Development of the Brain and Plasticity

• Factors that influence the teens' brain is drug use, genetics, and trauma.
• The human central nervous system begins to form when the embryo is about 2 weeks old.
• The dorsal surface thickens and then long thin lips rise, curl, and merge, forming a neural tube that surrounds a fluid-filled cavity.
• Cerebrospinal fluid is an ultrafiltrate of plasma contained within the ventricles of the brain and the subarachnoid spaces of the cranium and spine.
• CSF performs vital functions, including providing nourishment, waste removal, and protection to the brain.
• Adult CSF volume is estimated to be 150 ml, with a distribution of 125 ml within the subarachnoid spaces and 25 ml within the ventricle.
• Hydrocephalus is a pathological condition in which CSF abnormally accumulates due to increased CSF production, blockage of flow, or decreased absorption.
• Hydrocephalus may be congenital or acquired. Blocked CSF flow throughout the ventricles is classified as non-communicating, or obstructive, hydrocephalus.
• Meningitis is a condition in which the coverings of the brain become inflamed. Aseptic is from fungi, medications, cancer VIRUSES; Fever, nuchal rigidity, and photophobia.
• Pre-frontal cortex develops rapidly from 7-12 months, allowing object permanence.
• Folding: 2-3 weeks after conception.
• Human neurons proliferate longer. Nearly all neurons form within the first 28 weeks of gestation.
• The average human brain weighs about 350 grams. By the end of the first year, it weighs 1,000g.
• In early infancy, the primary sensory areas of the cortex—responsible for registering vision, hearing, and other senses—are more mature than the rest of the cortex.
• Folding of the cerebral cortex results in the formation of gyri (folds and bumps) and sulci (indenation and grooves).
• Development of neurons: proliferation, migration, differentiation, synaptogenesis, myelination
• Proliferation is the production of new cells. Early in development, the cells lining the ventricles of the brain divide. Some cells remain where they are as stem cells, continuing to divide.
• Migration refers to the newly formed neurons and glia to their eventual locations. It occurs in a variety of directions throughout the brain.
• Chemicals known as immunoglobulins and chemokines guide neuron migration.
• As a cell differentiates into a neuron, it begins to form its dendrites, axon, and synapses.
• Synaptogenesis, the formation of synapses, begins long before birth, but it continues throughout life, as neurons form new synapses and discard old ones.
• A synapse is a small gap at the end of a neuron that allows a signal to pass from one neuron to the next.
• Synapses refer to the points of contact between neurons where information is passed from one neuron to the next.
• Presynaptic neuron contains the terminal buttonhving neurotransmitters within the synaptic vesicles.
• Synaptic cleft is the gap between the pre and post synaptic neurons
• Postsynaptioc neurons is composed of dendrites and contains receptor sites to receive incoming signals from the presynaptic cells
• Myelination continues gradually for decades and increases as a result of learning a new motor skill.
• The myelin sheath protects the axons and helps speed nerve transmissions.