Learning & Memory 1 Flashcards
Define the term ‘learning’?
- Acquisition of new information or knowledge
(active process of acquiring information)
Define the term ‘memory’?
- Retention of learned information
(keeping them in store)
Why is ‘retrieval’ needed?
- Necessary to recall stored information
(need access to recall memory)
What three components could affect memory?
- Learning
- Memory
- Retrieval
(e.g. sometimes you can learn something but cannot retrieve the memory)
What is meant be ‘declarative’ memory?
- Memories for facts & events
- These can be accessed for conscious recollection
(e.g. my first bike was a present on my sixth birthday)
(these memories can be recalled & explained to someone else)
What are the three different types of declarative memory?
- Episodic Memory
- Semantic Memory
- Working Memory
What is meant by ‘episodic memory’?
- Recollecting specific events in time
What is meant by ‘semantic memory’?
- Remembering familiar objects or facts
(e. g. the capital of france - learnt it at some point but cannot remember the event where you learned it so not episodic anymore but semantic)
What is meant by ‘working memory’?
- Has qualities of both episodic & semantic memory (combination)
Memories for a short-period of time - They are not held forever (just for few minutes/hours)
(e.g. parking a car in the supermarket carpark)
What is another name for ‘working memory’?
- Short-term hold memory
What is meant by procedural memory?
- Memories that do not require conscious recollection
- These include habits (e.g. riding a bike)
(relatively long-term memory - these habits such as riding a bike need to be ‘learned’)
What is short-term memory?
- Lasts for a few minutes
- Usually involved mental rehearsal
- Easily disturbed
(e.g. initial stages of learning a telephone number - need constant rehearsal at first)
These can become long-term memory –> where they no longer need to be continued rehearsed –> they are resistant to disturbance
What is long-term memory?
- More permanent
- Does not require continued rehearsal
- Has a greater capacity
- Resistant to disturbance
(e.g. memory for familiar telephone numbers)
What are the two methods that process long-term memory called?
- Serial Process
- Parallel Process
Describe briefly the serial process of memorisation?
- Sensory information comes into system
- Held in the short-term memory
- Via consolidation (usually requires sleep) –> becomes stored in long-term memory
Describe briefly the parallel process of memorisation?
- Sensory information enters & held in short-term memory
- At the same time –> information is being consolidated over a longer period of time –> to acheive storage in long-term memory storage
Difference –> long-term memory is not a consequence of short-term memory –> but its own independent pathway
What is amnesia?
- Memory loss due to brain insult
(can range from minor to serious)
Name four potential causes of amnesia?
- Concussion (usually between 20-30 minutes)
- Chronic Alcoholism
- Tumours
- Strokes
(patients usually wake up confused with no recollection of event & no awareness of location)
What occurs with the memory of the event?
- Loss of Memory (amnesia) –> is permenant for that specific period of time
What is retrograde amnesia?
- Loss of memory for events prior (before) to the trauma
What is anterograde amensia?
- Inability to make or retrieve new memories after the trauma (event)
When can you not use the terms anterograde & retrograde?
- To describe memory (not such thing as anterograde memory)
- It is anterograde or retrograde amnesia
What is a clinical presentation of someone with retrograde memory loss?
- Able to recall early childhood memories
- Unable to recall a certain time window before the trauma (event) - no recollection
(this can range from minutes/days/weeks)
What are the clinical presentations of someone with anterograde amnesia?
Is isolated anterograde amnesia common?
- Usually serious anterograde amnesia is not seen alone
- Inability to form new memories from the date of event (trauma)
(usually patients present with both anterograde & retrograde amnesia)
What is the physical storage of memory called?
- Engram
How has memory circuitry been studied?
- Brain lesions
- Lashley (1920s) –> studied maze learning in rats with cerebral cortical lesions
Where is memory stored generally?
- Memories are distributed
(sizes of lesions correlated to memory impairment)
Is the cortical areas equipotential for learning?
- No
- Cortical areas are not equipotential for learning (some areas are more important than others)
- Lesions in certain areas have a more profound effect
What happens if there are large bilateral lesions of the temporal lobes?
- Psychic blindness
(animals will repeatedly put the same inedible objects into their mouth even having tried it before - usually animals learn from the first time)
Temporal lobe has specific regions involved in recognising specific objects (memory system for recognising visual objects)
What happened to patient HM?
- To treat severe epilepsy
- Received bilateral, medial temporal lobe resection
- Improved epilepsy
- Profound amnesia
What four areas are near or in the medial temporal lobe?
- Hippocampus
- Entorhinal Cortex
- Pernihal Cortex
- Parahippocampal Gyrus
Describe the medial temporal lobe area involved in memory.
In terms of amnesia, what happened to patient HM?
- Partial Retrograde Amnesia (could recalled early childhood but not years before surgery)
- Profound anterograde amnesia (no new declarative memory ever again - despite memory test experiments)
- Retrieval mechanism undamaged (could recall early childhood still)
- Short-term memory was normal (six numbers fine)
- Procedural memory (mirror writing) was normal
What areas in the temporal lobe are important in memory?
- Rhinal Cortex
- Perirhinal Cortex
- Amygdala
- Anterior Hippocampus
- Parahippocampal Area
Describe the loop involved in memory.
What is a good test for temporal lobe?
- Delayed non-match to sample (DNMS)
- Test of recognising object that have been seen recently (over seconds to minutes)
- Tests for declarative memory amnesia (seen in patient HM)
Particularly what part of the brain is implicated in declarative memory amnesia and therefore difficulty with DNMS task test?
- Temporal Lobe Lesions
- specifically Perirhinal Cortex damage
(monkey able to remember within a small amount of time –> but after 1 minute of screen going down the rule is forgotten - only have short-term memory)
Name the four critical areas for declarative memory loss (name the 2 most critical).
- Rhinal Cortex
- Perirhinal Cortex
- Hippocampus
- Amygdala
How does the associative circuitry work?
- There are a lot of reciptical connections
- These allow for additional output pathways from associative circuitry
What is less damaging to memory than parahippocampal & rhinal area damage?
- Lesion in Hippocampus
(those others were more improtant as they are in the middle of reciprical connections)
Describe the declarative memory circuitry.
What is the diencephalon involved in?
Which structures specifically?
- Memory
- Thalamus & Mammillary Bodies
How is memory located in the brain?
- Different structures are involved at different times
- Depends on memory type & time the memory is at (minutes or weeks from start)
- Memory constantly moves & distributes (does not remain)
- Stored in different brain regions
- System must work together to recall memory properly
What occurs when there is damage to either?
- Anterior Nuclei of the Thalamus
- Dorso-Medial Nuclei of the Thalamus
- Mamillary Bodies
- Distruption to Memory
Describe pathway 1 invovled in memory.
Describe pathway 2 involved in memory.
What test is affected with midline thalamic lesions in monkeys?
DNMS Test Deficits
What occured with patient NA?
- Stabbed with fencing foil
- Went up through right nostril –> into left dorsomedial thalamus
- Severe anterograde amnesia & retrograde amnesia (2 years up to accident) - difficult reading books & TV
(strong similarities in deficits with patient HM –> related to temporal lobe - diencephalic connections)
What causes Korsakoff’s syndrome?
- Chronic Alcoholism
- This depletes thiamine (vitamin B1) reserves
What happens in Korsakoff’s syndrome?
- Anterograde amnesia
- Limited retrograde amensia
What is damaged in Korsakoff’s syndrome?
Degeneration of:
- Mammillary Bodies
- Dosomedial Nucleus of the Thalamus
- Cerebellar Anterior Lobe Vermis
What are the neurological signs of Korsakoff’s syndrome?
- Anterograde amnesia
- Limited Retrograde amnesia
- (maybe) Confusional State
- Ataxia (especially gait ataxia - cerebellar anterior lobe vermis)
(gait is affected but distal limb control is not)
What is the treatment of Korsakoff’s Syndrome?
What can we expect?
- Treatment with Vitamin B1
- Leads to remarkable & rapid recovery of the motor & confusional problems
- Amnesia usually persists
(confusional state can be helped a lot but damage to memory such as to mamillary body is permenant)
What does chronic alcoholism do to the cerebellum?
- Damage to anterior lobe vermis
- Causes gait ataxia
Name three causes of dementia?
- Vascular Dementia
- Senile Dementia
- Alzheimer’s Dementia
What causes Alzheimer’s Disease?
- Neurofibrillary tangles (phosphorylated tau)
- *Neuritic plaques** (amyloid)
What does AD severity correlate with?
- Increase in neurofibrilary tangles (phosphorylated tau)
(not plaques/amyloid)
What are the two structures first affected by AD?
- Hippocampus
- Posterior Parieto-Temporal Cortex
Secondly, what does AD affect?
Degeneration of:
- Basal Nucleus of the Forebrain (nucleus of Meynert)
- Cholinergic Neurones
- Noradrenergic neurons (locus coeruleus)
- *Serotonergic raphe neurons**
What neurological sign is seen in AD?
- Retrograde amnesia
- Spreads back in time as the disease progresses
Which type of memory is affected the most & least in AD?
- Episodic memory (affected most & early on)
- *Working & semantic memory** (affected less so and middle of disease)
- Procedural memory (not impaired until final stages)
What is the basis of one of the treatments called cholinesterase inhibitors?
- Degeneration of basal nucleus of the forebrain (nucleus of Meynert) and its cholinergic neurones
It does not address the cause but its supportive & helps delay some amnesic symptoms
- Maximises residual cholinergic function
- Results are marginal but delays progression of disease
What are the 2 pathologies associated with AD?
- Neurofibrillary Tangles
- Amyloid Plaques
What is working memory exactly?
-
Information of several types needs to be held in a short-term store at the same time
(e. g. book title, colour of the cover, location on the shelf) - Information can be either be new sensory information or information retrieved from long-term storage which is ready to access
(ability tto hold onto information for a short period of time & lose memory when needed - does not need to be consoldiated)
Describe the connections between the medial temporal areas & cortical association areas.
Involved in working memory
Where does prefrontal cortex get information from to do with working memory?
- Temporal Lobe inputs via dorsomedial thalamus
Which part of the brain is very important in working memory?
- Prefrontal Cortex
What occurs if there is a lesion in prefrontal cortex?
Which test is there a deficit in?
- Deficits in working memory for problem solving
- Wisconsin card-sorting test
Where are neurons active during a delayed response test?
- Prefrontal Cortex
What is the wisconsin card sorting test?
- Asked to sort cards out in terms of a certain rule (e.g. numbers or suites or pictures)
- Asked to keep doing it
- They eventually forget what the rule was
When are prefrontal cortex cells active during ?
- Delay period in delayed-response task
(asked to do a task but cannot execute straight away –> need to wait for a momeny –> thus neurone activity is high whilst handing on & waiting –> then prefrontal activity drops as soon as action can be executed)
What does pre-frontal cortex code for in terms of memory?
Pre-frontal cortex –> codes for short-term information that you temporarily hold onto (i.e. working memory)
Where is memory found in the brain?
- No single place in the brain for ‘memory formation & storage’
- Different forms of memory mediated in different brain areas
Where is memory distributed within a brain area?
- Distributed everywhere within these brain memory areas (more involved in memory)
How can we describe the properties of short & long-term memory?
- Short-term memory –> FRAGILE
- Long-term memory –> ROBUST
Long-term memory depends on a form of structural change (consolidated in a stable form –> takes time & repitition & sleep)
Short-term memory is maintained by electrical activity and is therefore very fragile
What are declarative memories critically dependent on?
- Medial Temporal Lobe
- Nuclei in the Diencephalon (thalamic nuclei)
What are procedural memories with a strong motor component dependent on?
(e.g. riding a bicycle)
- Cerebellum
