Module B: Memory Flashcards
Where is declarative memory stored?
Medial temporal lobe diencephalon
Where is emotional memory stored?
Amygdala
Where is procedural memory stored?
Striatum. Basal Ganglia
Where are motor skill memories stored?
Cerebellum
Non-declarative memory can be divided into…
Procedural, Emotional and Motor skills
Declarative memory can be divided into…
Semantic and Episodic
Immediate memory
Holds ongoing memory for a fraction of a second
Large capacity
Each sensory modality has its own memory register
Working memory
Holds information for seconds to minutes
Used to achieve certain goal
Limited duration and capacity
Long-term memory
Retained for days, weeks, lifetime
Immediate or working memory can both enter long-term
Enters long-term by concious or unconcious rehearsal
An Engram is…
The physical embodiment of memory in neuronal machinery, depends on changes in synaptic connections and/or growth/reordering of connections
Memory consolidation
can be from short term to long term, or can be immediately consolidated into long term
Why is forgetting important?
Those who can’t erase information have difficulties distinguishing important cognitive stimuli from trivial information
Retrograde Amnesia
Memory deficit prior to time of trauma, can form new memories.
Typically involves generalised lesions from trauma or neurodegenerative disease. Suggests long term memories are distributed throughout cerebral cortex (evidence = larger numbers of errors in maze with larger lesions)
Anterograde Amnesia
Memories cannot be formed after time of trauma.
Case of H.M: Amygdala, incus, hippocampal gyrud and anterior hippocampus removed to alleviate epilepsy => loss of short term declarative memory
Case of R.B: Ischaemia in surgery, can’t form new declarative memory, had a bilateral lesion of hippocampus, CA1 region in particular
Declarative memory consolidation depends on…
The integrity of the hippocampus and its subcortical connections to mammilary body and dorsal thalamus
Morris water maze and radial arm tests are used for…
Testing spatial memory consolidation (declarative)
Where do lesions have marked effect on radial and spatial maze learning?
Hippocampal lesions
Perirhinal have some effect
Lesions in which region delay matching and non-matching?
Perirhinal cortical lesions
Conditioned Learning
Generation of a novel response that arises from pairing novel stimuli with a stimulus that generates response being studied. Non-declarative memory
i.e. Classical: Pavlov’s dogs. Causes innate relflex.
Operant: Skinner’s box. Reward/punishment
Phylogenetic Memory
memories stored in genes
i.e. predator recognition
Association and motivation can….
Increasing working memory recall
Motivated memory is what dependent?
modality dependent
Acquisition and storage of declarative information?
Short term memory storage (hippocampus and related structures)
To
Long term storage
(a variety of cortical areas: Wernicke’s area for the meanings of words, temporal cortex for memories of objects and faces etc.)
Acquisition and storage of nondeclarative information
Short term memory storage
(sites unknown but presumably widespread)
To
Long term storage
(cerebellum, basal ganglia, premotor cortex, and other sites related to motor behaviour)
Characteristics of Early Phase LTP
- about 2 hrs
- protein modification (e.g. phosphorylation)
- translation independent
Characteristics of Intermediate Phase LTP
- about 6 hrs
- mRNA editing, stability, translation, splicing
- translation dependent/transcription independent
Characteristics of Late Phase LTP
- about 10hrs +
- transcriptional regulation and epigenetic modification
- transcription dependent
Late Phase LTP is involved in long term memory and involves…
insert picture
Brain-Derived Neurotrophic Factor is…
- a neurotrophin
- regulates neuron survival and differentiation, along with structure and function of neural circuits
- acts in CNS and PNS
- increased by exercise and environmental enrichment
What are some features of BDNF regulation of structure and function of neural circuits?
- release activity dependent
- receptors often co-expressed with glutamate receptors
- synthesised, stored and released from glutamatergic neurons
- highest level of expression in hippocampus
What was the effect of BNDF on LTP observed in Huntingon’s model mice?
- only mice with supplemented BDNF maintained LTP
- this was recorded at CA1 region after Schaeffer collateral stimulation
What stage of LTP is effected by BDNF?
- CaMKII, PI-3K, PKA, PKC activation
- activation of all or some of these factors essential at all LTP Phases
What does BDNF do?
- increases production of under 4% of cellular proteins
- reduces specific miRNA levels, thereby increasing the expression of specific proteins that miRNA inhibits at traqnslation
- increases neurogenesis and LTP
What are some of the effects of age on the brain?
- a decrease in weight
- decrease in synapse count, decreased connectivity
- engrams of memories deteriorate due to above
What is dementia?
A failure of recent memory and intellectual abilities
What labelling was used to help locate engrams?
use of a promotor to drive expression of reporter gene - c-fos - and channelrhodopsin which opens with blue light stimulation, allowing sodium influx and action potential
How was false memory implanted experimentally?
- Viral transfection with ChR2 and optical fibre implantation to hippocampus
- Memory formed and engram labelled with ChR2
- Mouse placed in a different environment and engram stimulated at same time as foot shock
- Observe the reaction of the mouse to each environment, and see if it reacts to foot shock in first environment even though it has not recieved foot shock there
