Swedish researcher, studied the Sea Gypsies' ability to read placard under water and found that they were more than twice as skillful as European children. The Gypsies learned to control the shape of their lenses and, more significantly, to control the size of their pupils, constricting from 22 percent. This is a remarkable finding, because human pupils reflexively get larger under water, and pupil adjustment has been thought to be a fixed, innate reflex, controlled by the brain and nervous system.

This ability of the Sea Gypsies to see under water isn't the product of a unique genetic endowment. Gislén has since taught Swedish children to constrict their pupils to see under water – one more instance of the brain and nervous system showing unexpected training effects that alter what was thought to be a hardwired, unchangeable circuit.

The Sea Gypsies have survived using a combination of their experience of the sea and holistic perception. Illustration by Elena.

Cultural activities change brain structure

The Sea Gypsies's underwater sight is just one example of how cultural activities can change brain circuits, in this case leading to a new and seemingly impossible change in perception. Though the Gypsies' brain have yet to be scanned, we do have studies that show cultural activities changing brain structure. Music makes extraordinary demands on the brain. A pianist performing the eleventh variation of the Sixth Paganini Etude by Franz Liszt must play a staggering eighteen hundred notes per minute. Studies by Taub and others of musicians who play stringed instruments have shown that the more these musicians practice, the larger the brain maps for their active left hands become, and the neurons and maps that respond string timbers increase; in trumpeters the neurons and maps that respond to “brassy” sound enlarge. Brain imaging shows that musicians have several areas of their brains – the motor cortex and the cerebellum, among others – that differ from those of nonmusicians. Imaging also shows that musicians who begin playing before the age of seven have larger brain areas connecting the two hemispheres. 

Giorgio Vasari, the art historian, tells us that when Michelangelo painted the Sistine Chapel, he built a scaffold almost to the ceiling and painted for twenty months. As Vasari writes,“The work was executed in great discomfort, as Michelangelo had to stand with his head thrown back, and he so injured his eyesight that for several months he could only read and look at designs in that posture.” This may have been a case of his brain rewiring itself, to see only in the odd position that it had adapted itself to. Vasari's idea might seem incredible, but studies show that when people wear prism inversion glasses, which turn the world upside down, they find that, after a short while, their brain changes and their perceptual centers “flip”, so that they perceive the world right side up and even read books held upside down. When they take the glasses off, they see the world as though it were upside down, until they readapt, as Michelangelo did.

It is not just :highly cultured” activities that rewire the brain. Brain scans of London taxi drivers show that the more years a cabbie spends navigating London streets, the larger the volume of his hippocampus, that part of the brain that stores spatial representations. Even leisure activities change our brain; mediators and meditation teachers have a thicker insula, a part of the cortex activated by paying close attention.

The Sea Gypsies are an entire culture of hunter-gatherers on the open sea, all of whom share underwater sight. For Sea Gypsies it is seeing under water. For those of us living in the information age, signature activities include reading, writing, computer literacy, and using electronic media.

In all cultures members tend to share certain common activities, the “signature activities of a culture.” Signature activities differ from such universal human activities as seeing, hearing, and walking, which develop with minimal prompting and are shared by all humanity, even those rare people who have been raised outside culture. Signature activities requires training and cultural experience and lead to the development of a new, specially wired brain. Human beings did not evolve to see clearly under water = we left our “aquatic eyes” behind with scales and fins, when our ancestors emerged from the sea and evolved to see on land. Underwater sight is not the gift of evolution; the gift is brain plasticity, which allows us to adapt to a vast range of environments.

(The Brain That Changes Itself by Norman Doidge, M.D., excerpt).

The implosion of the media into us, affecting our brains, is not so obvious, but we have seen many examples in our lives. Photo by Elena.

Culturally Modified Brain

The Culturally Modified Brain

Not only does the brain shape culture, culture shapes the brain.

What is the relationship between the brain and culture?

The conventional answer of scientists has been that the human brain, from which all thought and action emanate, produces culture. Based on what we know about neuroplasticity, this answer is no longer adequate.

Culture is not just produced by the brain; it is also by definition a series of activities that shape the mind. The Oxford English Dictionary gives one important definition of “culture”: “the cultivating or development... of the mind, faculties, manners, etc.... improvement or refinement by education and training... the training, development and refinement of the mind, tastes and manners.” We become cultured through training in various activities, such as customs, arts, ways of interacting with people, and the use of technologies, and the learning of ideas, beliefs, shared philosophies, and religion.

Neuroplastic research has shown us that every sustained activity ever mapped – including physical activities, sensory activities, learning, thinking and imagining – changes the brain as well as the mind. Cultural ideas and activities are no exception. Our brains are modified by the cultural activities we do – be they reading, studying music, or learning new languages. We all have what might be called a culturally modified brain, and as cultures evolve, the continually lead to new changes in the brain.

Our brains are vastly different, in fine detail, from the brains of our ancestors. In each stage of cultural development the average human had to learn complex new skills and abilities that all involve massive brain change. Each one of us cant actually learn in incredibly elaborate set of ancestrally developed skills and abilities in our lifetimes, in a sense generating a re-creation of this history of cultural evolution via brain plasticity.

The many brain modules a child must use for reading, writing, and computer work evolved millenia before literacy, which is only several thousand years old. Illustration by Elena.

So a neuroplastically informed view of culture and the brain implies a two-way street: the brain and genetics produce culture, but culture also shapes the brain. Sometimes these changes can be dramatic.

A popular explanation of how our brain comes to perform cultural activities is proposed by evolutionary psychologists, a group of researchers who argue that all human beings share the same basic brain modules (departments in the brain), or brain hardware, and these modules developed to do specific cultural tasks, some for language, some for mating, some for classifying the world, and so on. These modules evolved in the Pleistocene age, from about 1,8 million to ten thousand years ago, when humanity lived as hunter-gatherers, and the modules have been passed on, essentially unchanged genetically. Because we all share these modules, key aspects of human nature and psychology are fairly universal. Then, in an addendum, these psychologists note that the adult human brain is therefore anatomically unchanged since the Pleistocene. This addendum goes too far, because it doesn't take plasticity, also part of our genetic heritage, into account.

The hunter-gatherer brain was as plastic as our own, and it was not “stuck” in the Pleistocene at all but rather was able to reorganize its structure and functions in order to respond to changing conditions. In fact, it was that ability to modify itself that enabled us to emerge from the Pleistocene, a process that has been called “cognitive fluidity” by the archaeologist Steven Mithen and that, I would argue, probably has its basis in brain plasticity. All our brain modules are plastic to some degree and can be combined and differentiated over the course of our individual lives to perform a number of functions – as in Pascual-Leone's experiment in which he blindfolded people and demonstrated that their occipital lobe, which normally processes vision, could process sound and touch. Modular change is necessary for adaptation to the modern world, which exposes us to things our hunter-gatherer ancestors never had to contend with. An fMRI study shows that we recognize cars and trucks with the same brain module we use to recognize faces. Clearly, the hunter-gatherer brain did not evolve to recognize cars and trucks. It is likely that the face module was most competitively suited to process these shapes – headlights are sufficiently like eyes, the hood like a nose, the grill like a mouth – so that the plastic brain, with a little training and structural alteration, could process a car with the facial recognition system.

(The Brain That Changes Itself by Norman Doidge, M.D., excerpt).

Our brain is modified on a substantial scale, physically and functionally, each time we learn a new skill or develop a new ability. Illustration by Elena.

Rejuvenation

Rejuvenation

At the beginning of the twentieth century the world's most outstanding neuroanatomist, Nobel Prize winner Santiago Ramon y Cajal, who laid the groundwork for our understanding of how neurons are structured, turned his attention to one of the most vexing problems of human brain anatomy. Unlike the brains of simpler animals, such as lizards, the human brain seemed unable to regenerate itself after an injury. This helplessness is not typical of all human organs. Our skin, when cut, can heal itself, by producing new skin cells; our fractured bones can mend themselves; lost blood can replenish itself because cells in our marrow can become red or white blood cells.

But our brains seemed to be a disturbing exception. It was known that millions of neurons die as we age. Whereas other organs make new tissues from stem cells, none could be found in the brain. The main explanation for the absence was that the human brain, as it evolved, must have become so complex and specialized that it lost the power to produce replacement cells. Besides, scientists asked, how could a new neuron enter a complex, existing neuronal network and create a thousand synaptic connections without causing chaos in that network? The human brain was assumed to be a closed system.Ramon y Cajal devoted the later part of his career to searching for any sign that either the brain or spinal cord could change, regenerate, or reorganize its structure. He failed.

In his 1913 masterpiece, Degeneration and Regeneration of the Nervous system, he wrote, “ In adult brain centers the nerve paths are something fixed, ended, immutable. Everything may die, nothing may be regenerated. It is for the science of the future to change, if possible, this harsh decree.”

There matters stood.

The neuronal stem cells I see are vibrating with life. They are called “neuronal” stem cells because they can divide and differentiate to become neurons or glial cells, which support neurons in the brain. The ones I am looking at have yet to differentiate into either neurons or glia and have yet to “specialize,” so they all look identical. Yet what stem cells lack in personality, they make up for in mortality. For stem cells don't have to specialize but can continue to divide, producing exact replicas of themselves, and they can go on doing this endlessly without any signs of aging. For this reason stem cells are often described as the eternally young, baby cells of the brain. This rejuvenating process is called “neurogenesis,” and it goes on until the day that we die.

Paradoxically, sometimes losing neurons can improve brain function, as happens in the massive “pruning back” that occurs during adolescence when synaptic connections and neurons that have not been extensively used die off, in perhaps the most dramatic case of use it or lose it. Illustration by Elena.

Neuronal stem cells were long overlooked, in part, because they went against the theory that the brain was like a complex machine or computer, and machines don't grow new parts. When, in 1965, Joseph Altman and Gopal D. Das of the Massachusetts Institute of Technology discovered them in rats, their work was disbelieved.

Then in the 1980s Fernando Nottebohm, a bird specialist, was struck by the fact that songbirds sing new sons each season. He examined their brains and found that every year, during the season when the birds do the most singing, they grow new brain cells in the area of the brain re responsible for song learning. Inspired by Nottebohm's discovery, scientists began examining animals that were more like human beings. Elizabeth Gould of Princeton University was the first to discover neuronal stem cells in primates. Next, Eriksson and Gage found an ingenious way to stain brain cells with a marker, called BrdU, that gets taken into neurons only at the moment they are created and that lights up under the microscope. Erikson and Gage asked terminally ill patients for permission to inject them with the marker. When these patients died, Erikson and Gage examined their brains and found new, recently formed baby neurons in their hippocampi. Thus we learned from these dying patients that living neurons form in us until the very end of our lives.

The search continues for neuronal stem cells in other parts of the human brain. So far they've also been found active in the olfactory bulb (a processing area for smell) and dormant and inactive in the septum (which processes emotion), the striatum (which processes movement), and the spinal cord. Gage and others are working on treatments that might activate dormant stem cells with drugs and be useful if an area where they are dormant suffers damage. They are trying to find out whether stem cells can be transplanted into injured brain areas, or even induced to move to those areas.

To find out if neurogenesis can strengthen mental capacity, Gage's team has set out to understand how to increase the production of neuronal stem cells. Gage's colleague Gerd Kempermann raised aging mice in enriched environments, filled with mice toys such as balls, tubes, and running wheels, for only forty-five days. When Kempermann sacrificed the mice and examined their brains, he found they had a 15 percent increase in the volume of their hippocampi and forty thousand new neurons, also a 15 percent increase, compared with mice raised in standard cages.

Mice live to about two years. When the team tested older mice raised in the enriched environment for ten months in the second half of their lives, there was a fivefold increase in the number of neurons in the hippocampus. These mice were better at tests of learning, exploration, movement, and other measures of mouse intelligence than those raised in unenriched conditions. They developed new neurons, though not quite as quickly as younger mice, proving that long-term enrichment had an immense effect on prompting neurogenesis in an aging brain.

(Rejuvenation. The Brain That Changes Itself by Norman Doidge, M.D., excerpt).

Keeping unused neurons supplied with blood, oxygen, and energy is wasteful, and getting rid of them keeps the brain more focused and efficient. Illustration by Elena.

Content of Thought

Imagination : Content of Thought

One reason we can change our brains simply by imagining is that, from a neuroscientific point of view, imagining an act and doing it are not as different as they sound. When people close their eyes and visualize a simple object, such as the letter “a”, the primary visual cortex lights up, just as it would if the subjects were actually looking at the letter “a”. Brain scans show that in action and imagination many of the same parts of the brain are activated. That is why visualizing can improve performance. 

In an experiment that is as hard to believe as it is simple, Drs. Guang Yue and Kelly Cole showed that imagining one is using one's muscles actually strengthens them. The study looked at two groups, one that did physical exercise and one that imagined doing exercise. Both groups exercised a finger muscle, Monday through Friday, for four weeks. The physical group did trials of fifteen maximal contractions, with a twenty-second rest between each. The mental group merely imagined doing fifteen maximal contractions, with a twenty-second rest between each, while also imagining a voice shouting at them, “Harder! Harder! Harder!”

At the end of the study the subjects who had done physical exercise increased their muscular strength by 30 percent, as one might expect. Those who only imagined doing the exercise, for the same period, increased their muscle strength by 22 percent. The explanation lies in the motor neurons of the brain that “program” movements. During these imaginary contractions, the neurons responsible for stringing together sequences of instructions for movements are activated and strengthened, resulting in increased strength when the muscle are contracted.

The research has led to the development of the first machines that actually “read” people's thoughts. Thought translation machines tap into motor programs in a person or animal imagining an act, decode the distinctive electrical signature of the thought, and broadcast an electrical command to a device that puts the thought into action. These machines work because the brain is plastic and physically changes its state and structure as we think, in ways that can be tracked by electronic measurements.

Experiments show how truly integrated imagination and action ar, despite the fact that we tend to think of imagination and action as completely different and subject to different rules. Illustration by Elena.

These devices are currently being developed to permit people who are completely paralyzed to move objects with their thoughts. As the machines become more sophisticated, they may be developed into thought readers, which recognize and translate the content of a thought, and have the potential to be far more probing than lie detectors, which can only detect stress levels when a person is lying. 

These machines were developed in a few simple steps. In the mid-1990s, at Duke University, Miguel Nicolelis and John Chapin began a behavioral experiment, with the goal of learning to read an animal's thoughts. They trained a rat to press a bar, electronically attached to a water-releasing mechanism. Each time the rat pressed the bar, the mechanism released a drop of water for the rat to drink. The rat had a small part of its skull removed, and a small group of micro-electrodes were attached to its motor cortex. These electrodes recorded the activity of forty-six neurons in the motor cortex involved in planning and programming movements, neurons that normally send instructions down the spinal cord to the muscles. Since the goal of the experiment was to register thoughts, which are complex, the forty-six neurons had to be measured simultaneously. Each time the rat moved the bar, Nicolelis and Chapin recorded the firing of its forty-six motor-programming neurons, and the signals were sent to a small computer. Soon the computer “recognized” the firing pattern for bar pressing.

After the rat became used to pressing the bar, Nicolelis and Chapin disconnected the bar from the water release. Now when the rat pressed the bar, no water came. Frustrated, it pressed the bar a number of times, but to no avail. Next the researchers connected the water release to the computer that was connected to the rat's neurons. In theory, now, each time the rat had the thought “press the bar,” the computer would recognize the neuronal firing pattern and send a signal to the water release to dispense a drop.

After a few hours, the rat realized it didn't have to touch the bar to get water. All it had to do was to imagine its paw pressing the bar, and water would come. Nicolelis and Chapin trained four rats to perform the task.

(Imagination. The Brain That Changes Itself by Norman Doidge, M.D., excerpt).

If the brain is easily altered, how are we protected from endless change? Photograph by Elena.

Gray and White Matter

Gray and White Matter in Our Brain

Neurons are connected to one another in their billions. Building on this, we must add that the cell bodies tend to group together, rather like debris on the surface of an expanse of water. When cell bodies clump together like this, the resultant tissue appears somewhat grayish The stringy connections between gray tissues, formed principally by the axons interconnecting the cell bodies, appear white by contrast (mainly because axons are surrounded by a sheath of fatty tissue, and fat has a white appearance). This is the basis of the famous distinction between gray matter and white matter. Collections of cell bodies are gray; the fiber connections between them are white.

The cell bodies forming the gray matter group together in one or two ways – either as nuclei or in layers. The nuclei are simply balls of cell bodies, lumped together. The layers are more complicated. They are formed when the cell bodies line up in rows. The resultant sheets of cells are typically found on the outer surface of the brain – and form its cortex (“cortex” means outer layer). There is a shortage of space in the human cranium, because the amount of cortex has expanded dramatically in recent evolution; so the brain saves space by folding the layers in upon themselves, in a wavelike pattern. This  is what gives the outer surface of the brain its well-known convoluted appearance. The nuclei lie deeper within the brain, underneath these layers of cortex – and the white matter is located between the two. The white matter – principally axons – thereby connects the cell bodies of the nuclei and cortical layers with one another. The precise anatomy of the resultant systems is enormously complex, but these basic principles are easier to understand.

Mind and brain are entwined like yin and yang. Illustration by Elena.

Brainstem and forebrain

A further basic division of the brain is that between the brainstem and the forebrain. This is a distinction of great importance for understanding some of the psychological functions. These two structures are, in turn, intricately subdivided. There are innumerable terms for the various regions within them – often (and quite confusingly) more than one term for the same structure. The terms we mention here form the standard (or most widely accepted) terminology.

The brainstem is a direct extension of the spinal cord into the skull, and it is phylogenetically (i.e., in evolutionary terms) the most ancient part of the brain. The best way to depict it is by slicing the brain down the midline to produce a medial view. The lowest portion of the brainstem, the part immediately adjoining the spinal cord, is the medulla oblongata (Latin for “oblong core”) - a structure that has little to do with what is traditionally conceived of as “the mind” (the medulla contains nuclei that govern heartbeat, breathing, etc.) Above the medulla oblongata is the pons (Latin for “bridge”). Hanging behind the pons is the cerebellum (“little brain”). The top of the brainstem proper is the midbrain.

Above this region are structures that are not technically part of the brainstem (opinions on this point have changed over the years), but they are very closely connect in functional terms to the medulla oblongata, pons, and midbrain. These structures are referred to as the diencephalon. There is no generally accepted English word for this region of the brain, although at one time it was called the “twixt-brain,” which conveyed the essential fact that it lies between the brainstem and the forebrain. There are two main parts to the diencephalon. The largest, the upper portion, is the thalamus. Below the thalamus lies the hypothalamus, which is directly connected to the pituitary gland. All of these brainstem and diencephalic structures contain nuclei that are connected to one another (and to the forebrain structures) in intricate patterns.

The forebrain is phylogenetically younger than the brainstem. It consists principally of the two great cerebral hemispheres that fill the vault of the cranium. The outer surface of these hemispheres is the cerebral cortex, made up of folded layers of gray matter. Within the cerebral hemispheres, and hidden from view, are various forebrain nuclei.

Each hemisphere is divided into four lobes. At the back of the head is the occipital lobe; in the center is the parietal lobe (situated above and slightly behind the ears); below and in front of the parietal lobe is the temporal lobe (at the temples); the reminder of the hemisphere is the large frontal lobe, which lies over the eyes and is perhaps our greatest (and, in parts, uniquely human) phylogenetic acquisition. Buried between these lobes, if one pulls the temporal lobe down and lifts the frontal and parietal lobes up, lies a further region of cerebral cortex known as the insula.

Inside the cerebral hemispheres are the forebrain nuclei. The most substantial such nuclei are the basal ganglia. Close to the basal ganglia, nestled within the lower half of the frontal lobe, are the basal forebrain nuclei. Behind them, inside the anterior ((I.e.front) part of the temporal lobe, is the amygdala (Latin for “almond,” which this group of nuclei resembles in shape).

The Brain and the Inner World, Introduction to Basic Concepts. Mark Solms, Oliver Turnbull.

Although neuroscience and psychiatry/psychology have struggled to illuminate mind and brain in its own way, it is now clear that both need to work together intimately for any comprehensive understanding to emerge. Illustration by Elena.