Lecture 10: Learning and Memory 2 Flashcards
What is Hebbian synaptic weight change?
A theory that connections in neural networks can be strengthened if frequently activated or weakened if used less
Proposed by Donald Hebb in 1949 in his book ‘The Organization of Behavior’.
What is long-term potentiation (LTP)?
An increase in synaptic strength following repeated stimulation
Involves the NMDA receptor and plays a role in learning and memory.
What role does hippocampal LTP play?
It is involved in navigation memory.
What is synaptic plasticity?
Biological processes at the synapse by which patterns of synaptic activity change, affecting synaptic strength.
Who is credited with the discovery of cells?
Robert Hooke
His work in the 1600s led to the scientific study of cells, known as cell biology.
What is neuron theory?
The concept that neurons are the basic structural and functional units of the nervous system.
Who proposed the idea that synapses play a role in memory formation?
Santiago Ramón y Cajal in 1893.
What did Foster & Sherrington name the sites of contact between neurons?
Synapses.
What does the phrase ‘Cells that fire together, wire together’ imply?
The strength of synaptic transmission increases if the presynaptic cell persistently activates the postsynaptic cell.
Why is Aplysia studied to understand synaptic weight changes?
It has a small number of neurons with large soma and axons, allowing for measurement and manipulation of neural signals.
What is habituation?
A decrease in response to a repeated stimulus, such as the gill withdrawal response to siphon tap.
What is dishabituation?
The recovery of a response that has undergone habituation, often triggered by a novel stimulus.
What characterizes short-term habituation?
Effects last less than 30 minutes and recover at about 1 hour.
What characterizes long-term habituation?
Effects can last for weeks following extensive training.
What is short-term sensitization?
A heightened response to a stimulus that lasts for about 3 days after mild pain exposure.
What is long-term sensitization?
A sustained increased sensitivity to a stimulus that can last for over a week after repeated training.
What is classical conditioning in the context of Aplysia?
Learning where a siphon tap (CS+) predicts a tail shock, leading to a conditioned gill withdrawal reflex.
What are the four main cellular adaptations that underlie weight change between sensory and motor neurons?
- Synaptic Facilitation
- Long-Term Potentiation (LTP)
- Long-Term Depression (LTD)
- Synaptogenesis.
What is synaptic facilitation?
Changes in neurotransmitter availability and release in the pre-synaptic sensory neuron affecting short-term habituation and sensitization.
What does long-term depression (LTD) refer to?
A decrease in the density of postsynaptic receptors following prolonged training.
What is synaptogenesis?
The formation of new synapses or the removal of existing synapses.
What is Long Term Potentiation (LTP)?
A cellular mechanism that underpins memory and learning, particularly in the hippocampus.
LTP is characterized by a lasting increase in synaptic strength following high-frequency stimulation of a synapse.
What role does the NMDA receptor play in LTP?
It controls calcium channels that are essential for LTP, which are blocked by magnesium ions until depolarization occurs.
NMDA receptors are a type of ionotropic glutamate receptor.
What happens when the post-synaptic membrane is depolarized?
Magnesium ions are pushed out of the calcium channel, allowing calcium to enter the cell.
This process is crucial for the induction of LTP.
What are the effects of fornix damage?
Produces wide-ranging abnormalities in memory, navigation, emotion, and voluntary motor control.
The fornix is a major output tract of the hippocampus.
How long can LTP last?
At least 96 hours.
This persistence is critical for long-term memory formation.
What is the relationship between weak and strong stimulation for LTP?
They must be contingent, or co-occur, for LTP to be produced.
What role does NMDA-dependent LTP play in navigation memory?
It underpins the hippocampus’s function in navigation learning.
This suggests that NMDA-dependent mechanisms are integral to how spatial memory is formed.
What is the function of place cells in the hippocampus?
They fire maximally at specific locations, contributing to spatial navigation.
Place cells help in mapping the spatial layout of the environment.
What are grid cells?
Neurons in the entorhinal cortex that help in spatial navigation by forming a grid-like representation of the environment.
What happens when the hippocampus is damaged?
Greater damage leads to more significant impairment in memory tasks, suggesting a network of regions is involved in memory, not just the hippocampus.
What are egocentric boundary cells?
They respond to boundaries relative to the animal’s body position.
What is neuroinformatics?
A research field focused on the integration of neuroscience and computational science for analyzing and sharing experimental data.
True or False: NMDA-dependent LTP occurs only in the hippocampus.
False.
It occurs wherever NMDA-expressing neurons are present in the brain.
Fill in the blank: LTP is controlled by specialized _______ receptors.
ionotropic glutamate
What is the significance of single cell recordings in navigation memory studies?
They allow researchers to observe the activity of individual neurons in living animals, providing insights into how spatial memory works.
How do different place cells contribute to navigation?
They collectively map the spatial layout of the animal’s environment by encoding different locations.
What does current research aim to understand at a systems level?
How the brain represents space as a whole.
