Learning, memory and cognition Flashcards
how can memory be split into categories
short term/long term
long term - explicit/implicit
explicit - episodic / somatic
implicit - procedural, priming, classical conditioning, non associative learning
Declarative memory can be split into
episodic and semantic
episodic memory
memories of specific events (wedding)
semantic memories
knowledge of facts about the world
derived from episodic memory
what are non declarative/ implicit memories divided into
procedural
primming
classical conditioning
non associative learning
what is procedural memory
how to do things (juggling)
what is priming memory
exposure to ones stimulus influences a response to subsequent stimulus
what is classical conditioning
pairing of stimulus response associations
(pavlova dog - food and bell)
non associative learning
habituation or sensitisation
alter response to stimulus without association if it causes positive or negative outcomes
habituation
over time will stop responding to repeated sequence
sensitisation
over time a repeated sequence will make you more sensitive to one sequence
what part of CNS is associated with explicit memory
medial temporal lobe
diencephalon
association cortices
what part of CNS is associated with procedural memory
striatum
what part of CNS is associated with priming memory
cortex
what part of CNS is associated with classical conditioning memory
amygdala and cerebellum
what part of CNS is associated with non associative learning
reflex pathways
what part of CNS is associated with non associative learning
reflex pathways
where is the hub for declarative memory
the hippocampus
where is the hippocampus
medial temporal lobes in primates
inputs to the hippocampus
mainly from structure in the parahippocampal gyrus (entorhnal cortex)
outputs of the hippocampus
entorhinal cortex
fornix
circuitry of the hippocampus - pathways
commissural pathway
Schaffer collateral pathway
mossy fibre pathway
prefroant pathway
circuitry of the hippocampus steps
- Excitatory neurons in entrotianal cortex send axons to the dentate gyrus (granual cells)
- Via perferent pathway
- Then send own axons to CA3
- Via mossy fibre pathway
- Excitatory neurons in CA3 then send axons to CA1 of hippocampus
- Schaffer collateral pathway mediates this
- Via structure called fimbria
- CA1 also receive inputs from contralateral CA3 (opposite side of the brain)
- Mediated by pathway = commissural pathway
Out of hippocampus into cortex
fimbria
becomes continuous with crus (elongation) of the fornix - units to form body of fornix
Neurons in CA3 project axons out the hippocampus through fimbria
fornix
connects hippocampus to maxillary bodies
hippocampal commissure
hippocampal fibres cross between 2 hippocampi
function of parahippocampal cortex
the site of convergence of cortical input
- information relayed to the hippocampus where associations formed
- information output from the hippocampus back to parahippocampal cortex.
cortico hippocampal information flow
primary sensory cotices
association cortices
parahippocampal cortices
entorhinal cortex
hippocampi formation
how do we know that the hippocampus id important in declarative memory
patient HM (Henry molaison)
had a bilateral mediat temporal lobectomy to control severe epilepsy (1957)
after surgery
could remember events form past
could participate in short convocations
could learn new skills
BUT
could not form new declarative memories
good animal model for hippocampal studies
rats
hippocampal structure conserved across mammalian species
how do we study memory in rats
- curiosity to explore
- food seeking
- freeze when afraid
- avoidance of dangerous situations
natural behaviours in rats
what does morris water maze test study
spatial memory test
explain the morris water maze test
rodents want to avoid dangerous situation (water)
water made opaque so animals can’t see submerged platform
after 7 days - remembered where platform is placed in pool
when platform removed - animal spends a lot more time in area where platform was
what do lesions of the hippocampus impair
spatial memory
how do lesions of hippocampus effect performance in morris water maze test
latency - time taken to escape from water maze
number of trials the animal took
control and cortical lesion animals
latency and number of trials increased
blockade of NMDA receptors effect on hippocampus
impairs LTP in hippocampus
What happens when a blockade (antagonist) of NMDA receptors (D-AP5) in the hippocampus in rats in vivo?
treatment contains active (DAP5) and inactive (LAP5) isomers of AP5
control - inactive isomer of AP5
antagonist of hppocampal NMDA receptors blocks preference for the target quadrant
this shows that rats treated with DAP5 can’t learn location of hidden platform
what does muscmol (GABA(a) receptor agonist) do to CA1 of hippocampus
GABA (a) agonist infused into CA1 of hippocampus = temporarily inactivates it
impairs retrieval of previously learned hidden plated location
evidence that the hippocampus is involved in spatial memory in people
size of London taxi drivers posterior hippocampus correlates with years of experience
test to show that the hippocampus is involved in spatial memory in humans
fMRI imaging during virtual navigation task around Londons soho district
activity in the hippocampus positively correlates with distance to the goal location during active navigation
the grandmother cell
a theoretical type of recognition neuron that represents a group of features about a single complex item or cencept
is there evidence that grandmother cells exist
no
more likely features of complex item are represented by a sparse distributed neuronal network
Jennifer anniston cells (concept cells)
recorded individual neurones in hippocampus of epilepsy patents
found neurons that reliably responded to specific familiar people (Jennifer Anniston)
how to investigate visual recognition emory in animals
by novel object preference - inquisitiveness
animals spend more time exploring new objects than familiar ones
discrimination ratio
exploration preference expressed
D = (novel - familiar) / (novel + familiar)
what kind of memory is the pirirhinal cortex important for
inject recognition memories
lesions on perirhinal cortex not hippocampus or medial prefrontal cortex impair novel object preference memory
where is the Peririhinal cortex
Located adjacent to the hippocampus in medial temporal nodes
directly and indirectly innervated the hippocampus
