15. LEARNING & MEMORY Flashcards
What are the broad two types of memory?
- Declarative memory
2. Non-declarative memory
What is declarative memory?
- Explicit
- Declarative memory refers to facts & events that can be recalled or retrieved consciously
- These memories are explicitly stored & recalled
What is non-declarative memory?
- Implicit
- Non-declarative memory is accquired & can be used unconsciously
- Can affect thoughts & behaviors
What are three types of non-declarative memory?
- PROCEDURAL MEMRY - Striatum
- SKELETAL MUSCULATURE- Cerebellum
- EMOTIONAL RESPONSE - Amygdala
*What is procedural memory?
- Procedural memory is part of long term memory, involves knowing how to do certain procedures without conscious awareness of previous memories
- Involves the striatum
What is associative learning?
- A type of learning where a new response is associated with a particular stimulus
- E.g Pavlov
What are the three types of declarative memory?
- WORKING MEMORY
- SHORT TERM MEMORY
- LONG TERM MEMORY
What is working memory?
- Type of declarative memory
- Cognitive system with limited capacity
- Temporary storage lasting seconds
- Found in pre-frontal cortex
What is short term memory?
- Type of declarative memory
- Can hold information for short amount of time but not modified
- Vulnerable to disruption
What is long term memory?
- Type of declarative memory
- unlimited capacity
- Can recall memory after months or years
- Issue is accessibility not availability
How can short term memory be converted into long term memory?
- Memory consolidation
- Memory consolidation is a time dependent process where learned experiences can be transferred into the long term memory
Describe the pathway of information from the sensory information into long term memory?
Sensory information -> Short term memory or short term memory
- Short term memory -> long term memory
What type of memory is found in the pre-frontal cortex?
- Working memory
What are the functions of the pre-frontal cortex?
- Decision making
- Problem solving
- Planning
- Self-awareness
Describe an experiment showing the importance of the pre-frontal cortex
- In an animal study, where the animal had to remember where the object was located from memory., there was a delay phase
- During this delay phase, the animal was trying to remember where the object was using it’s working memory
- There was increased firing in the pre-frontal cortex showing the importance of the working memory
What is an engram?
- Memories are encoded in groups of neurones called engrams
- Engrams are where memories are stored
What is the Hebbian theory for memory?
- The Hebbian theory suggests that cell assemblies are formed during learning & memory as a result of the synaptic changes arising from a stimulus
- These cell assemblies can then be modified & strengthened
- Partial activation of the cell assembly, leads to activation of the entire representation
Which brain structure is involved in memory consolidation?
- Hippocampus is involved in memory consolidation
Which lobe is the hippocampus found in?
- Medial temporal lobe
**Describe the flow of sensory information through the medial temporal lobe?
Sensory information -> Para hippocampal/entorhinal areas -> Hippocampus/Medial temporal lobe -> Hypothalamus via the fornix
What is amnesia?
- Amnesia refers to the loss of memory and/or the ability to learn
What are some causes of amnesia?
- Concussion
- Encephalitis
- Brain tumour
- Chronic alcoholism
- Stroke
What are the two types of amnesia?
- Retrograde amnesia
2. Anterograde amnesia
What is retrograde amnesia?
- Retrograde amnesia refers to the inability to recall previous/old memories before the point of trauma
What is anterograde amnesia?
- Anterograde amnesia refers to the inability to form & recall new memories after the point of trauma
- However long term memory before point of trauma is still in tact
What is spatial memory?
- Spatial memory is a type of memory responsible for the recording & recall of information needed for navigation
What are place cells?
- Place cells are neurones located in the hippocampus
- They are involved in spatial memory
- Place cells fire when an animal is in a location
- Place cells are neurones which are glutamatergic, so glutamate antagonists can disrupt the process of learning
Where are place cells located?
- Place cells are located in the hippocampus
- Neurons involved in spatial memory
What are the two models of memory consolidation?
- Standard model of memory consolidation
2. Multiple trace model of memory consolidation
What is the standard trace model of memory consolidation?
- Sensory information form the neocortex (cerebral cortex) is sent to the hippocampus (medial temporal lobe) for processing
- Synaptic systems consolidation: Memories are transferred to different brain regions from the hippocampus, stored in engrams of different regions
- After memory consolidation, the hippocampus is no longer needed & doesn’t play a role in memory
What is the multiple trace model of memory?
- Multiple trace model of memory suggests that even after memories have been transferred to engrams in different regions of the brain, the hippocampus is still involved
- Changes to hippocampal activity can modify the memory stores
What is synaptic plasticity?
- Both models of memory consolidation involve synaptic plasticity
- Synaptic plasticity is a biological process where changes in patterns of synaptic activity lead to changes in synaptic strength
**What is the trisynaptic circuit?
- The trisynaptic circuit is the relay of synaptic transmission in the hippocampus/medial temporal lobe
**Describe the flow of information in the trisynaptic circuit?
- Entorhinal cortex –> Dentate gyrus via the PERFORMANT PATH
- MOSSY FIBRES from the dentate gyrus synapse with pyramidal neurons CA3 of the hippocampus
- Axons of CA3 known as SCHAFFER COLLATERALS synapse with CA1 hippocampal region
Define long-term potentiation
- Long term potentiation is the process by which repeated patterns of synaptic activity result in the consistent strengthening of a synapse
Why does dendritic spine growth occur as a result of long term potentiation?
- Long term potentiation results in increased AMPA expression in the post-synaptic membrane
- The membrane increases in size to accommodate the increase in receptors which leads to dendritic spine growth
