L28: Neuroplasticity Flashcards
The sensory (and motor) areas of the brain are arranged in “_____”.
body maps
Larger area/volume devoted to “important” areas –____ and ______
face, hands.
What are 3 things that change in area depends on (regions are not fixed)?
- injury - peripheral, central
- training – skill, strength
- cognitive factors – normal and pathological
How does the brain re-organise?
Factors that promote neuroplasticity
What is neuroplasticity?
change in CNS structure and function
- Occur throughout life (while less effective in older age)
What is the purpose of neuroplasticity?
Important in learning, memory and recovery from neurological injury (e.g., stroke).
What are 5 mechanisms of neuroplasticity?
- Several mechanisms involved.
- Changes occur rapidly (mins/hours) and slowly (days/weeks/years).
- Different mechanisms involved in rapid and slow changes.
- Rapid changes are due to unmasking of hidden synaptic connections and changes in excitability.
- Short term changes = short term effect on function
- Longer-term changes involve structural changes too
What are 4 characteristics of importance of peripheral input?
- median nerve supplies glabrous surface of digits 1 and 2.
- section of median nerve modifies maps in S1.
- immediately following nerve section, large silent area in the S1 area receiving median nerve inputs. Large area now responds to stimulation of dorsal surface of digits 1-3.
- after 22 days, very little cortex remained unresponsive. Neurons previously responsive to median nerve inputs are activated by inputs from other intact nerves.
What are 4 characteristics of importance of correlated input?
- Suturing the skin between the fingers 3 and 4 produces a functional fusion of the two digits, and a high degree of temporal correlation in afferent signals arising from the two digits.
- S1 reorganises after several months of use of the fused digits.
- Blurring of boundaries in S1 representation of digits 3 and 4. A large intermediate region of neurons is found in S1 responding to stimuli on either digit.
- Responded to both digits, while already biologically represented individually
- The normal demarcation in representation of adjacent fingers in S1 is established genetically, but modified by experience.
- Functionally relevant, correct technique/mvt = don’t want them to learn the wrong task
What are 4 characteristics of importance of training?
- 10 days of skilled reaching
- Training increased wrist (green) and digit (red) representation in caudal forelimb area (CFA)
- Expansion of digit cortex = learning to use it
- No changes in unskilled reaching condition (control)
- Use-dependent change in excitability – relevance to physios!
- Neuroplasticity can only occur when doing the mvt multiple times (thousands)
Skilled training is necessary for neuroplasticity to occur
- Use dependent functional changes
Food reward = good way to increase neuroplasticity (repetitive training)
What is the stroke changes in blood flow (when gripping with right hand)?
Several experimental protocols now exist that can not only probe brain activity, but can induce plasticity in humans - therapeutic application?
Brain stimulation
- Reorganise networks
- How stimulated they are
What is the non-invasive brain stimulation in humans?
Foil on head –> electrical current –> EMG field underlying cortical area –> movements of the part of the cortex that is responsible for the movement (eg. finger flexion)
- How excitable the area from the cortex (brain neurons) in a pain-free way
- More excitable = larger evoked response
What are 6 characteristics ____?
- Training increases excitability/ representation of motor maps of trained hand – size and area.
- Modification of motor maps due to short-term and longterm changes.
- Other studies have shown changes in structural
- connectivity with training (e.g., juggling).
- Structural changes can occur remarkably quickly (~2hrs)
- Mechanisms?
What are 4 ways to improve functional recovery?
- Stroke patient with stable motor performance.
- Combined repetitive afferent stimulation (1 hr) with physiotherapy.
- Clinically significant improvement in motor performance.
- Demonstrates that experimental induction of neuroplastic change may help drive recovery.
Subtle improvement when combine physiotherapy treatment and brain stimulation
Physio alone = effective
Physio + brain stimulation (combination) = more effective
What are 3 characteristics of selective, targeted changes in plasticity?
- Inhibitory drive from unaffected hemisphere can also impair motor recovery after stroke.
- Inhibitory rTMS (low-frequency) can be used to “knock-out” this inhibitory drive.
- Both methods show some clinical improvements.
What are 3 improvement in motor learning via action observation?
- Observing a motor action can promote subsequent learning of that movement (but the “wrong” movement can impair learning!)
- Similar effects reported with imagination of actions.
- Relevant in dense CVAs where active movement is not possible.
Motor imagery as well as observation of other people’s movement = important for neuroplasticity = improve functional recovery
- Activates same area of brain as if you were doing the movement
- Don’t get them to learn antagonistic movement (eg. if you want to improve wrist extension, do not learn wrist flexion)
What are 4 characteristics of attention modulates plasticity?
- Attending to the limb undergoing training/rehab enhances magnitude of plasticity induced.
- Right-sided CVAs, particularly those involving fronto-parietal brain regions can often develop spatial neglect.
- Functional recovery in neglect is dramatically reduced.
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Promoting attention to the affected limb can increase training-related change – use of cues, constant reminders, avoiding distractors
- Do not diverge attention = significant impacted (negatively)
- Maintain attention = so important
What are 3 characteristics of sleep promoting learning?
Information related to change has been managed but downscaled so it is maintained in a functional range (baseline)
- Relevance to physio?
- Make sure patients get good amount of sleep
- Disrupted sleep when in hospital
- Encourage napping before (help to stabilise and downscale) and after (cement information??) rehab
Recovery from certain neurological conditions is reliant on _____ change.
neuroplastic
______ is promoted by a change in sensory input from the periphery, sensorimotor training, attention.
Plasticity
CVAs and their associated functional deficits are not _____ , so there is no ______ that will work for all patients.
homogenous; single treatment approach
What are 5 treatment strategies that have been shown to promote functional recovery after stroke?
- observing and/or imagining movements;
- avoiding unwanted muscle activity/tone;
- maintaining attention to the limb/muscle being targeted;
- encouraging sleep following training;
- ? brain stimulation to augment conventional neurorehabilitation approaches
