Neurophys Exam #2

Genes provide what?

instructions for brain development (aka blueprints)

What influences expression of gene instructions?

experience

brain development results from what?

continuous interaction between biology and the environment

what mechanism helps regulate how genes are expressed in response to experience?

epigenetic mechanisms

what do epigenetic mechanisms do?

helps regulate how genes are expressed in response to experience?

SLPs rely on what?

brain plasticity bc it allows therapy to be effective

brain organization changes…

across the lifespan

how does experience shape developing brain networks?

by strengthening and weakening neural connections

when is neuroplasticitiy the greatest?

in infancy & early childhood

does neuroplasticity continue throughout life? How do we know?

yes

supports recover after injury & enables responsiveness to interventions such as therapy

why does neuroplasticity enable responsiveness to interventions such as therapy?

practice strengthens neural networks… this is why repetition is so important

what brain development process begins at 3-7 weeks gestational age?

dorsal induction

what is an example of a possible disorder if the dorsal induction developmental process is disrupted?

spina bifida

what brain development process begins at 2-3 months gestational age?

ventral induction

what is an example of a possible disorder if the ventral induction developmental process is disrupted?

holoprosencephaly

what brain development process begins at 3-4 months gestational age?

proliferation

what is an example of a possible disorder if the proliferation developmental process is disrupted?

microcephaly

what brain development process begins at 3-5 months gestational age?

migration

what is an example of a possible disorder if the migration developmental process is disrupted?

lissencephaly, AgCC

what brain development process begins at 5+ months gestational age?

synaptogenesis

what is an example of a possible disorder if the synaptogenesis developmental process is disrupted?

rett syndrome

what brain development process begins at childhood

pruning

what is an example of a possible disorder if the pruning developmental process is disrupted?

connectivity disorders

what brain development process begins at birth-early adulthood

myelination

what is an example of a possible disorder if the myelination developmental process is disrupted?

hypomyelination

brain development begins immediately after…

fertilization

brain development is built by…

spontaneous activity and sensory experience (language, audio, etc.)

______ & ______ help brain

nature and nurture

good metaphor to consider….

brain development is like a LARGE construction project with strict schedule/order of events

________ matters for brain development

prematurity

brain development continues rapidly during the….

third trimester

what is considered premature birth

less than 37 weeks

premature birth interrupts what?

normal developmental timing

interruption in developmental timing leads to increased risk for…

language delays, executive function function difficulties, motor impairments, and feeding/swallowing challenges

what occurs during the stages of cortical development

brain gets more specialized, NOT bigger

what are the four stages of cortical development

1. neurogenesis

2. migration

3. differentiation

4. synapsis genesis

what is the difference between pruning & myelination

1. pruning means gets rid off

2. myelination means more speed and correction

what happens during 1st trimester?

1. neurons develop

2. neurons multiply

3. neurons migrate (happens at the end of 1st trimester)

what happens during the 2nd trimester

1. neurons multiply

2. neurons migrate

3. neurons branch, form synapses

what happens during 3rd trimester

1. neurons branch, form synapses

2. pruning (apoptosis)

3. synapses reorganize

4. myelination

when does dorsal induction occur?

GA: 3-7 weeks

what is dorsal induction

period when neural tube forms

what does the neural tube create?

the foundation of the CNS

what happens during week 3

neural plate forms from ectoderm

what is the ectoderm

outer layer that forms skis and nervous system

what happens during week 4?

neural plate folds to form the neural tube

what is the process of the neural plates folding to form the neural tube called

neurulation

what happens during weeks 4-6

neural tubes closes at both ends

what does the neural tube eventually become?

the spinal cord

disruptions during the process of dorsal induction can result in…

neural tube deficits

failure for the neural tube to close results in…

neural tube deficits which has several implications for later in life

substantial changes occur in neural tube development between…

4-5 weeks of gestation

neuro issues can be traced back to…

point in neural tube development

when do neural tube defects occur?

developing nervous system fails to fully close during early gestation

clinical outcomes for neural tube defects vary based on…

location and severity

early disruptions in development have…

critical implications

primary brain/spinal impact of the condition anancephaly

absence of cerebral hemispheres

what are the likely functional outcomes of anancephaly

incompatible with long-term survival

primary brain/spinal impact of encephalocele

brain tissue protrudes through skull

what are the likely functional outcomes of encephalocele

variable cognitive, motor, and communication disorders

what is the primary brain/spinal impact of spina bifida

incomplete closure of spinal structures

what are the likely functional outcomes of spina bifida

motor impairments, learning difficulties, possible language & executive function weaknesses

when evaluating a child with a congenital neurologic condition, consider these 5 things

1. which developmental processes are disrupted

2. which brain structures are affected

3. which communication functions rely on those structures

4. what additional developmental concerns are likely

5. how might intervention plans need to change

what is the second major stage of neural development?

ventral induction

when does ventral induction occur?

GA: 2-3 months

what is ventral induction

neurodevelopmental period when face and brain develop out of superior end of the neural tube

how does the face and brain develop from the neural tube?

neural tube bends ventrally; superior end forms major components of brain

what is the neural tube brain organization?

1. forebrain

2. midbrain

3. hindbrain

why should SLPs care about ventral induction

during ventral induction, major brain regions begin to form and when this process is disrupted, children may be born with structural differences

what do structural brain differences from ventral induction disruption look like?

issues in:

-language development

-cognitive development

-social communication

-feeding & swallowing

-motor skills

-long-term learning

what is holoprosencephaly?

failure of developing brain to divide into left and right hemispheres

severity of holoprosencephaly ranges from…

profound brain malformations to relatively mild structural differences

holoprosencephaly may be associated with…

cognitive, motor, feeding, and communication impairments

outcomes of holoprosencephaly depend on…

extent of brain involvement

when does neural proliferation/neurogenesis occur?

GA: 3-4 months

what is neurogenesis/neural proliferation

birth of new neurons

neurogenesis/neural proliferation involves rapid cell division that will form…

the brain and spinal cord

overproduction of neurons provides the foundation for

later brain organization and connectivity

microcephaly results from

disruptions in neural proliferation and early brain growth that effects multiple domains

microcephaly is characterized by…

abnormally small head and brain

what is microcephaly associated with?

variable cognitive, motor, and communication impairments

what are possible causes of microcephaly

genetic conditions, prenatal infections (e.g., Zika), and prenatal exposures

when does neuronal migration occur?

GA: 3-5 months

what occurs during neuronal migration

brings cells into their appropriate spatial location and forms spatial relationships between cels that later form brain structures

in the mature brain, neurons are organized into

layers as well as columns

disruptions in migration can result in _______-_______-_______ and later communication, cognitive, and motor impairments

structural brain abnormalities

how do neurons reach their locations

neurons don’t move sporadically, they move with purpose

neurons migrate along _____-_____ from deep layers outward

radial glia

**acts as construction elevators

migrations errors create…

structural brain abnormalities

neuronal migration deficitis:

disorder: Agnesis of Corpus Callosum (AgCC)

-what are the brain structures affected

absent corpus callosum

neuronal migration deficitis:

disorder: Agnesis of Corpus Callosum (AgCC)

-what is the language profile

pragmatic weakness

neuronal migration deficitis:

disorder: Agnesis of Corpus Callosum (AgCC)

-Social communication profile

difficulty communicating emotions

neuronal migration deficitis:

disorder: Autism Spectrum Disorder (ASD)

-what are the brain structures affected

connectivity differences

neuronal migration deficitis:

disorder: autisum spectrum disorder (ASD)

-what is the language profile

variable

neuronal migration deficitis:

disorder: autism spectrum disorder (ASD)

-what is the social communication profile

core social communication deficits

neuronal migration deficitis:

disorder: rett syndrome

-what are the brain structures affected

synaptogenesis disruption

neuronal migration deficitis:

disorder: rett syndrome

-what is the language profile

regression

neuronal migration deficitis:

disorder: rett syndrome

-what is the social communication profile

loss of previously acquired skills

what is differnetiation?

specialization after migration, gives neurons correct jobs

when does differentiation occur?

2-5 months and beyond