Brain Development (Neuroscience of Learning)

Hitherto, this lesson hath been chiefly concerned with the mature operation of the Central Nervous System. Many instructors, however, are engaged with pre-schoolers, children, and adolescents. The subject of cerebral development is of interest not merely intrinsically, but also by reason that the pedagogical implications for instruction and assimilation are contingent upon the degree of cerebral advancement. In the introductory scenario, Bryan doth advert to the significance of educators possessing a comprehension of cerebral development. This section shall discourse upon influential factors in development, the trajectory of development, critical junctures in development, and the function of development in linguistic acquisition and application.

Albeit human brains exhibit a structural similarity, individual variances are indeed extant. Five influences upon cerebral development encompass: genetics, environmental stimulation, nutrition, steroids, and teratogens (Byrnes, 2001).

Genetics

The human cerebrum is distinguished in its dimensions and constitution from those of other fauna. Whilst the dissimilarity between the human genome and that of our closest animal cognate (the chimpanzee) is a mere 1.23% (Lemonick & Dorfman, 2006), that difference, coupled with other genetic variations, begets a species capable of conceiving and erecting bridges, composing musical works, penning novels, and resolving complex equations, inter alia.

Human cerebra evince a congruent genetic structure, yet diverge in size and conformation. Studies of monozygotic (one-egg) twins intimate that they occasionally manifest cerebra that are structurally disparate (Byrnes, 2001). Genetic directives ascertain the dimensions, configuration, and neural connectivity of the cerebrum. In the main, such discrepancies yield cerebra that function normally; however, cerebral research persists in identifying how particular genetic variations engender anomalies.

Factors Affecting Cerebral Development:

• Genetics
• Environmental Stimulation
• Nutrition
• Steroids
• Teratogens

Environmental Stimulation

Cerebral development necessitates stimulation from the environment. Prenatal development lays the groundwork for learning by cultivating a neural circuitry capable of receiving and processing stimuli and experiences. These experiences further mould the circuitry through the accretion and reorganisation of synapses. For example, pregnant women who engage their infants in speech and song may, through such means, aid in establishing neural connections in the babes (Wolfe, 2001). Cerebral development falters when experiences are wanting or minimal. Although critical periods exist when stimulation may wield profound effects (Jensen, 2005), research implies that stimulation is of import throughout the entire lifespan to ensure continued cerebral development.

Nutrition

A dearth of proper nutrition may exert substantial effects upon cerebral development, with the specific effects contingent upon the timing of the nutritional privation (Byrnes, 2001). Prenatal malnutrition, for instance, retards the production and expansion of neurons and glial cells. A critical period transpires between the 4th and 7th months of gestation, during which the majority of brain cells are produced (Jensen, 2005). Subsequent malnutrition curtails the velocity at which cells augment in size and acquire a myelin sheath. Whilst the latter predicament may be rectified with a suitable diet, the former is often irreversible due to an insufficient quantity of cells having developed. Hence, pregnant women are counselled to abstain from drugs, alcohol, and tobacco; maintain a salubrious diet; and eschew stress (as stress, too, poses complications for the developing foetus).

Steroids

Steroids denote a class of hormones that impinge upon sundry functions, encompassing sexual development and stress responses (Byrnes, 2001). Steroids may influence cerebral development in divers manners. The cerebrum possesses receptors for hormones. Hormones such as oestrogen and cortisol are absorbed and may potentially alter cerebral structure during prenatal development. Excessive stress hormones may induce neuronal death. Researchers have also scrutinized whether disparities in gender and sexual predilection arise, in part, from differences in steroids. Albeit the evidence concerning the role of steroids in cerebral development is less conclusive than that pertaining to nutrition, steroids possess the potential to affect the cerebrum.

Teratogens

Teratogens are extraneous substances (e.g., alcohol, viruses) capable of inducing abnormalities in a developing embryo or foetus (Byrnes, 2001). A substance is deemed a teratogen only if research demonstrates that a not unrealistically elevated level may affect cerebral development. For instance, caffeine in modest quantities may not constitute a teratogen, but may become one upon higher intake. Teratogens may impinge upon the development and interconnections of neurons and glial cells. In extreme instances (e.g., the rubella virus), they may precipitate birth defects.

During prenatal development, the cerebrum doth expand both in magnitude and in architecture, as well as in the quantum of neurones, glial cells, and neural connections (synapses). Prenatal cerebral evolution is expeditious, occurring within nine months, with the majority of cells being engendered between the fourth and seventh months (Jensen, 2005). Cells ascend the neural tube, migrating to divers locales within the cerebrum, and thenceforth establish connections. It is estimated that, at its zenith, the embryo generates a quarter of a million cerebral cells per minute.

At birth, the cerebrum possesses in excess of a million connections, representing approximately 60% of the peak number of synapses that shall burgeon throughout the lifespan (Jensen, 2005). Given these quantifications, it is scarcely astonishing that prenatal development holds such import. Alterations occurring during this epoch may engender far-reaching and enduring ramifications.

Cerebral evolution transpires rapidly within infants as well. By the age of two years, a child shall possess as many synapses as an adult, and by the age of three years, the child shall possess billions more than an adult. The cerebra of young children are dense, possessing numerous intricate neural connections, exceeding any other juncture in life (Trawick-Smith, 2003).

Verily, young children possess a surfeit of synapses. Approximately 60% of an infant's energy is expended by the cerebrum; in contrast, adult cerebra require but 20–25% (Brunton, 2007). As development ensues, children and adolescents lose far more cerebral synapses than they gain. By the time adolescents attain the age of eighteen, they have forfeited approximately half of their infantile synapses. Cerebral connections that are neither utilised nor necessitated simply evanesce. This 'use it or lose it' stratagem is propitious, as connections that are employed shall be reinforced and consolidated, whereas those left unexercised shall be permanently lost.

By the age of five years, the child's cerebrum has assimilated language and cultivated sensory-motor skills and other proficiencies. The rapid vicissitudes of the initial years have decelerated, yet the cerebrum persists in augmenting synapses. Neural networks are becoming more intricate in their linkages. This process persists throughout development.

As noted by Bryan in the opening vignette, substantive alterations occur during the teenage years, when the cerebrum undergoes structural modifications (Jensen, 2005). The frontal lobes, which oversee abstract reasoning and problem-solving, are maturing, and the parietal lobes are increasing in magnitude. The prefrontal cortex, which governs judgement and impulses, matures at a measured pace (Shute, 2009). Alterations also transpire in neurotransmitters—especially dopamine—that may render the cerebrum more susceptible to the pleasurable effects of narcotics and alcohol. There is a thickening of cerebral cells and massive reorganisations of synapses, rendering this a pivotal epoch for learning. The 'use it or lose it' stratagem results in cerebral regions becoming fortified through practice (e.g., practising the pianoforte thickens neurones in the cerebral region controlling the digits) (Wallis, 2004).

Given these widespread cerebral alterations, it is scarcely surprising that teenagers frequently make injudicious decisions and engage in high-risk behaviours involving narcotics, alcohol, and coitus. Instructional strategies must needs consider these alterations.

Many treatises on child rearing do emphasize that the initial biennium of life constitutes a critical juncture, such that a deficiency in requisite experiences shall occasion permanent detriment to the child's developmental trajectory. Whilst this assertion possesses a modicum of verity, it is nonetheless unduly exaggerated. Five facets of cerebral development, for which critical periods appear to exist, are: language, emotions, sensori-motor development, auditory capacity, and visual acuity. Discourses on language and emotions are presented elsewhere in this chapter; the subsequent three topics shall be presently elucidated.

Sensori-Motor Development

The systems pertaining to vision, audition, and motor functions undergo extensive development via experiential engagement within the first two years of life. The vestibular apparatus, ensconced within the inner ear, exerts influence upon the senses of motion and equilibrium, and concomitantly affects other sensory modalities. Evidence suggests that insufficient vestibular stimulation amongst infants and toddlers may precipitate learning disabilities in later years (Jensen, 2005).

Aspects of brain development having critical periods.

• Sensori-motor
• Auditory
• Visual
• Emotional
• Language

Too frequently, however, infants and toddlers find themselves bereft of stimulating milieus, particularly those children who frequent day care centres wherein mere custodial care is principally dispensed. Furthermore, many children do not receive adequate stimulation beyond these settings, owing to protracted periods spent within car seats, ambulators, or before the televisual apparatus. Affording the young movement, even simple rocking motions, proffers stimulation. Approximately 60% of infants and toddlers devote an average of one to two hours per diem to the perusal of television or video recordings (Courage & Setliff, 2009). Albeit young children may derive some learning from these media, they do not do so with facility. Children's comprehension and assimilation are augmented when their parents partake in these viewings and furnish descriptive elucidations (Courage & Setliff, 2009).

Auditory Development

The child's initial biennium is crucial for auditory development. By the age of six months, infants are capable of discriminating the majority of sounds within their environment (Jensen, 2005). During these formative years, children's auditory systems mature in terms of the range of discernible sounds and the capacity for sound discrimination. Deficiencies in auditory development may engender impediments in language acquisition, given that much of linguistic proficiency hinges upon the auditory perception of speech emanating from others within their surroundings.

Vision

Visual acuity is largely developed during the first year of life, particularly subsequent to the fourth month. Synaptic density within the visual system undergoes a dramatic augmentation, inclusive of the neural connections governing the perception of colour, depth, motion, and hue. The attainment of proper visual development necessitates a visually opulent environment wherein infants may explore objects and movements. Television and cinematic presentations constitute poor substitutes. Albeit they present colour and movement, they are two-dimensional, whilst the developing brain requires depth. The action depicted via television and in the cinema often transpires with excessive rapidity for infants to properly focus upon (Jensen, 2005).

In summation, the initial biennium of life is critical for the propitious development of the sensori-motor, visual, and auditory systems, and the development of these systems is facilitated when infants inhabit a rich environment that allows them to experience movements, sights, and sounds. Concomitantly, cerebral development is a lifelong process; brains require stimulation beyond the age of two years. The brain incessantly adds, deletes, and reorganises synaptic connections, undergoing continual structural alterations. Whilst researchers have evinced that certain facets of cerebral development transpire more rapidly at certain junctures, individuals of all ages derive benefit from stimulating milieus.

As hath been previously observed, certain functions associated with language do operate within the cerebral matter. Albeit researchers have plumbed the depths of cerebral processes with diverse content encompassing various mental faculties, a plethora of inquiry hath been directed toward the acquisition and employment of language. This constitutes a pivotal aspect of cognitive development, possessing profound ramifications for the pursuit of knowledge.

As noted afore, a substantial corpus of cerebral research into language hath been conducted upon individuals who have suffered cerebral trauma and experienced some measure of linguistic impairment. Such investigations are instructive as to which functions are affected by injury to particular cerebral regions, yet these studies do not address the acquisition and employment of language in the developing brains of children.

Cerebral studies of developing children, albeit less commonplace, have furnished significant insights into the development of linguistic functions. Studies oft compare normally developing children with those who experience difficulties in the scholastic sphere. In lieu of the surgical techniques frequently employed upon brain-injured or deceased patients, these studies employ less invasive methodologies, such as those delineated earlier in this chapter. Researchers oft measure event-related potentials (or evoked potentials), which are alterations in cerebral undulations that transpire when individuals anticipate or engage in sundry tasks (Halliday, 1998).

Disparities in event-related potentials reliably differentiate amongst children of below-average, average, and above-average aptitude (Molfese et al., 2006). Children exhibiting normal development evince extensive bilateral and anterior (frontal) cortical activation, along with accentuated left-sided activations in linguistic and speech regions. Contrasting with reading maintenance, it doth appear that reading development also doth hinge upon anterior activation, perchance on both sides of the cerebrum (Vellutino & Denckla, 1996). Further research doth reveal that developing children who experience left-sided dysfunction apparently compensate to some extent by learning to read utilising the right hemisphere. The right hemisphere may be capable of sustaining an adequate level of reading, yet it doth seem critical for this transition to occur prior to the development of linguistic competence. Such assumption of linguistic functions by the right hemisphere may not occur amongst individuals who have sustained left-hemisphere damage as adults. A critical period in language development doth appear to exist between birth and the age of five. During this epoch, children's brains develop the bulk of their linguistic capabilities. A rapid augmentation in vocabulary occurs between the ages of nineteen and thirty-one months (Jensen, 2005). The development of these linguistic capabilities is enhanced when children are situated within language-rich environments where parents and others engage in discourse with the children. This critical period for language development doth overlap the critical period of auditory development between birth and the age of two.

In addition to this critical period, language development also doth seem to be an element of a natural process with a timetable. We have observed how the auditory and visual systems develop capacities to furnish the input for the development of language. A parallel process may occur in language development for the capacity to perceive phonemes, which are the smallest units of speech sounds (e.g., the 'b' and 'p' sounds in 'bet' and 'pet'). Children learn or acquire phonemes when they are exposed to them within their environments; should phonemes be absent from their environments, then children do not acquire them. Thus, there may exist a critical period wherein synaptic connections are properly forged, but only if the environment doth furnish the inputs. In summation, children's brains may be 'ready' ('prewired') to learn various aspects of language at disparate junctures in accordance with their levels of cerebral development (National Research Council, 2000).

Importantly for education, instruction can serve to facilitate language development. Disparate areas of the cerebrum must collaborate to learn language, such as the areas implicated in sight, hearing, speech, and cogitation (Byrnes, 2001; National Research Council, 2000). Acquiring and employing language is a coordinated activity. People listen to speech and peruse text, reflect upon what was uttered or what they perused, and compose sentences to write or speak. This coordinated activity doth imply that language development should benefit from instruction that coordinates these functions, that is, experiences that necessitate vision, hearing, speech, and cogitation.

In summary, disparate areas of the cerebrum participate in language development in normally developing children, albeit left-hemisphere contributions typically are more prominent than those of the right hemisphere. Over time, linguistic functions are heavily subsumed by the left hemisphere. In particular, reading skill doth seem to necessitate left-hemisphere control. Yet further research is requisite before we fully comprehend the relationships between cerebral functions and developing language and reading competencies.

Like other facets of cerebral development, language acquisition reflecteth the interaction between heredity and environment. The cultural experiences of infants and children will determine to a great extent which cerebral synapses they retain. Should the culture emphasise motor functions, then these shall be strengthened; whereas, should the culture emphasise cognitive processes, then these shall ascend. Should young children be exposed to a rich linguistic environment that stresseth oral and written language, then their language acquisition shall develop more rapidly than shall the linguistic capabilities of children in impoverished environments.

The implication for facilitating early cerebral development is to furnish rich experiences for infants and young children, stressing perceptual, motor, and linguistic functions. This is especially critical in the earliest years of life. These experiences should enhance the formation of synaptic connections and networks. There also existeth evidence that babies who have suffered in utero (e.g., from mothers' drug or alcohol abuse), as well as those with developmental disabilities (e.g., retardation, autism), benefit from early intervention in the first three years (Shore, 1997).

Facilitating Language Development

Albeit the period from birth to the age of five representeth a critical juncture for language development, language acquisition and employment are lifelong activities. Instructors may work with students of all ages to aid in the development of their linguistic skills. It is imperative that instruction coordinate the component linguistic functions of sight, hearing, cogitation, and speech.

A kindergarten instructor worketh regularly with her students on learning phonemes. To aid in the development of recognition of phonemes in "__at" words (e.g., mat, hat, pat, cat, sat), she hath each of these words printed upon a large piece of cardboard. The phoneme is printed in red, whilst the "at" appeareth in black. She giveth students practice by holding up a card, requesting them to utter the word, and then requesting individual students to employ the word within a sentence.

Kathy Stone teacheth her students animal names and spellings. She hath a picture of each animal and its printed name upon a display board, alongside two to three intriguing facts about the animal (e.g., where it doth reside, what it doth consume). She hath children pronounce the animal's name several times and spell it aloud, then write a succinct sentence utilising the word. This is especially advantageous for animal names that are difficult to pronounce or spell (e.g., giraffe, hippopotamus).

A middle-grade mathematics instructor is working with her students on place value. Some students are experiencing substantial difficulty and cannot correctly order numbers from smallest to largest (e.g., .007, 7/100, seven-tenths, 7). The instructor hath three large magnetic number lines, each ranging from 0 to 1 and partitioned into units of tenths, hundredths, and thousandths. She requested that students place a magnetic bar upon the appropriate number line (e.g., place the bar upon the 7 of the hundredths line for 7/100). Subsequently, she divided students into small groups and furnished them with problems, and requested that they utilise number lines or pie charts to illustrate where numbers fell so that they might properly order them. Next, she worked with them to convert all numbers to a common denominator (e.g., 7/10 = 70/100) and to place the markers upon the same board (e.g., thousandths) so that they might perceive the correct order.

Students in Jim Marshall's class learn about key historical documents in U.S. history (e.g., Declaration of Independence, Constitution, Bill of Rights). To appeal to multiple senses, Jim brought facsimile copies of these documents to class. Subsequently, he had students engage in role-playing where they read selections from the documents. Students were taught how to place emphasis at appropriate junctures whilst reading to render these passages especially distinctive.

Many students in Gina Brown's educational psychology class experience difficulty comprehending and correctly utilising psychological terms (e.g., assimilation, satiation, zone of proximal development). Where feasible, she obtaineth films that demonstrate these concepts (e.g., a child being administered Piagetian tasks). For others, she utiliseth websites with case studies that students peruse and respond to, after which they discuss in class how that concept doth come into play. For instance, in one case study, a student is repeatedly praised by an instructor. Eventually, the student becometh satiated with praise and informeth the instructor that she need not always tell him that he did so well.