Task 3 Consolidation, plasticity and LTP Flashcards
Synaptic plasticity
The ability of synapses to change as a result of experience
Hebbian learning
The principle that learning involves strengthening the connections of coactive neurons
o Can also enhance the ability to recognize stimuli (incomplete version of stimulus activates still the whole network)
• Neurons that fire wire together: Neurons that often fire together become better connected in a sense that when neuron A fires Neuron B is more likely to fire too.
Long-term potentiation
A process in which synaptic transmission becomes more effective as a result of recent activity
o When a synapse has NMDA and AMPA receptors, the NMDA receptors are blocked by Mg2+ blocks which are removed when the AMPA receptors already depolarized the cell.
Protein kinase
can change the properties of many protein molecules (PKA, PKC, Cam kinase, TK)
Blockage of these kinases can prevent the induction of LTP
Cam kinase
remains activated once it is put into a state by CA2+even if the level of CA2+ subsequently falls
Could play a role in maintaining LTP
It also enhances influx of NA+ and K+ ions and increase the number of AMPA receptors
Immediate early genes (IEG)
a class of genes that are rapidly but transiently expressed in response to extracellular signals such as neurotransmitters and growth factors Many IEGs code for transcription factors that govern the growth and differentiation of cell types by regulating the expression of other genes.
IEG and LG
these IEGs in turn produce other RNAs and Proteins –
o These protein trigger the activation of so-called ‘Late Genes’ (LGs) –
o Late genes produce the RNAs and in the end the proteins that contribute to the structural changes in the neuron that can support long-lasting changes in synaptic efficiency (more receptors), or even the building of entirely new synapses from scratch.
Long-term depression
A process by which synaptic transmission becomes less effective as a result of recent activity
o Requires the entry of Ca2+ through NDMA receptors
o A large surge of Ca2+ in the postsynaptic neuron triggers the induction of LTP by activating Ca2+—dependent protein kinases. In contrast, small increases of postsynaptic Ca2+ induce LTD by selectively activating the opposite kind of enzyme
Hebbian synapses
a kind of hippocampal synapses which show kinds of conditional changes that could mediate aspects of associative learning
Cell assamblies
o Large groups of cells that tend to be active at the same time because they had been activated simultaneously or in close succession in the past
Physiological changes at synapses may store memory
Greater release of neurotransmitter or the receptors become more numerous or more sensitive
Structural changes at synapses my provide long-term storage
new synapses can be formed or eliminated as a function of training, could also lead to rearrangement of synaptic connections (taking over endings from less used competitor)
• neurons that fire to the same spot tend to get connected and fire together
dual trace theory
Learning experience sets up activity that tends to reverberate through the activated neural circuits. This activity holds the memory for a short period. If sufficient, the activity helps build up a stable change in the nervous system— a long-lasting memory trace
Enriched experiences
• Enriched experience has beneficial effects on brain anatomy
o Develops new synapses and more elaborate information-processing circuits (20% more)
o Length of synapses gets bigger too
Filopodia
fine extensions from the axon that are promoted by electrical activity. They only occur In development
o They may become dendritic spines if they make contact with an axon
