Phases of Neuro development Flashcards
what is neural proliferation?
the neural plate folds to form the neural groove and becomes the neural tube
3 layers of embryonic cells
Ectoderm (outer), Mesoderm (middle), Endoderm (inner)
what happens after Neural Tube Cells Proliferation (multiply)
3 swellings at the anterior end will become the forebrain, midbrain, and hindbrain
(Cell Migration directions) 2 types
Radial Migration & Tangential Migration
Radial Migration
Moving out
Tangential Migration
Moving up
(cell migration) 2 methods
Somal & Glial
Somal Migration
extension that develops and leads migration; cell body follows
Glial Migration
(mediated migration) the cell moves along a radial glial network (most cells engage in both types of migration)
Aggregation
happens after migration; when cells form a cluster and create structures
Cell Adhesion molecules (Cam’s)
aid both migration and aggregation (recognize and adhere to cells)
What do gap junctions do?
- prevalent in brain development
- play a role in migration and aggregation
What happens after migration and the structures have formed?
Axons and dendrites begin to grow
How do axons and dendrites know where to connect?
Growth Cone
Growth Cone
(happens @ the growing tip of each extension) extends and retracts filopodia to guide its way through things
Chemoaffinity Hypothesis
postsynaptic targets release a chemical that guides axonal growth (doesn’t explain everything)
Sperrys Classic Study
(Frog Study)
What happens once an axon reaches its target?
-Synaptogenesis
-Astrocytes are critically important
% of neuron death
Up to 50% of neurons that are created die during the course of normal
development.
Why do neurons die?
- most are due to apoptosis some developing neurons
- are genetically programmed
for early death—once their functions are fulfilled, groups of
neurons die together in the absence of any obvious physical stimulus; - some die because they fail to obtain life-preserving chemicals supplied by their targets.
Synapse rearrangement
- membranes are filled by sprouting axon terminals of surrounding neurons.
- Cell death results in synapse rearrangement; its effect is to focus the output of each neuron on fewer postsynaptic neurons.
Neurotrophins
promote growth and survival, guide axons, and stimulate synaptogenesis
Necrosis
Apoptosis
necrosis: passive cell death
apoptosis: active cell death
Postnatal growth is a consequence of
- synaptogenesis ( the formation of synapses, the points of contact where information is transmitted between neurons.)
- myelination
-increased dendritic branches
What part of the brain is last to develop?
prefrontal cortex
Development of prefrontal cortex
The development of the prefrontal cortex parallels the course of human cognitive development.
linked to four types of cognitive function: working memory, planning and completing sequences of actions; inhibiting inappropriate responses; and following rules for social behavior.
Neurodevelopment
a result of interaction between neurons and their environment
One effect of experience on brain development is…
Experience in adulthood can lead to a reorganization of sensory and motor
cortical maps
Neurogensis
growth of new neurons
Where does neurogenesis occur?
hippocampus and olfactory bulbs
What promotes neurogenesis
exercise and enriched environments
Tinnitus
ringing in the ears// produced a major reorganization of primary auditory cortex
