Brain Story Certification: Module 2

Module 2 notes here are all taken from resources provided by Alberta Family Wellness (n.d.) materials for the Brain Story Certification:

Brain architecture

• Early childhood experience shapes the brain throughout life – this is especially the case with toxic stress.  Toxic stress can include serious hardship, abuse, and/or neglect.
• These experiences impact how the brain makes connections.  The early connections shape how later structures develop as we grow.
• Environmental instabilities can lead to lifelong learning difficulties, health problems (immune response and cardiovascular health are examples), addictions,  and mental illness.

Responsive Relationships and Positive Experiences Build Strong Brain Architecture – Taken from “Eight (Failed) Assumptions: What We Thought We Knew About Early Child Development” Boyce, Tom, MD:

• Phrenology is not the way to look at and understand the brain and its development.
• All development is rooted in changes in brain structure and function.  A neuron has 10,000 synapses, and there are 100 billion brain cells in a brain.
• There is cortical specialization, but immense interconnectivity, which is refined by brain development.
• Development is more like the growth of a tree – interrelated areas of maturation supported by the neurological foundation of brain growth.
• Give-and take relationships with others are the active ingredient of environmental influence in development.
• Sensitive and responsive relationships produce stronger cognitive and language skills, enhanced social competence, and better work skills in school.
• Children are vulnerable to the adverse impacts of their parents’ mental health.
• Currently, no scientific evidence that other nurturing relationships interfere with the strength of the parent-child bond.

Brain Development: From conception to adolescence.  Excerpt from “Embryonic & Neural Development: Setting the Stage for the Lifespan” Charles Nelson, PhD:

•  The rear side of the ectoderm forms the neural plate.
• The neural plate forms a grove to create the neural tube.
• The tube then closes up at both the top (rostral) and bottom (caudal) by the 24th day.
• Cells inside the tube form the Central Nervous System (CNS), while those outside the tube form the Autonomic Nervous System (ANS).
• From this, the forebrain, midbrain, and hindbrain form, along with the spinal tube.
• Precursors to neurons and supportive tissues (glia) form.
• Neurogenesis is not complete at birth – continues to happen in the olfactory bulb and the hippocampus.
• The hippocampus is influenced by experience.  Learning in addition to exercise increases the creation of new neurons.  Stress and negative events decrease the creation of new neurons in the hippocampus.
• After neural tube closure, the proliferation of a single layer of epithelial cells lines the tube.
• The cells are connected to each other and in some cases, they are connected to radial glial fibres.
• Expansion takes place between the layers.  The neuron goes onto the fibre, and can then migrate radially or tangentially over time.
• The layers of the cortex form in an inside-out fashion – cells for outer layers pass through the deeper layers.  Cells know what layer they belong to by chemical signals.  All six layers developed by 24th week (post-conception).
• Because cells migrate through earlier layers of cells, there are columns of cells.  These columns often have a functional purpose.
• What is differentiation?
  • Growth of axons and dendrites
  • The formation of synapses
  • synthesis of neurotransmitters
• Some dendrites and axons form as early as the 15th week, with a big increase seen after the 25th week.
• Axons and dendrites continue to develop second postnatal year – thus there is an over-production of axons and dendrites followed by a retraction.  Think of synaptic pruning!
• Not all of the cells differentiate – there is massive death of cells (apoptosis).  40-60% of the cells die.  Over-produce many elements of the brain, and then let certain components die-off (including axons and dendrites).
• There is an initial overproduction of synapses – children have many more synapses than adults.  Synapses occur as early as the 23rd prenatal week (this impacts the viability of the fetus).  Proliferation continues postnatally but depends on the creation/development of axons and dendrites.
•  A retraction to adult levels then takes place.  the retraction rate varies by brain area.
• Vision and hearing (visual and auditory cortices) cortices obtain adult levels of synapses in early childhood (2-6 years).
• The middle frontal gyrus does not reach adult levels until mid-late adolescence.
• Experiences shape what the pruning of connections looks like for the child.  As the pruning takes place a more narrow definition of stimuli/cognitions is worked with by the brain system.
• In essence, synapse overproduction occurs early, and elimination occurs later – there is a varying rate that is related to the brain area/structure.  We can use this information to provide interventions at certain windows of opportunity when the brain regions begin to be pruned and help shape the child’s outcome.
• Myelination: a lipid/protein produced by glial cells.  It wraps itself around axons as a form of insulation – increasing conduction velocity.  It also has implications for serial and parallel processing (multitasking).
• Myelination takes place in “waves” – it begins prenatally and ends in young adulthood.  myelination requires the brain to have axons that can be myelinated.  There is an experience-dependent component to myelination – diet influences myelination.  Myelin can be seen with MRIs and DTIs.
• Myelination by region begins with the sensorimotor cortex, then the parietal and temporal association cortex, and the prefrontal cortex. Myelination continues through to middle-age.
• Full adult-like development of the prefrontal cortex takes place around the age of 25.

Brain Function is Related to Structure.  Excerpt from “Brain Plasticity & Behavioural Development.” Bryan Kolb, PhD:

• The complexity of neurons depends on their experiences.  They can get more or less complicated with time.
• More connections are not necessarily good, as are fewer connections necessarily bad.  They go up and down with experiences – a balancing act.
• The complexity of computations done by a cell is related to the function of the cell.
• IQ estimates based on education correlation – people who complete university have more synapses than those who did not (not causation of education and synapse numbers).
• The occupation had a correlation of synapse numbers in certain areas of the brains used for the area of work.
• Sex differences – language areas of females as opposed to males in childhood.  Male children have a larger structure, but females have more complex neurons.
• Piaget’s stages of development principles are likely wrong, but the correlation between the emerging brain and behavioural development is important.
• Maturing of neurons in specialized brain regions allows for more complex tasks to emerge.
• The age at which we start mastering tasks influences the number of synapses we have. – this is related to the timing of developmental milestones of synaptic pruning for brain regions.

Experiences Tune the Developing Brain. Excerpt from “The Core Story of Brain Development.” Judy Cameron, PhD:

Cameron outlines several concepts:

• Brains and skills are built over time.
  •  It takes time for the brain to be built, and during this time it can be easily influenced.  Both experiences and genes impact the architecture of the maturing brain
  • As the brain architecture develops, its quality can range from a sturdy to weak foundation – this impacts all learning and behaviour that will follow.
  • At birth, the high number of neurons begin to connect (synapses) – each brain’s timeline for synapses is different.  The decreasing number of connections is quality over quantity – what experiences shaped the connection.  The function of the brain can then be looked in context to how society values the capacities embodied by the brain in response to its experiences. This fits well with the “neurons that fire together wire together” concept.
  • It is a matter of which circuits are strengthened and which circuits stay.  This is why interventions that target the relevant regions of the brain that are under plasticity changes are important to consider.  It does not mean that individuals outside of the plasticity window can not benefit from interventions – it just means that it takes much more time and effort.
  • Complex circuits build over the foundation of less complex circuits.
• Simple skills come first, and more complex skills build on top of them.
• Brain circuits are strengthened by use; having children practicing skills they will need over their lifetime strengthens those brain circuits.

Brains are Built from the Bottom Up. Center on the Developing Child at Harvard University.  (2016). From “Best Practices to Breakthrough Impacts: A science-based approach to building a more promising future for young children and families.”

•  The periods of time where the brain becomes sensitive to environmental influences are known as “critical” or “sensitive they begin and end at different times for different regions of the brain periods.”
• It is important that the earliest years of experiences are appropriate to the child’s stage of development.  Self-directed play helps support that goal. This is done by promoting a low-state of anxiety where opportunities for novel experiences and active engagement with adults can take place.

Sensitive Periods of Development.  Excerpt from “Embryonic & Neural Development: Setting the Stage for the Lifespan.” Charles Nelson, PhD:

• Experiences placed on the brain are not constant throughout life.
• Early experiences often exert a particularly strong influence in the shaping of the functional properties of the immature brain.
• Neural connections go through a period of development when there is greater capacity for experience-driven modification than in adulthood.  These are the sensitive and critical periods in development.
• Language skills, emotional responses, and social behaviour – along with basic sensory and motor capacities – are shaped largely and permanently by early experiences.
• 24 months is the critical period for attachment!
• Anxiety and depression influenced by interventions that target critical periods, conduct disorder not impacted by critical periods.  Thus, internalizing disordered can be addressed by this, but not externalizing disorders.
• The use of “sensitive” over “critical periods” as the impacts of experiences it is dependent on the cognitive domain the experiences influence.

 

References

Alberta Family Wellness. (n.d.). Brain story certification.  Retrieved from https://training.albertafamilywellness.org/