L11 - modern questions in memory and learning Flashcards
what is the evaluator module
memories stored in specific locations in the brain, written by the evaluator module, so when something good happens get a change in synaptic connections. When see stimulus again activate certain parts of the brain previously modified. Modifies that part of the brain to a certain motor action
outline Pavlov’s dog exp
bell + food - dog learned to salivate when bell rang due to conditioned learning
bell = neutral stimulus before conditioning, after conditioning it is a conditioned stimulus - predicts reward
outline conditioning in flies
pair door with sugar reward or electric shock
flies have a choice between odours - go towards odour associated with reward
what is a Kenyon cell
intrinsic neurons of the mushroom body
outline properties of Kenyon cells
receive multiple projection neurons
require multiple simultaneous inputs to fire
what do different Kenyon cells respond to
different odours
why do Kenyon cells fire selectively
as they require multiple simultaneous inputs to fire
outline the olfactory associative memory in drosophila
receives reward/punishment, activates different dopaminergic neurons and simultaneous co-activation of an odour specific subset of Kenyon cells, leads to synaptic plasticity at the output synapses of Kenyon cells activated by the odour. This changes the outward synapse of Kenton cell leading to another neuron
changes the behavioural output
what does the GAL4/UAS system allow
to artificially express arbitrary transgenes in specific cells
what is GAL4
transcription factor expressed in yeast
how can it be put into the fly genome
combine with an enhancer that will be active within certain cells in bodu
can be done randomly or specifically
what does GAL4 bind to
the upstream activating system (UAS)
what happens when GAL4 binds to UAS
recruits RNA polymerase, which induces upstream transcription of anything following UAS
what does the split-GAL4 system allow
greater specificity in which cells express our transgene
how to get enhancer specific to small populations of neurons
take Gal4 and cut into 2 pieces - DNA binding domain and activation domain.
Take the halves and express under control of different promotors. Only cells in where both halves are active will you have both halves of GAL4 being expressed
add zipper domain on each half and then In cells with both being expressed the 2 zipper domains will join up
what binds the UAS sequence
DNA binding domain
what recruits the RNA polymerase
activation domain
what is the mushroom body made up of
Kenyon cells
what is the relationship between output neurones (MBONs) and dopaminergic neurons (DANs)
1-1 matching
what was expressed in the flies in the behaviour chamber
CsCrimson
what did the flies with CsCrimson do ?
approached the light
what does having reward dopaminergic neurons in the same compartment as avoid output neurons do / punishment with approach output
weaken connections
what happens if shocked then get odour
the odour is positive as it indicates end of the pain
what happens if get odour then shock
avoid odour as it predicts pain
in forward and backward pairing experiments, how is the connection modulated
artificial stimulation of the dopaminergic neuron by using an ATP receptor (P2X2) apply different stimulation protocols
what happens if dopamine stimulation comes before
strengthen synapse
what are the 2 dopamine receptors in Kenyon cells
DOPR1 and DOPR2
what is DOPR1
signals through Gs pathway - signals production of cAMP - important for forward learning (odour precedes reward/potentiating synapse)
what is DOPR2
signals through Gq pathway - results in ER Ca2+ release - backward pairing (depressing synapse)
what is EPAC
sensor for cAMP
what is ER-GCaMP
measure calcium in the endoplasmic reticulum
what happens when dopamine comes before the odour
get a calcium release from the ER
what are projections neurons onto Kenyon cells in humans
mossy fibres onto granule cells in cerebellum
what do mossy fibres form
parallel fibres which are intersected by purkinje cells
what depresses synapses between granule cells and purkinje cells
signals coming from the climbing fibres
what drives motor learning
LTD between granule cells and purkinje cells
function of the electro sensory lobe of weakly electric fish
actively emits electric pulses to detect prey using an electric field
how does it ignore its own electric pulse
active granule cell cancelled out by the matching efferent copy by depressing the synapse between the granule cell and the purkinje cell
