Nervous System Changes Flashcards
Experience dependent
Unique, unpredictable experiences dependent on the context
Motor learning as part of motor development
PNS growth rate
1 mm per day
1 in per month
Better chance of recovery with myelin sheath intact
Dead CNS neurons replaced by…
Glia
Vicariation of fx
Another part of brain takes over fx of damaged areas
Brain weight changes
@ birth = 25% of adult brain
Puberty = adult brain weight obtained
Periods for brain growth?
Yes and it is related to stages of cognitive development and language development
Decline in brain weight…
20
Cortex becomes thinner
Majority of loss occurs in WHITE matter (myelin)
Frontal + temporal > Parietal
15% loss throughout lifespan
Frontal lobe
Executive fx
Decision making
Personality
Primary motor cx
Parietal lobe
Somatosensory
Temporal lobe
Memory
Language
Communication
Limbic system
Max neuron and glial cells…
Prenatal period
Dendritic branching
Adult levels at 12-16 years
Hippocampus
30% loss after 30
ST to LT memory integration
Spatial navigation
Brain structures that don’t typically show significant loss of neurons
Basal ganglia
Vital fx areas of brain stem
Neuronal shrinkage v death
Shrinkage more dominant when aging
Glial changes
Increased number of astrocytes and microglia
Decreased number of oligodendrocytes
CNS adaptability
Into 70!
Glucose metabolism
Measure of fxl maturation of brain
Newborn: primary motor and sensory cx, thalamus, brain stem, and midline of cerebellum
2-3 mo: P, T, primary visual cx, basal ganglia, and cerebellum hemispheres
6-8 mo: increase in frontal lobes
8-12 mo: frontal the most
Glucose metabolism lower in…
Infancy
NCV
PNS myelination done at birth
All CN except optic myelinated
Increases quickly after birth
Begins to decline at 30
Decreased by 1 m/sec each decade after 15-24 years
Rxn time
Time btwn stimulus and motor response
Slower in children than adults
Peaks in young adulthood
Slows by 15-30% in older adulthood
3 parts of rxn time
- Sensory transmission of input
“Visual cue”
- Motor execution time
“Foot from gas to break”
- Central processing - majority loss c age, but TRAINABLE
Stimulus ID - that’s a light
Response selection - what are you going to do
Response programming - motor planning
Implicit memory
Procedural
Riding a bike
Explicit memory
Declarative
Recall
Working memory
Process of integrating ST into LT memory
Intellectual ability peak
20-30
Maintained til 75
Dementia
Impairment of some or all aspects of intellectual functioning as compared to previous level of cognition
Reversible - TBI, concussion
Irreversible - disease
Affects at least one... Abstract thinking Judgement and problem solving Language Personality
Criteria for dementia diagnosis
- Unmistakable deterioration in at least 2 cognitive domains
- History of intellectual decline
- Formal mental status testing
Mini-Mental State
30 is normal
Lower = lower cognitive level
Benign Senescent Forgetfulness
Persons with evidence of cognitive impairment who do not meet present clinical criteria for dementia
Mild cognitive impairment
Mild but measurable impairment in thinking skills without presence of dementia
Memory-related: forget they had a convo, forget appts
Non-memory related: more prevalent
- thinking skills
- making sound decisions
- abstract thinking impaired
AD
Prevalent
Onset after 65
Females > males (estrogen, longer life expectancy)
No known cause
AD genetic predisposition
RISK gene apolipoprotein E-e4 (APOE-e4)
Deterministic genes - APP, PS-1, PS-2
*if caused by these, it’s called ADAD or familial Alzheimer’s
AD Risk Factors
Age APOE-e4 Fewer years formal education Head trauma HTN High cholesterol Family history
AD clinical manifestations
Gradual memory loss Decline in ability to perform routine tasks Disorientation time and space Impaired judgment Personality changes Difficulty in learning Loss of language and communication skills General physical decline
AD pathology
Atrophy and dilation of ventricles
Neurotic (beta-amyloid) plaques
Neurofibrillary tangles (tau)
Larger # in T + P with extension into F
Narrow gyri
Wide sulci
Seen especially in F and T lobes
Pick’s disease
Degenerative dementia of unknown origin
Personality changes precede intellectual decline
MRI: + for frontal and temporal lobe atrophy
AD course/prognosis
May be periods of plateau
Initial symptoms = memory loss
Later = physical deficits and will need complete care
Appropriate goals for AD stages
Early stage - balance training, caregiver education
Middle stage - gait training, mm disuse atrophy, flexibility, rxn times
Late stage - PROM, caregiver instruction, assistive device use, bed mobility
AD implications for PT
Physical activity - can alter progression
Motor learning - implicit/procedural learning and memory remain intact later
BLOCKED practice
AD outcome measures
TUG
6MWT
Gait speed
Experience expectant
If exposed to expected environmental stimuli = appropriate development
