Chapter 9 - Development of the Nervous System Flashcards
Zygote
The cell formed from the amalgamation of a sperm cell and an ovum
Totipotent
Capable of developing into any type of body cell
Pluripotent
Cells that can develop into many, but not all, classes of body cells
Multipotent
Capable of developing into different cells of only one class of cells (e.g., different kinds of blood cells)
Unipotent
Cells that can develop into only one type of cell
Stem cells
Cells that have an almost unlimited capacity for self-renewal and the ability to develop into many different types of cells
Neural plate
A small patch of ectodermal tissue on the dorsal surface of the vertebrate embryo, from which the neural groove, the neural tube, and, ultimately, the mature nervous system develop
Mesoderm layer
The middle of the three cell layers in the developing embryo
Neural tube
The tube that is formed in the vertebrate embryo when the edges of the neural groove fuse and that develops into the central nervous system
Neural proliferation
The rapid increase in the number of neurons that follows the formation of the neural tube
Ventricular zone
The region adjacent to the ventricle in the developing neural tube
Subventricular zone
A region adjacent to the ventricular zone; the ventricular zone is adjacent to the ventricles
Radial glial cells
Glial cells that exist in the neural tube during the period of neural migration and that form a network along which radial migration occurs. Some radial glial cells are stem cells
Migration
The movement of cells from their site of creation in the ventricular zone of the neural tube to their appropriate target location
Radial migration
Movement of cells in the developing neural tube from the ventricular zone in a straight line outward toward the tube’s outer wall
Tangential migration
Movement of cells in the developing neural tube in a direction parallel to the tube’s walls
Somal translocation
One of two major modes of neural migration, in which an extension grows out from the undeveloped neuron and draws the cell body up into it
Radial-glia-mediated migration
A type of migration in which the developing cell uses the long process that extends from each radial-glia cell as a sort of rope along which it pulls itself up and away from the ventricular zone.
Radial-glia-mediated migration allows a cell to migrate in only a radial fashion.
pg.241
Inside-out pattern (come back to this)
Early research on migration in the developing neural tube focused on the cortex. Based on the results of that research, it was asserted that cells migrated in an orderly fashion, progressing from deeper to more superficial layers. Because each wave of cortical cells migrates through the already formed lower layers of the cortex before reaching its destination, this radial pattern of cortical development is referred to as an inside-out pattern.
pg.241
Neural crest
A structure situated just dorsal to the neural tube. It is formed from cells that break off from the neural tube as it is being formed
Aggregation
The alignment of neurons during the development of the nervous system
Cell-adhesion molecules (CAMs)
Molecules on the surface of cells that have the ability to recognize specific molecules on the surface of other cells and adhere to them
Growth cone
Amoebalike structure at the tip of each growing axon or dendrite that guides growth to the appropriate target
Retinal ganglion cells
Retinal neurons whose axons leave the eyeball and form the optic nerve
Optic tectum
The main destination of retinal ganglion cells in nonmammalian vertebrates
Chemoaffinity hypothesis
The hypothesis that growing axons are attracted to the correct targets by different chemicals released by the target sites
Pioneer growth cones
The first growth cones to travel along a particular route in the developing nervous system
Fasciculation
The tendency of developing axons to grow along the paths established by preceding axons
Topographic gradient hypothesis
The hypothesis that axonal growth is guided by the relative position of the cell bodies on intersecting gradients, rather than by point-to-point coding of neural connections
Synaptogenesis
The formation of new synapses
Necrosis
Passive cell death
Apoptosis
Cell death that is actively induced by genetic programs; programmed cell death
Neurotrophins
Chemicals that are supplied to developing neurons by their targets and that promote their survival
Nerve growth factor (NGF)
The first neurotrophin to be discovered
Brain-derived neutrophic factor (BDNF)
One type of neurotrophin
Prenatal period
The period of development before birth
Postnatal period
The period of development after birth
Perseveration
The tendency to continue making a formerly correct response that is currently incorrect
Critical period
A period during development in which a particular experience must occur for it to influence the course of subsequent development
Sensitive period
An interval of time during development when an experience can have a greater effect on development if it occurs during that interval, as opposed to outside that interval
Neurogenesis
The growth of new neurons
Pattern separation
The ability to separate distinct percepts into individual memories for storage
Autism spectrum disorder (ASD)
A complex neurodevelopmental disorder characterized by a reduced capacity for social interaction and communication and restricted and repetitive patterns of behavior, interests, or activities
Savants
Individuals with developmental disabilities who nevertheless display amazing and specific cognitive or artistic abilities; savant abilities are sometimes associated with autism spectrum disorder
Williams syndrome
A neurodevelopmental disorder characterized by intellectual disability, accompanied by preserved language and social skills
Orbitofrontal cortex
The cortex of the inferior frontal lobes, adjacent
to the orbits, which receives olfactory input from the thalamus
Superior temporal gyrus
The large gyrus of the temporal lobe adjacent to the lateral fissure; the location of the auditory cortex
