Lecture elevem: Learning and Memory Flashcards
What is Perceptual learning ?
(better and faster identification of faces/objects if seen before)
Stimulus-Response learning
Classical conditioning (initial neutral stimulus induces reflexive behavior)
Instrumental conditioning (relation between stimulus and behavior for reward/punishment)
Motor learning
(ride a bike, tennis, etc)
Relational learning (declarative, explicit memory
- Relations in time (episodic: on my 18th birthday I got a car)
- Relations with concept (semantic: object with 4 wheels is a car)
- Relations in space (spatial: navigation)
S-R learning at neural level
- Food induces salivation
(hardwired connection between neurons that detect food and neurons that induce salivation) - Sound Bell: no response
(weak connection between neurons that detect the bell sound and neurons that induce salivation
after learning
- Sound bell induces salivation
(synapses connecting neurons that detect the sound and neurons that induce salivation have been strengthened
Hebb Rule
“If a synapse is active at about the same time that the post-synaptic neuron is active, that synapse will be strengthened”.
Long Term Potentiation (LTP)
Repeated stimulation of axon (causing an action potential in the post-synaptisch neuron) leads to long-lasting increase of excitatory post-synaptic potential (EPSP
LTP is frequency specific
LTP requires repeated stimulation at high frequency
As a result of this, EPSPs will overlap and sum to become strong enough to depolarise the postsynaptic neuron
LTP requires …
LTP requires activation of the axon and depolarisation (action potential) of the post synaptic neuron
Associative LTP:
If a strong and weak synapse are activated together (and the postsynaptic neuron depolarises) the weak synapse will become stronger
Requirements for LTP:
- Axon active (secretion neurotransmitter (glutamate) in synaptic cleft)
- Depolarisation postsynaptic neuron
Precisely these 2 conditions have to be met for opening the N-methyl-D-aspartate (NMDA) receptor
Axon active (secretion neurotransmitter (glutamate) in synaptic cleft) . Why cant the calcium channel open?
Magnesium Ion blocks the NMDA receptor
Glutamate can bind with the NMDA receptor, but ion channel is normally blocked by Mg2+ ion
Depolarisation postsynaptic neuron
depolarisation of the postsynaptic neuron evicts the magnesium ion and unblocks the channel.
Now glutamate can open the ion channel and permit the entry of calcium ions.
What is calcium doing after it enters the cell?
Ca2+ works as 2nd-messenger and activates the enzyme CaM-KII to add new AMPA receptors
2 types of reinforcement
Reinforcement promotes behavior
Positive Reinforcement: reward promotes behavior
pushing lever leads to food
If you behave good you get a sweet
Negative Reinforcement: removal negative stimulus promotes behavior
pushing lever stops electrical shock
If you behave good you may get out of your room
2 types of punishment
Punishment reduces behavior
Positive Punishment: negative stimulus reduces behavior
pushing lever leads to electrical shock
if you behave badly you have to go to your room
Negative Punishment: removal of positive stimulus reduces behavior
pushing lever ends food supply
If you behave badly you don’t get sweets
Neural mechanism involved with reinforcement: “the pleasure center”
Around 1950, James Olds en Peter Milner studied if electrical stimulation of the brainstem reticular formation could improve spatial navigation in rats.
As a control, they first studied if the stimulation was not perceived as unpleasant
In fact, just the opposite was true!
The rats kept turning back to the place that led to stimulation: they liked it!!
Pleasure center localized in medial forebrain bundle
Connects dopaminergic neurons in ventral tegmental area with neurons in nucleus accumbens
Dorsolateral prefrontal cortex
Particularly strong evidence for involvement of the dlPFC in working memory a.o. from research in monkeys by Patricia Goldman-Rakic
non-declarative memory (implicit memory.
memories you are not aware of
declarative memory (explicit memory):
Memories you are aware of and that can be verbally expressed
DECLARATIVE MEMORY IS LOCALIZED IN?
TEMPORAL LOBES
declarative memory is:
relative memory
brain regions: episodic (events experienced)
Relations in time
Medial temporal
brain regions of semantic (facts)
Conceptual relations
Lateral temporal
brain regions: spatial
Spatial relations
Para hippocampus
retrograde amnesia is:
cannot remember events prior to brain damage
anterogate amnesia is:
cannot remember events after brain damage
what happened to patient HM (Henri Gustav Molaison
operated in 1953, died in 2008
bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy.
But.. NO storage of new DECLARATIVE memory
In patients with hippocampal damage, which kind of learning is still possible?
E.G.: Perceptual priming: improved recognition if seen before
does retrograde amnesia occur to patients with hippocampal brain damage?
Hippocampus lesions also lead to retrograde amnesia, the severity depends on the extent of damage:
is the activation of the hippocampus related to consolidation of memory?
That hippocampus damage results in limited retrograde amnesia suggests an involvement limited to the initial anchoring of the memory trace in other brain regions (memory consolidation).
london taxi drivers have a larger… and that is because…
a larger (posterior) hippocampus…. because the
Reconsolidation of memories
If we learn something new about a specific subject (or person) we need to change/extend our memories
During reconsolidation the old memory is retrieved and adjusted. In this period, the memory is vulnerable!!
what can we use Electroconvulsive Shock (ECS) for?
ECS used to treat depression
Electrical current through the head excites many neurons in the brain and produces an epileptic seizure
is there a side effect of electroconvulsie shock? :D
Side effect: retrograde amnesia for events around the time of stimulation
(the seizure erases short-term memory active at that moment and consequently prevents consolidation of these memories into long-term memory)
If long-term memories are retrieved during reconsolidation, can we then erase these e.g. with ECS!!!???
