memory Flashcards
what surgical procedure did patient hm have
bilateral temporal lobectomy
which brain structures did HM have removed
hippocampus, amygdala and overlying cortex
what type of amnesia did patient HM suffer from
anterograde amnesia
what is anterograde amnesia
total inability to form new memories after event that caused amnesia
define memory
how info is stored, reactivated and retrieved
what is a memory deficit
damage to brain region and damages to specific brain system
what is the digit span +1 test
Pp hear sequence of digits, once repeated correctly a digit would be added to the sequence
what is the normal average performance on digit span test
15 digits after 25 trials
does hm have a long term capacity
HM has NO long term memory capacity
which digit span test can hm pass
pass digit span test
fail digit span +1 test
what performance did hm achieve on digit span +`1 task
6 digits recalled after 25 trials
is hm amnesia modality specific
NOT MODALITY SPECIFIC
occurs across all sense modalities
did HM pass the block tapping +1 task
fail task
cant learn sequence after 12 attempts
which memory tasks can HM complete
rotatary pursuit task
mirror drawing task
can Hm remember performing memory task
no concious memory of task
Hm has anterograde amnesia
pavlovian conditioning
what is the correlation between errors and attempts in Hm performance
errors decrease as attempts increase
does hm pass implicit memory tasks
YES - THEY ARE UNCONSCIOUS
does hm pass explicit memory tasks
NO - conscious process that needs episodic memory
does hm have an episodic memory
Hm has no episodic memory
what is the implicit memory system made up of
procedural memory - walk/talk
what is korsakof syndrome
too much alcohol
what caused patient NA amnesia
sword up nose
what type of amnesia does patient NA have
medial temporal lobe amnesia
what is global cerebral ischemia
blood supply cut to the brain
which patient obtained memory problems as a result of a bungled operation
PATIENT RB
what brain region was damaged in patient RB?
damage to pyramidal cells of CA1 subfield of hippocampus
which brain region is damaged in medial diencephalic amnesia
damage to medial nuceli of thalamus
what symptoms occur in medial amnesia
motor problems and extreme confusion
what experimental design problems occur to study memory
- no pre lesion performance data
- case studies = low sample sizes
- lesions can’t be reversed
- . some memory tasks use more than 1 cog process
does patient Hm have a normal short term capacity
Hm DOES have a normal short term capacity
why can Hm pass pavlovian conditioning task
able to retain conditioned response in short term memory
which memory systems compose the explicit memory system
semantic and episodic memory
why do we use animal models to study memory
able to make lesions in animals eg. rats
why do we study memory
increase understanding of which brain regions are responsible for different types of memory
what changes must be made in studies that use animal models
- adapt tasks for animals
- animals and babies dont have same complex brain as humans
what is the delayed non matching to sample task
monkeys had to remember the sample object and select unfamiliar object to obtain food
what is the research findings for monkeys in the non matching to sample task
increase in time of delay reduce percentage likelihood chance of being correct
if the medial temporal lobe is damaged where does a deficit occur
damage to medial temporal lobe - deficit in long term memory
what is the difference performance in control monkeys and monkeys with a lesion in their medial temporal lobe
lesion in medial temporal lobe = worse performance eon non matching sample task compared to controls
what similarities occur between monkeys and humans with medial temporal lobe damage
- poor task performance
- similar brain structure
- deficit in long term memory
what is the name of the delayed non matching sample tasks in rats called
mumby box
which other region of the brain becomes damaged when you lesion the hippocampus in the monkey
rhinal cortex
is the rhinal cortex damaged in rats when you remove the hippocampus
rhinal cortex is not damaged when you remove the hippocampus from a rat
what is the difference between removal of the hippocampus between monkeys and rats
monkeys would be impaired if hippocampus removed as rhinal cortex is damaged
rats would not be impaired if hippocampus is removed because rhinal cortex would not be damaged
which area of the brain when lesioned produces memory deficits in delayed to non matching sample task
rhinal cortex
which area of the brain was damaged during surgery for patient rb
damage to CA1 subfield of the hippocampus
what is the reasoning for the brain damage during patient RB surgery
ischemia
what is the key role of the hippocampus
key role in object memory recognition
where are glutamate receptors located
hippocampus
what is the result of too much glutamate in the hippocampus
overexcites brain regions
kill neurons = cell death
what happens in a rat’s brain when you remove the hippocampus and exposed to ischemia
no impairment in the brain as the hippocampus has been removed
what happens when a rat is exposed to ischemia and the hippocampus is not removed
IMPAIRMENT OCCURS
explain why impairment occurs when the hippocampus is not removed in the rat
by leaving the hippocampus - glutamate receptors can become over excited - kill other brain regions causing cell death
explain why impairment does not occur when the hippocampus is removed
removal of hippocampus - no impairment - glutamate receptors can’t become over excited
what kind of memory is the hippocampus associated with
spatial memory
what is the size difference of the hippocampi between taxi drivers and other humans
taxi drivers have larger hippocampi
how do rats with a hippocampal lesion perform on morris water maze task
lesion in rats - poor spatial memory - poor performance on morris water maze task
which tasks do rats with hippocampal lesions have a poor performance in
morris water maze
radical arm maze
why do rats with hippocampal damage have poor performance in certain tasks
poor spatial memory
which cells are in the medial temporal lobe of humans and monkeys
grid cells and place cells
what do grid cells in the entorhinal cortex show
how hippocampal place cells obtain spatial information
what is another name for a hippocampus neuron
place cells
what effect does placing an electrode in a place cell have
show where neuron fires in hippocampus - form spatial map of neuron firing
where does electrical neurtransmission occur
down the axon
where does chemical neurotranmission occur
across synapse
what type of neuron does electrical neurotranmission
post synaptic neuron
what is hebbs postulate for learning
in neurotransmission, a chemical component allows this process to become more efficient
what did bliss and lomo study
study of LTP in hippocampus in rats
what key properties of LTP are there
increases responses
long lasting
COCURRENCE OF FIRING
what is meant by co currence of firing
firing of presynaptic neuron is followed by firing of post synaptic neuron
how to obtain baseline response in bliss and lomo study
Adminster a low intensity pulse to perforant path of the hippocampus
in bliss and lomo study where was the pulse intensities administered
perforant path of the hippocampus
what happens when you administer higher intensity, higher frequency pulses to the perforant path
LTP would be induced
what is the difference after administering a high intensity pulse
response become bigger after administering high frequency pulse
what is LTP critical for
learning and memory
what happens in the morris water maze if you maximise LTP
learning would be stopped in the morris water maze
explain evidence that LTP is linked to learning and memory
LTP can be triggered at low levels of stimulation
low intensity pulses - LTP demonstrated
what happens when LTP becomes saturated
stop spatial learning in hippocampus
is LTP needed to complete morris water maze
LTP is essential to complete morris water maze
how does the chemical part of the synapse become more efficient
glutamate
would knock out mice (missing gene for LTP) be able to complete morris water maze
No, LTP is essential for morris water maze task
what is an ionotrophic receptor
receptor protein
what is the function of ionotropic receptors
bind to receptors causing ion channels to open
what is the NMDA receptor permeable to
calcium ions
what does it mean for a dual process requirement for NMDA receptors
NMDA receptors respond maximally when 2 events occur at the same time
what does glutamate NT bind to
glutamate receptor
what is the glutamate receptor often blocked by
magnesium
how can the glutamate receptor get rid of magnesium
partially depolarise neuron, magesium would move away as it is positively charged
what happens when the glutamate receptor partially depolarises the neuron
magnesium would no longer block the ion channel
the ion channel would be clear
what occurs when calcium influx enters the cell
changes inside the cells occur related to memory function - LTM memory changes
what happens in LTP experiments when you induce stimulation in the perforant path of the hippocampus
baseline measurement
first pulses would depolarise post synaptic cell - removal of magnesium blockage
what is the result on LTP process when you administer higher frequency trains to the perforant path of the hippocampus
allow calcium influx into cell - causes LTM changes
where does LTP often occur
dendrite spines
what is the function of nitric oxide in LTP
transitory substance that is synthesised in post synaptic neuron and diffuse to pre synaptic neuron
where does LTP begin
post synaptic neuron
how is LTP maintained
structural changes - size of synapse or size of dendrite spines
what is required for LTP expresion which is greater than 2 hours
protein synthesis and structural changes
what is glutamate
principal excitory neurotransmitter
name an example of an ionotropic receptor
NMDA
summarise the LTP process
- glutamate NT bind to glutamate receptor
- partially depolarise neuron to remvoe magesium blocking ion chanel
- ion channel allows calcium influx
- calcium influx cause LTM changes inside cell
what does repeated cocaine exposure faciliate
LTP induction
