Learning and Memory Flashcards
Define Learning and Memory.
Learning: the process of acquiring new and relatively enduring information, behaviour patterns, or abilities as a result of practice, study, and/or experience
Memory: the ability to learn and neurally encode information, consolidate the information for long-term storage, and retrieve or reactivate the consolidated information for a later time.
What is the H.M Case study? What did it tell us about memory/learning?
H.M. had his anterior temporal lobe removed due to uncontrolled epilepsy. Ended up with Anterograde amnesia; he was unable to form new memories but demonstrated evidence of skill-based learning and conditioning/association learning.
This tells us that the hippocampus is not necessary for skill-based memory and conditioning but is for other forms of memory (e.g. declarative memory).
What is the difference between declarative and non-declarative memory.
Declarative memory: facts and infomration aquired through learning that can be stated or described. Includes episodic (autobiographical) memory and semantic memory (facts; e.g. Tigers can be found in India).
Non-declarative Memory: shown be performance. Includes skill learning (e.g. how to ride a bike), priming (unconsciously being “nudged” in a certain direction. E.g. showing you the word cat (to fast for conscious recognition) and then asking you to list types of pets ). and Conditioning (e.g. associating two stimulus together.)
Where are the different forms of memory stored in the brain?
Episodic (autobiographical): Cortex Semantic: Cortex Skill Learning: Basal Ganglia, motor cortex, cerebellum Priming: Cortex Conditioning: Cerebellum
What is Karasakoff Syndrome?
A degenerative disease which damages the mamillary bodies and affects memory. Karasakoff syndrome reinforces the theory that it is a combination of the medial temporal lobe (hippocampus) and the midline regions of the limbic system that are part of the larger memory system.
What is the pathway for forming declarative memories?
Sensory Processing cortex –> parahippocampal entorhinal and Perihinal cortex –> hippocampus –> medial diencephalon + mamillary bodies –> declarative memory storage in the cortex.
What is spatial learning and what areas of the brain are involved?
Spatial Learning: learning to navigate a space, the formation of a mental map. The hippocampus is involved in spatial learning and animals that hide food in many locations (e.g. some birds, squirrels) tend to have a larger hippocampus
What is neuroplasticity?
Neuroplasticity is changes in neurons and synapses as a result of experience. It is the neural mechanism of memory.
Examples of neuroplasticity:
- the neuron produces/releases more of a neurotransmitter
- the post synaptic area gets larger
- Other axons get involved
- new synapses form
- synapses shift their arrangement
What did the rat environment study demonstrate about experience and neurological changes?
This study demonstrated that experience can result in real, physiological changes.
In comparison to the rats in the impoverished condition, rats in the enriched condition showed:
- heavier, thicker cortex
- enhanced cholinergic activity (increased ACh activity –> an excititory effect)
- More dendritic branches and spines
- larger cortical synapses
- more hippocampal neurons
- greater recovery from brain injury
What are the three processes involved in memory systems?
Encoding: information enters the sensory channels and is passed into short-term memory
Consolidation: Information in short term memory is transferred to long term memory
Retrieval: A stored memory is used by the organism.
What are some characteristics of long term memory?
It is seemingly limitless, we have yet to discover a cap for the amount of information we can hold in long term.
Memories in Long-term can be subject to distortion
Forgetting is a normal part of long term memory, it helps filter out unimportant information.
What are memory traces?
Memory traces are persistent changes in the brain that reflect the storage of memory. They don’t fade with time but they do deteriorate due to interference from events before and after formation.
For example, reconsolidation is the return of a memory trace to a stable long term storage after it has been made temporarily changeable during the process of recall. This process of reconsolidation can lead to the creation of false memories.
What is a Long Term Potentiation?
When a Tetanus (a high frequency burst of electrical stimulation) is applied to a presynaptic neuron, it causes them to produce a high rate of action potentials that drive the post synaptic cell to fire repeatedly. Stable long lasting enhancement of the synaptic transmission is called Long Term Potentiation.
For example, in neurons using glutamate: Glutamate stimulates AMPA receptors under normal conditions. When a tetanus occurs, so much glutamate is released that the AMPA receptors depolarize the cell more than normal. When it reaches a certain threshold, the magnesium ion that blocks NMDA receptors is dislodged and Ca2+ can also enter the cell, further depolarizing it. This activates a second messenger system that increases the number of AMPA receptors and increases the receptors conductance of Na+ and K+. It also causes the release of a retrograde transmitter which induces the presynaptic cell to release more glutatmate than it did before. All of this results in long term enhancement of the synaptic strength because there is increases sensitivity, increased # of receptors, and increased amount of the neurotransmitter.
