Chp 10: Neuroplasticity Flashcards
Neuroplasticity
The nervous system’s potential for physical or chemical change that enhances its adaptability to environmental change and its ability to compensate for injury
Past cases mentioned on neuroplasticity
Michelle
- Stroke in utero
- Missing left hemisphere
- Language shift to right hem.
Jody
- Rasmussen’s Encephalitis
- Right hemispherectomy
- Dexterity issues with left hand
Stages of neurodevelopment (7)
Never Make Dog Mom Smell Cat’s Farts
- Neurogenesis
- Migration
- Differentiation
- Maturation
- Synaptogenesis
- Cell death and synaptic pruning
- Formation of myelin
Neurogenesis: Neural Tube (Development of Brain) (4)
- Rolled up sheet of cells that will form the brain and spinal cord
- Begins developing about 3 weeks after conception
Neural groove folds to become neural tube
7 months: Sulci and syri start to form
100 days and 7 months: most obv for external apparence
Neurogenesis: Neural Stem Cells (Development of Brain) (4)
- Grow out of the neural tube
- Capacity for Self-renewal
- Produce progenitor cells that produce neuroblasts and glioblasts
Ventricular zone
- Lined with neural stem cells
Damage susceptibility at developing brain
4 and a half months: finish neuro blast,
- Less susceptible to damage: still generate neurons
After 4 ½:
- More susceptible to damage
Cell Migration (4)
- Continues to about 8 months after birth
- Brain is more sensitive to trauma during migration
Radial Glial Cells
- Extend from the ventricular zone to cortex
- Neurons migrate out by traveling along the cells
Differentiation (2)
- Neuroblasts become specific types of neurons
- Complete at birth
Neural Maturation: Development of the dendrites (3)
- Dendritic arborisation
- Growth of dendritic spines
- Slow process, continues after birth
Neural Maturation: Development of the axons (3)
- Have specific targets to reach
- Grow away from the cell body
- Some follow chemical or electrical signals
Postnatal differentiation of human cerebral cortex around Broca’s area (3)
- Neurons first show simple dendritic fields
- Fields increase in complexity until child reaches approximately 2 years of age
- This parallels the development of language
Synapse Formation and Pruning, 5 phases
Good Rabbit Poops Pleasantly
– 10^14 connections – 100 000 000 000 000
Genes, cues, and signals guide the formation of synapses
Five phases
- 1 and 2: Generated independently of experience (40000 synapses/ sec)
- 3: Rapid growth (Related to experience)
- 4: Plateau and rapid elimination through puberty (100000 synapses per second: being moody)
- 5: Plateau in middle age and steady decline with age
Synapse Formation and Pruning: Experience Expectant
- Development depends on the presence of sensory experiences
- Phases 3 and 4
Synapse Formation and Pruning: Experience Dependent
- Generation of synapses that are unique to the individual
- Phases 3,4, and 5
Glial Development (4)
Begins after neuronal birth and continues through life
Myelination (Myelogenesis)
- Allows for normal adult function
- Begins after birth and continues until 18 years old
- Different areas of the cortex are myelinated at different times
Myelination
Tertiary areas myelinate last
Highest levels of cognitive functioning
Cortical thinning (3)
- Over course of development, thickness of cortex decreases
- Pattern of cortical thinning mirrors the myelination patterns
- Found thinner grey matter functioning was associated and increasing verbal ability and reading comprehension
The Adolescent Brain (5)
- Increased neural plasticity
- Decreased cortical thickness
- Increases in glial cells
- Changes in connectivity/synapse reduction
Sensitive to damage
- Stress, psychoactive drugs, brain trauma, harmful relationships
Experience plays role in sculpting the brain (4) Speaking:
how much the child is being spoken to:
- Promotes cortical thinning
- Serve and return one-on-one
Parentese: speaking in high voice
- Can help speaking ability
Lack of experience: Case of Genie
Kept in room and no speaking
Kept in crib, inability to walk
Aft 6 months, passed critical period
More than 18 months, has a generally lower IQ, (15 less)
Adverse Childhood Experiences (3)
- Abuse
- Neglect
- Household challenges
Deprive animal of visual stimulation in one eye
Ocular dominance:
Input come in left and right eye,
Sew left eye shut, prune the unused and extend the one terminal being used
Terminal arborization (3)
arborization describes the tree-like branching out of dendrites.
- This branching out allows dendrites to make new synaptic connections.
- extensive arborization can be considered a sign of complexity due to the increased number of synaptic connections it allows for
Do domestic animals and wild animals have a different brain growth?
Yes
- Cortical areas are smaller in domestic animals
- Biggest reduction in size in the visual cortex (35%)
- General size reduction is 10-20%
Environmental complexity and the brain (4)
Increases in:
- Glial density
- Dendritic length
- Dendritic Spines (more potentials for connections)
- Synapse size
Environmental enrichment: key ingredients (rats) (3+3)
1) Opportunities of physical activities
2) Social interactions
3) Changing environment (novelty)
Showed:
- Better at learning memory tasks
- Showed better skilled motor movements
Not all rats respond to complex environments the same
Response of dendrite and spine (2) to environment encrichment
Dendritic length:
- Increase regardless of age
Spine density:
- Decrease in spine density when young
- Not all animal respond the same
Prenatal effect of mother’s enrichment
Pregnant dams receiving tactile stimulation or environmental enrichment produced big brained babies
Tactile Stimulation = Same Effect as env enrichment
Plasticity in representational zones: Individuals who played stringed instrument
- Left hand used more
- Fingers used a lot more, the amount of brain space devoted will increase
- Expansion in representation in somatosensory cortex
- Start very young, expansion is larger than starting later in life
Brain Injury and Plasticity (5) (age and recovery)
- Mid 1800’s observation of language development in children with left frontal lesions, but still developed normal adult language
IDEA: brain injury milder and effects more short lived when sustained in childhood
- Kennard principles (children has better recovery)
- Hebb – studied poor outcomes following childhood prefrontal damage
(Not always true, depend on where the brain in damaged
Prefrontal damage is worse,
But Kennard principle is generally true )
Which year of life is most sensitive to damage?
1st
Potential Treatment (4)
A potentially very potent treatment
- tactile stimulation
Soft brush strokes promoting recovery
- Synaptogenesis
- Increases BFGF: Basic-fibroblast growth factor
- Increases acetylcholine
Neurotrophic Factor (4)
- Also known as growth factor
- Chemical compound that supports growth and differentiation in developing neurons
- May be important for supporting survival of neurons in adulthood
- bFGF is one example of a neurotrophic factor
BDNF: brain derived neurotrophic factor
Another neuotrophic factor
More important than bFGF
What physical changes underlie growth? (6)
- Neurogenesis (new neurons)
- Axon terminal arborization
- Dendrites spines grow (arborization)
- Expansion of cell body (soma)
- Increased synaptic connections
- Long Term Potentiation: neurons that fire together, wire together
Once neural tissue has been destroyed and lost…
through neuron death, that brain tissue won’t be regenerated, it is lost forever, like an amputation
Neurogenesis persists in the adult brain (on slides)
Subventricular zone : new neurons are born here too
