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Welcome to 2 minute neuroscience, where I simplistically explain neuroscience topics
in 2 minutes or less.
In this installment I will discuss early neural development.
The development of the nervous system begins at around the third week of embryonic development,
when an area of the ectoderm, or the outer tissue layer of the embryo, thickens and forms
what is known as the neural plate.
This plate begins to fold inward, forming a groove called the neural groove.
The sides of the neural groove, known as the neural folds, begin to come together.
At the end of the third week, the folds will begin to fuse together.
By the end of the fourth week, they have completely fused together to form the neural tube, which
will eventually become the brain and spinal cord.
As the neural tube closes, bulges and bends begin to appear and they gradually become
more noticeable.
During the fourth week, there are three of these bulges present.
They are called the primary vesicles.
They are the prosencephalon, which will eventually form the cerebrum.
The mesencephalon, which will eventually become the midbrain.
And the rhombencephalon, which will eventually become the rest of the brainstem and the cerebellum.
This end of the neural tube will form the spinal cord.
As the brain continues to develop, two of these vesicles further subdivide to form secondary
vesicles.
The prosencephalon forms the telencephalon and diencephalon.
The telencephalon will become the cerebral hemispheres, the diencephalon will eventually
consist of thalamus, hypothalamus, and other structures.
The mesencephalon does not subdivide any further and will become the midbrain.
The rhombencephalon will subdivide into the metencephalon and myelencephalon.
The metencephalon will become the pons and the cerebellum, and the myelencephalon will
become the medulla.
And the end of the neural tube will remain the spinal cord.
Next, the neural tube will continue to develop to look more like the brain.
The telencephalon will grow more rapidly than other parts of the tube and by 11 weeks, the
brain will have a similar shape as to what it will at birth.
Although it will continue to develop after birth, the brain at birth is structurally
similar to a fully developed brain.