Cellular learning and memory Flashcards
What is learning?
the process by which experiences change our nervous system and hence our behavior
What are memories?
the changes in the nervous system that derive from the learning
What is memory retrieval?
the process of accessing to memories
What is the cellular basis of long-term memory?
neuronal plasticity
What does the term neuronal plasticity refer to?
the ability of the nervous system to change and adapt
What are the two elements used to measure neuronal plasticity?
- intrinsic excitability
- synaptic strength
What is the intrinsic excitability of a neuron?
- number of action potentials a neuron exhibits in response to an influx of positive current
What determines the intrinsic excitability of a neuron?
the number and type of action channels it expresses
What makes a neuron more excitable?
- neuron starts making and expressing less potassium leak channels, which makes its base membrane potential more depolarized, thus facilitates action potentials
What is synaptic plasticity?
Changes in the strength of the synaptic connection between two neurons
What does the strength of a synaptic connection refer to?
the size of the reaciton in a post-synaptic neuron after a pre-synaptic neuron releases neuro transmitters
What influences synaptic strength on a presynaptic neuron?
amount of voltage gated calcium channels (influences intensity of neurotransmitter release)
What influences synaptic strength on a post synaptic neuron?
amount of neurotransmitter receptors
What is habituation?
Reduced intensity of an innate physiological or behavioural responding to a repeated stimulus
What is sensitization?
increased sensitivity to a stimulus
What are the two factors that make a a cell less excitable?
- more depolarized state at rest
- fewer ion gated voltage channels, so releases the glutamate when excited
What are the two effects that can be had on synapti strength/the two iterations of synaptic plasticity?
- long term potentiation
- long term depression
What type of stimulation causes long term depression?
- persistent low frequency stimulation
What structural changes are generally associated with long term depression?
- changes on the post synaptic side
- mostly: decrease in neurotransmitter receptors
What is the condition for the apparition of long term potentiation?
the release of a neurotransmitter must coincide with a substantial depolarization of the postsynaptic cell
What type of stimulation causes long term potentiation?
- persistent high frequency stimulation
What structural changes are generally associated with long term potentiation?
- changes on the post synaptic side
- mostly: increase in neurotransmitter receptors
How can there be a pre-synaptic long term potentiation?
- retrograde signaling of nitric oxide can cause the release and formation of more vesicles of neurotransmitters
Why are action potentials and cell activity both necessary for potentiation to occur IN THE ABSOLUTE (logical reason, not biological facts)
- if the post synaptic neuron is not active at the same time as there is information sent from the pre-synaptic neuron, then this synapse is useless and there is no advantage for the animal in strengthening it.
When do NMDA receptors let in ions?
When the cell is deplarized AND they are bound to glutamate
What type of receptors are NMDA receptors?
ionotropic glutamate receptors
What is the coincidence mechanism of the NMDA receptor?
- If there is glutamate, but the cell is hyperpolarized: Mg2+ blocks the pore
- If there is a depolarization, but no glutamate: the channel does not open
- need a combination of both to open the channel wide enough so that Ca2+ enters
What neurotransmitter are NMDA receptors sensitive to?
glutamate
What are AMPA receptors?
- classic glutamate receptors
- mediate most excitatory fast synaptic currents in the brain (lets in sodium ions)
- ## ionotropic
What is the enzyme that allows for the strengthening of the synapse?
CaMKII
What activates the signaling sent by the CaMKII enzyme?
the entry of calcium in the neuron
What is the role of the CaMKII neuron?
Stimulate the formation of new AMPA receptors
What does the strength of glutamate synapses correlate with?
- size of the postsynaptic dendritic spine
- number of AMPA glutamate receptors
What is the definition of perceptual learning?
Learning to recognize stimuli as disctinct entities
What is the definition of motor learning?
learning to make skilled and choreographes movements
What is the definition of relational learning?
Learning relationships amon individual stimuli
What is the definition of stimulus-response learning?
learning to perform a particular behavior when a particular stimulus is present (classical AND instrumental conditioning)
What is Hebb’s rule?
- the cellular basis of learning involves the strengthening of synaptic connections that are active when the postsynapitc neuron fires an action potential
- the synaptic connection has to exist
What is associative long-term potentiation?
- increase in synaptic strength
- occurs in weak synapses
When does associative long-term potentiation occur?
- stronger inputs caused the post-synaptic neuron to spike
