Wk 4 - Neuroplasticity Flashcards
(50 cards)
Two critical principles in the maintenance/organisation of neural circuits are…
Time-dependence, eg critical/sensitive periods
Experience/use - neurons that fire together wire together
Two major manipulations used historically to impact neural generation
Plus one more recent
Deprivation
Enrichment
Exercise
Deprivation, re neural generation, involves…. (x2 egs)
And leads to… (x2)
Rearing animals in the dark, sewing eye shut
Fewer synapses and dendritic spines
Poor depth and pattern perception
Enrichment of environment involves (x1)
And leads to …
With impacts on… (x4)
Comparing rats raised in standard – food, water, each other – with those in cage with wheels, ladders etcn
Neural difference in cortex - more dendritic spines and synapses
Vision, sensorimotor function, hippocampus, cortex
Effects of enrichment on the hippocampus (x2)
Leading to conclusions of (x1)
60% increase neurones in the dentate gyrus of the hippocampus, also in olfactory bulbs
Association with exercise and interaction with enriched environment
Van Praag et al, 2000, studied the effects of enrichment on neuroplasticity by (x2)
Concluding that… (x1)
Looking at hree different levels of environment
Key is number of small red dots appearing = new cells in the dentate gyrus
Runner, esp enriched-runner, environments, = more new neurons
Voss et al, 2013, furthered understandings of exercise and neuroplasticity through study of rats in... (x4 conditions) Enabling the (x1) and finding that.. (x1)
Control cage, enriched only, running equipment only, and all
Separation of running from enrichment – it’s the exercise that’s driving generation of new neurons in adult rats
Studies on impact of exercise on human neuroplasticity have shown… (x4)
Exercise also works for us
Image shows human hippocampus - specific to the dentate gyrus
Study measured blood flow during list learning task – you remember more and more over time
Post-exercise, blood volume goes up during first trial learning
Hubel and Wiesel’s research on cats showed the effects of deprivation in study involving… (x7)
Looking at ocular dominance columns
Sutured one eye shut in kittens from birth - 2.5 months, and recording the neurons
No cells now activated by contralateral eye - attributed to lack of input,
An example of a critical time period
Then sutured eye shut at 12-38 months
Find similar pattern to normal, but attenuated – few that respond only to ipsi or contra
Shows a sensitive period
Effects of competition in neural development is seen in evidence from vision studies on… (x1)
Showing that… (x1)
For example (describe evidence, x 3)
Monocular dominance columns
When you take one system away, others shift and rebalance
Deprivation in one eye during sensitive period = reduced activation of layer IV of corresponding visual cortex,
But activation of other cortex by intact eye is increased
Not just a single process – a shifting and re-balancing
Evidence for the effects of experience on modifying cortical maps is seen in studies involving.. (x3 egs)
Which lead to… (x1 plus eg)
And allows the conclusion that… (x1)
Cutting nerves, sewing together fingers of one hand, altering demands on system by increased use
Changed somatosensory mapping, eg relevant part of cortex no longer responds, but starts to respond to adjacent finger
Adult cortex is dynamic - we can enact change
Effects of reorganisation of sensory maps has been found in… (x3)
With effect mediated by… (x1)
Primates - sewing fingers together = merging of map boundaries
Musicians - larger somatosensory digit representation
Athletes, other specialised skills
Age - earlier you start, bigger the effect
Research into sensory reorganisation in non-elite people involved (x1)
Finding (x1)
Leading to conclusions that (x1)
fMRI; trained and untrained sequences
Greater changes in corresponding motor cortex for trained than for untrained after a few weeks
Training can induce rapid changes in organisation that reflect plasticity - still evident 8 weeks on
Knudsen and Brainard looked at effects of experience on topographic sensory maps in study involving... (x1) Describe study (x5)
Raised barn owls with prisms over their eyes - displace visual field
Owls auditory and visual systems integrated for successful hunting - reduces success
Vision mapping shifted in the direction of the prism
Auditory map also shifted in the tectum
Makes sense, because objects need to be heard in the location in space they occupy
Visual mapping shifts, so that success normalises
Phantom limb phenomena provides evidence for… (x1)
For example, Ramachandran (1993)… (x2)
Effects of experience on topographic sensory cortex maps
Studied a patient with an amputated left arm. When parts of his cheek were stroked, the Ps reported sensations in his left hand
Anterograde brain damage is… (x1)
And happens… (x1)
From the point of disruption forwards to the synaptic terminals (the distal segment)
Quickly b/c of separation from metabolic centre
Retrograde brain damage is.. (x1)
And happens… (x1)
With potential for… (x1)
From the point of disruption backwards to the cell body (the proximal segment)
Slow, over days - reduction in size, then death
Increase in production of proteins, but regeneration is not guaranteed
Transneural degeneration is when… (x1)
Brain tissue damage spreads to neurones that are linked synaptically
The principles of brain tissue damage are… (x3)
A whole bunch of neurons communicate with each other
Then there’s a cut = anterograde degeneration – axon ceases to function, neuron disappears from system
Then two unconnected neurons are subject to retrograde degeneration - whole system is disrupted
Concussion is due to… (x2)
Brain keeps travelling, impacts into skull, then goes backwards
Also twists - shearing of axons and bleeding in brain, and adaema (cushions impact area, but can press in on brain)
Effects of concussion (x7)
Extremely brief loss of consciousness, or may have no loss at all
Temporary confusion
Behavioural, affective and cognitive problems
No evidence of structural (neuronal) damage
Cumulative effect
Internal bleeds
Linear and rotational forces can lead to cell death
Punch-drunk symptoms in boxers are due to... (x1) Leading to (x3)
Concussions
General cognitive deterioration
Scarring after repeated concussions.
Effects are summative
Closed head injuries are when… (x1)
Plus five examples
Blow doesn't penetrate skull, but causes: Contusions Haematomas Oedema Loss of consciousness Epilepsy
Contusions are… (x1)
Bruises from brain slamming against skull
