Memory Flashcards
LO
- Discussing the different types of memory and the brain networks that support these.
- Discuss molecular mechanisms proposed to underpin memory.
- Discuss the experimental strategies that link plasticity and memory.
We need to make distinctions of memory types…
- Memory vs Habit e.g., memory= person, habit= how to brush teeth
- Explicit vs Implicit e.g., explicit= recollect answer and say it
- Knowing that vs Knowing how
- Memory without record vs memory with record
- Declarative vs procedural
- Biological information
Structure –> Function seems to underpin the different types of memory
Tell me about a study that gave insights into hippocampal-dependent memory
- Bilateral resection of the medial temporal lobe, to relieve severe epilepsy
- Profound memory impairment (scenes, words, faces)
- Learnt a hand – eye coordination skill (mirror drawing) over a period of 3 days (is all you need motor skills? As he couldn’t remember he did it a few days later)
HM= Henry Molaison (patient)
Tell me about memory impaired patients but what some people like HM was able to do…
- Impaired in declarative:
- Conscious, verbal/ non-verbal idea, sound, image, sensation, odor, or word
- –> Could also learn to read mirror-reversed words
- Poor memory for the task and for the words that were read
- Perceptual skills, not just motor skills, were intact.
Whats procedural knowledge?
- Skill-based
- Expressed through performance.
- Individuals have acquired a disposition to perform in a particular way
Whats priming?
Give an example
What patients is it intact with?
- Distinct from declarative memory (e.g., reading a list of words and recalling what was there when can’t see anymore)
- priming—the improved ability to detect, produce, or classify an item based on a recent encounter with the same or related item
- Word priming
- Intact in patients with amnesia
- EEG – reduction in cortical activity –> could allow for faster perceptual processing (i.e., priming)
Tell me the conscious/ unconscious memory systems
Tell me the divisions of long-term memory
What is declarative and non-declarative memory?
Tell me about short term memory
Tell me about how short term memory can become long term memory using HM as an example
Tell me about the experiments with eyeblink conditioning
What does the amygdala have critical role in?
The amygdala has a critical role in fear learning
What about the amygdala is conserved widely across species?
Function and connectivity conserved widely across species.
What is the amygdala activated by?
Amygdala activated by fear and strongly positive emotions
Tell me about the amygdala and fear learning in people with amnesia
What is procedural Habit memory characterised by?
Characterized by automatized, repetitive behavior.
Habit memory and rats with disrupted hippocampal function…
Rats with disrupted hippocampal function, failed when they needed to acquire a flexible behavior but succeeded when they needed to respond repetitively.
Rats with caudate lesions showed the opposite pattern
Tell me about the contrast seen in rats, similarity in humans between declarative memory and habit memory in memory-impaired patients with hippocampal lesions and those with Parkinsons
- A similar contrast between declarative memory and habit memory was shown for memory-impaired patients with hippocampal lesions and patients with nigrostriatal damage caused by Parkinson’s disease
- The neostriatum – affected in Parkinson’s disease (caudate nucleus and putamen, not the medial temporal lobe) is important for gradual feedback- guided learning that results in habit memory “gut feeling”
What is the Caudate nucleus?
The caudate nucleus. Component of the basal ganglia. Brain’s reward system and functions as part of the cortico–basal ganglia–thalamic loop. Goal directed behavior (shown in above image).
Tell me two strategies
LO II
- Discussing the different types of memory and the brain networks that support these
- Discuss molecular mechanisms proposed to underpin memory
- Discuss the experimental strategies that link plasticity to memory
“Neurons that fire together wire together”
What is the neurotransmitter between synapses?
Complexity of input pathways
Experiment example…(1)
Experiment example (2)
Why are NMDA receptor voltage-dependent?
Tell me about AMPA and NMDA components?
Response greater with AMPA receptors?
Synaptic plasticity
Tell me about CA3 synapses (MOSSY FIBRES)
- What is required for AP
- dependent on
- what the mechanism may allow
- Pronounced short term plasticity (facilitation) in these synapses. (2nd potential could happen relatively quickly after first due to presence of large amounts of Ca2+)
- Unitary EPSPs not sufficient to initiate a spike in CA3 neurons under control conditions, but reliably cause action potentials if stimuli delivered in “bursts” Presynaptic short-term plasticity
- Plasticity- dependent detonation may be critical for efficient coding, storage, and recall of information in the granule cell–CA3 cell network.
- “Full detonator mode” for tens of seconds after high frequency stimulation
- With longer bursts (100 stimuli in 1 second) plasticity can be extended for tens of seconds to allow “full detonator mode” for tens of seconds after high frequency stimulation.
- Depended on Ca2+ / calmodulin.
- This mechanism may allow a single highly specific cue to trigger the encoding, storage, or recall of complex information in CA3 pyramidal neurons.
CA3 synapses
Whats a memory trace and why is it studied?
A memory trace, also know as an engram, is a theoretical means by which memories are physically stored in the brain. The actual method of storage of memory, whether by biophysical or biochemical means, is still being debated.
There are multiple levels of analysis to understand memory storage
Tell me about short and long term sensitisation in synapses and what they’re due to
- Short-term sensitization is due to an acute, PKA-dependent enhancement of glutamate release from the presynaptic terminals of sensory neurons
- Long-term sensitization is due to changes in gene expression, causing expression of proteins that change PKA activity and lead to changes in synapse growth
Tell me some characteristics of engram cells
Engram cells are:
1) Activated by a learning experience,
2) Physically or chemically changed by the learning experience, and
3) Reactivated by subsequent presentation of the stimuli present at the learning experience
Tell me about Morris water maze memory experiment with mice
- https://www.youtube.com/watch?v=Ak7eyPGL03I&t=174s
- Put mice/rat in water to find platform and once on platform, they sit for 20 seconds roughly and then they keep doing to see how their memory changes with increased attempts. Then change scenario to see how they behave and how it changes
- Contextual fear conditioning.
- Activation of widely distributed neuronal ensembles in the dentate gyrus, cortex and lateral amygdala (LA).
- These active neurons can be tagged! (Engram?)
The evolution of lesion techniques in the search for the engram
Tell me about another experiment done on mice/rats in order to investigate memory and memory storage
- Contextual fear conditioning. (fear that a foot shock will come which is a measure of its memory)
- Activation of widely distributed neuronal ensembles in the dentate gyrus, cortex and lateral amygdala (LA).
- These active neurons can be tagged! (Engram?)
- CREB viral vector used to make neurons more likely to be part of the engram.
- The same vector allowed toxin-mediated destruction of neurons.
- Mice with ablated neurons could still acquire fear learning task.
- Ablating a similar number of random neurons did not disrupt memory retrieval
Experiments for loss/gain of function
Fear conditioning and memory experiment
Whats an emerging concept about a given memory?
An emerging concept is that a given memory is stored in functionally connected multiple engram cell ensembles dispersed in multiple brain regions, each ensemble providing a unique component of the overall memory
What are the two types of long term memory and their subdivisions?
Tell me the areas of the brain associated with the following areas…
- Episodic memory
- Procedural memory, classical conditioning and semantic memory
- familarity and priming
Cracking the mneminic code…
What does early phases of alzheimers diesease affect?
