A.1: Neural development

• Essential idea: Modification of neurons starts in the earliest stages of embryogenesis and continues to the final years of life.

• Nature of science: 

Use models as representations of the real world—developmental neuroscience uses a variety of animal models. (1.10)

Understandings:

• The neural tube of embryonic chordates is formed by infolding of ectoderm followed by elongation of the tube.

• Neurons are initially produced by differentiation in the neural tube.

• Immature neurons migrate to a final location.

• An axon grows from each immature neuron in response to chemical stimuli.

• Some axons extend beyond the neural tube to reach other parts of the body.

• A developing neuron forms multiple synapses.

• Synapses that are not used do not persist.

• Neural pruning involves the loss of unused neurons.

• The plasticity of the nervous system allows it to change with experience.

Applications and skills:

• Application: Incomplete closure of the embryonic neural tube can cause spina bifida.

• Application: Events such as strokes may promote reorganization of brain function.

• Skill: Annotation of a diagram of embryonic tissues in Xenopus, used as an animal model, during neurulation.

Guidance:

• Terminology relating to embryonic brain areas or nervous system divisions is not required.