Final Exam New Material: Chapters 18-20 Flashcards
What did Theodule Ribot propose?
In what order do memories disappear?
That during diseases of the brain, memories disappear in an orderly fashion.
Recent memories –> Personal memories –> Habits, skills –> Emotional memories
What is Ribot’s law?
Old memories are more resistant to disease/disruption than new memories.
What is the Standard Model of Systems Consolidaiton?
After initial learning, the memory trace consists of weakly connected neocortical patterns held togehter by their temporary connections with the medial temporal hippocampal (MTH) system. As the memory ages, intrinsic processes result in the consolidation or strengthening of the connections among the neocortical patterns and can therefore be retrieved without the hippocampus.
According to the Standard Model, what are the reasons that old memories are more resistant to disruption?
- Over time the memory content in the neocortex becomes consolidated and no longer requires the hippocampus for retreival.
- The hippocampus is more vulnerable to disruption than neocortical areas.
- Since retrieval of recent memories requires the hippocampus, they would be more disrupted by hippocampal dysfunction.
Why might the contextual fear model be inappropriate for evaluating the standard model of systems consolidation?
The retrieval of the memory does not require the pattern completion properties provided by the hippocampus.
What is cellular vs. systems consolidation?
- Cellular Consolidation: Consequence of synaptic biochemcial events initiated by the original experience, time frame of hours
- Systems Consolidation: Conseqeunce of an interaction between the medial temporal hippocampal system and neocortex, time frame days, weeks, months, years
What did Nadel and Moscovitch conclude?
What was the evidence?
Both old and new episodic memory always depend on the hippocampus. Patients with almost complete damage to the hippocampus could not recall either new or old episodic memories.
What are the 2 main problems associated with testing people who have damage to the medial temporal lobes?
- The brain damage extend beyond the regions of interest
- There is no way to completely control for the initial strength of the memory.
What is the advantage of animal studies?
- Provide animals with a known behavioral experience
- Vary the exact time between the experience and the occurence of the brain damage
- Vary the extent of the brain damage
Did animal studies support the standard model?
No support for the standard model, the older 3 and 6-month old memories were still disrupted by hippocampus damage. New memories were also disrupted.
What experiment showed that retrograde but not anterograde damage to the hippocampus produced amnesia?
What did they suggest?
Damage to hippocampus prior to contextual fear conditioning does not impair retreival of the memory, but damage to the hippocampus after conditioning prevents subsequent retrieval of the memory.
Without a hippocampus, the memory may be stored extrahippocampal
What experiment showed that new memories can survive hippocampus damage if training is distributed?
Contextual fear conditioning produced by several shocks delivered in the same session is impaired by subsequent damage to the hippocampus, but contextual fear produced by the same number of shocks delivered in sepearte sessions is not affected by damage to the hippocampus.
What experiment showed that the extrahippocampal system acquires the memory when the hippocampus is present?
Silencing the hippocampus prior to the retrieval test has no effect on retrieval of a contextual fear memory acquired when the hippocampus was funcitoning normally.
What is a fundamental problem with the contextual fear conditioning paradigm?
It does not depend on pattern completion processes. There is no need for the animal to pattern complete because all features of the context are present as the animal continuously explores the context.
What is competitive trace theory?
As memories age, repetition and replay may consolidate connections among the core overlapping elements of neocortical units to create a semantic memory that may be recalled in the absence of the hippocampus.
What is an instrumental behavior?
Studying how a behavior is modified by the outcome it produces
What is Thorndike’s Law of Effect?
Outcomes produced by behavior ultimately adapt the animal to the situation by strenghtening and weakening exsisting stimulus-response connections.
Outcomes that reward behavior strengthen S-R connections, while nonrewarding outcomes weaken connections.
What is Tolman’s Cognitive Expectancy Theory?
Instrumental behaviors are organized around goals and mediated by expectation of an outcome.
According to Thorndike what is learned and what is the role of the outcome?
S-R connections are strengthend or weakend and the role of the outcome determines which
According to Tolman what is learned and what is the role of the outcome?
Expectancies are learned and the outcome provides incentive motivation for perfoming the behavior
How do actions and habits differ on what 4 dimensions?
What is the reward devalution strategy?
The reward devalution strategy centers on changing the value of the outcome after the animal has solved the problem.
What can one conclude if the subsequent test performance is influenced by the devalution?
That the behavior was supported by the action system.
What is the progession of control between action and habit systems as training continues?
Instrumental behaviors are initially controlled by the action system, but following limited training the animals behavior is reduced following reward devalution. With extensive practice they become habits and reward devaultion has no effect compared to the control condition.
Describe the relationship between action and habit systems.
What happens when you reverse the contingencies?
Action and habit systems compete for control. Once an instrumental response is well learned, the two systems can work together to support the same behavior, with the habit system dominating. However, when you reverse the contingencies the action system attempts to rapidly adjust to the system, but the output from the habit system can interfere with adaptation.
Ex: American crossing the street in England has to overcome the habit of looking left before crossing
What was the Pauli experiment?
What happened when the action or habit system was inhibited prior to phase 2?
In Phase 1, rats are trained to press levers associated with different outcomes. Rats pressed the lever with the more rewarding outcome more. In Phase 2, the contingencies were reversed.
Inactivating the action system impaired the rat’s learning the new contingency, whereas inactivating the habit system facilitated this learning.
How does the adjacent arm task show that the acquisition of instrumental behaviors depends on the striatum?
Rats with damage to the striatum could not learn that immediately turning left or right to enter the adjacent arm would be rewarded.
Where do fear neurons project?
Fear neurons provide excitatory projections to the central nucleus and to neurons in the prelimbic region of the prefrontal cortex.
Where do extinction neurons project?
Extinction neurons project to infralimbic projecting ITC-b neurons.
What happens inside the amygdala when an aversive event occurs?
Specifically referring to ITC cells
The inhibitory influence of ITC-b neurons on central neurons will be removed by ITC-a cells and excitatory drive produced by fear neurons and prelimbic cortex neurons will increase.
What is the neural basis for fear extinction?
Extinction training strengthens synaptic connections linking the context and CS input to extinction neurons in the basal nucleus to ITCs and to neurons in the infralimbic prefrontal cortex that also projects to ITCs. Thus, when the CS is presented ITC-b is activated and neurons in the critical amygdala are inhibited.
What is the role of perineuronal nets in the regulation of plasticity?
Early in development, immature perineuronal nets surround spines and during this period extinction training can erase a memory. When these nets are mature, extinction training does not erase the fear memory and extinction is due to new learning.
