Learning, Memory, and Plasticity Flashcards
Clive wearing - What were effects demonstrated by damage to his FRONTAL LOBE?
Repeating himself
What did Clive wearing suffer from/how did it effect him?
Viral Encephalitis
Effects were extensive
Mostly affected medial temporal lobe bilaterally, hippocampus
Frontal lobe, amygdala
Caused him to develop temporal lobe amnesia
-
Clive wearing - What were effects demonstrated by damage to his AMYGDALA?
Trouble regulating emotions
Highly emotional behaviour
Who was H.M?
Epileptic who had his temporal lobes removed
Seizures were removed, so was his LTM
Mild retrograde amnesia, severe anterograde amnesia
Retrograde amnesia
Backward-acting
Unable to remember the past
Anterograde amnesia
Forward-acting
Unable to form new memories
What was learned from both Clive Wearing and H.M.?
- Medial temporal lobe is important for memory
- Although both show significant memory deficits, both show certain memorial capabilities e.g. Clive could still play music and knew who is wife was/H.M. could still tie his shoelaces
What could both Clive Wearing and H.M do surprisingly?
Both could learn new skills
Not remember being taught, would remember the skill
Retrieval
Bringing information from LTM back to STM to perceive/think about it actively
Encoding
Putting things from STM into LTM storage
Rehearsal
A control process
To keep information in the STM/active working memory
Neuroanatomy of object-recognition memory
- Early animal models of amnesia involved implicit memory and HIPPOCAMPUS
- Monkeys with bilat. medial temporal lobectomies show LTM deficits in explicit memory
- Performance normal for active 150-20 seconds, then lose the information
Episodic memories
Involves conscious recollection of previous experiences
(together with their context in terms of time, place, and associated emotions)
Semantic Memories
Involves general world knowledge that we accumulate
e.g. facts, figures, numbers etc.
What type of memory (beyond anterograde etc.) did H.M and Clive lose?
Both lost most of their explicit memory, kept much of their implicit memory
Medial Temporal Lobe Amnesia
- Not all pts. with this form are unable to form new explicit LTM
- Semantic memory may function normally while episodic memory does not
- May have difficulty imagining future events
Important Regions for Explicit Memory Function – Hippocampus
Heavily in explicit, not much in implicit
Encoding (especially explicit)
Spatial location
Important Regions for Explicit Memory Function – Neocortex
Transfer from STM to LTTM
Planning
Important Regions for Explicit Memory Function – Amygdala
Emotional memories
strengthening memory formation
Activate memory formation in hippocampus
Important Regions for Explicit Memory Function – Prefrontal Cortex
Retrieval of information from LTM
Rhinal Cortex
Play an important role in object recognition
Hippocampus and Memory for spatial location
Rhinal cells
Hippocampectomy produces deficits on morris and radial arm maze
Place cells
Once taught, more quickly through the maze, when remove, each trial is a new trial
Place cell
In hippocampus
Respond to when a subject is in a particular place and to other cues
Procedural Memories
Memory for how to do things
Motor actions, balance etc.
Priming
Facilitation of inhibition of a process after repeated exposure to a stimulus
Conditioning
Developing a positive or negative associations with a stimulus being paired with a positive/negative outcome
H.M –> Digit-Span task
Can repeat digits provided the time between learning and recall is within duration of short-term memory
H.M –> Block-Tapping memory-span test
Demonstrates that HM’s amnesia was global
AKA Not limited to one sensory modality
H.M. –> Intact procedural memory
Improves with practice on sensorimotor tasks (mirror-drawing, rotary pursuit) and on non-sensorimotor tasks (Incomplete pictures)
Without recalling previous practice sessions
H.M. —> Conditioning
Readily learns responses through classical conditioning
no memory of conditioning trials
Where are memories stored?
Across multiple systems
Memory storage - Hippocampus
Spatial location
encoding of explicit mem.
Memory storage - Perirhinal cortex
Object recognition
Memory storage - Cerebellum
Sensorimotor skills
Memory storage - Stratium
Habit formation
Prefrontal cortex - memory
- Temporal order of events and working memory
- Tasks involving series of responses
- Different parts of PFC mediate different types of working memory according to fMRI
Basal forebrain and memory
- Involved in acetylcholine release
- facilitating plasticity at neuronal level
- Appears role in alzheimers disease
Which area is largely involved in STM or working memory?
Prefrontal regions
Hebbian Learning
Changes in synaptic efficiency are the basis of LTM
Long-Term Potentiation
- Synapses are made stronger by repeated stimulation
- Increases AP/firing rate over time, each time the same stimulus is introduced
Explain long-term-potentiation: Depolarization, glutamate binders, and calcium ions
○ If the postsynaptic neuron is not already depolarized, when glutamate binds to its receptors, the receptors only permit few calcium ions to come in.
○ If the binding of glutamate to NDA receptors happens, at any time other than when the postsynaptic neuron is already depolarized, then we do no get any increase in action potentials (doesn't mean we don’t get them, just means we do not get more)
LTP - Sequence of events
- NDMA receptors respond if glutamate bonds and neuron is partially depolarised
- CA2+ open do not open until both conditions are met
- See synaptic changes (amount of NT released and bound)
- Leads to increase in speed and excitation of AP
Clive Wearing and Long-term potentiation
Clive does NOT have LTP
Does not have increased action potentials based on explicit learning
LTP can last for…
Many weeks
LTP only occurs if presynaptic firing is followed by…
Postsynaptic firing
Hebb’s Postulate for learning
- Co-occurrence of firings in pre-and postsynaptic neurons necessary for learning and memory
- Pairing together of neuronal information leading to strengthening of neural path
Opposite of long-term potentiation
Long-term depression
What brain structure is largely known for its role in memory consolidation?
Hippocampus
What is another term used when referring to long-term potentiation?
Synaptic consolidation
- As it involves the reorganization of synaptic structures
Systems Consolidation
The gradual reorganization of neural circuits
Three important regions for Explicit Memory Formation
Neocortex
Hippocampus
Amygdala
Hippocampus holds more ________ memory, the cortex holds more __________ memory
Hippocampus - recent memory
Cortex - Remote memory
Concussions and memory
Concussions disrupt consolidation and storage of recent memories
Which stage of sleep does consolidation occur?
slow-wave sleep
Age and sleep
As we age, slow-wave sleep becomes increasingly interuppted
Reconsolidation
- Each time a memory is retrieved from LTM, is temporarily held in STM
- Memory in SM is susceptible to post-traumatic amnesia until reconsolidated
Anisomycin
Protein synthesis inhibitor
Prevents reconsolidation of fear in rats if applied directly to amygdala
