Memory and Learning 1 Flashcards
Define learning
Process whereby new info is acquired by the nervous system and leads to a change in behaviour
Memory
The encoding, storage and retrieval of learned info
Name the two modes of memory
Declarative and Non-declarative(Procedural)
What is declarative memory?
memory available to consciousness and can be expressed by language i.e. can be declared
What is non-declarative memory
memory that involves skills and associations that are acquired and retrieved at an unconscious level
What are the types of non-declarative memory and where are they stored long-term?
Procedural-striatum
Motor skills-cerebellum
Emotional- amygdala
What are the types of declarative memory and where are they stored long-term?
Episodic (events)
Semantic (facts)
Both stored in the medial temporal lobe diencephalon
Name the three temporal types of modes of memory?
Immediate memory
Working memory
Long-term memory
What is immediate memory and what are its features?
The ability to hold ongoing experiences for a fraction of a second
Large capacity, each sensory modality has its own ‘memory register’
What is working memory and what are its features?
Ability to hold information in the mind for seconds to minutes while it is used to achieve a certain goal
Limited in duration and capacity
What is long-term memory and what are its features?
Memory that is retained for days/weeks/lifetime
Immediate or working memory can enter long term memory by conscious or unconscious rehersal
What is an engram?
The physical embodiment of memory in the neuronal machinery which depends on changes in synaptic connections and/or growth/reordering of these connections
What is memory storage called?
Consolidation. Sensory info can go be consolidated to long term memory via short term memory or directly
Forgetting
Unimportant info and unrehearsed memories deteriorate over time
Important not to retain everything, particularly immediate and working memories
Importance of forgetting illustrated by Patient ‘S’
individual that cannot erase info- has difficulties distinguishing important cognitive stimuli from trivial info
What is pathological forgetting called and how can it arise?
Amnesia
Arises from CNS injuries and disease
What are the two types of amnesia?
Retrograde- loss of memories for events preceding the trauma with greater loss towards the time of trauma
Anterograde- continued loss of a large percentage of memory function after the time of the trauma,
Case of H.M. anterograde amnesia
Bilateral medial temporal lobe resection
Amygdala, incus, hippocampal gyrus and anterior hippocampus removed to alleviate epilepsy
Resulted in profound loss of short term declarative memory function
Case of R.B. anterograde amnesia
Ischaemic episode during surgery
Failed on tests on ability to form new declarative memories
Bilateral lesion of hippocampus, particularly CA1 regions
What does declarative memory rely on?
Depends on the integrity of the hippocampus and its subcortical connections to the mammillary body and dorsal thalamus
What is the route of declarative memory consolidation?
Cortical association areas —-> Parahippocampal and rhinal cortical areas ——> Hippocamus ———> Thalamus, hypothalamus via the fornix
AND
———–> feeds back to cortical association areas
What structures are used to test spatial memory consolidation?
Morris water maze (invisible platform in pool)
and the radial arm maze (arms radiate from center area and some arms have food at end, others don’t)
What are the effects of lesions on radial arm and spatial maze learning?
Lesions specific to hippocampus - marked effects
Perirhinal lesions - less effect
Model for human episodic memory
Non-matching to sample, with or without delay
- train to visual stimulus, reward choice of non-matching pattern
- tests working memory and how long the memory is retained
What are the effects of lesions on delayed matching and non-matching to sample?
Lesions restricted to hippocampus - very little effect
Perirhinal cortical lesions- profound effect on performance (much reduced mean percentage correct)
Long term memory storage and retrograde amnesia
Tells us about how and where memories are stored
Typically involves lesions from trauma or neurodegenerative diseases e.g. Alzheimer’s
Suggests long term memory storage is distributed through the cerebral cortex
Karl Lashley’s experiments
1920s
Searching for food reward in maze
Cortical lesions made, the larger the lesion the worse the performance
Long term memory stored in networks through cortex
Long term declarative memory storage
fMRI studies - Bird and car images shown to bird and car experts
Declarative memories stored in specific cortical regions
How do we acquire non-declarative memories?
Conditioned learning
What is conditioned learning?
Generation of a novel response that arises from paring a novel stimulus with the stimulus that generates the response being studied
What are the two types of conditioned learning?
Classical conditioning and Operant conditioning
What is classical conditioning and how does it work?
An innate reflex (e.g. dog salivates in response to food) is modified by associating its normal triggering stimulus (e.g. food) with an unrelated stimulus (e.g. a bell).
By ringing the bell when the dog is presented with food, the dog will learn to salivate in response to the ringing of the bell even without food being present
What is operant conditioning and how does it work?
Alter the probability of a response by associating it with a reward/punishment
Developed by Frederick Skinner - Skinner’s box
Mouse learns to push lever to get food or gets a foot shock and learns where not to step
Testing where non-declarative memories are stored using conditioned responses
Emotion- classical fear conditioning (amygdala) - Foot shock associated with stimulus, give foot shock and animal freezes, eventually animal will freeze in response to stimulus alone
Motor skills - classical eye blinking conditioning (cerebellum) Tone followed by puff of air-> eye blink. Tone alone —> eye blink
Procedural memory- (basal ganglia) subjects learn that selecting e.g. pink door in condition A leads to reward and then learn the doors to select in conditions B,C and D to get to the reward so that overall path is D->C->B->A->reward.
Parkinson’s patients with dopamine replacement therapy do almost as well as controls, but those not on therapy have impaired ability to learn the task
What is phylogenetic memory and how does it arise/become established?
Memories stored in genes
Arise from the experiences of a species over eras
Established by natural selection acting on neural development
Association and motivation in memory
Working memory = can remember 7-9 numbers, with association and motivation -> 80 numbers.
Motivated memory is modality dependent e.g. food>non-food, hungry>sated
Memory capacity also depends on the meaningfulness and perceived importance of the info to the subject
e.g. memorise piece positions in real chess game - % correct master>beginner, memorise pieces randomly arranged - % correct beginner>master
