NEUR 2600 Lecture Notes - Lecture 8: Attention Deficit Hyperactivity Disorder, White Matter, Psychopathology
CHAPTER 8: HOW DOES THE NERVOUS SYSTEM DEVELOP AND ADAPT
● Three perspectives on brain development
○ Structural development can be correlated with emerging behaviours
○ Behavioural development can be predicted by the underlying circuitry that must
be emerging
○ Research can focus on factors such as language, injury, or socioeconomic
status, which influence both brain structure and behavioural development
■ Correlating emerging brain structures with emerging behaviours
● Brain development predicts behaviour development
● Eg. frontal lobe predicts ability to plan efficiently
■ Correlating emerging behaviours with neural maturation
● Behavioural development predicts brain development
● Language predicts brain areas involved in language
■ Identifying influences on brain and behaviour
● Correlation between hormones, genes, experience, injury and
behavioural + brain development
● Neurobiology of development
○ Early in development, all vertebrates look alike
○ Embryonic vertebrate nervous system
■ Forebrain, midbrain, and hindbrain are visible in the human embryo at
about 28 days
○ Gross development of the human nervous system
■ By the fifteenth day after fertilization, the emerging embryo is a structure
consisting of several sheets of cells with a raised area in the middle called
the embryonic disc
● Essentially the primitive body
■ Prenatal stages
● Zygote: fertilization to 2 weeks
● Embryo: 2-8 weeks
● Fetus: 9 weeks to birth
■ Neural plate (3 weeks after conception)
● Thickened region of the ectodermal layer that gives rise to the
neural tube
■ Neural tube
● Structure in the early stage of brain development from which the
brain and spinal cord develop
■ Major events
● Day 49: embryo begins to resemble a miniature person
● Day 60: sexual differentiation
○ Genitals and brain regions
● Day 100: brain looks distinctly human
● 7th month: gyri and sulci begin to form
● 9th month: brain looks like an adult brain
○ Origins of neurons and glia
■ Neural stem cell
● A self-renewing multipotent cell that gives rise to neurons and glia
● Lines the neural tube and has an extensive capacity for
self-renewal
● When a stem cell divides, it produces two stem cells; one dies and
the other lives to divide again
● The process repeats again and again throughout life
■ Subventricular zone
● Lining of neural stem cells surrounding the ventricles in adults
■ Progenitor cell
● Precursor cell derived from a stem cell; it migrates and produces a
neuron or glial cell
● Produces nondividing cells known as neuroblasts and glioblasts
■ Neuroblast
● Product of a progenitor cell that gives rise to different types of
neurons
■ Glioblast
● Product of a progenitor cell that gives rise to different types of glial
cells
■ How do stem cells know what to become
● A chemical signal turns on genes (gene expression) which initiates
protein synthesis for specific proteins and finally the specific cells
develop
● Epigenetics
○ Methylation alters gene expression dramatically during
development
● Chemical environment in the brain is different from that of skin, so
different genes are activated, producing different proteins and
different cell types
● Neurotrophic factor
○ A chemical compound that acts to support growth and
differentiation in developing neurons
○ May help keep certain neurons alive in adulthood
● Epidermal growth factor (EGF)
○ Stem cell produces progenitor cell
● Basic fibroblast growth factor (bFGF)
○ Progenitor cell produces neuroblast
○ Neuronal growth and development
■ The human brain requires approximately 10 billion (1010) cells to form the
cortex that blankets a single hemisphere
● This means it must produce about 250,000 neurons per minute at
peak of prenatal brain development
■ The brain also prunes unnecessary cells and connections, sculpting itself
according to the particular person’s experiences and needs
■ Stages of brain development
● Cell birth (neurogenesis; gliogenesis)
○ A chemical compound acts to support growth and
differentiation in developing neurons; begins about 7
weeks after conception
○ Largely complete by 5 months
○ Exception: hippocampus makes new cells throughout life
○ Brains can more easily cope with injury during this time
(first 5 months of gestation)
● Cell migration
○ Begins shortly after first neurons are generated
○ Continues for 6 weeks in cortex and throughout life in
hippocampus
○ Damage has serious consequences
○ Radial glial cell
○ Path-making cell that a migrating neuron follows to its
appropriate destination
● Cell differentiation
Document Summary
Chapter 8: how does the nervous system develop and adapt. Structural development can be correlated with emerging behaviours. Behavioural development can be predicted by the underlying circuitry that must be emerging. Research can focus on factors such as language, injury, or socioeconomic status, which influence both brain structure and behavioural development. Correlating emerging brain structures with emerging behaviours. Eg. frontal lobe predicts ability to plan efficiently. Language predicts brain areas involved in language. Correlation between hormones, genes, experience, injury and behavioural + brain development. Early in development, all vertebrates look alike. Forebrain, midbrain, and hindbrain are visible in the human embryo at about 28 days. Gross development of the human nervous system. By the fifteenth day after fertilization, the emerging embryo is a structure consisting of several sheets of cells with a raised area in the middle called the embryonic disc. Thickened region of the ectodermal layer that gives rise to the neural tube.
