unit 1: textbook

early brain development: (2)

• much of what parents naturally do when they interact with babies is highly supportive of healthy brain development

• our earliest experiences in infancy and childhood influence our brain development and reach long into adulthood and senescence; our brains remain open to environmental influence as long as we live

baby-parent interactions may include: video (4)

• gazing at a parent

• copying a parent’s actions ; tap the floor

• mimicking a parent’s face

• emotional tone is supportive/loving/caring

parents showed they noticed babies’ subtle social signs: video (3)

• by responding with hi, what are you doing, etc

• by touching them

• by repeating the babies’ noises/little gestures

brain history: (4)

• ~5 mya hominid ancestors begin to walk upright (bipedalism) & brains grew larger and larger (encephalization)

• to accommodate the bipedal development human babies are born prematurely

• our babies are fetuses out of the womb for the first 9 months out

• this means our babies brains are highly adaptable because of the necessary prematurity

at full term, human babies are born with a brain…

¼ the size of an adult brain

highly adaptable brain because of prematurity means: (2)

• heavy reliance on caregiver and caregiver interactions/experiences to develop healthy brain

• seeing caregivers’ gestures and facial expressions paves the way for the baby’s brain architecture; sets the foundation for their understanding of their own experiences

Indigenous child rearing practices: (3)

• Indigenous peoples have always known that children learn through their senses

• singing to the baby in womb; hearing the drum —> supports children’s development

• swaddles/cosleeping —> support attachment which is critical for development

teratogens:

environmental substances such as tobacco, alcohol, drugs, toxins, or infections that can cause a birth defect or damage during the prenatal period - similarly if a mother is malnourished or exposed to chronic stress during pregnancy her baby’s developing brain may be harmed

brain wiring: (2)

human brains are not fully developed at birth; as babies begin to learn about the world around them, neurons connect forming neural pathways in their brains which is referred to as brain wiring

• this process starts towards the end of pregnancy but the majority of connections happen after birth

senses:

during the first few months/years, as babies use all their senses to experience the environment around them, they learn about their world at an amazing pace - rapidly forming a huge number of neural pathways/connections in their brains

sculpting:

as babies get older, their brains begin to eliminate rarely used pathways & reinforcing those that are used often, this process of refining/pruning connections is often called brain sculpting

what is the essence of the term ‘experience-based brain development’:

sculpting! (refining/pruning of connections)

experience-based brain development:

experiences/environments affect how neurons connect, ultimately affecting learning, health and behaviour

brain wiring/sculpting continues throughout…

childhood/adolescence but is particularly active in the first few years of life

neuron:

a brain cell; the basic building block of the brain

sensitive period:

a time that is optimal for behaviour to emerge and the brain is particularly primed to respond to environmental stimulation

critical period:

discrete period of time in development when a specific growth must occur for normal development to take place - critical periods are a special class of sensitive periods that result in irreversible changes in brain function

epigenetics:

field about how experience and genetics intertwine - at a molecular level, how genetic inheritance (nature) interacts with our environment (nurture) to turn on or to turn off genetic expression

• in short how environments and experiences together affect the expression of a person’s genes

pruning:

natural brain process occurring between early childhood and adulthood - synaptic pruning occurs when the brain abolishes extra synapses

synapses: (2)

• are brain structures that permit neurons to transmit an electrical/chemical signal to each other and is the site of communication between neurons

• the connections between neurons

cells:

the central working units of every human being

chromosome:

a structure found in the nucleus of cells that carries genetic information in the form of genes; human cells normally contain 23 pairs of chromosomes (totalling 46)

autosomes:

of the 23 pairs of human chromosomes, 22 are similar for both females and males, these are autosomes

sex chromosomes:

final 23rd pair of human chromosomes which differ between the sexes; XX for females and XY for males

DNA:

deoxyribonucleic acid is a molecule containing instructions that guide cellular processes that allow an organism to develop, live, and reproduce - DNA is made up of two strands joined together via complimentary base pairs, together the strands coil around one another to form a double helix

genetic mutation:

the permanent modification of the sequence of the genome of an organism

genotype:

the genetic makeup of an individual

phenotype:

an individual’s observable characteristics, results from the combination of their genes (genotype) and environments/experiences

polymorphism: (2)

existence of two or more distinctly different genotype forms in a population of a specific species - in genetic terms it illustrates variations that differentiate species individuals from each other; these are maintained by natural selection

• these are inter (between) individual, often silent variances in the sequences of DNA that make members of a species unique

nucleotide bases:

in the human, DNA is comprised of approximately 3 billion nucleotide bases: adenine (A), cytosine (C), guanine (G), thymine (T); the DNA sequence or order of the bases determines the instructions of life

genes: (2)

sequences of bases within the 3 billion DNA bases - there are roughly 20,000 genes and they give the instructions on the production of proteins, complex molecules eliciting a variety of biological actions necessary to life - genes are transferred from parent to offspring

• the basic unit of heredity, made up of DNA, each chromosome contains many of these

allele:

one of two or more alternate forms of a gene; different alleles might result in different observable traits

genome:

an organism’s complete set of DNA - entire human genome contains +3 billion DNA base pairs

epigenetics:

changes in the expression of genes (active/inactive) which do not comprise alterations to underlying DNA sequences, therefore epigenetics involves changes in phenotype without changes in genotypes - epigenetic changes affect how our cells read our genes

epigenome:

the set of chemical modifications to the DNA, which change the way cells use the DNAs instructions - epigenome changes in response to environmental exposures or disease

synaptic cleft:

the gap that separates the two axon terminal membranes, once a signal reaches the axon terminal, the neuron’s neurotransmitter is released into the synaptic cleft and reacts with the receptors on the post-synaptic membrane/dendrite

synaptic vesicle:

a small spherical structure that contains molecules of neurotransmitters

neurotransmitters:

chemical messengers, once a signal reaches the axon terminal, the neurons neurotransmitter is released into the synaptic cleft

receptors:

proteins that capture and react to molecules of a neurotransmitter or hormone on the post-synaptic membrane/dendrite

cerebral cortex (cerebrum): (3)

• largest part of the human brain and dominates the brain’s exterior surface, it is highly specialized and significantly larger than the cortex found in other mammals

• made up of two hemispheres (L-R), each of which is divided into 5 lobes: frontal, temporal, parietal, occipital, insular

• it contains the centres that initiate movement, receive and interpret sensory information, hold memories, process thoughts and experience emotions

limbic system: (3)

• network of structures located under the cerebral cortex (cerebrum) that includes tiny structures including the amygdala, hippocampus, thalamus, pituitary gland, basal ganglia, cingulate gyrus, and hypothalamus

• it is involved in emotion, motivation, memory, and influences motivation, mood, and sensations of pain and pleasure

• the structures in this system directly connect with regions in the cerebral cortex (cerebrum), cerebellum and the brain stem

brain stem: (2)

• at the base of the brain, at the top of the spinal cord

• controls reflexes and automatic functions like heart rate and blood pressure; visceral functions such as digestion and urination; and the movement of limbs

cerebellum:

integrates information from the vestibular system (sensory system providing info about movements and sense of balance) to identify position and movement and uses that information to coordinate limb movement

parietal lobe function:

sensory integration, knowledge of numbers, object classification and visuospatial processing

brain stem function:

regulation of body temperature, heart rate, swallowing, and breathing

insular lobe function:

integrating bodily states, interpreting sensation (pain, hunger), expression of emotions, and sensorimotor processing

occipital lobe function:

vision, visual processing, and colour identification

temporal lobe function:

hearing, memory, language, comprehension, and facial recognition

cerebellum function:

gross and fine motor skills, eye-hand coordination, and balance

frontal lobe function:

thinking, planning, behavioural control, decision making, and inhibition

experience-expectant brain development w/ex:

early in life, when synapses are being overproduced and the pruned, the brain is expecting certain specific experiences that are required for brain functions to develop optimally

• ex: brain’s auditory cortex expects to be able to hear sounds and then responds to those sounds and develops accordingly

experience-dependent brain development w/ex:

throughout life, an individual’s positive and negative circumstances/experiences affect brain development and functioning - how the brain develops depends on one’s experiences

• ex: typically, as a child hears a particular language early in life that child will come to understand and speak that language

it is not nature vs. nurture but epigenetic interactions:

early development situations/circumstances drastically alter genetic markers

symphonic causation:

nature and nurture working together to create health/wellbeing or disease - describes interactions between aspects of person that are biologically given/heritable and the kinds of experiences the individual has to produce health/development/wellbeing outcomes

disease:

a disharmonious combination of individual susceptibility (heritable factors) and external threat (environmental factors)

brain plasticity:

refers to the idea that the brain is changeable/moldable at various different levels - brain becomes less plastic over time to maintain basic foundations (ex: mother’s name; how to breathe; etc)