Learning and Memory

Question 1

what is the definition of memory

Answer 1

a mechanism by which past experience alters present experiences or behaviours

Question 2

what are engrams

Answer 2

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)

Question 3

what did an experiment with rats and 3 different types of maze show about engrams

Answer 3

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

Question 4

what is habituation

Answer 4

if there is a repeated response this leads to a decrease in response (and NT release)

take less notice of stimulus

Question 5

what is sensitisation

Answer 5

if there is a repeated response this leads to in an increase in response (mediated by an interneuron)

Question 6

what is associative learning

Answer 6

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

Question 7

what is long term potentiation

Answer 7

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

Question 8

what is long term depression

Answer 8

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.

Question 9

what are the 3 defined types of memory

Answer 9

short term memory
working memory
long term memory

(also executive function)- CONSCIOUS DRIVE- only works if you WANT it to happen

Question 10

what is short term memory

Answer 10

1. a very brief (ms-seconds) memory from external stimulus or retrieval from a long term memory
2. easily displaced by another stimulus (problem in ADHD)
3. can be extended into working memory
   - PHONIC LOOP (temporal extension)
   - CHUNKING which links familiar chunks together to extend the size of chunk

Question 11

what is chunking
how can you test it

Answer 11

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

Question 12

what is working memory

Answer 12

1. maintenance and integration of info in an active state for a brief time in order to achieve a goal (short term)
2. 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

Question 13

describe the pathway/ involvement of other kinds of memory with working memory

Answer 13

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)

Question 14

what is long-term memory sub-divided into
and describe them

Answer 14

1. declarative memory
   can say what that memory is
   RECOLLECTION
2. non-declarative memory
   memory allows you to do things
   -riding a bike
   PERFORMANCE

Question 15

describe the taxonomy (classification) of declarative memory

Answer 15

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

Question 16

describe the taxonomy (classification) of non-declarative memory

Answer 16

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

1. PROCEDURAL (habits and skills) BASAL GANGLIA, CEREBELLUM
2. PRIMING (habituation) and (sensitization- DORSAL HORN WIND UP)
3. ASSOCIATIVE LEARNING (classical conditioning- PAVLOVIAN, HYPOTHALAMUS) and (emotional responses, AMYGDALA)

Question 17

what are the 4 types involved with learning (storing memory)

Answer 17

1. ENCODING
   -memory creation
2. STORAGE
   -persistence of memory traces
3. RETRIEVAL
   -memory recovery
4. CONSOLIDATION
   -strengthening of memory traces

Question 18

what are the structures associated with the formation of memory in the temporal lobe system

Answer 18

1. hippocampus
2. fornix
3. mamillary body and hypothalamus
4. thalamus (reconnects with engrams all over cortex)

Question 19

describe memory formation

Answer 19

1. 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
2. if this info is recalled prior to consolidation the hippocampus performs the retrieval from its index
3. 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)

Question 20

how can plasticity in LTM be used in counselling for post-traumatic stress disorder

Answer 20

patients re-live events then given ADRENERGIC BETA RECEPTOR BLOCKER
(propanolol)
this blocks re-consolidation of the memory
and decrease anxiety over it

Question 21

what is consolidation a result of

Answer 21

physical changes at the synapse

Question 22

what are some structural changes that can occur at the synapse (consolidation)

Answer 22

1. increase pre-synaptic vesicles, postsyn vesicles, ribosomes
2. synapses develop separate synaptic zones (cleft/ wall in spine)
3. single spine may divide into two
4. new dendritic spines

Question 23

which structures are important in consolidating non-declarative memory

Answer 23

CORPUS STRIATUM- caudate nucleus and putamen (influenced memories involving movement and procedural memory– Olympic diving)

CEREBELLUM- influences fine motor learning (speech movements)

Question 24

describe the case of HM

Answer 24

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)

Question 25

what is retrograde amnesia

Answer 25

can't recall memories that were formed before the event that caused the amnesia.

Question 26

what is anterograde amnesia

Answer 26

cant form new memories after the accident

Question 27

what is dissociated amnesia

Answer 27

amnesia occurring without any other deficits

Question 28

describe the case of patient NA

Answer 28

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

Question 29

was HMs ability to form non-declarative memories impaired

Answer 29

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

Question 30

what is the role of diencephalon and memory consolidation

Answer 30

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).