Journey of Nerve Cells

Question 1

Nerve Cell Induction Pathway

Answer 1

mesoderm signal molecules –> on/off genes –> some ectoderm = nerve tissue –> more signals –> categories, sub-categories of cell type.

Question 2

Migration

Answer 2

3-4 weeks after conceived, effected by external forces.
radial migration w/ guidance mechanisms.
ectoderm builds flat neural plate, folds up into hollow tube, hindbrain, midbrain, forebrain.

Question 3

Connections

Answer 3

depends on interactions with environment.
dendrites and axons grow, more interconnected.

Question 4

Growth cones

Answer 4

enlargements at axons, seek precise location, guided by netrins, semaphorin, ephrins.

Question 5

Specificity

Answer 5

mechanisms guide axon to proper area, target recognition, part of target.

Question 6

Myelination

Answer 6

saltatory conduction due to nodes of ranvier.

Question 7

Paring back

Answer 7

early postnatal critical periods.
apoptosis unless cell recieves trophic factors and is active.

Question 8

Critical Periods

Answer 8

obtain the experiences needed for healthy maturation.
high learning rates+neuronal connectivity.

Question 9

Neuron connections due to environmental stimuli

Answer 9

turn into maps that reflect the world.
injury or deprivation of input reshapes circuit development.
but heightened activity isn’t good either (eg epilepsy).

Question 10

Plasticity

Answer 10

ability to modify and adapt to challenges.

Question 11

Experience-Expectant

Answer 11

integrate environmental stimuli into development (e.g. Finches hear adult song before sexual maturation to sing at appropriate intricacy).