Lecture 2- Learning and Memory Flashcards
What are the two general types of memory
- Declarative memory involves conscious recall of facts and events,
- Non-declarative memory is unconscious and includes procedural memory and skills
What are examples of nondeclarative memory?
- Motor skills (e.g., riding a bike)
- Associations (e.g., classical conditioning like Pavlov’s dog)
- Priming cues (e.g., quicker recognition of words you’ve seen recently)
- Puzzle-solving skills (e.g., solving a jigsaw puzzle without recalling previous steps)
What demonstrates the evolutionary conservation of memory?
The instinctive crouching of young birds at the sight of a predator silhouette demonstrates evolutionary conserved memory responses
How are evolutionarily conserved memories linked to brain processes?
These memories involve instinctive behaviors that must have cellular and molecular processes involved in the brain, possibly through epigenetic mechanisms.
What happens in the monkey pulvinar neurons when exposed to snake images compared to other stimuli?
Monkey pulvinar neurons show increased spiking when exposed to snake images compared to other stimuli, indicating an exaggerated neural response to a potential threat
How does the response time of monkey pulvinar neurons to snake images compare to other stimuli?
The response time of monkey pulvinar neurons to snake images is faster compared to other stimuli, indicating a quicker reaction to perceived threats.
What was the hypothesis and conclusion of Lashley’s 1920s studies on maze learning in rats regarding memory storage?
Hypothesized that memory is not localized but distributed throughout the cortex, a concept known as “equipotentiality.”
- Conclusion (incorrect): memory centers do not exist
What principle did Lashley’s 1950s lesion studies support, and what was observed?
Lashley’s studies supported the “mass action principle,” observing that the more complex the task, the greater the impact of cortical lesions on learning and memory.
What are the two forms of non-associative learning described in Aplysia and what do they signify?
The two forms of non-associative learning are habituation (decreased response to repeated stimuli) and sensitization (increased response to a stimulus), exemplify two different forms of learning/memory, mediated by the same set of cells.
What happens to the Aplysia’s gill-withdrawal reflex with repeated stimulation of the siphon?
With repeated stimulation, the Aplysia’s gill-withdrawal reflex decreases in magnitude (becomes weaker and less intense over time), demonstrating short-term habituation.
What initiates short-term sensitization in Aplysia’s gill withdrawal reflex?
A short-term sensitization is initiated by a tail shock, which leads to an increased reflex response to touch.
How is long-term sensitization achieved in Aplysia’s gill withdrawal reflex?
Long-term sensitization is achieved through repeated tail shocks over several days, where the gill-withdrawal reflex is enhanced over time.
Describe the roles of glutamate and GABA in synaptic transmission.
Glutamate: Acts as an excitatory neurotransmitter, causing the postsynaptic neuron to fire.
GABA: Acts as an inhibitory neurotransmitter, preventing the postsynaptic neuron from firing.
What is the role of serotonin in short-term sensitization?
Serotonin increases glutamate release from the presynaptic sensory neuron, which enhances the stimulation of the postsynaptic motor neuron, leading to stronger gill withdrawal.
What is the common process that leads to gill withdrawal in both short-term and long-term sensitization?
- Sensitizing stimulus triggers serotonin release from the modulatory neuron.
- Serotonin boosts glutamate release from the sensory neuron.
- Glutamate stimulates the motor neuron, leading to gill muscle contraction and withdrawal
What happens inside the sensory neuron after serotonin is released? - internal mechanism the mechanism that causes the sensory neuron to release more glutamate.
- Serotonin binds to receptors on sensory neuron.
- This increases cAMP inside the neuron, which activates PKA.
(Protein Kinase A). - PKA helps the sensory neuron release more glutamate, leading to stronger activation of the motor neuron.
How do short-term and long-term sensitization differ in terms of neuron changes?
- In short-term sensitization, the effect is temporary with no lasting changes inside the neuron.
- In long-term sensitization, repeated stimuli cause increased serotonin release, which activates cAMP and PKA, leading to gene expression changes and synapse growth, creating lasting effects.
What changes occur inside the sensory neuron during long-term sensitization?
- Repeated serotonin release increases cAMP.
- cAMP activates PKA (Protein Kinase A).
- PKA moves to the nucleus of the sensory neuron.
- PKA triggers changes in gene expression.
- New proteins are produced.
- These proteins strengthen synapses, leading to longer-lasting responses.
What are metabotropic glutamate receptors and how do they differ from ion channels?
They activate intracellular signaling cascades that modulate synaptic and cellular functions instead of allowing ions to pass directly.
What are the steps involved in the signaling cascade for short-term sensitization? -this describes how the signal starts from serotonin binding outside the neuron and leads to internal changes that ultimately result in the release of glutamate, which enhances communication between neurons.
- Serotonin (5-HT) binds to its receptor.
- Adenylate cyclase (AC) is activated, increasing cAMP levels.
- cAMP promotes the dissociation of PKA regulatory subunits.
PKA blocks potassium (K+) channels. - Depolarization activates voltage-dependent calcium (Ca2+) channels.
- Calcium influx triggers the release of glutamate, enhancing synaptic transmission.
What are the steps involved in the signaling cascade for long-term sensitization?
- Serotonin (5-HT) binds to its receptor.
- Adenylate cyclase (AC) is activated, increasing cAMP levels.
- cAMP promotes the dissociation of PKA regulatory subunits, activating PKA.
- PKA activates transcription factors, including CREB.
- CREB promotes the synthesis of ubiquitin hydrolase (UH) and pro-synaptogenic signals.
- UH degrades the regulatory subunits of PKA, keeping PKA persistently active.
- Persistent activation of PKA leads to long-term changes in synaptic strength, resulting in long-term sensitization.
What are pro-synaptogenic signals?
Pro-synaptogenic signals strengthen and build synapses, improving neuron communication for learning and memory.
What are the main components of the tri-synaptic hippocampal circuit, and what are their roles?
The components are:
1. Entorhinal cortex - Input to the hippocampus via the preforant path
2. Dentate gyrus - Responsible for pattern separation, projects via mossy fiber pathway to CA3
3. CA3 - Handles pattern completion, Projects via Schaffer Collateral pathway to CA1
4. CA1 - Processes spatial and contextual memory.
What role do the Dunce, Rutabaga, and Amnesiac genes play in memory in fruit flies?
- Dunce: Breaks down cAMP
- Rutabaga: Helps produce cAMP
- Amnesiac: Connects signals to adenyl cyclase (affects cAMP production).
- Impact of Mutations: Impair memory in fruit flies.