Lecture slides - Chapter 14.4 - 14.5 Flashcards
Memory and learning does not occur unless what changes?
the brain!
What is Hebb’s Postulate?
neurons that fire together, wire together
____ _____ is essential for learning and memory
back propagation
LTP plays a role in _____ learning
associative
“linkage of two or more unrelated stimuli to elicit a behavioural response”
associative learning
“in response to stimulation at a synapse, changed amplitude of an excitatory postsynaptic potential that lasts for hours to days or longer”
LTP
For LTP to occur and the EPSP to increase in size, what two things must occur? (can happen individually or both can happen)
- increase the number of neurotransmitters that are released from the presynaptic membrane
- postsynaptic membrane must become more sensitive to the same amount of transmitter
When animals learn problems, we should see enhanced LTP in ___ ___
recruited pathways
LTP should produce enduring changes in ___ ____ that resembles those seen in memory
synaptic morphology
What is synaptic morphology?
changes in the dendritic spines
“decrease in EPSP size”
long-term depression
In LTD, neurons become less active in response to repeated stimulation. It involves ____ receptors and requires ___ ENTRY.
NMDA; Ca++ entry
Ca++ entry in LTD causes what two changes in morphology?
- decreased responsiveness of AMPA receptors
- decreased numbers of AMPA receptors
What two receptors does glutamate act on (on the postsynaptic membrane)?
- AMPA
2. NMDA
AMPA normally responds to _____
glutamate
NMDA is a _____ gated channel that is normally blocked by ________
doubly; magnesium
What must happen for NMDA receptors to open?
two events must occur together in rapid sequence:
- depolarization of postsynaptic membrane, which displaces MG from pote (STRONG)
- activation by glutamate from the presynaptic neuron (WEAK)
What happens after the NMDA receptors open?
Ca enters the postsynaptic neuron, altering the postsynaptic neuron
After the NMDA receptors open and Ca enters, what gets altered in the postsynaptic neuron? (3)
- Increased responsiveness of AMPA receptors to glutamate
- Formation of new AMPA receptors
- Retrograde messengers that trigger more glutamate release from presynaptic neuron
Plasticity of ______ (inhibitory) synapses plays some fundamental role in modulating networks of excitatory neurons.
GABAergic
Ca enters postsynaptic neuron and activates a ____ _____
second messenger
____ alters gene expression in nucleus, which physically alters synapse. How?
cAMP; dendritic spines and formation or loss of synapses
Neurons change their structure in response to their changing ____
experiences
Changes in the # of dendrites can be used to infer what?
synaptic changes - the more dendrites = more connections
2 effects of experience on dendrites?
- more dendritic spines
2. axon collaterals can increase
There is evidence that ____ does occur in the mammalian brain all the time.
neurogenesis
The capacity for memory improvement and correlated structural changes in the ____ extends will into adulthood.
hippocampus
Being raised in an enriched culture is associated with? (6)
- increased brain weight
- more dendrites
- more astrocytes
- more blood capillaries
- more synapses per neuron
- increased mitochondrial volume
Enriched experience and plasticity leading to increased mitochondrial volume is a marker of what?
greater metabolic activity
High levels of estrogen = more ___ in the ____
dendritic spines in the hippocampus
How can low levels of estrogen relate to memory decline in middle aged women?
low estrogen = more dendritic spines in neocortex but rewer in the hippocampus
Low levels of testosterone = more what?
dendritic spines in the neocortex
______ are released from the adrenal cortex in times of stress
glucocorticoids
_____ assist in the metabolism of proteins and carbohydrates and the control of sugar levels in the blood cells
glucocorticoids
steady levels of ____ that are seen with prolonged stress may be neurotoxic; can kill _____ cells
glucocorticoids; hippocampal
“Neurotrophic factor that stimulates neurons to grow dendrites and synapses and in some cases promotes the survival of neurons”
nerve growth factor
“may enhance plastic changes, such ass the growth of dendrites and synapses”
Brain-derived neurotrophic factor
increased levels of ____ when animals learn to solve problems
BDNF
What stimulates neurons to grow dendrites?
nerve growth factor
Sensitization to psychoactive drugs is associated with an increased number of what three things? Where are these changes localized to?
receptors, synapses, and dendrites; regions that receive a large dopamine projection (prefrontal cortex, nucleus accumbens)
Plastic changes are ___ specific
age
Prenatal events can influence brain plasticity throughout life. This is called?
methylation
Experience-dependent changes interact (________)
metaplasticity
two cons of brain plasticity?
drug addictions and fused finger movements in musicians fingers
What are three possible ways to recover from brain injury?
- Learn new ways to solve problems
- Reorganize the brain to do more with less
- Generate new neurons to produce new circuits
Two examples of behavioural therapy to help with recovery from brain injury?
speech therapy or physiotherapy
Two examples of pharmacological therapy to help with recovery from brain injury?
nerve growth factor or amphetamine
What are some methods of lost-neuron-replacement?
fetal tissue implantation and epidermal growth factor
What is the problem with using stem cells to fill injury sites?
Although it fills it in, the structure that exists is not the same.
