Memory Flashcards
Animal Picture- What did you see?
- visual system and “what” (ventral) pathway helped you identify that you saw a group of animals
- but, out of sight is NOT “out of mind”
- you can still remember the picture and you can still recall some details
long term memory-declarative
- things you know that you can tell others
long term memory nondeclarative
- aka procedural
- things you know that you can show by doing
What are sensory buffers?
- brief of iconic memors
- ex. fleeting image of scene
Short-term memory (STM)
- eg. phone number
- complex because multiple sensory modalities for multiple purposes
- 30 sec to few min (rehearsal)
- limited capacity
- temporarily retain information
Intermediate-term memory
- longer than STM
- ex. lunch today vs. last week
Long-term memory (LTM)
- enduring, near-permanent
- eg. what you worde to prom
- not perfect record, but important events to shape future behavior
- strength based on emotion
- “unlimited” capacity
encoding
- information in sensory buffer (ex. iconic memory) is placed in STM
Consolidation
STM are converted into enduring LTM
Retrieval
- LTM are returned to STM tobe used
- Memories are integrated with current working memory, to allow predictions about your current situation
- Memories can be updated and strenghtened before reconsolidation into LTM
Working memory
- retain and manipulate short-term information
- Ex. what to eat for lunch? What ingredients do you have? what did you have for breakfast? are you going to the gym later?
regions involved in forming working memory
Spatial location memory
Step 1: rat chooses an arm of maze to get a treat
Step 2: soon afterm the rat must recognize and enter same arm to get treat
Hippocampal cells
What is a cognitive map?
brain map of the relative spatial organization of objects and information
hippocampal cells
What do place cells do?
- encode for a specific location
What do grid cells do?
encode for intersections of superimposed abstract grid
What do border cells do?
encode for edges of map (perimeter)
Response memory experiment
Step 1: Rat placed in box 2, and turns left or right to get a treat
Step 2: Soon after, rat is placed in box 5 and only gets treat if turns the same way (left or right)
Which brain region is important for response memory?
- the caudate nucleus
- rats with lesion struggle w response memory (turn left-right task)
Object memory experiment
Step 1: rat knocks over yellow square object to get treat
Step 2: Soon after, rat must knock over the new (green, circular) box to get a treat
Which brain area is most important for object memory?
the extrastriate visual cortex
Where is information about an event distributed?
in the sensorimotor (visual, auditory, spatial) and prefrontal cortices
Information is linked so…
it is retrieved together
What does retrieval involve?
hippocampus and medial temporal structures
What does declarative/explicit memory deal with?
- facts and information
- things that you can tell (declare) to others
- includes semantic and episodic memory
What is semantic memory?
- general knowldge
- ex. our mascot is bearcat
What is episodic memory?
- memory of specific time, place, incident
- ex. HS graduation
How do we study declarative memory?
- test in humans by asking them to memorize list or recall an important event in their life
- test in animals by traning them on “object recognition memory” task- ex. monkey
Medial temporal lobe
- involved in forming declarative memory
- includes hippocampus and associated cortex areas
medial diencephalon
- important in forming declarative memory
- includes hypothalamus, thalamus, and mammillary bodies
Cortex stores declarative memory
- LTM about an event is distributed in same regions as STM
- information is linked so retrieved together
- retrieval may occur independent of medial temporal lobe
Declarative memory process
- sensory processing in cortex
- parrahippocampal, entorhinal, perirhinal cortex
- hippocampus
- medial diencephalon (thalamus, thypothalamus, mammillary bodies)
- declarative memory storage in cortex
Parts of the brain in medial temporal lobe
- hippocampus
- associated cortex areas (entorhinal, perihinal, and parahippocampal cortex)
Parts of brain in medial diencephalon
- thalamus
- hypothalamus
- mammillary bodies
What are other ways to describe nondeclarative memory?
- procedural
- implicit
What does nondeclarative memory deal with?
- deals with the “how”- skills and simple associations
- things shown by performance
What types of memory are included in nondeclarative memory?
- skill memory
- priming
- associative/conditioning
How do you test non-declarative memory in humans and animals?
- by asking them to learn a new skill
skill memory example
juggling
nondeclarative memory
priming explained
change in processing stimulus based on prior exposure
ex. rhyming word
nondeclarative memory
associative/conditioning
learning relation between stimulus/response or action/consequence
how do you study associative memory?
- training an animal to respond to an unrelated cue by pairing it with a related cue
Which parts of the brain are involved in forming skill memory? (nondeclarative)
- basal ganglia
- motor cortex
- cerebellum
Which parts of the brain are involved in priming? (nondeclarative memory)
specific areas of cortex (neo cortex)
Which parts of the brain are involved in associative learning?
- amygdala
- cerebellum
- striatum
Declarative and non-delarative can be best described as verbal vs. motor memory (T/F)
false, they are NOT motor vs. verbal
When does loss of information occur?
as time progresses between consolidation and retrieval
What does myelination do in terms of memory?
allows for faster information transfer
What makes memory possible?
synaptic plasticity
What is adult neurogenesis?
newly born neurons store information
What is synaptic plasticity?
- process of changing synapses to store information
- structure and function
What happens to neurons after training?
- more NT release
- more receptors on the membrain
- OR both!
- This means a larger postsynaptic potential (i.e. strengthened synapse)
Explain synaptic remodeling
- reorganization of existing pre- and postsynaptic strucures connect
- A more frequently used neural pathway takes over synaptic sites formerly occupied by a less active competitor
Synaptic plasticity- new synapses
- increased number of synaptic contacts between 2 neurons
- a neural circuit that is used more often increases the number of synaptic contects
short-term habituation explained
- if you repeatedly disturb siphon, the animal stops retracting gill
- sensory neurons release less neurotransmitter due to habituation to the stimulus
long-term habituation explained
- if you disturb siphon repeatedly over days, animal stops retracting gill faster
- this is due to a retraction (loss) of some synapses
Hippocampus highly organized circuit order
- entorhinal cortex inputs take perforant pathway to the…
- dentuate gyrus sends mossy fibers to…
- CA3 which sends shaffer collaterals to
- CA1 subregion of the hippocampus
Where is the entorhinal cortex and why is it important?
- adjacent to the hippocampus
- where the hippocampus gets the majority of its’ inputs from
Which neurons in the hippocampus circuit are pyramidal?
CA3 and CA1
What is long-term potentiation?
- stable and long-lasting enhancement of synaptic transmission
Explain tetanus and LTP importance
- When researchers stimulate presynaptic neurons w a brief high-frequency burst (thus inducing tetanus- an intesnse volley of action potentials), the response of the postsynaptic neurons was changed
- not the postsynaptic cells responded to normal levels of presynaptic activity by producing much larger EPSPs
- basically, synapses appeared to become stronger or more effective after the tetanus
Where does adult neurogensis occur? How?
- in the dentate gyrus
- cells will mature and receive input from the perforant pathway, strengthening this circuit
- dentate gyrus neurogenesis is incresed by exercise, enriched environments, training in memory games
Mechanisms of LTP
What happens if you stimulate perforant pathway at 1 Hz?
- get a stable response in dentate gyrus cells
- glutamate released which activates AMPA receptors
- NMDA receptors, however, are blocked by Mg2+
mechanisms of LTP
What happens if you briefly stimulate perforant pathway with a burst of electrical activity (tetanus)?
- lots of glutamate released
- Many AMPA receptors activated (stimulating more strongly)
- This stronger depolarization drives Mg2+ plugs from the NMDA receptors
- Now, the NMDA receptors are also able to respond to glutamate, allowing large amounts of Ca2+
- This large Ca2+ influx causes more AMPA receptors to be produced (via CaMKH protein) and inserted into the postsynaptic membrane
Mechanisms after LTP
After synaptic changes due to tetanus, what happens when you stimulate the perforant pathway at 1 Hz?
- you get a larger stable response in Dentate gyrus cells
- due to more AMPA receptors
What kind of receptor is AMPA?
only ligand-gated
What kind of receptor is NMDA?
ligand gated and voltage-gated for Na+ and Ca+
What is long-term depression?
- long-lasting and stable reduction- decrease in postsynaptic strength
- encodes information/memory
