Developmental - Lecture 8 - Brain structure

Question 1

Describe basic brain structures.

Answer 1

Neurons:
Cells that store chemicals called neurotransmitters.
Specialised for sending and receiving neurotransmitters within the brain and between the brain and the body via an electro-chemical process.
The human brain contains approximately 100 billion neurons!

Basic neuronal  structure:
Cell body
Dendrites
Axon
Myelin sheath
Synapses

Grey matter = cell bodies, dendrites, axon terminals
VS White matter = axons (appearing white due to fatty myelin sheath surrounding the axons).

The Cortex
Consists of the outer layer of the brain, composed of grey matter.
Divided into 4 lobes:
- Frontal
- Temporal
- Parietal
- Occipital
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Question 2

Describe neurogenesis and neuron development before and after birth.

Answer 2

Neurogenesis = Birth of new neurons.
Neurodevelopment = Growth of neurons (e.g. development of a dense network of neurons in the brain via connections with each other).

These processes are partly controlled by genes, and partly by environmental experiences:
Nature and Nurture Interaction

Before Birth (inside mother’s womb)
Neurogenesis: birth and proliferation of neurons occurs through cell division.
Neurulation (first 4 weeks): folding process of neurons into the neural tube, differentiating brain and spinal cord.
Migration: Neurons ‘migrate’ to their ultimate location in the brain.

After Birth - Myelination:
formation of myelin (a fatty sheath) around the axons; facilitates neuronal conduction.
Synaptogenesis:
formation of synapses
Synaptic pruning: elimination of redundant synapses
Dendritic arborization: growing and branching of dendrites to form connections with other neurons.
Casey et al. (2005)

Question 3

Explain the different types of plasticity.

Answer 3

The human brain remains plastic throughout life.
Plasticity = the ability of the brain to change its structure and function to learn and refine new skills.

Major stimulants of plasticity:
Exposure to new experiences, rich environments.
1. Experience – Expectant Plasticity
The brain is designed to ‘expect’ basic, common experiences for normal brain wiring to occur throughout infancy and childhood.

2. Experience – Dependent Plasticity
   Neural connections that are created and reorganized throughout life as a result of an individual’s unique experiences.

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Question 4

Discuss brain development from a nature and nurture perspective.

Answer 4

Nature (our genetic endowment):
Influences physical appearance, personality, intellect, mental health, preferences, propensity for sensation seeking, etc.

Nurture (our physical and social environment):
Referring to our prenatal environment (womb), homes, schools and work, broader communities, people we interact with.

Nature – Nurture debate:
The question whether our genetic make-up or our environment has a greater influence on our development.