Fatima Adam
Learning and Memory (Physiology 2)
Learning and Memory - Dr Mark Preece Lecture Outline Learning is the acquisition of new knowledge or skills and memory is the retention of learned information. There are different types of memory including declarative, nondeclarative memory and different types of learning including associative (conditioning) and non associative. There are key brain regions known to be involved in different types of memory; prefrontal cortex for working memory, neocortex for declarative memory, the striatum for procedural memory and habit formation. The hippocampus plays a major role in memory formation, retention, consolidation and retrieval. We now understand some of the molecular mechanisms underlining learning and memory including LTP, LTD, synaptic plasticity and the role of AMPA and NMDA receptors in the hippocampus. Desired Learning Outcomes By the end of this lecture unit, students should be able to: Explain the different type of memories Describe the role of the prefrontal cortex, the neocortex, the striatum and the hippocampus in different types of memory Outline key experiments performed which helped us with the understanding of the neurobiology of memory and learning Discuss some of the prime molecular mechanisms involved in memory and learning Session Resources Download the lecture slidesDownload lecture slides Session Activities Activity 1. Learning and memory part 1 In this video, the concepts of declarative and nondeclarative memory are introduced, together with an overview of memory consolidation Activity 2. Learning and memory part 2 In this video experimental evidence supporting the importance of the role of the prefrontal cortex in working memory function is discussed Activity 3. Learning and memory part 3 This video introduces the hippocampus as a key structure in consolidation of declarative memory. Activity 4. Learning and memory part 4 This last video explores that role of the hippocampus in spatial memory, and provides an overview of important molecular mechanisms involved in the phenomenon of long term potentiation (LTP), a form of synaptic plasticity. Now test yourself A short quiz on the lecture content can be found HERE Further Reading Neuroscience: Exploring the Brain' by Bear, Connors, Paradiso Chapter 24 and 25 available from SGUL library HERELinks to an external site. Glossary Declarative memory – Declarative memory consists of facts and events that can be consciously recalled or "declared." Also known as explicit memory, it is based on the concept that this type of memory consists of information that can be explicitly stored and retrieved. Non declarative memory – Is one of the two main types of long-term human memory. It is acquired and used unconsciously, and can affect thoughts and behaviours. One of its most common forms is procedural memory, which helps people performing certain tasks without conscious awareness of these previous experiences Procedural memory – Procedural memory is a part of the long-term memory that is responsible for knowing how to do things, also known as motor skills. As the name implies, procedural memory stores information on how to perform certain procedures, such as walking, talking and riding a bike Associative learning – Associative learning, in animal behaviour, any learning process in which a new response becomes associated with a particular stimulus. In its broadest sense, the term has been used to describe virtually all learning except simple habituation Long term memory – The final stage of the multi-store memory model proposed by the Atkinson-Shiffrin, providing the lasting retention of information and skills. Theoretically, the capacity of long-term memory could be unlimited, the main constraint on recall being accessibility rather than availability. Short term memory – Is the capacity for holding, but not manipulating, a small amount of information in mind in an active, readily available state for a short period of time. Memory consolidation – Is defined as a time-dependent process by which recent learned experiences are transformed into long-term memory. Working memory – Is a cognitive system with a limited capacity that is responsible for temporarily holding information available for processing. Working memory is important for reasoning and the guidance of decision-making and behaviour. Long term potentiation – Is a persistent strengthening of synapses based on recent patterns of activity. These are patterns of synaptic activity that produce a long-lasting increase in signal transmission between two neurons. Long term depression – Is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus Synaptic plasticity – Synaptic plasticity is the biological process by which specific patterns of synaptic activity result in changes in synaptic strength and is thought to contribute to learning and memory. Both pre-synaptic and post-synaptic mechanisms can contribute to the expression of synaptic plasticity.
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What is the difference between declarative and nondeclarative memory? (2)
Declarative memory (explicit): Involves facts and events, typically associated with the hippocampus.
Nondeclarative memory (implicit): Involves procedural memory, such as motor skills and habits, associated with the striatum.
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What is the role and location of working memory? (2)
Working memory is responsible for temporarily holding and manipulating information.
It primarily occurs in the prefrontal cortex.
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What is memory consolidation and how does it occur? (3)
Memory consolidation refers to the process of stabilizing a memory trace after initial acquisition.
It involves the transfer of information from short-term memory to long-term memory.
This process occurs through neural mechanisms, including changes in synaptic strength and the hippocampus's involvement.
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What is synaptic plasticity? (1)
Synaptic plasticity refers to the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity.
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What is the trisynaptic circuit of the hippocampus? (3)
The trisynaptic circuit is a pathway in the hippocampus involved in memory processing.
It consists of:
Entorhinal cortex → Dentate gyrus
Dentate gyrus → CA3
CA3 → CA1
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What is long-term potentiation (LTP) and how does it relate to memory? (3)
Long-term potentiation (LTP) is the process by which synapses become stronger with frequent activation.
It is thought to play a critical role in memory formation and consolidation.
LTP occurs in the hippocampus, especially in the CA1 and CA3 regions, and is a key mechanism for learning.
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State the Types of Declarative Memory (6)
• Working memory • Temporary storage, lasting seconds • Short-term memories—vulnerable to disruption • Facts and events stored in short-term memory • Subset are converted to long-term memories. • Long-term memories • Recalled months or years later
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What is working memory and how long does it last? (2)
Working memory: Responsible for temporary storage and manipulation of information.
It lasts only for seconds and is vulnerable to disruption.
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What are short-term memories and how are they affected? (2)
Short-term memories: Store facts and events temporarily.
They are vulnerable to disruption and may not last long without further encoding.
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How are short-term memories converted into long-term memories? (2)
A subset of short-term memories are encoded and consolidated into long-term memories.
This process is key for memory stability over time.
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What are long-term memories, and how long can they be recalled? (2)
Long-term memories: Stored and recalled months or years after being formed.
They are more stable and less vulnerable to disruption compared to short-term memories.
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Picture demonstrating Memory consolidation: process ofconverting short- to long-term memories:
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What is the function of the prefrontal cortex in primates? (2)
The prefrontal cortex is involved in self-awareness.
It also plays a key role in planning and problem-solving.
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Why is the prefrontal cortex significant in primates? (1)
Primates have a large frontal lobe, which supports advanced cognitive functions.
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Picture demonstraing Working Memory Activity in Monkey Prefrontal Cortex: delayed response task:
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What brain region is involved in working memory, particularly in tasks like delayed-saccade? (1)
The lateral intraparietal cortex is involved, where neuron response is observed in tasks such as delayed-saccade.
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Where are memories stored, and what is the concept of the engram? (2)
Memories are stored in the engram, which refers to the physical representation of memory in the brain.
According to Hebb's Cell Assembly theory, memories are stored through the strengthening of synaptic connections between neurons that fire together, creating a network or "assembly" of neurons that represent the memory.
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What is the role of the medial temporal lobes in memory consolidation? (2)
The medial temporal lobes (MTL), including the hippocampus, are crucial for memory consolidation, the process of transferring short-term memories to long-term storage.
These structures are particularly involved in episodic memory consolidation, aiding in the stabilization and integration of new information.
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Picture demonstrating Information flow through the medial temporal lobe:
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What is amnesia, and what are its common causes? (2)
Amnesia refers to a serious loss of memory and/or the ability to learn.
Common causes include concussion, chronic alcoholism, encephalitis, brain tumor, and stroke.
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Who was Henry Gustav Molaison (HM), and what was the result of his surgery? (3)
Henry Gustav Molaison (HM), born Feb 26, 1926, had epilepsy after a bicycle accident at age 9.
In 1953, William Scoville removed parts of HM’s right and left medial temporal lobes (MTL) to reduce seizures.
The surgery reduced seizures but resulted in HM losing the ability to form new long-term memories. However, he could remember events before the surgery and could learn new motor skills, although he had no memory of learning them.
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What was the impact of H.M.'s case on memory research? (4)
In 1957, Brenda Milner reported H.M.'s profound memory issues following bilateral medial temporal lobe resection to treat epilepsy.
H.M. experienced anterograde amnesia (unable to form new memories) and retrograde amnesia (couldn't access some past memories).
His case revealed that memory is a distinct cerebral function, separate from other cognitive abilities, and that the medial temporal lobe, particularly the hippocampus, is essential for memory formation.
H.M.'s case laid the foundation for modern memory research, influencing subsequent studies on memory and hippocampal function.
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How are spatial memory and place cells involved in the Morris water maze? (3)
Learning the Morris water maze requires the hippocampus to form spatial memories.
Place cells in the hippocampus fire when an animal is in a specific location, contributing to spatial navigation.
Place fields of these cells are dynamic, changing as the animal moves through different environments.
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Flashcard: What are the two models of memory consolidation? (3+3)
Standard model of memory consolidation:
Information from sensory areas in the neocortex is sent to the medial temporal lobe for processing.
Synaptic consolidation and systems consolidation occur.
After consolidation, the hippocampus is no longer necessary for memory recall.
Multiple trace model of consolidation:
Hippocampal involvement continues throughout memory consolidation.
Multiple memory traces are formed.
Dependent on synaptic plasticity, where synaptic activity strengthens synapses, enabling memory storage.
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Picture demonstrating Model of Distributed Memory:
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What is the trisynaptic circuit of the hippocampus and how does information flow through it? (3)
Information flow:
Starts at the entorhinal cortex, transmitting signals through the perforant path to the dentate gyrus.
Mossy fibers from the dentate gyrus synapse onto pyramidal neurons in the CA3 region of the hippocampus.
Axons from CA3 (Schaffer collaterals) synapse onto pyramidal neurons in the CA1 region of the hippocampus.
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Picture demonstrating Bliss and Lomo (1973)Long-Term Potentiation (LTP) in CA1 region of the hippocampus:
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What are the mechanisms of Long-Term Potentiation (LTP) in the CA1 region of the hippocampus? (2)
Glutamate receptors mediate excitatory synaptic transmission.
NMDA receptors and AMPA receptors are involved in LTP.
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Picture demonstrating Structural changes following LTP include dendritic spine growth:
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What is declarative memory and what does it involve? (2)
Declarative memory consists of facts and events that can be consciously recalled or "declared."
Also known as explicit memory, it involves information that can be explicitly stored and retrieved.
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What is non-declarative memory and how is it acquired? (2)
Non-declarative memory is acquired and used unconsciously.
It affects thoughts and behaviors, with procedural memory being one of its most common forms.
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What is procedural memory and what does it store? (2)
Procedural memory is part of long-term memory responsible for knowing how to do things.
It stores information on how to perform tasks like walking, talking, or riding a bike.
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What is associative learning? (1)
Associative learning is a process where a new response becomes associated with a particular stimulus.
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What is long-term memory and its capacity? (2)
Long-term memory is the final stage of memory, retaining information and skills for a long time.
Theoretically, its capacity is unlimited, with accessibility being the main constraint on recall.
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What is short-term memory and how is it different from working memory? (2)
Short-term memory holds a small amount of information for a short period without manipulation.
It differs from working memory, which temporarily holds information for processing and decision-making.
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What is memory consolidation? (1)
Memory consolidation is the process by which recently learned experiences are transformed into long-term memory.
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What is working memory and its role in cognition? (2)
Working memory temporarily holds information for processing.
It is essential for reasoning, decision-making, and behaviour guidance.
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What is long-term potentiation (LTP)? (2)
LTP is the persistent strengthening of synapses based on recent patterns of activity.
It results in a long-lasting increase in signal transmission between two neurons.
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What is long-term depression (LTD)? (2)
LTD is a reduction in the efficacy of neuronal synapses after long patterned stimuli.
It can last for hours or longer.
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What is synaptic plasticity, and how does it contribute to learning? (2)
Synaptic plasticity is the process by which patterns of synaptic activity change synaptic strength.
It is thought to contribute to learning and memory, involving both pre- and post-synaptic mechanisms.
