Kolb Chapter: 7
Title: Factors of Plasticity and Recovery
Key Points:
Student name: Andra Caulder
1. External factors like experience and internal factors like hormones can alter
gene expression, resulting in plastic and behavioural changes.
2. Sex hormones can modulate the cortex, and testosterone re-organizes the cortex
during development, while estrogen re-organizes during adulthood.
3. Behavioural therapy seems to be the most effective in cases where functional
recovery is usually poor.
Student name: Megan Cook
1. Environmental enrichment appears to provide the greatest increase in
functional recovery in situations where there would otherwise be minimal
RoF.
2. Hormones can remodel the cortex, leading to sex difference in brain structure
and recovery.
3. There are many ways to build a functional brain.
Student name: Tyler Bugden
1. There are different ways in which neuronal changes can support functional
recovery as evidenced by the difference in the cortical changes in males and
females after lesion.
2. Experience (ex. rehabilitation) can be used to decrease or inhibit changes in the
brain associated with loss of function.
3. Changes in the brain that support functional recovery can be brought about in
different ways. For example, through an enriched environment, training, or
stroking infants.
Student name: Thomas Ferguson
1. Kolb says that the effects of gonadal hormones organize the cortex and can
help explain differences in cortical morphology and, consequently function,
found between males and females.
2. Enrichment has selective effect on recovery, it will only help if prior recovery
has not occurred. Implies a limit to plasticity according to Kolb.
3. There is more than one way to stimulate cortical plasticity after early injury
Student name: Jill Harris
1. There is a difference in cortical functioning in males and females which is
related to testosterone exposure.
2. Behavioural therapies play an important role in treating cortical injuries with
a poor behavioural outcome.
3. Neurotrophic factors NGF and FGF may stimulate brain plasticity and
recovery of function after injury.
Student name: Olivia Wale
1. There is more than one way to build the brain.
2. Gonadal hormones alter the structure of cortical neurons and cortical
morphology.
3. Gonadal hormones may influence which mechanism of cortical plasticity is
employed for recovery of function.
Student name: Stephanie Brown
1. Hormones play an important part in neuronal structure.
2. Testosterone influences dendritic growth/arborisation after injury.
3. Neurotrophic factors help stimulate the brain, facilitating plasticity and
recovery after surgery.
Study Questions:
1. What is the difference between Nerve Growth Factor and Fibroblast Growth
Factor?
A: NGF works with cholinergic neurons whereas FGF is more generalized.
2.
Give an example of how gonadal hormones influence the brain.
a. Gonadal hormones influence the overall morphology of the cortex.
3.
What are some of the effects of testosterone on the cortex?
a. Testosterone influences the number of neurons and glia present.
4.
Why would you not want to just inject a patient with TBI with NGF or FGF
in order to stimulate growth in the brain? What should you do?
A-both these factors cannot cross the blood brain barrier, so other than
direct administration into the brain, it would not help the plastic processes.
What you could do is to inject a compound that up regulates NGF or FGF
that has the ability to cross the blood-brain barrier.
5.
Male and female infant rats were given a frontal lesion with both sexes
showing recovery. Looking at the brain, males showed an increase in spine
density while females showed an increase in dendritic branching. What is
an implication of this finding? ANSWER: Functional recovery can be
supported in more than one way through neuronal change.
6.
Why is it strange the NGF seems to stimulate the growth of pyramidal
neurons? What is a proposed mechanism for this stimulation?
a. This is a somewhat strange occurrence because NGF targets
cholinergic neurons, but pyramidal neurons are glutaminergic.
Some possible mechanisms of stimulation include:
enhancing activity in other neurons, which then stimulate
pyramidal neuron growth activating astrocytes to alter neuronal
morphology
7.
What are two neurotrophic factors that have been shown to positively
influence the injured brain?
a. Nerve growth factor and Fibroblast growth factor.
Discussion Questions:
1. In comparison to controls, Kolb explained frontal lesions and
norepinephrine depletion in p7-10 rats showed reduced arborization, no
change in spine density and behavioural deficits in adulthood. Do you think
frontal lesions and norepinephrine depletion at p1 and in adulthood would
exhibit similar deficits?
2.
Could females have different outcomes of recovery following TBI
depending on what stage of their menstrual cycle they are on?
3.
Kolb talks about similar lesions affecting males and females differently.
Does this information have any implications towards the treatments that
individuals receive?
4.
In the book they discuss the “accepted fact” that the largest time you get an
effect is the first time you do the experiment. What are some reasons that
you think this is true and do you think that this generalizes to other
disciplines as well, such as physics?
5.
If too much change may interfere with the functioning of the brain, then
might we see an increase in dementia in aged individuals who have
recovered from injury earlier in life?
6.
If recovery of function after cortical injury is correlated with testosterone
levels, would administering testosterone to females result in any functional
improvements if male and female brains are organized differently?
7.
Why did male rats with frontal lesions perform worse than females in the
Morris Water Task?