experience-dependent plasticity Flashcards
What are the two main types of memory in the taxonomy of memory?
- Declarative/Explicit Memory: Conscious memories that can be verbally expressed.
Semantic Memory: Factual knowledge about the world.
Episodic Memory: Memories of events and autobiographical experiences. - Non-declarative/Implicit Memory: Unconscious memory that influences behavior.
Procedural Memory: “If…then…” type of memories, associated with skills and habits.
Skill Learning & Conditioning: Includes motor skills and non-associative learning.
What is the “engram” in the context of memory research?
The engram refers to the theoretical physical representation of memory in the brain. Researchers, including Karl Lashley, sought to locate the engram but failed to identify a specific site for memory storage. Lashley concluded that memory is not localized in a single area of the brain.
What were Karl Lashley’s key findings in memory research?
Principle of Equipotentiality: All cortical regions can mediate learning equally.
Principle of Mass Action: The ability to learn is proportional to the amount of cortex available.
Lashley’s experiments showed that damage to specific cortical areas did not disrupt maze learning, but large-scale damage did impair memory.
Which subcortical areas are involved in learning and memory, and what are their roles?
Hippocampus: Critical for declarative and spatial memories.
**Cerebellum: **Involved in procedural memory and simple Pavlovian conditioning.
**Amygdala: **Responsible for emotional memories and emotional responses through Pavlovian associations.
Frontal Cortex: Involved in short-term and working memory processes.
What is Pavlov’s cortical model of memory formation?
Pavlov’s model suggests that forming psychological associations, such as between a conditioned stimulus (CS) and an unconditioned stimulus (US), results in the creation of new cortical connections, leading to the formation of new memories.
What is the cellular basis of memory as proposed by Santiago Ramón y Cajal?
Cajal proposed that memory is stored through structural changes in neurons, such as the formation of new synapses and the growth of dendritic processes (branches and spines). These structural changes store memories by altering the physical morphology of neural circuits.
What is neurogenesis, and how does it relate to learning and memory?
Neurogenesis refers to the formation of new neurons in the brain. While once thought to occur only during development, it has been shown that neurogenesis can occur in areas like the hippocampus and olfactory bulb in adults. The exact role of neurogenesis in memory is still debated, but it is believed to contribute to memory formation and adaptation to new experiences.
How do environmental factors influence brain morphology?
Environmental experiences can alter brain structure, such as:
- Increased brain weight
- Greater dendritic length and complexity (measured by Sholl analysis)
- Increased synaptic connections
- Higher mitochondrial volume (indicating greater metabolic activity).
Rats raised in enriched environments show these changes, which enhance their learning and memory capabilities.
What is Donald Hebb’s theory of memory?
In 1949, Donald Hebb postulated that when two neurons (A and B) are repeatedly activated together, a metabolic or growth change occurs that strengthens the synaptic connection between them. This phenomenon, known as Hebbian learning, suggests that “cells that fire together, wire together.” Hebb’s theory laid the groundwork for understanding how synaptic changes contribute to learning and memory.
What is synaptic learning in the context of memory?
Synaptic learning refers to the process by which synaptic connections are modified to store new memories. In Hebbian learning, synapses between neurons are strengthened when they are simultaneously activated, allowing for more efficient communication between neurons, which is crucial for memory formation.
What is Long-Term Potentiation (LTP)?
LTP refers to the long-lasting increase in synaptic strength following high-frequency (tetanic) stimulation of one neuron by another. LTP is most commonly observed in the hippocampus and is believed to be a key mechanism underlying learning and memory. It enhances the efficacy of synaptic transmission, making it easier for neurons to communicate and form memories.
How is learned fear measured in the laboratory?
One common method is the Conditioned Emotional Response (CER) paradigm, where an animal (often a rat) is conditioned to associate a neutral stimulus, like a tone, with an aversive stimulus, like a mild shock. Over time, the animal will show emotional responses (e.g., freezing) to the tone alone, demonstrating learned fear.
How is LTP related to emotional memories?
LTP is believed to occur in the amygdala during Pavlovian conditioning, which plays a key role in forming emotional memories. The strengthening of synapses in the amygdala during emotional conditioning enhances the encoding and retrieval of emotional memories.
What role do AMPA receptors play in LTP?
AMPA receptors are a type of glutamate receptor that is crucial for synaptic transmission. During LTP, the activation of AMPA receptors increases the sensitivity of the postsynaptic neuron to glutamate, strengthening the synaptic connection and contributing to long-term changes in synaptic efficacy.
