PSYC 2410 Lecture Notes - Lecture 3: Fasciculation, Prefrontal Cortex, Filopodia
27 Jun 2018
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Phases of neurodevelopment:
Because we stand upright our neuroaxis changes the orientation of the nervous system between
the brain and the spinal cord
The top of our brain is dorsal and the bottom is ventral but when you look at the spinal cord the
back is referred to as dorsal and ventral as the front. The same thing occurs with anterior being on
the left and switching to top and posterior being on the right and switching to the bottom
References of medial (toward the center) and lateral (toward the outside) remain the same
Induction of the neural plate
oZygote -> blastula -> gastrula
oThere are three primary cell types that develop during gastrulation: ectoderm,
mesoderm, and endoderm - these cell lines go on to form the various cell lineages that
create our human form
oAt about three weeks after conception there is a small patch of ectoderm on the dorsal
surface of the embryo that is different from the remaining ectoderm - this patch is the
neural plate and develops into the nervous system
oCells in the neural plate are referred to as embryonic stem cells meaning that they have
the capacity for self-renewal and the ability to develop into different types of cells
oThe earliest cells of the embryo are totipotent but as development proceeds this
situation changes and after about 4 days the stem cells of the embryo become pluripotent,
capable of becoming any cell type that makes up the body
oThe stem cells of the neural plate are multipotent and are destined to become either
glial cells or neurons and since they can still engage in self-renewal they are termed glial
stem cells and neural stem cells
Neural proliferation
oOnce the neural tube is formed, cells of the developing nervous system begin to rapidly
develop
oMost of this proliferation occurs in the ventricular zone, a region that is adjacent to the
ventricles
oOnce the cells leave the cell division cycle they migrate from the ventricular zone to
other layers
Migration and aggregation
oMigrating immature cells lack axons and dendrites
oCell migration occurs by one of two methods: radial migration or tangential migration
allowing cells to move towards a final destination
oThere are two methods by which developing cells will migrate
oGlia-mediated migration: a temporary network of radial glial cells is found in the
developing neural tube
oIn the neocortex the cells migrate in an inside-out pattern, meaning that the deepest
layers of the cortex develop first and later cells must migrate through these layers for
development of the superficial layers
oThe neural crest is formed from cells that have broken off from the neural tube as it
develops - these cells will later migrate and aggregate to form the peripheral nervous
system
oAggregation is the process that occurs when developing neurons have migrated to the
same area and will align themselves to form structures of the nervous system
oCell adhesion molecules (CAM), found on the surface of neurons and other cells, can
recognize molecules on other cells and 'stick' to them
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