Neuroplasticity Flashcards
models of nervous system function
- have historically influenced…
- what are they?
have historically influenced ideas about the system’s ability to reorganize
Hierarchical Control Model
Distributed Systems Model
Hierarchical Control Model
- what is it?
- 2 specific ideas
higher brain centers control primitive behaviors in lower brain centers
localization of function
-specific brain areas control specific functions
no regeneration in CNS because of inability of central axons to regenerate following lesions
distributed systems model
- what is it?
- 3 specific ideas
numerous reciprocal connections between and within levels of CNS
information and motor commands flow in all directions
function is a cooperative effort among regions of the CNS
control site depends on the task to be executed
-voluntary movement - area 4 vs. automatic movement - area 6; both may be active
habituation
- what is it
- why does it happen
- eventually may result in…
decrease in a response due to a decrease in the synaptic effectiveness (decreased neurotransmitter released from presynaptic membrame)
eventually may result in decreased number of synaptic connections
sensitization
- what is it
- may involves what synapses?
enhancement of synaptic transmission
experience with one type of stimulus (i.e. painful) enhances responsiveness to other stimuli (i.e. nonpainful)
may involve axo-axonal synapses (presynaptic)
sensitization
-chemial reason for why it works
facilitating neurons, some of which are serotonergic, enhance transmitter release from the sensory neurons by increasing the amount of second messenger cAMP in the sensory neurons
these effects are short-term
sensitization
-with repeated exposure to stimulus, what can happen?
long-term changes may occur that involve the synthesis of new protein and gene activation (mRNA)
long term potentiation
-what is it?
cellular mechanism proposed for formation or consolidation of memories through hippocampal formation
long term potentiation
- how does it occur
- the effects of the LTP are specific to…
cooperative and associative activation of numerous neurons in the hippocampal formation increases the amplitude of EPSPs (increased depolarization) on a receptive cell
the effects of the LTP are specific to those synapses that are activated by the stimulus
long term depression
- what circuitry?
- purpose
cerebellar cortical circuitry proposed to be responsible for motor learning
long term depression
-essential process required for this to occur
the persistent desensitization of selective glutamate receptors that mediate mossy fiber –> parallel fiber –> Purkinje cell transmission
long term depression
-role of climbing fibers
play a leading role in induction of LTD
monitor the performance of a system in which the cerebellar circuitry plays a role and informs Purkinje cells about control errors due to misperformance of the plan
long term depression
-classic example
change in gain of VOR
neuroplasticity development
-thought to serve as…
a process template for lateral neuroplastic changes
development: radial glial cells
- function
guidance system for neuronal migration in neural tube
development: process growth
- what is it
the axons and dendrites extend outward from the soma, the axon first process in vivo in vitro (petri dish), undetermined neurite outgrowth occurs until a "guiding signal" is recognized that determines axon vs. dendrite
development: guidance of the process (axon and dendrites) formation is governed and directed by…
a number of external signals
development: growth cone
- importance of the enlarged tip
has multiple filopodia or lamellipodia
- contain organelles and cytoskeleton necessary for growth and addition of neuron membrane as well as movement proteins
- the membrane is rich in receptors responding to directing signals
development: directing signals
- what are the various signals?
contact inhibition
growth factors
calcium
GAP 43
development: adhesion different dependent upon…
extracellular matrix
contact inhibition
-can be…
recognition of neurotransmitters
growth factors
-nerve growth factor function
what other growth factors may play a role?
nerve growth factor supports and directs process outgrowth other growth factors -BDNF -epidermal growth factor (EGF) -fibroblast growth factor (FGF) -cytokines and hormones
calcium
- function
- how does it work?
- too much may result in…
- what other role of calcium is useful to remember when thinking about this concept
modify growth cone mitility
thought to act by facilitating depolarizing currents as the neurite grows
too much may result in hyperpolarization, effectively slowing down growth
Ca++ has a role on terminal activity specific to neurotransmitter release
GAP 43
-found in…
growth cones of axons, not dendrites
synaptogenesis and pathfinding
-contact guidance
membrane molecule mediated (neural cell adhesion molecule, laminin, neural cadherin)
synaptogenesis and pathfinding: chemotropism
- specific to…
- example
- evidence has been noted in…
neurotransmitter specific, region specific
example
-the growth of individual neuronal cell axons in response to extra-cellular signals, which guide the developing axon to innervate the correct target tissue
-evidence of chemotropism has been noted in neuronal regeneration, where chemotropic substances guide the ganglionic neurites towards the degenerated neuronal stump