Introduction to Neurodevelopment and Brain Plasticity

A set of vocabulary-based flashcards covering the stages of prenatal brain development, cellular processes like migration and differentiation, adult neurogenesis, and mechanisms of neuroplasticity.

Germinal stage

The initial phase of development where the nuclei of the egg and sperm fuse to form a zygote, which begins to divide at $12\,\text{h}$.

Cleavage

The process by which a zygote divides to form a morula, a cluster of homogeneous cells.

Blastocyst

A structure consisting of approximately $200\text{-}300$ cells that forms from the morula during the germinal stage.

Gastrulation

A process in the embryonic stage involving an uneven rate of cell development that forms three layers: the ectoderm, mesoderm, and endoderm.

Neural tube

A structure formed when the ectoderm folds in on itself, which eventually becomes the nervous system.

Spina bifida

A neural tube defect resulting from the failure of the closure of the neural fold at the level of the spinal cord, occurring in $1$ in $1000$ live births.

Anencephaly

A condition where the brain fails to develop, generally resulting in a stillborn birth, which can be prevented by folic acid supplements.

Neurogenesis

The birth of new neurons; at its peak, approximately $250,000$ neurons are born per minute.

Stem cells

Immature cells that divide to form progenitor (precursor) cells, which can then become neuroblasts or glioblasts.

Ventricular zone

Referred to as the 'brain’s nursery,' this area closer to the inner surface of the neural tube is where cells undergo mitosis.

Cell Migration

The movement of newly formed cells toward outer layers; in the cortex, this occurs in an 'inside-out' manner.

Radial glia

Cells that provide physical support and act like wheel spokes for neurons to 'climb' along to reach their destination.

GABAergic interneurons

Inhibitory neurons that represent a large wave of cells still migrating into the human frontal lobe up to $3\text{-}7$ months after birth.

Dendritic arborization

The branching process of dendrites that occurs as neurons differentiate and acquire their distinctive shapes.

Pluripotency

The ability of immature cells to differentiate into any type of cell based on area characteristics, a property lost once the cell matures.

Growth cone

The growing end of an axon, characterized by Santiago Ramon y Cajal as an 'ameboid' structure with exquisite chemical sensitivity.

Filopodia

Thin extensions of growth cones that sense their environment through contact guidance or chemotropism.

Synaptic pruning

The elimination of unsuccessful or inactive synapses based on the 'use it or lose it' principle, which allows for brain plasticity.

Apoptosis

Programmed Cell Death (PCD), an active process requiring the expression of 'death genes' such as caspases.

Neural Darwinism

The concept that neurons and connections compete for survival, leading to the elimination of those that do not form active synapses.

Nerve Growth Factor (NGF)

A survival signal protein discovered by Rita Levi-Montalcini and Stanley Cohen that promotes neuronal growth and prevents apoptosis.

Myelination

The process by which glia form a fatty sheath around axons to speed up neural transmission via saltatory conduction.

Rostral Migratory Stream (RMS)

The path along which newborn cells from the subventricular zone (SVZ) migrate to the olfactory bulb to become interneurons in the adult brain.

Collateral sprouting

A recovery mechanism where non-damaged axons form new branches to attach to vacant spots on dendrites or cell bodies following injury.

Neuroplasticity

The ability of the brain to adapt its structure and function according to environmental stimuli, such as the reorganization of the somatosensory cortex after injury.

Experience expectant

Developmental processes that are species-specific and will not occur unless a specific experience happens during a critical period.

Experience dependent

Neural processes that are not predetermined but generated in response to the environment, varying between individuals based on their unique experiences.

Critical Period

A window of time during which the brain is most sensitive to specific experiences, such as the imprinting observed by Konrad Lorenz.