Lecture 3 Flashcards
(39 cards)
Monkey Stroke Study
Nudo
compared changes in cortical
motor representations among three groups
of monkeys: control, spontaneous recovery, rehab
In the spontaneous recovery group -infarct no training-
hand and digit cortical areas surrounding the lesion decreased when compared to the control animals
In the rehabilitation group-
infarct - training - hand and digit cortical areas did not
differ from the controls
training helped prevent cell death
Nudo has suggested that the rehabilitative
training prevented the loss of cortical areas
His work provides evidence in an animal model that the motor cortex is alterable not only in normal animals but in those with brain pathology
Nudo Stroke Study Results
Nudo has suggested that the rehabilitative
training prevented the loss of cortical areas
His work provides evidence in an animal model that the motor cortex is alterable not only in normal animals but in those with brain pathology
Brain Post Injury
Rewired System
There are more widespread changes that occur post injury. He has shown that there are modifications in the intracortical pathways between the primary motor areas, the premotor areas and the primary sensory areas.
He is saying that plasticity post injury is not just a local phenomenon but also involves connections to other areas, suggesting that we need to think of the
post-injury brain – not just as a brain with a lesion but as a rewired system
Drug for Neuroplasticity Study
Jeff Kleim
Use of drugs that promote plasticity.
Administration of the experimental drug Rolipram helped to improve the reaching performance in the rats post infarct
An increase in the cortical area around the infarct.
Did not work unless accompanied by motor skill training
Estim to promote neuroplasticity
What happens if you pass electrical current directly on to the rat’s brain while they are being rehabilitated.
Animals receiving electrical stimulation to the brain improve faster and reached a higher end point in terms of percent of successful reaches
Brain areas around the infarct were preserved with changes in the cortical maps.
PET Scan Studies
Frackowiak & Chollert
To look at changes in regional blood flow.
Changes in regional blood flow reflect increased neuronal metabolism, and
Neuronal metabolism and functional activity are highly correlated
In recoverd fingers- contralateral side of brain is more active than ipsilateral side of brain but there is much more activity on ipsilateral side in recovered fingers than in a normal finger
Some recovery due to ipsilateral cortex working more
ipsilateral cortex after stroke shows more activity, helping drive recovery
Have also seen as recovery of function occurs, amt of activity in ipsilateral cortex decreases- it seems to be a mechanism that decreases once there is a better recovery
Braile Study
Pasqual Leone
Used TMS to look at cortical reorganization of 1st dorsal interossei and abductor digiti minimi
Saw that the representation of index finger was much larger in hadn they use to read braile than in the other hand
Abductor was same in both- bc abductor is passive
More proof of use it and improve or lose it
Principles of Experience –Dependent Neural Plasticity
- Use it or lose it
- Use it and improve it
- Specificity
- Repetition Matters
- Intensity Matters
- Time Matters
- Salience
- Age Matters
- Transference
- Interference
Use it or lose it
suggests that neural circuits not actively engaged in task performance for an extended period of time tend to degrade.
Use it and improve it
suggests that training can protect neurons and networks that might be otherwise lost after injury
Use of a body part enhances its function - representation areas can either increase or decrease depending upon use.
Specificty
indicates mere repetition of a movement that is already learned does not lead to changes in the motor cortex – the practice has to be associated with the acquisition or reacquisition of a novel or lost skill.
Repetition Matters
– continued repetition of the newly learned task is required to drive the plasticity. Lasting - long term potentiation of synaptic responses require numerous practice sessions
Intensity Matters
implies that the training must be progressive - must be continually modified so that the activity is dynamic and requires increased skill levels.
Time Matters
– during motor skill training – gene expression precedes synapse formation which in turn precedes motor map reorganization. (Kleim et.al 1996).
Salience Matters
suggests that in order to maximize activity-dependent neural plasticity - training must be functionally relevant and significant to the individual
Age Matters
it has been shown that the aging brain has the capacity to demonstrate neural changes related to intensive activity – though the changes may not be as profound as those observed in younger brains.
Transference
refers to the ability of plasticity within one set of neural circuits to promote concurrent or subsequent plasticity
Interference
refers to the ability of plasticity within a given neural circuit to impede the induction of new plasticity within that circuit
CIMT authors
Leipert;Taub;Wittenberg
Mudie - bilateral arm training
Whitall - BATRAC
Ipsilateral hemisphere can contribute to motor control
Ridding - peripheral nerve stimulation (TMS, NMES)
Sensory stimulation enhances plasticity
Genetics in Motor Recovery after Stroke
Someone with vall66met variant- have decreased levels of bdnf, therefore don’t respond to motor learning paradigms as well
They have decreased levels of the brain derived neurotrophic factor and that affects their recovery from brain damage.
increase BDNF
Evidence is beginning to develop that suggests that aerobic exercise may be a valuable intervention for improving/ increasing levels of BDNF through aerobic exercise
Neural Plasticity and Degenerative diseases
In animal models - Casting of the affected limb for 7 days – led to increased behavioral deficits and increased dopamine loss compared to animals that were not casted (Tillerson 2001)
Animals that initiated intensive exercise within 5 days of the experimental lesion showed improved movement speed and balance.
Although the loss of dopamine remained similar in the two groups there was an increased availability of synaptic dopamine – including increased release and reduced uptake
