Learning and Memory Flashcards
what is the definition of memory
a mechanism by which past experience alters present experiences or behaviours
what are engrams
An engram is a unit of cognitive information imprinted in a physical substance, theorized to be the means by which memories are stored.
as biophysical or biochemical changes in the brain or other biological tissue, in response to external stimuli.
the link between memory and remembering presumed biochemical in nature
nobody knows with certainty where how they are formed
located all over the brain in places related to processing the learning (amygdala)
what did an experiment with rats and 3 different types of maze show about engrams
quite large areas of cerebral cortex had to be removed to prevent learning and memory of complex tasks.
these lesions had little effect on simple tasks
implying that memory and learning is performed using PARALLEL PROCESSING SYSTEMS
not serial processing systems
what is habituation
if there is a repeated response this leads to a decrease in response (and NT release)
take less notice of stimulus
what is sensitisation
if there is a repeated response this leads to in an increase in response (mediated by an interneuron)
what is associative learning
as cells fire simultaneously they increase the synaptic associations
this results in networks of cells which are synaptically linked
eg. touch hot stove
now associate hot stove with pain
dont touch hot stove
behaviour modified/learned
conditioning
what is long term potentiation
process involving persistent strengthening of synapses that leads to a long-lasting increase in signal transmission between neurons.
long term increase in response lasts a long time
-also requires genetic involvement
major cellular mechanism underpinning learning and memory
what is long term depression
it prevents whole brain potentiation
therefore counteracts LTP, modulates it
LTD is initiated by a slower train of stimulatory impulses over a longer period
Long-term depression is the process of reduction in the efficacy of neuronal synapses that last for hours or longer, while long term potentiation is the process of strengthening neuronal synapses based on recent patterns of activity.
what are the 3 defined types of memory
short term memory
working memory
long term memory
(also executive function)- CONSCIOUS DRIVE- only works if you WANT it to happen
what is short term memory
- a very brief (ms-seconds) memory from external stimulus or retrieval from a long term memory
- easily displaced by another stimulus (problem in ADHD)
- can be extended into working memory
- PHONIC LOOP (temporal extension)
- CHUNKING which links familiar chunks together to extend the size of chunk
what is chunking
how can you test it
can be involved to extend short term memory to working memory
group info together- so just remember groups as content is organised effectively within the groups
test-DIGIT SPAN
read increasing series of numbers and IMMEDIATELY repeat to show digital span
– normal 6-7 digits
if you already know several sequences you can remember what to recall by chunking into KNOWN things
what is working memory
- maintenance and integration of info in an active state for a brief time in order to achieve a goal (short term)
- comprised of a mix of short and retrieved long term memory
short term memory only lasts a few seconds- therefor must be REPEATEDLY RE-ACTIVATED
when the task is over the working memory either is encoded into LONGTERM or left to lapse
describe the pathway/ involvement of other kinds of memory with working memory
sensory info jogs an idea
feeds into short term memory (few seconds)
phonic loop to continue the thought and stay on tract to achieve the short term goal
working memory feeds into LTM
can retrieve memories via the LTM
it is also possible for LTM to be formed directly from sensory input under control of executive functions
(pre-frontal cortex)
what is long-term memory sub-divided into
and describe them
- declarative memory
can say what that memory is
RECOLLECTION - non-declarative memory
memory allows you to do things
-riding a bike
PERFORMANCE
describe the taxonomy (classification) of declarative memory
declarative memory is conscious memory
which feeds into two parts
1. SEMANTICS (language/ facts)
2. EPISODIC (events/experiences)
-familiarity
-recollection
1 and 2 join to form autobiographical memory
(eg. remember that lecture because that mic didn’t work)
MEDIAL TEMPORAL LOBE STRUCTURES/ ASSOCIATION AREAS
describe the taxonomy (classification) of non-declarative memory
non-declarative does not require conscious effort
(eg. riding bike- need repeated movements, but dont remember move this leg, – just do it)
this feeds into 3 parts
- PROCEDURAL (habits and skills) BASAL GANGLIA, CEREBELLUM
- PRIMING (habituation) and (sensitization- DORSAL HORN WIND UP)
- ASSOCIATIVE LEARNING (classical conditioning- PAVLOVIAN, HYPOTHALAMUS) and (emotional responses, AMYGDALA)
what are the 4 types involved with learning (storing memory)
- ENCODING
-memory creation - STORAGE
-persistence of memory traces - RETRIEVAL
-memory recovery - CONSOLIDATION
-strengthening of memory traces
what are the structures associated with the formation of memory in the temporal lobe system
- hippocampus
- fornix
- mamillary body and hypothalamus
- thalamus (reconnects with engrams all over cortex)
describe memory formation
- series of events are encoded by the hippocampus and a reference is made to their location
– HIPPOCAMPAL INDEX (storage method that connects sensory modalities as an experience), like vision, smell, auditory - if this info is recalled prior to consolidation the hippocampus performs the retrieval from its index
- after consolidation of the memory, retrieval can be initiated directly from the sensory cortices
– become less reliant on the hippocampal index
–retrieval stimulates less hippocampus
– can just remember as consolidated (eg. studying lol)
how can plasticity in LTM be used in counselling for post-traumatic stress disorder
patients re-live events then given ADRENERGIC BETA RECEPTOR BLOCKER
(propanolol)
this blocks re-consolidation of the memory
and decrease anxiety over it
what is consolidation a result of
physical changes at the synapse
what are some structural changes that can occur at the synapse (consolidation)
- increase pre-synaptic vesicles, postsyn vesicles, ribosomes
- synapses develop separate synaptic zones (cleft/ wall in spine)
- single spine may divide into two
- new dendritic spines
which structures are important in consolidating non-declarative memory
CORPUS STRIATUM- caudate nucleus and putamen (influenced memories involving movement and procedural memory– Olympic diving)
CEREBELLUM- influences fine motor learning (speech movements)
describe the case of HM
Patient HM suffered from
severe epileptic seizures from
aged 9 following a bike
accident.
These increased in severity
with time until he was getting
up to 10 minor seizures per
day, and a major one every
few days. The source was
assumed to be the medial
temporal lobes
At age 27 had an 8 cm length of
medial temporal lobe
removed bilaterally (which
included entorhinal cortex,
amygdala and the anterior 2/3
of the hippocampus)
alleviated symptoms with no effect on:
perception
intelligence
personality
working memory
RETROGRADE AMNESIA
-some years before operation could not remember
EXTREME ANTEROGRADE AMNESIA
-inability to remember identify of new people
-couldnt remember numbers/evetns
could not consolidate NEW DECLARATIVE LONG TERM MEMORIES
short term working memory was in tact (3-5 mins could remember)
what is retrograde amnesia
can’t recall memories that were formed before the event that caused the amnesia.
what is anterograde amnesia
cant form new memories after the accident
what is dissociated amnesia
amnesia occurring without any other deficits
describe the case of patient NA
The case of patient NA:
Aged 21 , whilst in the armed forces a colleague accidently thrust a
miniature fencing foil up through NA’s nose and into the left dorsomedial thalamic
nucleus. In addition his Mammillary bodies were damaged bilaterally.
The hippocampus however was undamaged
Diencephalon and amnesia
In this patient cognition was normal and his IQ was unaffected (125).
He suffered from some retrograde amnesia extending about 2 years prior to the
accident but also profound anterograde amnesia
Taken together with the case of HM this supports the idea of a functional link
between the dorsomedial thalamus and the medial temporal lobe (hippocampus
and associated structures) in memory consolidation
was HMs ability to form non-declarative memories impaired
He was able to learn to learn and retain how to draw in a mirror – viewed as a skill and therefore non-declarative
HM’s case illustrates that declarative, non-declarative, short term and long term memory are not processed in the same place or by the same mechanisms
dont need hippocampus
what is the role of diencephalon and memory consolidation
brain structures other than the temporal lobes can cause amnesia when damaged and are
involved in memory consolidation.
Lesions in either the anterior or dorsomedial nuclei of the thalamus, or in the Mammillary
bodies can cause anterograde amnesia
In addition, the dorsomedial nucleus of the thalamus receives input from temporal
lobe structures (like the amygdala of the limbic system) which is then relayed almost
exclusively to the frontal cortex (executive function).
