ch 25 - Plasticity of the Adult Brain

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examples of plasticity

learning, memory, addiction, maturation, recovery

behavioral changes are accompanied by

changes in the nervous system

plasticity is common to 

all animal nervous systems (and the governing principles of plasticity hold across species)

plasticity occurs at

many levels (from complex to simple: behavior, neural imaging, cortical maps, physiology, synaptic organization, mitotic activity, molecular structure)

how can you infer plasticity from changes in behavior?

changes in behavior resulting from an environmental stimulus can be seen neuronally. neural changes can disappear when the environmental stimulus is removed (wolfgang kohler’s prism adaptation)

describe Wolfgang Kohler’s Prism adaptation experiment

subjects fitted with prisms that change their vision can adapt to the shifted visual world, accompanied by neural changes. after prism removal and adaptation back to the normal world, neural changes disappear

how can you infer plasticity from cortical sensory maps?

motor and sensory maps can be altered by experience (ex. musicians show more complex finger regions in motor cortex)

if connections are cut, cortical area is taken over by

the area next to it

motor and sensory maps can be altered by

experience (not always adaptive)

Loss of motor control in a digit after making repetitive synchronous movements (career musicians, golfers)

focal hand dystonia

what is an example of somatosensory plasticity?

reorganization of somatosensory maps after amputation

focal hand dystonia

denervated hand and arm area (ex. after amputation) respond to stimulation of

face on the affected side of body (has to do with somatosensory organization)

what is an example of plasticity in physiological organization?

LTP/LTD

what is long-term potentiation?

Enhanced synaptic transmission after electrical stimulation of a cell, leads to changes in dendritic length and spine density. model of how learning occurs

what is kindling?

Development of persistent seizure activity after repeated exposure to an initially subconvulsant stimulus

LTP was first found in the 

amygdala

what can be studied in postmortem tissue?

dendritic arborization through staining

synapse numbers and size through microscope

what is the computational challenge when studying synaptic organization?

cells with more challenging tasks to complete are more complex, and theres an individual difference in cell complexity based on life experiences

where can the adult brain manufacture new neurons (stem cell mitosis)

subventricular zone to olfactory bulb

hippocampus granule cell layer

sometimes in cortex in response to injury

precurser cells migrate along a path known as ___ migratory system to the olfactory bulb

rostral

rats in complex environments significantly increase ___ in response to ___

increase the activity of genes in response to the experience

what are the two types of plasticity caused by experience?

experience-expectant plasticity

experience-dependent plasticity

brain changes to neuronal assemblies that are already present

experience-dependent plasticity

behavioral changes result in (increase/decrease) of synapses

either. increase in synapses in one place and decrease in synapses in another place can result from behavioral change

what is metaplasticity?

changes from the experiences from a whole lifetime of living

pre-experiment ___ affects the outcome of the experiment

lifestyle (effects on synapses due to job, susceptibility to drug addiction, etc)

plasticity is ___-dependent

age-dependent and time-dependent

how is plasticity age and time dependent?

the same experience triggers different plastic responses at different ages.

synaptic changes can be stable or change over time (if not used in 14 days, may be lost)

___ of experience affects plasticity

relevance

plasticity is related to ___ and ___ of experience

intensity and frequency

(practice makes permanent)

what are some examples of plasticity being maladaptive?

chronic pain, tinnitus, focal hand dystonia

loss of oxygen for a period of time

ischemia, often a cause of stroke

why is it said that brain damage after a stroke is a cascade?

cascade of events set in motion even is blood flow is restored, so even if the stroke is treated immediately, damage to function can occur for months after.

what is the aphasia quotient?

a standardized measure of language incorporating spontaneous speech, fluency, comprehension, etc

recovery from surgical lesions

little to no recovery of function following surgery, even after 20 years

after a stroke, reorganization takes place (unilaterally/bilaterally)

bilaterally

what are some variable affecting recovery from a brain injury?

age, sex, handedness, intelligence, personality

which sex has more interhemispheric connections

female

what is constraint-induced therapy?

making the patient complete a task with their impaired limb. has great outcomes.