Brain Development
Role of Brain Maturation
- Brain maturation refers to the process by which the brain develops and refines its structure and function over time.
- This process is sequential and hierarchical, meaning that simpler functions develop first, followed by more complex functions.
- For example, the prefrontal cortex, responsible for decision-making and impulse control, matures last, often continuing into the mid-20s.
The Role of Neurons
- Both neurons and glial cells are involved in the process of maturation.
- Neurons have an axon (where signals are sent), dendrites (where signals are received, and a soma (cell body).
- Neurons generate electrical impulses called action potentials that run along the axon to transmit messages.
- The myelination of neurons, which increases the speed of neural transmission, occurs progressively from the back to the front of the brain.
- This explains why children develop basic motor skills before higher-order cognitive abilities.
- Glial cells are involved in the protection of neurons.
- They maintain homeostasis, generate myelin, aid in signal transmission, and ensure neurons get nutrients.
Processes of Brain Maturation
- Neurogenesis: The process by which new neurons are made. Stem cells split into progenitor cells, which become neurons or glial cells.
- Cell Migration: New brain cells move to where they need to be in the brain.
- Cell Differentiation: Stem cells turn into specialized cells, in this case neurons or glial cells.
- Cell Maturation: Stem cells divide and turn into neurons or glial cells.
- Synaptogenesis: The creation of synapses between neurons.
- Cell Death: Eliminating excess neurons and synapses through apoptosis.
Johnson (2001)
Aim
To look at the current understanding of human development and to provide an overview of the process.
Method
Literature Review
Results
- Brain continues developing after birth.
- Most neurons are present at birth, but synaptogenesis is significant in he first year of life.
- Sight fully develops by the age of 2.
- There are 3 theories that explain brain development.
- Maturational Perspective: As the brain matures, cognition develops.
- Specialization Approach: As cortical areas interact, skills are developed.
- Skill-Learning Hypothesis: Certain areas of the brain are used while skills are developing, others take over once the skill is developed.
Critical Periods
- Critical periods are specific windows of time during which the brain is particularly sensitive to certain environmental stimuli.
- If these stimuli are absent during the critical period, normal development may be compromised.
The critical period for language acquisition is often cited as occurring before puberty. Children deprived of linguistic input during this time may struggle to develop normal language skills later in life.
NoteCritical Thinking
- How may brain development explain adolescent behaviour?
- This ignores social factors of development (e.g. SLT, Vygotsky's theory)
- How fixed are critical periods?
Attachment Theory
- Attachment theory was established by John Bowlby in the 1950s.
- He posited that the critical period to form secure attachments with others was between birth and two to three years.
- Inconsistent care from parents may lead to unstable relationships in adulthood.
Simons et al. (2014)
Aim
To investigate the correlation between childhood and romantic relationships in the future
Method
Recruited participants who were taking part in a different longitudinal study and examined their data.
Results
- Parenting style had some influence on the style of their children’s attachment in their romantic relationships as adults.
- A secure childhood attachment cultivated by supportive parenting was correlated with securely attached adult relationships.
- There was some evidence that poor attachment in childhood were correlated with aggression towards partners as adults.
Critical Thinking
- Studies have shown that later experiences in relationships may affect attachment as well.
- Longitudinal studies give deep insight.
Neuroplasticity
- Neuroplasticity refers to the brain's ability to reorganize itself by forming new neural connections throughout life.
- This adaptability is especially pronounced in childhood but continues into adulthood.
- Research on London taxi drivers showed that the hippocampus, a region involved in spatial navigation, was larger in drivers who had undergone extensive training.
- This finding highlights the brain's ability to adapt to environmental demands.
Source: Maguire et al., 2000
NoteProcesses in Neuroplasticity
- Neural Pruning: Eliminating excess neurons and synapses that are not used.
- Long-Term Potentiation: The connections between neurons strengthening after repeated use.
- Long-Term Depression: The opposite of LTP.
- Dendritic Arborization: The dendrites growing branches to improve the efficiency of a neuron.
- Axonal Sprouting: The axons forming new branches to form connections with other neurons. This typically happens after brain injury.
Sowell et al. (2004)
Aim
To investigate how the brain's structure changes over the lifespan.
Method
A longitudinal study of MRI scans with different age groups.
Results
- Significant changes throughout the lifespan.
- The prefrontal cortex continues develop in early 20s.
- Myelination is a constant process.
Critical Thinking
- High quality MRI yields rich data.
- Studies may have sample bias (e.g. Sowell et al., 2004)
Sociocultural Factors in Development
Cultural Influences
- Culture shapes development by providing the norms, values, and practices that guide behavior.
- These cultural frameworks influence everything from language acquisition to moral reasoning.
