Lecture: Devlopment Flashcards
At what age does the brain begin to shrink?
20
What is the youngest age a baby can survive outside the womb?
25 weeks
True or False?
By the time you are born, your brain is similar to adult state
True
Do men or women tend to have larger brains?
Men
What are the three parts of the brain during development?
Forebrain
Midbrain
Hindbrain
What developmental part of the brain becomes the largest?
Forebrain
What part of the brain grows the most during development?
Forebrain
What is the forebrain made up of?
Two cerebral hemispheres/Cortex
What is another term for the outer cerebral hemisphere?
Cortex
How many cerebral hemispheres are there?
Two
What are the ridges and grooves on the brain called?
Ridges: gyrus
Grooves: Sulcus
Why does the brain have wrinkles?
It decreases the surface area, allowing it to fit into the skull
True or False?
The developmental process creates both hemisphere’s simultaneously
False, makes one at a time
What are the six stages of CNS development?
Neurogenesis
Migration
Differentiation
Synaptogenesis
Neuronal cell death
Synaptic refinement
What layers does the CNS begin with
Ectoderm
Mesoderm
Endoderm
Which initial layer of the CNS develops into the brain?
Ectoderm
True or false?
Doctors can make brain diagnosis by looking at a fetus’ skin (if genetic)
True
What happens after the CNS begins as a plate with three layers?
It rolls into a tube
_____ becomes skin and the _____ _____ becomes central nervous system.
Ectoderm
Neural Plate
What is stage 1 of CNS development
Neurogenesis
Neurogenesis in simple terms
Mitosis produces neurons and glial cells along the ventricular border
What is the central canal filled with during neurogenesis?
CSF
What is a possible failure of neurogenesis?
Failure of mitosis produces microcephaly
Microcephaly
Not enough cells are made during neurogenesis
What is stage 2 of CNS development?
Cell migration
What can go wrong during cell migration in CNS development?
Cells can migrate to the wrong place
What happens if cells migrate to the wrong place during the cell migration stage of development?
They are stuck there
What is the result of cells migrating to the wrong place during CNS development?
Double-band cortex
What forms a double cortex?
50% of cells stop in the wrong place during cell migration stage of development
What common condition is attributed to a double-band cortex?
Dyslexia
Where does the second band of a double-band cortex border?
Ventricular border
What is the third stage of CNS development?
Differentiation
What happens during the differentiation stage of CNS development in simple terms?
Neurons and glial cells are created
In what process are glial cells and neurons made during the differentiation stage of development?
Self renewing stem cells >
Early progenitor cells >
Neurons, oligodendrocytes, and astrocytes
What can go wrong during the differentiation stage of development?
Medulloblastoma
What is a medulloblastoma
Early progenitor cells make too many copies and do not evolve, brain tumor
What is stage four of CNS development?
Synaptogenesis
What happens during the synaptogenesis stage of CNS development in simple terms?
Cells make as many connections as possible, then eliminate bad ones
What is the analogy to remember for synaptogensis?
Make as many friends as possible at first before weeding out the fake and bad ones
What can result from failed synaptogenesis
Autism: doesn’t get rid of enough connections
Schizophrenia: get rid of too many connections
What is stage 5 of CNS development?
Neuronal cell death
What happens during the neuronal cell death stage of CNS development in simple terms?
Brain shrinks, destroying many neurons before birth
__% of neurons are destroyed before birth
50%
What mechanism facilitates the neuronal cell death stage of CNS?
Apoptosis
Apoptosis
Cells explode, destroying themselves
What condition is Fragile X syndrome similar to?
Autism
What can result in failure of the neuronal cell death stage of CNS development?
Fragile X syndrome: too many neurons
Children with Fragile X syndrome have (large/small) heads.
Large
What gender can Fragile X Syndrome occur in?
Boys only
What is the highest genetic cause of retardation in boys?
Fragile X syndrome
What is the 6th stage of CNS development?
Synapse refinement
What does the synaptic refinement stage of CNS development consist of?
Learning and forgetting
Are the changes during the synaptic refinement stage of CNS development large or small?
Small
How is neurogenesis facilitated?
Precursor (stem cells) divide to form ventricular zone
What is the job of stem cells?
Make babies
When does the neurogenesis stage conclude?
Birth
Do any stem cells remain in the brain after birth?
Yes
Why do a few stem cells in the brain remain after birth?
Unknown
During neurogenesis, cells with leave the _____ _____ to become either _____ or _____ cells.
Ventricular zone
Neurons
Glial
What conditions can be caused by failure of the migration stage of CNS development?
Dyslexia
Pachygria
During the differentiation stage of CNS development, _____ are guided by _____ released by _____targets.
Axons
Chemicals
Targets
Chemicals that attract certain growth cones in CNS development
Chemoattractants
Chemicals that repel certain growth cones in CNS development
Chemorepellants
Sensory-motile organelles at tip of growing axons and dendrites
Growth cones
During the differentiation stage of CNS development, ____ have chemical receptors
Growth cones
_____ and _____ are outgrowths of growth cones
Filopodia
Lamellipodia
Both filopodia and lamellipodia adhere to the _____ _____ and pull the cone in a particular _____
Local environment
Direction
How are the specific chemoattractant and chemorepellents of a growth cone determined?
Genetic predispositioning
Each cell has a genetic chemical identity that guides its development
Chemoaffinity
Chemoattractant/repellants act at _____ or _____ range
Close
Long
What type of protein is released by cells in the notochord and directs cells in the spinal cord to differentiate
Sonic hedgehog
What type of cells release the sonic hedgehog protein during CNS development?
cells in the notochord
What determines whether a cell in the spinal cord becomes a motor or sensory neuron
How much sonic hedgehog protein it is exposed to
_____ is the influence of a set of cells on the fate of nearby cells
Induction
The Notochord _____ developing neurons to become motoneurons
Induces
Are sensory or motor neurons more important?
Motor
What happens to the notochord by the time a baby is born?
It disappears
What is the main job of the notochord?
To create motoneurons
What is the distribution between sensory and motor neurons in the spinal cord?
Half and half
True or False?
During the differentiation stage of CNS development, neurons become sensory by default unless intervened by sonic hedgehog
True
What structure is in charge of the differentiation stage of CNS development?
Notochord
How long does synaptogenesis take?
2 weeks
True or False?
During synaptogenesis, an axon will create many synapses, then drastically reduce them
True
What determines which synapses are kept and which are destroyed during synaptogenesis?
Competition
During which stage of CNS development do synapses form rapidly on dendrites and spines?
Synaptogenesis
Dendritic spines _____ after birth
Proliferate (increase rapidly in numbers; multiply)
After birth, synaptic connections are affected by _____.
Experience
After birth, neuron cell bodies _____ in size to support the _____ dendritic tree
Increase
Growing
What cellular mechanism is the result of a lethal influx of calcium into a neuron?
Apoptosis
How to neurons kill others during the neuronal cell death stage of CNS development?
Open calcium channels to induce apoptosis
_____ cut up proteins and DNA
Caspases
What is released when apoptosis is triggered by a calcium influx?
Diablo
What organelle releases the diablo protein
Mitochondria
What is the function of the Diablo protein?
Trigger apoptosis
What is Diablo’s first step when released by mitochondria?
binds to inhibitors of apoptosis proteins (IAPs)
What are IAPs?
Inhibitors of Apoptosis
What is the regular function of IAPs?
Inhibit Capases
What happens when Caspases are no longer inhibited?
the cell enters apoptosis
During apoptosis, the cell _____
dissolves
What are the two things cells compete for during the neuronal cell death stage of CNS development
- chemicals target cells make
- Synaptic connections
What is the neurotropic factor cells compete for during the cell death stage of CNS development?
Chemicals target cells make
Without enough of both competition factors during the cell death stage of CNS development, cells _____
die
Disorder caused by cells not getting enough of both competing factors during cell death stage of CNS development
Mental retardation
During CNS development, there is a steep _____ in the number of neurons before birth
Decline
After the sharp decline stage of the number of cells during CNS development, what happens?
It stabilizes
What is the mechanism that causes apoptosis at the dendrite spine level throughout one’s life?
Forgetting
Prunning
The process of removing dendrite spines
True or False?
During CNS development, cells make many more synapses than needed, then destroy many
True
What conditions result in synaptic pruning failure during CNS development?
Fragile X syndrome
Autism
Fragile X syndrome only occurs in _____
boys
Boys with Fragile X syndrome have _____ heads
Large
The absence of what protein leads to fragile X syndrome?
FMRP
What happens to the pruning mechanism when a fetus doesn’t have the FMRP system
Bad neuronal connections are not pruned when they should be
True or False?
The more synapses, the better
False
Fragile X Syndrome and Synaptogenesis both indicate failure of the _____ stage of CNS development
Synaptogenesis
molecules that help neurons grow, survive, and differentiate
Neurotropic factors
What does NGF stand for?
Nerve growth factor
What does BDNF stand for?
brain-derived neurotropic factor
NGFs and BDNFs keep neurons _____ or help them _____ after _____
alive
regrow
injury
True or False?
NGFs can accidentally cause uncontrolled axonal growth
True
What are the two kinds of neurotropic factors
Nerve growth factors (NGFs)
Brain-derived neurotropic factor (BDNF)
NGFs and BDNFs are _____ _____ by incoming neurons
Taken up
Neurons with more neurotropic factors are more _____ and _____
Accurate
Faster
Cells that don’t get enough neurotropic factors _____
Die
_____ visual deprivation can lead to blindness
Early
Infants with cataracts removed after 6 months have _____ facial recognition later
Poor
the diagnosis rate of autism is _____
Increasing
What is the communication/language feature of autism?
range to nonverbal communication to complex skills
What are the two common language impairments in autistic children?
Delayed language
Echolalia
Echolalia
Repeating last word of everything said to them
What is the fundamental issue with echolalia?
It is not using speech to communicate
What is characteristic of autistic individual’s social interactions
Failure to share enjoyment with other
Poor eye contact
Why do autistic indivduals not make eye contact?
It feels threatening
What is an autistic trait that all individuals have?
Comfort foods
What is characteristic of Autistic individual’s repetitive behaviors, obsessions, and perseveration
Self-injurious behavior
What is characteristic of Autistic children’s odd movements?
Abnormal posture and movements
Repeated gestures and manerisms
What is the term for autistic individuals off movements?
Stimming
What is characteristic of autistic individual’s predictability?
Change in routine is stressful
Autism occurs in children from _____ to _____
Gifted
Retarded
__% of autistic children have IQs below 70
75
Salvant syndrome
Autistic with genius memory
Autism has a _____ cause
Genetic
Autism is caused by _____ genes
Various
What does ASD stand for?
Autism spectrum disorder
Autistic brains are _____ locally
Hyperconnected
Autistic brains have too _____ dendritic spines
Many
Is there a relation between vaccines and autism?
No
Regression is caused by a problem in _____
Synaptogenesis
X-linked progressive autism is also termed _____
Rett syndrome
Rett syndrome is also termed _____
X-linked progressive autism
X-linked progressive autism only happens in _____
girls
Regression in Rett syndrome occurs after __ months
12
What is lost in Rett’s syndrome
Purposeful hand use
Spoken language
What is developed in Rhett’s syndrome
Gait abnormalities
Hand posturing
What do parent typically look towards when their children develop Rett syndrome?
Environmental causes
Why does regression occur after 12 months in children with Rhett syndrome after seemingly normal development?
Unknown
What is the typical cause of death for children with Rett syndrome?
Holding of breath eventually causes heart to fail
What is the life expectancy of a girl with Rett syndrome?
18-22 y/o
What did Esme have?
Rett syndrome
What was Esme’s characteristic symptom?
Periodically held breathe during sleep
