Memory Mechanisms and Learning Flashcards
What is Long-term potentiation (LTP)?
A persistent increase in synaptic strength following high-frequency stimulation of a chemical synapse
What are the two key properties of LTP proposed by Hebb?
- Endurance for months
- Coincident firing
What does it mean for LTP to endure?
LTP can last for months
What is meant by coincident firing in LTP?
LTP develops only if the presynaptic neuron fires followed by the postsynaptic neuron firing
What happens when the presynaptic neuron fires but the postsynaptic neuron does not?
LTP does not develop
What is Hebb’s postulate for learning?
The co-occurrence of firing in presynaptic and postsynaptic cells is necessary for learning and memory
Is the evidence for LTP in learning and memory direct or indirect?
Much evidence is indirect and laboratory-induced
How is the evidence for LTP often obtained?
Through electrical stimulation in laboratory settings
True or False: LTP can develop when the postsynaptic neuron fires without the presynaptic neuron firing.
False
Fill in the blank: LTP is recognized as a critical physiological necessity for _______.
learning and memory
What role does the NMDA receptor play in memory formation?
Acts like a gate at synapses where memories are built
Which neurotransmitter does the NMDA receptor respond to?
Glutamate
What two conditions must be met for the NMDA receptor to function effectively?
- Glutamate must bind to the receptor
- The receiving brain cell must be partially active (partially depolarised)
What type of ions do AMPA receptors allow to enter the neuron?
Sodium ions
What is the primary function of AMPA receptors?
Responsible for fast excitatory signaling in the brain
What blocks NMDA receptors under normal conditions?
Magnesium ions
How does AMPA receptor activity affect NMDA receptors?
Depolarises the neuron enough to remove the magnesium block
What is long-term potentiation (LTP)?
Strengthens connections between brain cells, making memories last longer
What combination is needed to trigger long-term potentiation (LTP)?
- Glutamate binding to NMDA receptors
- Neuron being sufficiently depolarised by AMPA receptor activity
What cascade of events does calcium entering through NMDA receptors trigger?
Enhances memory connections
Fill in the blank: NMDA acts as a _______ for memories, ensuring they’re worth keeping.
security guard
What do AMPA receptors help facilitate in relation to NMDA receptors?
Get the door open for calcium to enter
True or False: AMPA receptors and NMDA receptors work independently of each other.
False
What phenomenon is primarily researched in relation to memory in the hippocampus?
NMDA receptor-mediated LTP
LTP stands for long-term potentiation, a process that strengthens synapses based on recent patterns of activity.
What has been revealed about LTP beyond the hippocampus?
LTP has been documented in various parts of the central nervous system and mediated by different mechanisms
This indicates that LTP is more widespread than initially thought.
What is the opposite phenomenon of long-term potentiation (LTP)?
Long-term depression (LTD)
LTD occurs in response to extended low-frequency stimulation of presynaptic neurons.
What is essential for truly comprehending LTP and its role in memory?
Knowledge of long-term depression (LTD)
Understanding LTD helps contextualize the role of LTP in memory formation.
What was the traditional view of astrocytes in relation to synaptic activity?
Astrocytes were traditionally viewed as passive support cells
This view has evolved with new research indicating their active role in synaptic modulation.
What do astrocytes release that may influence LTP?
Glitransmitters
Glitransmitters are a type of signaling molecule involved in communication between astrocytes and neurons.
List the functions of astrocytes in relation to synaptic plasticity.
- Regulate extracellular ion concentrations
- Clear excess neurotransmitters
- Contribute to synaptic plasticity
These functions highlight the multifaceted role of astrocytes in neural processes.
What is still being investigated regarding astrocytes and LTP?
The precise mechanisms by which astrocytes affect LTP
This includes whether astrocytes enhance or modulate synaptic strength.
What has the study of LTP contributed to the broader understanding of the brain?
Advanced knowledge of neural system functions and adaptability
This contributes significantly to unraveling the neural basis of learning and memory.
