Memory Flashcards
Define memory
the processes by which information is encoded, stored and retrieved for the purposes of remembering the past, informing current behaviour and planning the future
Name the 3 stages of memory as well as a short description about each
Encoding: converting the info acquired by your senses into patterns of activity within groups of neurons within the brain
Storage: retention of information acquired by your senses
Retrieval: recollection of information stored in memory
What is the “tip of the tongue” phenomenon?
a type of retrieval failure accompanied by the strong feeling that temporarily forgotten info is one the verge of being recalled
What is sensory memory?
persisting representation of a sensory stimulus for a brief period after it is no longer physically present
Name the 3 main types of sensory memory as well as the cortical areas in which they are mainly processed
- Visual: iconic memory (visual cortex)
- Auditory: echoic memory (auditory cortex)
- Tactile: haptic memory (somatosensory cortex)
Describe iconic memories (how much time they are stored for, example)
Iconic memories
Stored for less than 500 milliseconds
Essential to detect changes in the environment
• Ex: writing name in the air with a sparkler
Describe echoic memories (how much time they are stored for, example)
Echoic memories
Persist up to 10 seconds
• Ex: keeping track of speech during a conversation
Describe haptic memories (how much time they are stored for, example)
Haptic memories
Approx. 2 seconds
• Ex: manipulating and recognizing objects by touch
Define working memory
A memory register of limited capacity for both the amount of information it can store and the time for which information is retained. ( AKA short term memory)
WM is vulnerable to…
Vulnerable to disruption: if the info in working memory ceases to be the focus of our attention, it will be forgotten
• Ex: meeting a friend while going to the store, chatting, and forgetting what you rehearsed earlier
According to the multicomponent WM model, what are the 4 essential components of WM?
• Visuospatial sketch pad (stores visual images)
• Phonological loop (stores verbal info - rehearses and transforms images in phonological code)
• Episodic buffer (integrates info from loop and sketch pad with a sense of time, so they are remembered as a sequence of events)
• Central executive
○ Focuses attention
○ Divides attention
○ Permit switching from task to task
○ Interface with long-term memory
Name 2 ways in which WM interacts with LTM
- Subset of info in WM may be stored in LTM eventually
* Info in WM comes from focusing on info in LTM and incoming sensory info
Name a few of the functions of the prefrontal cortex
Prefrontal cortex: responsible for executive functions (AKA cognitive control) • Control of attention • Planning • Goal Setting • Judgement • Self-Control • Working Memory
Name the areas of the prefrontal cortex. Which of these are mostly associated with WM?
Areas of prefrontal cortex: • Orbitofrontal • Rostral • Dorsolateral** • Ventrolateral** • Dorsomedial • Ventromedial **: most associated with WM
What is the delayed response task?
1- food randomly placed on one of 2 plates in front of monkey
2- monkey’s view is covered for some time
3- monkey reaches for the food
What is the oculomotor delayed response task?
Oculomotor delayed-response task: Another similar task where monkeys had to remember where a square was on a blank screen indicated that neurons in the dorsolateral area were active during the task, confirming that the prefrontal cortex is involved in WM
Define Long Term Memory
Refers to a memory register of potentially unlimited capacity for both the amount of information it can store and the time for which information is retained
What are the 2 main types of LTM?
Declarative and nondeclarative memories
What is declarative memory? Name and describe its 2 sub types
Declarative memories: require the conscious recollection of information (AKA explicit memories)
Semantic Memories: memories for learned facts (no need to re-experience the context in which it was learned)
Episodic memories: memories for life events (rich in contextual details) - their retrieval requires mental time travel (re-experiencing the event)
Episodic memories require 2 important components, what are they?
- Include the awareness of the passage of subjective time (chronesthesia)
- Require autonoetic consciousness (ability to reflect on past event while being aware that those are your own memories)
Describe non declarative memories
expressed only through the performance of a task/habit without the need for conscious recollection of information (AKA implicit memory)
Name the 3 main ways in which nondeclarative memories can be acquierd
Acquired through:
Classical Conditioning
• Of emotional responses: pairing stimulus likely to trigger an emotional reaction with a neutral stimulus
• Of motor responses: pair stimulus likely to trigger a motor response with a neutral stimulus
Priming
• Type of nondeclarative memory in which exposure to a stimulus influences your response to a stimulus presented later
§ Ex: more likely to notice a piece of clothing on someone if you own the same piece
NonAssociative Learning
• Reflex pathway
There is 1 sub type of nondeclarative memory, what is it?
Procedural memory (a sub-type of nondeclarative memory)
• Type of nondeclarative memory that leads to the performance of skills and habit without the need for the conscious recollection of information
§ Ex: unlocking a lock without knowing what the numbers are
Name the 2 main brain regions involved in declarative memories
- Medial temporal lobes
- Including the hippocampus and related cortical areas; the perirhinal, entorhinal, and parahippocampal cortices and the amygdala
- Medial Diencephalon
- Includes the thalamus and the mammillary bodies of the hypothalamus
- Hippocampus is connected via bundle of fibers named fornix
Name the 2 main brain regions involved in nondeclarative memories
Depend on areas outside of the hippocampus and of the diecephalon
Name and describe the 2 main types of brain injury
- Traumatic brain injury: damage is done to a particular brain area (ex; gunshot wound) or can be more diffuse (concussion)
- Anoxic/hypoxic brain injury: Total (anoxia) or partial (hypoxia) deprivation of blood to the brain (ex: cardiac arrest)
What is amnesia?
Amnesia: memory deficits resulting from brain injury or psychological trauma
Name and describe the 3 types of amnesia
Retrograde amnesia: there is memory loss for info acquired before the brain damage
Anterograde amnesia: inability to form new memories since brain damage has occurred
• Usually patients have a bit of both
Temporally graded amnesia: memories for info acquired shortly before the damage are lost, but memories from more remote times are kept
Describe the case of HM (Henry Molaison)
Henry Molaison (HM): got his medial temporal lobes removed to stop seizures
• Suffered from severe anterograde amnesia and temporally graded retrograde amnesia extending to his childhood
• His nondeclarative memory was untouched - no need for conscious recollection
• Mirror tracing task: participants are required to trace a star with only looking at their hand in a mirror
• HM was able to complete this task after practice (comparable to normal subjects) - however he never remembered having practiced the task
Describe the case of HA
HA case study: suffered brain injury to dorsomedial thalamus and the mammillary bodies on both sides
• Considerable anterograde amnesia and some retrograde amnesia (no impairments of nondeclarative memory)
What is Korsakoff syndrome? How is it related to HM and HA cases studies?
Korsakoff syndrome: thiamine deficit (result from alcoholism) - has deteriorating effects on the dorsomedial thalamus and the mammillary bodies on both sides (like HA) and the patients suffer from those same types of amnesia
Name 2 ways in which new memories can be formed
when new connections between neurons are formed OR when existing synapses are strengthened
How is the strength of a synapse measured?
Measured by the level of excitability/responsiveness of the post-synaptic neuron when receiving a stimulus from the pre-synaptic neuron
Name 2 processes that can strengthen synaptic connections
- High-frequency signals (strong experience)
* Repeating signals (ex: studying)
Where is long term potentiation best studied?
at the glutamate synapses of the hippocampus
What happens when there is a weak signal in the glutamate neurons of the hippocampus?
little glutamate released, little Na+ is admitted in the neuron via AMPA
What happens when there is a strong signal in the glutamate neurons of the hippocampus?
large amount of glutamate released, more Na+ admitted in AMPA and serves to expulse the magnesium that previously blocked the NMDA channel; More Na+ and Ca++ can enter the neuron
What happens when calcium is released into the neuron?
Calcium is the mediator of LTP induction
What happens in early LTP?
Calcium initiates pathways that activate protein kinases
Name the 2 ways in which kinases enhance synaptic communication
- Phosphorylate existing AMPA receptors (making them more conductant to sodium)
- Make more AMPA receptors come to the membrane
What happens in late LTP?
new proteins are made and gene expression is activated to further enhance the connection between the 2 neurons
• Ex: creating new AMPA receptors
Which phase of LTP correlates with the formation of LTM?
Late LTP
