My student Christoph Bleuler helped to collect these quotes:
Gary Marcus: THE BIRTH OF MIND – How a Tiny Number of Genes Create the Complexities of Human Thought
Basic Books, 2004
(Marcus, Birth of Mind, pg. 1: Mind) “The Mind is what the brain does”
(Marcus, Birth of Mind, 2004, pg. 5: Adequate Understanding of Genes) I won’t argue that genes dictate our destinies (they most certainly do not, and I’ll explain why not), nor that they outweigh the contributions of culture or experience (which are difficult to measure). The thesis of this book is that the only way to understand what nature brings to the table is to take a look at what genes actually do. (…)
(Marcus, Birth of Mind, 2004, pg. 5: The Genome – NO Blueprint) We must first abandon the familiar idea of a genome (the set of genes within a particular organism) as a blueprint. The Genome is not an exact wiring diagram for the mind or a picture of a finished product. (Marcus, Birth of Mind, 2004, pg. 6:) … a genome that is 1 percent different can lead to a radically different mind. (…) Genomes are too small to small to contain the kind of detail one would expect if genes were truly exact blueprint for a for the wiring of the mind. The human genome contains far fewer than 100,000 genes – perhaps as few as 30,000 paltry in comparison to the 20 billion or so neurons found in the human brain. Ehrlich’s gene shortage militates against any idea of the genome as a blueprint. Identical genomes do not yield identical nervous systems. (…) Just as twins do not have identical brains, they do not have identical minds.
(Marcus, Birth of Mind, 2004, pg. 7: Nature AND Nurture) The second biggest misconception about people harbor about genetics: that it will be possible one day to determine once and for all, whether nature or nurture is “more important”. Genes are useless without environment, and no organism could make any use of the environment at all if it were not for its genes.
(Marcus, Birth of Mind, 2004, pg. 11: Complex Structures for Flexible Minds; “Gene Shortage”) Until recently…Scientists knew that nature and nurture both mattered, but they didn’t know why and how. (Marcus, Birth of Mind, 2004, pg. 12:) Any theory that puts the role of genes in front and center must deal with two difficult challenges in the science of the mind, which I call to the Two Paradoxes: first, any adequate theory must face the challenge of neural flexibility. For every study that tells us then the newborn Can understand something about the overall there is another that shows that the brain can continue to function even when its structure is altered. How can the mind be once so richly structured and so flexible? The second challenge is Ehrlich’s “gene shortage”: how can the complexity of the brain emerge from relatively small chain on 20 billion neurons versus just 30,000 genes?
(Marcus, Birth of Mind, 2004, pg. 12: Learning) …we are more than anything else born to learn. (Marcus, Birth of Mind, 2004, pg. 20:) …what developmental psychologists have learned is that children are born with sophisticated mental mechanisms (nature) that allow to make the most of the information out there in the world (nurture). (Marcus, Birth of Mind, 2004, pg. 22:) Luckily most, perhaps all, animals are born not just with the ability to perceive and act but also with the ability to use past experience to improve subsequent behavior.
(Marcus, Birth of Mind, 2004, pg. 24: Genes [Nature] and Environment [Nurture]) Genes enable creatures to make sensible use of their particular environment. Learning is not the antitheses of innateness but one of its most important products. (Marcus, Birth of Mind, 2004, pg. 26: [Passing on/Acquisition of] Culture) The ability to detect statistical information is something that all mammals can do, to greater or lesser extents. (…) One learning talent that is less common in other animals is the human ability to imitate, with which humans seem to be born. (…) …imitation may have to do with something else humans are awfully good at: acquiring culture.
(Marcus, Birth of Mind, 2004, pg. 27: Communication System; Culture) My own guess is that it is hard to develop a rich culture without a rich communication system. …the gift for acquiring a communication system with the richness and complexity of language, a system for communicating not just here and now, but the future, the possible, and the dreamt-of.
(Marcus, Birth of Mind, 2004, pg. 28: Language Acquisition) One critical difference between us and other mammals is that we are awfully talented at learning new words. (Marcus, Birth of Mind, 2004, pg. 30: Language; Learning) Language is perhaps the most powerful example of what you can do if you are born with the right kind s of mental machinery for learning.
(Marcus, Birth of Mind, 2004, pg. 34: Nature THEN Nurture) Nature provides a first draft which experience then revises. (Marcus, Birth of Mind, 2004, pg. 36: Nature-Nurture) Most learning is thought to depend on electrical communication across “synapses” that join neurons. (…) The basic structure of the brain depends only minimally on experience.
(Marcus, Birth of Mind, 2004, pg. 37: Plasticity; Adaptation) … certain kinds of experience can radically alter brain organization. (Marcus, Birth of Mind, 2004, pg. 39: Plasticity; Adaptation) A few young children have had to have their entire left hemispheres removed (a rare, radical surgery that appears to be the only way to prevent certain life-threatening seizures). Astonishingly, these children learnt to talk more or less normally, shifting language function to the right hemisphere. In short, young human brains, like those of our animal cousins, are often (though by no means always) remarkably able to reconfigure themselves on-line.
(Marcus, Birth of Mind, 2004, pg. 37: Plasticity; Adaptation) Adult brains aren’t as “plastic” as brains of infants, but even here there is some room for change. University of California at San Francisco neuroscientist Michael Merzenich discovered that monkeys con reallocate parts of their cortex when those parts are no longer needed in their original function.
(Marcus, Birth of Mind, 2004, pg. 40: “Updating” Computer-Mind Metaphor) The terms “built-in” and “unmalleable” often get confused, perhaps because minds, like computers, process information, and early computers relied heavily on built-in circuitry that was “hardwired” and unchangeable. But there is no necessary equitation between the two. Engineers have long since moved on to reprogrammable “firmware” that is programmed at factory but always changeable, updateable with the latest version from the web. Evolution may have caught on far earlier: Just because something is preprogrammed doesn’t mean it can’t also be reprogrammed. In many systems, the brain may well use a mix of internally generated cues to prewire and environmentally generated cues to rewire.
(Marcus, Birth of Mind, 2004, pg. 41: Principles of Self-Repair) Taken in this broad perspective, the fact that the brain can recover from injury is hardly surprising. In fact, perhaps the only real surprise here is how inflexible the brain is. Most parts of the body constantly replace their cells, whereas the adult brain’s stock of neurons is almost entirely fixed. Your liver cells are constantly replenished, but your brain must largely (though not entirely) make do with the neurons you had when you were born… Still, the brain can, like most other pars of the body, manage a large degree of self-repair. (One form of self-repair takes advantage of built-in redundancy – if one kidney is lost, the body can shift function to the other; if one hemisphere is lost, at least some function is transferred over to preexisting counterparts on the opposite hemisphere.) Most cells in the body (except mature red blood cells platelets) are born with a complete set of instructions – about how to behave should it be called upon to be a stomach cell, instructions about how to behave should be called upon to be an eye cell, and so forth. Which instructions a given cell follows is partly determined by its neighbors. Being surrounded by stomach cells can lead an impressionable young cell to act like a stomach cell. (Marcus, Birth of Mind, 2004, pg. 44: self-repair; plasticity) Recovery from brain injury is much more dramatic in infants than in adults, but even in infants may be only partial. Although it is true that children whose brains are damaged early in life often recover to a remarkable extent, it is also true that such children face lasting deficits.
(Marcus, Birth of Mind, 2004, pg. 47: Nature of Genome; No Exact Correspondence Genotype-Phenotype:) There’s nothing in your genome that corresponds to a picture, no simple connection between parts of the genome and the parts of the brain.
(Marcus, Birth of Mind, 2004, pg. 48: Embryo Development) The bottom line is that we now realize that embryos unfold in a series of stages. During conception sperm and egg unite to form the fertilized egg known as zygote. The zygote, which begins in a single cell, soon divides again, and again, and again, ultimately forming a ball of eight nearly identical cells. The ball of cells eventually flattens, layers of cells start to form, and soon cells start to take on special fates, limbs begin to bud, an organs begin to blossom. … the principle of successive approximation (or gradual unfolding) applies as much to the development of the brain as it does to the rest of the body.
(Marcus, Birth of Mind, 2004, pg. 52: Nature of Genes; Common Misconceptions) …we tend to think of traits as qualities that vary from one person to another: I have brown eyes; you have green eyes. But most genes have nothing to do with differences between people; the vast majority of them are shared by all normal individuals. Genes do a lot more than just shape differences among individuals…most traits are influenced by more than one gene; skin color, for example, is influenced by at least thirty. Finally it is not uncommon for a single gene to influence several properties, sometimes not obviously related, as in the single gene that leads to two of the most distinctive features of Siamese cats – their unusual coloration (light body, dark extremities) and their crossed eyes.
(Marcus, Birth of Mind, 2004, pg. 54: Proteins) Proteins are long chains of twenty or so basic molecules known as amino acids that are twisted and folded into complex three-dimensional structures such as fibers, tubes, globules and sheets. Amino acids, in turn, are particular arrangements of carbon, hydrogen, oxygen, and nitrogen atoms. (…) There are literally hundreds of thousands of different proteins in the human body. An average cell has thousands different proteins, and, all told, they make up more than half the body’s dry weight. In addition to enzymes, there is a huge range of other proteins. For example keratin (the principle protein in hair) and collagen (the principle protein in skin) help build the structures of the body. (…) Proteins are involves in just about every aspect of life.
(Marcus, Birth of Mind, 2004, pg. 55: History of DNA) … the only substance left was a mysterious sticky acid that had been identified 1869 by a Swiss biochemist named Friedrich Miescher. That mysterious sticky stuff – DNA – was enough all by itself to transform the ordinary R [Pneumoccus bacteria] into deadly R. In modern language, what made transformed R deadly was genetic material incorporated from S-strain DNA [different variation of the same bacteria].
(Marcus, Birth of Mind, 2004, pg. 56, DNA; Watson&Crick) What the famous team [Watson and Crick] discovered, in February 1953 (…), was that the DNA molecule was a double helix… (…) The immediate significance of their theory was the way it connected to Mendel’s questions about hereditary. An organism could resemble its parent only if Mendel’s factors could be transferred from parent to child, and that, in turn, required that there be some way to make copies of the factors. DNA provided that possibility: Information was contained in the sequence of nucleotides. The two strand could serve as templates for more strands – voilà biological Xerox.
(Marcus, Birth of Mind, 2004, pg. 57: Transcription DNA-RNA) DNA must first be copied, or “transcribed”, onto RNA (ribonucleic acid), an intermediate complement of DNA, before it gets translated into amino acids [see side picture].
(Marcus, Birth of Mind, 2004, pg. 58: Genes; hereditary disorders) Genes genuinely do provide templates for protein building, and many disorders – mental and physical – are the result of “errors” in protein templates. (Marcus, Birth of Mind, 2004, pg. 59) Not all genetically influenced disorders, however, can be traced to errors in protein templates. Even the Protein Template Theory [as formulated by physicist George Gamow] was incomplete in a significant way. Proteins are marvelous molecular machines, but what makes one animal different from the other next door is not just its set of proteins but the arrangement of those proteins, and, remarkably the arrangement, too, are a product of genes. The Protein Template Theory captured only half of the real story. Each gene actually has two parts: the protein template, which is widely known and a second that provides a regulatory about when it should be used.
(For detailed information check: http://www.FreeScienceLectures.com)
(Gary Marcus, The Birth of Mind, 2004, pgs. 59/60: Enzymes; Genes; Genome) What Monod and Jacob discovered is that the gene for these lactose enzymes [as used in their experiment] switched on or off as needed according to a simple logical system. (…) First, the bacterium must have lactose around, and second, the bacterium must not have access to glucose. The logical juxtaposition of these two requirements (IF lactose AND NOT glucose) should instantly ring a bell with any reader who has computer programming experience – for the requirement “IF X AND NOT Y” is a piece with billions of IF-THEN rules that guide the genes software. (…) Patrick Bateson and Richard Dawkins have described the genome as a whole (…) as a recipe, but it is also possible to think of each individual gene as a recipe for a particular protein; on the latter analogy, what IF-THEN gene regulation means is each recipe can act on its own.
(Gary Marcus, The Birth of Mind, 2004, pg. 60: Genome; Cell; Body; IF-THEN) Understanding how genomes contribute to the construction of body and is thus a matter of understanding how the two parts of every gene – the regulatory IF and the protein template THEN work together to guide the fates of individual cells. Nearly every cell contains a complete copy of the genome… (…) …most cells specialize for particular tasks, some signing up for service in the circulatory system others in the digestive tract or the nervous system, relocating and even committing suicide when their job requires it. (…) What makes one cell different from the next is not which genes it has copies of, but rather which of those genes are switched on. (Gary Marcus, The Birth of Mind, 2004, pg. 61: IF-THEN) The THEN of one gene can satisfy the IF of another and thus induce it to turn on. In this way, a single gene that is at the top of a complex network can indirectly launch a cascade of hundreds of thousands of others, leading to, for example the development of an eye or a limb.
(Gary Marcus, The Birth of Mind, 2004, pgs. 65/66: Genes at Work [an Analogy]) Taken together, suites of these IF-THENS genes give cells the power to act as part of complicated improvisational orchestras. Like real musicians, what they play depends on both their own artistic impulses and what the other members of the orchestra are playing.
(Gary Marcus, The Birth of Mind, 2004, pg. 67/68: Brain Architecture) Physician Richard Restak: “Since the brain is unlike any other structure in the known universe, it seems reasonable to expect that our understanding of its functioning – if can ever be achieved – will require a drastically different approach from the way we understand other physical systems.” …the function of the brain is different from that of other organs, the brain’s capabilities, like those of other organs emerge from its physical properties. The fundamental components of the brain – the neurons and synapses that connect them – can be understood as physical systems with chemical and electrical properties that follow from their composition. (Gary Marcus, The Birth of Mind, 2004, pg. 69: communication within the brain; neuron) Neurons are electrically alive, capable of sending brief jolts of charged atoms down the length of their axons, and, even more remarkably, they are smart. Not smart as a person, but smart enough to synthesize vast arrays of information, and fast enough that a group of them working together can recognize a word or familiar object in a fifth of a second.
(Gary Marcus, The Birth of Mind, 2004, pg. 69/70: Neuron) Although their outward appearance and special talents for communication make them seem quite different from other cells, under the hood most of what neurons do is the same as what other cells do.
(Gary Marcus, The Birth of Mind, 2004, pg. 71: Brain Architecture) One divides into a series of segments that collectively compose your hindbrain, an evolutionarily ancient command center of nerves that contributes to processes such as respiration, balance and alertness. A second gives rise to the midbrain, which coordinates visual and auditory reflexes and controls functions such as eye movements. The surface of another bulge gives rise to the precursor of your forebrain, vital to decision making and reason.
(Gary Marcus, The Birth of Mind, 2004, pg. 72/73: Genes; Cells; Complexity of the Brain) Programmed cell death – deliberate cellular suicide – helps to fine-tune particular populations of neurons. (…) Like anything in development, the process of cell death must be turned on so: too much, and there are too few cells left to do the job, too little, and some unnecessary hangers-on get in the way. (…) Each of these cell processes – division, migration, differentiation, and planned cell death, is quite intricate. (…) To a remarkably large extent, all this complexity is guided by gene expression. (…) Genes guide neural development in precise and powerful ways, modulating virtually every process that is important in the life of a cell.
(Gary Marcus, The Birth of Mind, 2004, pg. 74: Genes; Signaling Proteins) The regulatory regions that direct those genes are guided in no small part by an intricate system of signpost and landmarks, made mostly of highly specialized signaling proteins. Such proteins (as always, the products of genes) often act a bit like radio waves that gradually fade out the further you get from the source. In the body, because they decrease gradually as they move away from the source, such signals are known as gradients.
(Gary Marcus, The Birth of Mind, 2004, pg. 75: The Biochemist Perspective: Triviality of Brain development & Functioning) What’s amazing is how little of the overall scheme for embryonic development is special to the brain. Although thousands of genes are involved in brain development, a large number of them are shared with (or have close counterparts in) genes that guide the rest of the body. The “motors”, for example, that allow neurons to move depend on a special protein called actin that can contract so as to pull the back edge of the cell forward toward the leading edge – exactly what actin does in limb development as it pulls finger cells toward the hand and toe toward foot. More generally, around 500 “housekeeping genes” – genes that guide processes such as metabolism, cell death, and the synthesis of proteins – do essentially the same thing in the brain as they do else where.
(Gary Marcus, The Birth of Mind, 2004, pgs. 76-79: Genes; Behavior) If genes influence the development of the brain, do they also influence the development of mind and behavior? In the animal world the answer is clearly yes. (…) We cannot, of course, ethically alter genomes to study the effect of genes on the human mind, but at least three lines of evidence suggest that genes play much the same role in the development of the human mind as they do in the animal mind. (…) To my mind, the strongest argument for a link between genes and the human mind comes from the study of animals. ...most of the genes expressed in the brain are entirely new…virtually every gene expressed in the human brain is also expressed (or closely related to a gene that is expressed) in the brain of the mouse. (…) The mind is, the body, significantly influenced by genes.
(Gary Marcus, The Birth of Mind, 2004, pgs. 79-81: Genes; Mind) Although the mind is significantly influenced by genes, it is not fixed by the genes – recall the difference between rigid hardwiring and flexible prewiring – and the connection between genes and the mind is far less straightforward than scientists had hoped. (…) It is highly unlikely that any single gene would ever be solely responsible for an entire complex behavior. In fact, I use the term “mental gene” as a bit of joke. (…) …”mental genes” are pretty much the same as other genes: self-regulated instructions for building parts of a very complex structure. And no gene works on its own. Complex biological structures … are the product of the concerted actions and interactions of many genes, not just one. One reason it makes no sense to talk about a gene for a particular behavior is that the neural circuitry involved in producing any given behavior is far more complex than any one gene. And except, perhaps, in the case of reflexes, most behaviors are the product of many neural circuits. In a mammal or a bird, virtually every action depends on a coming together of a multiplicity of systems for perception, attention, motivation, and so forth.
(Gary Marcus, The Birth of Mind, 2004, pg. 81: On the Possibility of Genes Producing Immediate Behavior) Genes do seem to play an active, major role in “off-line” processing, such as consolidation of long-term memory (which can happen during sleep) but when it comes to rapid on-line decision making, genes, which work at a time scale of seconds or minutes, turn over reins to neurons, which can act on a scale of hundredths of a second. Genes build neural structure – not behavior.
(Gary Marcus, The Birth of Mind, 2004, pgs. 82-85: Traits; Genes) Although there is unlikely to be any single gene for complex traits, there are likely to be many genes that profoundly influence those traits by tweaking (for better or worse) machinery that is already in place. (Gary Marcus, The Birth of Mind, 2004, pg. 84: Brain; Genes) That the relationship between genes and brains (or the mind) is complex does not mean that it is irrelevant. Critics of the idea that there might be “innate” mental structure have suggested that because there has thus far been no smoking gun – no single gene that there has been linked to language and only language – we should abandon the idea there is a built-in language “instinct”. Others have gone further, criticizing the whole new idea that the mind and brain might consist of a set of specialized modules… The view I advocated … that we are born with whole slew of specialized mechanisms (including some for different kinds of learning) – has been criticized as being implausible because, in the 1998 words of British psychologist Annette Karmiloff-Smith, “so far no gene…has been identified that is expressed solely in a specific region of the cortex. (…) An alternative way of specifying the fates of particular cortical areas relies on gradients – those signaling molecules that diminish in concentration as they move away from their source. For example, a gradient of Emx2… Rather than being discretely restricted to specific cortical areas, the protein product of Emx2 diminishes gradually from a source at the back of the cortex. But it is differently expressed, and that’s enough of a guide to dramatically affect development. Knocking it out dramatically shifts the boundaries between cortical areas – and perhaps enough to allow different areas to specialize in different ways.
(Gary Marcus, The Birth of Mind, 2004, pgs. 86/87: Simple Genetic Foundation for the Realization of Neural Complexity?) For the most part, what is good enough for the body, is good enough for the brain. (…) The one thing that is truly special about the development of the brain – the physical bases of the mind – is its “wiring”, the critical connections between neurons, but even there … genes play a critical role. (…) In the 1990s, the Decade of the Brain, cognitive neuroscientists showed that our minds are the product of our brains. Early returns from this century are showing that the mechanisms that build our brains are just a special case of the mechanisms that build the rest of our bodies. The initial structure of the mind, like the initial structure of the rest of the body, is a product of our genes.
(Gary Marcus, The Birth of Mind, 2004, pgs. 89/90: Wiring of the Brain; Neural Connections) … the wiring between neurons is arguably the single thing that makes the brain special. For it is that wiring that allows the to compute and analyze, reason and perceive. The essence of being an intelligent being is the ability to gather information. To do that, an organism’s nervous system must transmit information from the senses to higher-level command centers that make choices, and then translate those choices into specific instructions that must be conveyed to the muscles. The billions of neurons in your brain have trillions of connections between them, and what your brain does is largely a function of how those are set up.
(Gary Marcus, The Birth of Mind, 2004, pgs. 91/92: Axon Guidance) How do the brain’s axons and dendrites know where to go? (…) Much of what goes on is decided by special, wiggly, almost hand-like protuberances at the end of each axon known as growth cones. Growth cones (an the axonal wiring they trail behind them) are like little animals that swerve back and forth, maneuvering around obstacles, extending and retracing little feelers known as filopodia (the “fingers” of the growth cone) as the growth hunts in search of its destination. …growth cones constantly compensate and adjust, taking in new information as they find their way to their targets. (…) Thus growth cones do not just head in a particular direction and hope for the best. They “know” what they are looking for and can make new plans even if experimentally induced obstacles get in their way. (Amazingly growth cones can do this more or less on their own.)
(Gary Marcus, The Birth of Mind, 2004, pg. 95: ) What this all boils down to, from the perspective of psychology, is an astonishingly powerful system for wiring the mind. Instead of vaguely telling axons and dendrites to connect at random to anything else in sight, which would leave all of the burden of mind development to experience, nature supplies the brain’s wires – axons and dendrites – with collaborate tools for finding on their own. Rather than waiting for experience, brains can use the complex menagerie of genes and proteins to create a rich, intricate starting point for the brain and mind. (…) If our minds are more complex than the minds of other animals, it is in part because we have more ways of using genes to precisely shape the wiring of our brain.
(Gary Marcus, The Birth of Mind, 2004, pg. 98: Experience, Intelligence, Lifelong Learning; Genes) Every genetic process is triggered by some sort of signal. From the perspective of a given cell, it doesn’t matter where that signal comes from. The signal that launches the adjust-your-synapse cascade, may come from within, or it may come from without. The same genes that are used to adjust synapses based on internal instruction can be refused by refused by external instruction. …that is a – maybe even the – key secret to intelligent life on earth. The reason that animals can learn is that they can alter their nervous system on the basis of external experience. And the reason they can do that is that experience itself can modify the expression of genes. The role of genes is not just that to create the brain and body of a new born, but to create an organism that is flexible enough to deal with an ever–challenging world. Genes play an important role throughout life, not just until the moment of birth, and one of the most important way in which they participate throughout life is be making learning possible.
(Gary Marcus, The Birth of Mind, 2004, pg. 99: Genes; Experience; Learning) Not every gene, nor every brain connection can be modified by experience. Each species has a different way of connecting experience to gene expression, and these different links, make possible different kinds of learning. (…) Regardless which species we talk about, or which aspect of mental life we investigate, the ability to learn starts with the ability to remember.
(Gary Marcus, The Birth of Mind, 2004, pg. 99/100: synaptic strengthening; “long-term potentation” [LTP]; memory) Most research on biology of memory has focused on something I’ll call “synaptic strengthening”. Synapses, the connections between neuron and the next, are thought to vary in strength, with strong connections between neurons that are in some ways closely tied together. Let us suppose that a simple organism has one neuron for recognizing a special sound, lets call it the “bell neuron”, and another for triggering the complex set of cells involved in eating, call it the “munch neuron” The bell neuron would fire whenever the simple creature heard the bell, the munch neuron whenever the creature began to eat. If the animal was consistently fed right after the bell rang, one might expect that over time, the connection – the synapse – between the bell and the munch neuron would get stronger, making the creature more likely to want to munch whenever it heard the bell [, which is exactly what Pavlov suggested as the result of his experiments with dogs; see also following page 11: footnote on association/associative learning].
The idea is that certain kinds of learning depend on “potentiating” – strengthening the synaptic connections between neurons is long and complex (…) …they can be roughly divided in five basic stages. First the brain notices something interesting has happened and some neuron “fires”, releasing neurotransmitters on the “transmitting” side of the synapse [see pictures on page 6!]. Next, the neurotransmitters that are released on the transmitting side bind to appropriate receptors on the receiving side of that synapse. Those receptors then allow charged atoms through. Once inside the cell, those charged atoms launch a biochemical cascade that ultimately switches on a set of early-response genes. Those early-response genes then ultimately launch a second round of gene expression, which in some way (still under investigation) physically strengthens the synapse, quite likely using many of the same genes and proteins (such as cell adhesion molecules) that direct initial synapse formation endogenously, prior to experience.
(Gary Marcus, The Birth of Mind, 2004, pg. 102/103: Memory:
Storage & Retrieving) We know little about the mechanisms by which
memories are retrieved, and even less about the “codes” the brain uses to store
(…) Neural substrates for memory are found not just in on particular location in the brain, but spread out throughout, with different circuits supporting different kinds of memory. (…) …each memory system has a different function. Memory in the hippocampus has to do with spatial locations, … whereas amygdala has to do with emotional events. (…) Studies of memory go part of the way – but only part of the way – toward helping us to understand specialized learning mechanisms. It is likely that each specialized learning mechanism relies on its own specialized memory store. But another part of learning comes in deciding which information to store in the first place.
(Gary Marcus, The Birth of Mind, 2004, pg. 104/105: Animal Learning; Song-Learning) Song learning systems are especially interesting because they are so similar in abstract design to our own linguistic system. Learning a song appears to require separate systems (“modules”) in the songbird for detecting which songs are from its own species, for parsing those songs into notes and phrases, for recording the components of the song in memory, and for tuning those stored representations into vocal gestures. (…) The bird breaks down the process of learning into several subtasks, each supported by a separate bit of neural circuitry. Learning itself is likely to be a process of using experience to tune the modules and connections between them – mediated, always, by genes. (…) The genetic side of the process remains speculative, in part, because of the technical limitations involved in conducting experiments with birds (there is not yet an easy way to alter their genomes), and the ethical ones with humans (not even a mad scientist would dare study the effects of knocking out synaptic strengthening in Broca’s area). But one organism that genetics do know a lot about is the lowly C. elegans roundworm, and what we know about it fits well the overall picture I have been sketching. Even in the roundworm, learning is not due to a single, all-purpose mechanism: Worms use different learning mechanisms for different tasks. (…) … the molecular bases for memory are at least partly shared from one type of learning to the next, but each learning mechanism also depends on its unique genes.
(Gary Marcus, The Birth of Mind, 2004, pg. 106-108: Basic Learning Concepts; Association; Habituation; Critical period) Association and habituation are among the most basic processes involved in learning, but, as the worm studies make clear, they are not identical, and in fact they depend in part on different genes. (…) Studies of the genes involved in learning may also eventually lead to insights into why the ability to learn certain things diminishes over life span. …adult beings aren’t nearly as good as children in mastering new languages. (…) Adults are not a lost cause: You are learning (and rewiring your brain) as you read this book. Dozens of studies over the past few years have shown that adult animals have more “plasticity” as was once thought… (…) But the ability to learn does indeed vary over time, diminishing more sharply in some domains than in others. … an animal should be able to learn new things about its environment throughout life, but once its body stops growing, it shouldn’t need to recalibrate its hand-eye coordination on a daily basis. (…) A major push is under way to figure out the molecular basis of those “critical” or “sensitive” periods, to figure out how the brain changes as certain abilities come and go. (…) At the end of a critical period, a set of sticky sugar-protein hybrids known as protroglycans condenses into a tight net around the dendrites and cell bodies of some relevant neurons, and in doing so those protroglycans appear to impede axons that would otherwise be wriggling around as part of the process of readjusting the ocular dominance columns; no wriggling, no learning.
(Gary Marcus, The Birth of Mind, 2004, pg.108/109: “Innate Experience”) ...scientists have found that vertebrate brains spontaneously generate neural activity even before their senses are hooked up to the outside world ant that this self-generated activity allows embryonic brains to refine their own wiring. (…) …from the perspective of a neuron, it doesn’t matter whether a signal comes from outside or inside. Information is information, and evolution has wired our embryonic minds up to use all in the same way. Electrical and chemical activity can mediate many of the same process that make growth possible in the first place. Learning proceeds not by overriding the genes … but by repurposing them, by adapting ancient techniques of development for modern needs of on-line flexibility.
(Gary Marcus, The Birth of Mind, 2004, pg. 111: Evolution of Mental Genes) Where do the genes that participate in the building and maintenance of the brain come from? My goal … is not to consider what the brain evolved for – an ever-controversial topic that is outside the scope of this book – but to explain how (and when) the genes that help to build the brain evolved.
(Gary Marcus, The Birth of Mind, 2004, pg. 112: Principles of Genetic Change: Mutation) All evolution arises in one way or another from some change in the genetic code. The most familiar kind of genetic change is the simple mutation, an A changed to a C, a T to a G. … mutations can lead to disorders, but they also can lead to useful innovations. On occasions, a mutation – which might result from radiation, toxic chemicals, viruses, or errors in the process of DNA replication – turns out to be a good thing… A particularly valuable mutation may gradually spread through the population; such is the source of much evolutionary change.
(Gary Marcus, The Birth of Mind, 2004, pg. 112/113: Principles of Genetic Change: Duplication) Sunspots, viruses, and plain old copying errors can also lead to another kind of change: They can cause nucleotides to be inserted (for example, AG becomes ACG) deleted (ACG becomes AG) or inverted (ACG becomes GCA), and the same sort of thing happen with larger chunks of chromosomes. Perhaps less familiar is the mechanism known as duplication. Errors that occur during the process in which genetic information is copied or prepared for transmission from parent to child can inadvertently lead to the duplication of the entire gene, an entire chromosome, or even an entire genome, leading the child to have two copies where a parent had one. (…) But why should it matter if an organism should suddenly have an extra copy of a gene? (…) … an extra copy of a gene can mean an extra chance to make a particular protein. (…) an extra copy of the gene may increase the chance that the corresponding protein gets made. An extra copy can also mean that twice as much of the protein is made, yielding, say more rigid cell wall or increased gradient regulatory proteins, which might change the relative proportions of two bones. (…) Turning on the brain and mind, several kinds of mental retardation, such as Down syndrome (Trisomy 21) and Patau syndrome (Trisomy 13), appear to be caused by superfluous copies of genes. But there is an even more important reason why duplication may have had a large impact on evolution – it provides what Richard Dawkins described as the blind watchmaker–evolution… If one copy of a gene – perhaps already optimized to a particular function – remains stable, the second may vary without loss of the initial function, ultimately giving rise to new function.
(Gary Marcus, The Birth of Mind, 2004, pg. 114: In-Brain communication) A major role of what the brain does is to communicate signals from one place to another. It takes information from the senses, analyzes that information and translates it into commands that get sent back to the muscles. … the brain per se is a relatively recent innovation – perhaps only half a billion years old in a close relative of a pinheaded anchovy called amphioxus – many of the brain’s components are far older. Organisms as simple as the sponge Rhabdocalyptus dawsoni have the rudiments of a recognizable nervous system, and some of the brain’s components are even older. Many single-celled organisms, for example, profit from systems for internal communication. (…) Amazingly, some of the molecules used more than a billion years ago by ancestral bacteria to coordinate information and action remain with us today, in the form of ion channels (those protein gates that open and close so as to control the flow of electrically charged molecules across the borders of a cell). Such channels are found virtually in all living organisms and are major determinants of neural function, modulating the sensitivity of individual neurons to such factors as temperature and voltage and playing a role in everything from motion in paramecia to growth in plants and cognition in people. Channels specialized for the flow of potassium probably arose first, but it wasn’t long before duplication and divergence led to new classes of channels, each specialized to control the flow of different types of ion (for example calcium, others for sodium or chloride). As R. M. Harris-Warwick put it, “Once one channel gene was made, others could be generated by duplication, allowing diversity to arise in the “new” copy with no loss of function in the “old” one. Further mutation, duplication and divergence led to receptors, the “receiver” molecule that serves as go betweens, transforming signals from outside a cell into molecular events inside the cell. These, too, duplicated and diverged early in evolution, creating a variety of receptors, each specialized for receiving a particular kind of signal, such as glutamate, GABA, acetylcholine, or serotonin.
(Gary Marcus, The Birth of Mind, 2004, pg. 116: Biological Systems for Communication) … biological systems for communication (both internal and external) have steadily improved over the course of evolution. (…) …electrical impulses are biology’s medium of choice. They can travel very quickly, and, with the help of those thin, wire-like cables known as axons, they can be directed with precision to particular targets at great distances. When a neuron “fires”, it launches a spike of electrically charged atoms that travel rapidly down the axon, culminating in the release of the neurotransmitters that allow one neuron to communicate with another.
(Gary Marcus, The Birth of Mind, 2004, pg. 116/117: Evolution of Electrical Signaling) That biological system of communication goes back nearly half a billion years, to jellyfish (or some closely related ancestor common to us and them), when a growing trend toward cellular specialization led to the development of neurons. Jellyfish nerve cells are fare more primitive than ours; their signaling travels hundreds of times more slowly than ours do, and their nerve cells have to wait longer than ours do before they can fire again. Moreover, the dreaded jellies don’t have anything like a centralized brain; instead they have a loosely strung collection of neurons that biologists refer to as a mere “nerve net”. (…) Our nerve cells, like theirs, rely protein channels that can be modulated – opened and closed – by changes in voltage, and DNA analyses have shown that some recipes for building those channels go back at least as far as our common ancestors. After electrical signaling, the next major step in the evolution of brains like ours was a mix of centralization and bilateralization (a trend toward left-right split) – organization principle that apparently began a little over a billion years ago with a precedent-setting flatworm. (…) The flatworm’s rudimentary division of neural labor – between the central an the peripheral, the left and the right – was the first step toward an avalanche of specialization that has given rise to the complex neural systems of the vertebrates. The vertebrate nervous system radically differs from its predecessors in at least two major ways: Fish, shortly after the vertebrates came on the scene, intercellular communication got a whole lot better, with evolution of glial cells, biological insulators that surround axons and keep koving electrons on track.
(Gary Marcus, The Birth of Mind, 2004, pg. 118: Meylin Insulation; Energy Efficiency) Meylin insulation … made it possible for axons to be packed closer together without crosstalk, in turn making possible larger and denser brains. (…) Octopi for example, are among the few animals that can learn by imitation, but without myelin, their evolution may have reached the ceiling. (…) … with the development of meylin early in vertebra linage came larger brains, with greater organization, including a three-part division into forebrain, midbrain and hindbrain. Central to this transition was a set of ancestral genes known as Hox genes, named in honor of homeotic mutations.
Gary Marcus, The Birth of Mind, 2004, pgs. 119: 119/120: Evolution of the Human Brain) By the time those early vertebrates crawled out of the water, perhaps 400 million years ago, the rough structure of the mammalian brain was pretty much in place. (…) Humans have huge frontal lobes; birds have greatly enlarged basal ganglia. (…) Mammals with complex brains, such as cats, dogs, monkeys, chimpanzees, and humans, follow much the same plan but have significantly bigger cortices that devote more areas to each specialization. (…) … after carnivores and primates diverged roughly 90 million years ago, their cortical areas proliferated independently, perhaps in part as the result of independent gene duplication. (…) Mammals share not just an overall neural organization but also a system of developmental timing.
(Gary Marcus, The Birth of Mind, 2004, pg. 124: Uniquely Human; Language) …Homo sapiens, the loud mouthed ape. Humans are both similar and different from our close animal cousins. (…) In, for example, our body structure, our group dynamics, our perceptual systems, our aggression, and our sustained systems of maternal care, we surely have something in common with the chimp. Yet we are also plainly different. In our culture, our language, and in our thoughts, we have the capacity to contemplate beauty, justice calculus, and the meaning of life, concepts that we imagine no chimp has ever dreamed of. Language, of course, must be a key to what makes our species unique. If learning is the genome’s most powerful trick for moving beyond itself, language is arguably the most powerful tool for learning – the mother of all learning mechanisms and the single thing that most makes humans different. Language allows us to communicate information in ways that no other medium coud match. It is clearly critical for the rapid transmission of culture, and it may even be a necessary component of some kinds of thought.
(Gary Marcus, The Birth of Mind, 2004, pgs. 124-126: Language; Thought; Language of Thought) We often have the impression that we think in words. … scientific opinion is divided as to we really do… (…) As a medium for communication, it [Language] allows elders to teach the young; as a medium for thought it, it almost certainly helps us to store and retrieve information more efficiently, and it may even help us to reason more efficiently. (…) Not everybody would agree would agree that language is a medium for thought. Jerry Fodor, for example, has argued that language must separate from a “language of thought”, or “mentalese”, because there is a slippage between language and thought. There are, for example, thoughts that cannot be expresses with language and “tip-of-the-tongue” phenomena in which we know there’s a word for something but can’t quite come up with it. The psychologist Lila Gleitman has argued, rightly in my view, that there is little good experimental evidence showing last cognitive differences between speakers of different languages. She suggested instead that that “linguistic systems are merely the formal and expressive medium that speakers devise to describe their mental conceptual representations,“ and that “linguistic categories and structures (serve as) more-or-less straightforward mapping from preexisting conceptual space. Perhaps the most compelling argument for a difference between language and thought is one raise by Fodor and Steven Pinker: the contrast between sentences which are ambiguous (Does the bank mean a financial institute or a riverbed in “Lloyd sat next to the bank”? […]) and thoughts in mentalese, which presumably are unambiguous. When I think to myself … I know what I mean. But what do these arguments show? They show that there can be thoughts without language, but no language without thought, but not that language plays no role in thought. Babies, monkeys, aphasics (…) all have thoughts even if they cannot speak, and we all have thoughts that we can’t put into words – emotions, sensations, and so forth – but that shows only that some thoughts are not linguistic, not that no thoughts are.
(Gary Marcus, The Birth of Mind, 2004, pg. 126: Language; Story-Telling; Framing; Emphasis) I would like to suggest that language makes certain types of thought – including the kind of conscious, reflective reasoning you are engaged right now – possible. Language has the potential to affect our thoughts in at least two ways: first by “framing” the content of our ideas; second, by affecting what we remember. By “framing”, I mean that language can, like a flashlight (or hand gesture) point our attention in particular directions. When Henry Kissinger says that “mistakes were made”, he aims to use Language to divert from the embarrassing question of who made the mistakes. Language is all about emphasis: As Lila Gleitman pointed out, saying “Meryl Streep is my sister is entirely different from saying “Your sister met Meryl Streep”. As every good spin doctor must know, to frame a sentence is to frame a thought.
(Gary Marcus, The Birth of Mind, 2004, pg. 126: Language; Memory) When it comes to memory, language’s most obvious role is to help us rehearse information in our heads, as when you repeat a phone number to yourself.
(Gary Marcus, The Birth of Mind, 2004, pg. 126: Language; Thought; Allowing Management of Complexity) Language may also facilitate thought by providing simple hooks for complex concepts.
(Gary Marcus, The Birth of Mind, 2004, pg. 12: Long-Term Memory) … language may also play a crucial role in long-term memory by providing a special way of encoding complex information. To understand this point, it helps to … think about computers at work. A computer’s memory is made up of a long string of “bits” that can be either zeros or ones, but those zeros and ones mean nothing without an organizational scheme, or what computer programmers call “data structure”, a way of taking a particular set of zeros and ones that stand for a particular kind of entity, such as a number, a name, or an intensity for a picture element (pixel). What a particular computer program represents is a function of the particular types of data structures it can encode; some programs may store only pictures but not names, others the other way around. Language’s greatest contribution may be in providing a data structure for storing relationships between entities and bits of information about those entities, or what linguists call subjects (say G. W. Bush) and predicates (felt that American voters had misunderestimated him). Such a data structure might be a key to enabling humans to represent a uniquely broad range of thoughts.
(Gary Marcus, The Birth of Mind, 2004, pg. 128/129: Language as a Medium for Thought) But what about Pinker and Fodor’s point about ambiguity? Do we really store our thoughts as sentences? (…) It is possible … that for a subset of our thoughts, an annotated kind of language – rather than a separate mentalese – could serve as a medium form long-term storage. (If there is some kind of language-specific representational system, then it would stand to reason that children who have yet to learn a language would not have such a system and would therefore not be able to entertain the same range of thoughts as people who had acquired linguistic systems.) (…) Whether language is a medium for thought or just communication, its importance in our lives cannot be understated. Chimpanzees and orangutans have the rudiments of culture, but without language, and its capacity for rapidly transmitting – and perhaps encoding – a wide range of information, they will never have culture as rich as ours. But why is that we have language and our chimpanzee cousins who share more than 98 percent of our genetic material do not?
(Gary Marcus, The Birth of Mind, 2004, pg. 128: Language Evolution Theories) When it comes to evolution, the question seems almost too easy. Dozens of eminent scientists have made proposals. Today we have the aquatic ape hypothesis, the language gesture theory, the theory that language arose from the neural machinery that evolved to control our muscles, the theory that language came about as an accidental consequence of having bigger brains, the theory that language is an extension of our capacity for representing space, the theory that language evolved for the purpose of gossip, and the theory that language evolved as a means of engaging in courtship and sexual display. Perhaps more than a few of these theories have a grain of truth in them. Language does for example make gossip possible, and it couldn’t have hurt our ancestors to know a little more about their neighbors than the next guy did. But, as linguists are font of saying, languages don’t leave fossils, and thus far, there has been very little evidence to tease apart on theory of the origin of language from the next.
(Gary Marcus, The Birth of Mind, 2004, pgs. 128/129: Broca’s Area; Wernicke’s Area) … we haven’t yet figured out exactly what it is about the mind and brain that allows us to learn and use language in the first place. Until recently, most textbooks ascribed the ability to use language largely to two walnut-sized regions of the left hemisphere of the brain known as “Broca’s area” and “Wernicke’s area”. (…) … Broca’s area was the grammar area of the brain, Wernicke’s the meanings area of the brain. The only problem with this lovely story, now over a hundred years old, is that it’s wrong. … they [scientists using new neuro-imaging methods such as PET or functional MRI] have found that Broca’s area is indeed (in many experiments) active in syntactic processing and that Wernicke’s is active in understanding and processing of words, but they’ve also found that other areas participate in both kind of processing and that neither Broca’s nor Wernicke’s areas is restricted to purely linguistic function. Broca’s area, for example, seems to be active not just in Language but also in the comprehension of music (even by nonmusicians), in imitation and perhaps in motor control. (…) … it appears that syntactic processing engages other parts of the brain further up to the front, and perhaps “subcortical” areas that are not even in the evolutionary recent neocortex; studies of word learning have studies implicated not just Wernicke’s area but also visual areas and motor areas, and so forth. Rather than being confined to a single box in the head, our knowledge about words may be scattered among different regions of the brain. (…) Just as there is no simple one-to-one mapping between genes and the brain areas, there is no simple one-to-one mapping between brain areas and complex functions.
Gary Marcus, The Birth of Mind, 2004, pg. 130: Brain Size; Complexity) … the only immediate obvious difference between our brains and those of chimpanzees is in their size – the average chimpanzee weighs about 55 kilograms and has a brain of 330 cubic centimeters, but the average human, who weigh only 20 percent more, has a brain four times larger. Although that difference is important, it is unlikely to be enough for itself. Wales and elephants have bigger brains than ours, but they do not have language. (…) Intelligence (as measured by IQ tests) is only barely correlated with brain size. Men have bigger brains (on average) than women, but (on average) women have better language skills. Humans with unusually small brains can sometimes have language. In short, size isn’t everything. Having a normal human-sized brain may be perquisite for language, but it is clearly neither necessary nor sufficient.
(Gary Marcus, The Birth of Mind, 2004, pgs. 130/131: Brain Structure) At a gross level, our brains and those of chimpanzee are structured in almost identical ways. We both have occipital cortices in the back of our heads wherein we analyze visual information; we both have brains split into left and right hemisphere, with interconnecting cables that run through the corpus callosum. (…) … in humans the corpus callosum is proportionally smaller in comparison to the rest of the brain than in chimpanzees. That means that humans have less communication between hemispheres, but at the same time (as measured by the amount of white matter that contains neural connections) more communication within hemispheres… (…) I wouldn’t be surprised if there were many other important differences that our present-day microscopes just can’t detect.
(Gary Marcus, The Birth of Mind, 2004, pg. 131/132: NO “Language Area”; Modularity?) ... at present we cannot simply point to a particular spot in the brain and say this is the language area, this is the neural circuit that makes the brain uniquely human. To some scholars, these complex (and frankly unsatisfying) results challenge the innateness hypothesis because they spell the end of the “modularity hypothesis”, the idea that separate neural systems might be special for distinct neural functions. To me, they suggest, not that we should abandon modules … but that we should rethink them – in light of evolution. Nothing about the brain was built overnight; evolution proceeds, in general, not by starting over but by tinkering with what was already in place. As Francis Jacob puts famously puts it, evolution is like a tinkerer who “often without knowing what he is going to produce, … uses what ever he finds around him.”
(Gary Marcus, The Birth of Mind, 2004, pg. 132: No specialized structures needed)
The ingredients – and genes – that make up our brains are m like the ingredients that make up the rest of our bodies, the product of evolution. New cognitive systems are patchworks and modifications of old. Specialized biological structures need not be, and perhaps never are, made up entirely, or even in large part, of wholly novel material.
(Gary Marcus, The Birth of Mind, 2004, pg. 132: Genetic Foundations for a Language Module) A language module may depend on a few dozen or few hundred evolutionary genes, but it is also likely to depend heavily on genes – or duplicates of preexisting genes – that are involved in the construction of other cognitive systems, such as motor control system, which coordinates muscular action, or the cognitive systems that plan complex events. At the genetic level, figuring out what gives humans the unique gift of language will be a matter of not just finding out about those (perhaps relatively few) genes that are unique to people, but also a matter of finding out how those genes unique genes interact with all others that are part of our common primate heritage. .(…) Understanding language will be a matter of not just understanding unique bits of neural structure but also a matter of understanding how those unique structures interact with other structures that are shared the primate order.
(Gary Marcus, The Birth of Mind, 2004, pg. 132-134: What Makes Language Skills Possible; Learning of the Rules of Language; Word Learning) The Ability to learn the rules of grammar, for example, may depend on circuitry for short-term memory that spans the vertebrate world, circuitry for recognizing sequences and automatizing (speeding up) repeated actions that is common to all primates, and special circuitry for constructing “hierarchical tree structures” … that is unique to humans. Our ability to acquire words may depend on a mix of long-term memory abilities that are found in animals and some special human faculty, the details of which are not yet clearly understood. … we should expect a language system to consist not of a single, brand new chunk of brain but of a new way of putting together and modifying a broad array of previously existing subsystems. Different parts of the brain probably are specialized for different functions, but most pf these functions are likely to be shared subcomponents for computation, not complete systems for single-handedly solving complex cognitive tasks. … that neural machinery for new tasks evolved as a combination of mostly preexisting components… (…) We may ultimately understand language … as a powerful new combination of mainly old components.
 Gary Marcus, The Birth of Mind, 2004: Glossary. Genes. A combination of IF and THEN [see pages 4/5!] that specifies a protein template and conditions for that protein production, such as genetic recipe for insulin and coupled instructions that govern where (i.e., in the pancreas) that recipe should be followed.
 Gary Marcus, The Birth of Mind, 2004: Glossary. Genome. The total collection of a person’s genes.
 Gary Marcus, The Birth of Mind, 2004, Glossary. Protein. One of the basic building blocks of a cell, consisting of a string of amino acids bent of folded into three-dimensional structures that support factors such as Pax6.
 Gary Marcus, The Birth of Mind, 2004, Glossary. Amino acid. Any of the twenty or so different organic acids, such as valine and serine, from which flat proteins are composed.
 Gary Marcus, The Birth of Mind, 2004, Glossary. DNA (deoxyribonucleic acid): The double-helix-shaped molecule that serves as the principal repository of genetic information; made up of two sugar-phosphate backbones held together by pairs of nucleotides.
 Gary Marcus, The Birth of Mind, 2004, Glossary. RNA (ribonucleic acid). The complement of DNA that serves as the intermediary molecular template in the process of protein synthesis.
 Gary Marcus, The Birth of Mind, 2004, Glossary. Protein template. The coding region of a gene that dictates what protein will be synthesized if that gene is expressed.
 Gary Marcus, The Birth of Mind, 2004, Glossary: IF-THEN. The combination of regulatory region (IF) and coding region (THEN) that determines the protein product of a gene and the circumstances under which that protein should be synthesized.
 Gary Marcus, The Birth of Mind, 2004: Glossary. [LERNING:] Learning Mechanism, General. A neurocognitive device for learning that is general-purpose, not specialized for the acquisition of any particular kind of information. Learning Mechanism, Specialized. A neurocognitive device for learning that is tuned for the acquisition of particular types of information, such as language or social relations.
 Gary Marcus, The Birth of Mind, 2004: Glossary. Association (in psychology). A link between stimulus (e. g., a bell) and a response (e. g. food). Associative Learning. A process of Learning relations between a stimulus and its response based on their co-occurrence in time.
 Gary Marcus, The Birth of Mind, 2004: Glossary. Habituation. The process by which an organism learns to ignore (gets used to) a particular ongoing stimulus; also an experimental method by which to test the perceptual or cognitive abilities of an organism such as a human infant.
 Gary Marcus, The Birth of Mind, 2004, Glossary. Glia/Glia Cell. Neural support that produces oligodendrocytes (responsible for the myelin sheath that insulates the neurons) and astrocytes (which produce mechanical metabolic support); such cells are also implicated in neural migration.
 Gary Marcus, The Birth of Mind, 2004, Glossary. A subcortical group of neurons found at the base of the brains traditionally implicated in motor control, and more recently thought to be also important for language.
 Gary Marcus, The Birth of Mind, 2004, Glossary. Functional Magnetic Resonance Imaging (fMRI). A Brain imaging technique that traces local changes in blood flow as an index to brain activity [in relation to the results the test is supposed to deliver, the patient is asked to perform a specific task].