Mechanism of Learning, Memory, Addiction and Fear Flashcards
What are the major brain structures that make up Anatomy of Memory ?
**Cerebral cortex, amygdala, hippocampus make up anatomy of memory **
(also frontal lobes, parietal, occipital and temporal lobes, cerebellum, brain stem and hypothalamus also included)
-Hippocampus- is where memories are first triggered, then consolidated and transferred to long term memory (LTM)
Which structures make up the limbic system?
Corpus callosum, temporal lobe, cingulate grus, nuclei of thalamus, mammillary body parohippcoampal gyrus, amygdaloid body, and fornix make up limbic system
What is Learning? What are three types of Learning?
Learning: relatively permanent change in an individual’s behavior or behavior potential (or capability) as a result of experience or practice
Learning types:
1) change in behavior
2) change takes place due to practice or experience
3) Change is relatively permanent
What is Memory?
Memory: a complex cognitive or mental process that involves encoding, storage and retrieval of information
Define the words encoding, storage and retrieval that all relate to memory formation
1) Encoding: process of receiving input and transforming it into a form or code, which can be stored.
2) Storage: is process of actually putting coded information into memory
3) Retrieval: process of gaining access to stored coded information when it is needed.
Differentiate between word Learning and memory in terms of information
Learning is the process of acquiring NEW information
Memory: is the ability to store and retrieve information (the Specific information stored in brain)
Describe how informant is stored from sensory memory to long term memory.
Sensory memory –> Working Memory– Long-term memory
(Verbal/auditory channel and Visual/pictorial channel will be form of sensory memory that will be transferred to working memory.
Working memory has a limited capacity (of information that can be stored), and is where thinking and processing occurs. Encoding and retrieval occur next as information is stored in Long term memory (Unlimited capcity)
Describe the two types of memory that Hebb differentiated between: Short term memory and Long-term memory
Hebb (1949) differentiated between two types of memory:
Short-term memory: memory of events that have just occured
Long-term memory- memory of events from Previous times
What is consolidation ?
Consolidation: process by which short term memories are converted into long-term memories
discuss the different types of information present in short term vs long-term memory
Short-term memory: IMMEDIATE memory for events, which may or may not be consolidated into long-term memory
Long-term memory: Relatively STABLE memory of events that occurred in more DISTANT past
What type of memory are Declarative and non-declarative memories?
Discuss the subtypes of Declarative and non-declarative memories
Declarative and Non-declarative memories are forms of LONG TERM memory
-Declarative: things you know that you can tell others (hippocampus dependent) ex: biographical facts, geographical/historical facts
-Nondeclarative (procedural): things you can show by doing (hippocampus Independent) ex; Learn how to ride a bike
Subtypes;
Declarative divide into
1) Episodic: remembering the first day of school (storage in cortex)
2) Semantic : knowing the capital of France (storage in cortex)
Nondeclarative divide into
1) Priming: being more likely to use a word you heard recently (Cortex)
2) Conditioning: salivating when you see a favorite food (cerebellum)
3) Skill learning: knowing how to ride a bicycle (uses basal ganglia, motor cortex, and cerebellum)
Differentiate between declarative and non-declarative memory in terms how information is remembered
Declarative: EASY to form these memories; EASILY Forgotten
Nondeclarative: require repetition and practice over a long period of time, but LESS likely to be forgotten
(Declarative memory: medial temporal lobe; diencephaplon) cause memory of facts and events
Non declarative memory: Procedural memory; skills and habits (striatum) classical conditioning using skeletal musculature (cerebellum) and Emotional response (amygdala)
Describe the anatomical and functional organization of memory
A
Differentiate between anterograde vs retrograde amnesia
Anterograde Amnesia: amnesia for events that occur AFTER trauma
Retrograde amnesia: Amnesia for events that occur just PRIOR to brain trauma
What is global amnesia?
Global amnesia: when both retrograde amnesia and anterograde amnesia occur
What is medial Temporal Lobectomy? Also describes structures involved in anatomy of memory
Medial Temporal Lobectomy: Removes tissue to treat seizures
-Result: Remove hippocampus
Anatomy of memory: include frontal lobe, olfactory bulb, temporal lobe, optic chiasm and mammillary body
Compared a healthy brain with advanced Alzheimer’s brain
normal brain: normal shape and size
-Advanced Alzheimer’s brain: Brain is atrophied.
Discuss the differences between Short term memory and Long term memory
Differences between STM and LTM:
-Short-term memory has LIMITED capacity; long term memory does not
-Short-term memory fades quickly without rehearsal; Long-term memories persist
-memories from long-term memory can be stimulated with a cue/hint; retrieval of memories lost from STM do NOT benefit from presence of a cue
Define the term learning and discuss the non-associative types and associative types of learning
Learning (non-associative and associative): is process by which experiences change our nervous system and behavior
Non-assoicative and associative types of learning
-Habituation: decrement in reflexive response due to repeated stimulus presentation (ex: hear a noise, get used to the noise sound)
-Sensitization; INCREASE in reflexive response due to repeated stimulus presentation (ex: due to experiencing fire, when you smell smoke, tend to overreact)
-Classical conditioning: a learning process that occurs through associations between environmental stimulus and naturally occurring stimulus (ex: Pavlov)
-Instrumental conditioning: A learning procedure whereby the effects of a particular behavior in a particular situation increase (reinforce) or decrease (punish) the probably of the behavior (also called OPERANT Conditioning
What are the non- associative types of learning and how are they different?
Non-assocaitve Learning: a change in behavior over time in response to a single type of stimulus
Two types:
1) Habituation: Learning to ignore a stimulus that lacks meaning
-The response to a repeated stimulus DECREASES
2) Sensitization: a strong sensory stimulus can Intensify your response to all stimuli
- The response to a given stimulus INCREASES
Discuss the types of Associative learning and differentiate between them.
Associative Leanring: formation of associations between two events
Two types:
1) Classical Conditioning: Associating an effective, response-evoking stimulus with a second, normally ineffective stimulus
-Pavlov’s dogs (salivating to steak; then when bell is rung)
2) Instrumental (operant) conditioning: associating a MOTOR action with a stimulus
-pressing a level produces a food pellet
Describe what occurs in memory consolidation
Memory consolidation: Sensory information will be transferred through short-term memory. Once in short-term memories, rehearsal of this information will allow for consolidation or transfer of info be converted from short-term memory to Long-term memory
Sensory Info–> STM–> LTM
Which important people used Associative Learning ?
Classical conditions- I. Pavlov
Instrumental -Operant conditioning: B. Skinner
Describe the behaviorism that occurs Classical conditioning with pavlov
Classical Conditioning: Pavlov
-A stimulus is presented in order to get a Response
S—R
-S–> US–> UR
A stimulus such as meat becomes an unconditioned stimulus for dogs that will have unconditioned response of salivating when seeing meat
-Then a neutral stimulus (of bell ringing) will initially produce no salivation.
however when unconditioned stimulus (meat) is presented after neutral stimulus (bell), the dog will have unconditioned response (salivation)
-With the neutral stimulus presented alone (bell rings), the dog will produce a conditioned response of salivating. Hence the bell becomes conditioned stimulus.
Describe what learner does in classical conditioning vs operant conditioning
Classical conditioning: two stimuli (CS and UCS) are presented at certain times regardless of what learner does
-in operant conditioning; the learner’s behavior controls the presentation of reinforcer or punishment.
Describe what occurs in operant conditioning. Prvoide an example.
Operant conditioning: by Skinner
-The response is made first, then reinforcement follows.
ex: a pigeon learn how many times to push button to receive reward (Food)
-First pigeon will push button a certain number of times
-Then pigeon will receive food, which will be a reinforcer for pigeon to maintain behavior and keep pushing button
another example; rat enters one arm of maze, and will earn fruit loops to eat as a reinforcement to allow rat to increase responsibility of same response (continue behavior)
-however, if rat is shocked when going through one arm, that will be punisher to stop rat from going through that arm and shift to different response
Explain how stimulus and reinforcement stimulus works
Stimulus (ex: sight of lever)–> neural circuit that detects a particular stimulus–> Neural circuit that controls particular behavior–> Behavior (lever press)
-When rat presses lever, it receives food. Food is a reinforcing stimulus that will influence reinforcement system which will then strengthen connection of neural circuit that controls that behavior
Differentiate between reinforcers and punishment in operant conditioning
In Operant (instrumental) Conditioning; Responses are followed by reinforcement or punishment that either strengthen or weaken behavior
-Reinforcers- are events that INCREASE the probability that the response will occur again
-Punishment: are events that DECREASE the probably that response will occur again
Differentiate between a reinforcing stimulus and Punishing stimulus
Reinforcing stimulus: Appetitive stimulus that follows a particular behavior and thus makes the behavior become more frequent
Punishing stimulus: Aversive stimulus that follows a particular behavior that makes behavior LESS frequent
What drives our lives and learning ?
Describe how Apylsia California was used as a model for learning. How were Implicit memories used and where are they stored?
Aplysia California: Sea snail used as model for learning
-Implicit memory can be studied through the gill- and siphon withdrawal reflex of the marine invertebrate Apylysia californica (Sea Snail)
-Aplysia is capable o ASSOCIATIVE Learning (including classical conditioning and operant conditioning) and non-Associative learning (habituation and sensitization )
-Aplysia is able to learn very peculiar behaviors that, upon practice, can be consolidated into long term memories
-The animal learns to respond progressively more weakly to repeated innocuous stimuli (ex: light tactile stimulus), a behavior called Habituation, and to Reinforce the response to repeated noxious stimuli (painful electric shock) behavior known as sensitization
These implicit memories are stored in spinal reflex pathways
Explain what occurs in the Gill Withdrawal Reflex of Aplysia
Gill Withdrawal Reflex of Apylsia:
-Tactile or electrical stimulation of the siphon or mantle elicits withdrawal of the Gill and siphon into mantle cavity
-Snail contains body with mantle shelf, siphon, gill.
How does Habituation occur in Apylsia?
Habituation in Aplysia:
-If the siphon of the animal is stimulated mechanically, the animal withdraws the gill, presumably for protection
- With repeated activation, the stimulus leads to a DECREASE in number of dopamine-containing vesicles that relate their contents onto motor neuron
Who Was Eric Richard Kandel and what did he, Arvid Clarssoin and Paul Greengard have in common?
Eric Richard Kandel: Medical doctors from Austria who is known for his work with California Sea slug (aplasia California) aka California sea hare (since it resembled shape of rabbit or hare)
-Sea hares- shell-less sea snale
-He, and Arvid Clarsson (discovered dopamine) , Paul Greengard won Nobel Prize together in 2000 in Physiology for their discoveries conceiving signal transduction in nerve system and dopamine.
What causes Habituation?
Motor neuron, receives direct sensory input from the siphon and innervates muscles used for gill withdrawal
-Showed that habituation occurs at the synapse between sensory and motor neuron
-Progressive decrease in the size of excitatory postsynaptic potentials (EPSP’s)
-Mechanism:
-Less calcium enters presynaptic terminal
-So fewer transmitter molecules are released
Therefore presynaptic modification
Describe the sensitization in Aplysia
REVIEW THIS SLIDE (40)
Sensitization of Gill-Withdrawal Reflex
-Sensory neuron is activated by serotonin
-Sensory neuron is constantly triggered causing sensitization
Describe the associative learning that is seen in Aplysia
Associative learning in Aplysia:
-Classical conditioning:
-Unconditioned stimulus= Shock to tail
-Conditioned stimulus= siphon stimulation
-If the two stimuli were paired, subsequent gill withdraw response to siphon stimulation alone was greater
-Uses the same neuron as sensitization, through interneuron
Explain the Gill Withdrawal Reflex Sensitization and how it works
Gill Withdrawal Reflex Sensitization
-Shock to the head associated with stimulation of siphon increases gill withdrawal reflex= sensitization
-How does this work?
-Neuron from head synapses on the axon terminal of sensory neuron
-Releases serotonin
-Causes molecular cascade that sensitizes sensory axon terminal
What occurs in the sensitization cascade?
Sensitization Cascade
-Serotonin receptor on the sensory axon terminal is a G-protein coupled receptor
-Binding activates adenylyl cyclase enzyme
-Which produces cyclic AMP (2nd messenger)
-which activates protein kinase A (PKA)
-which phosphorylates a protein forming the potassium channel
-Which causes it to close
-Prolonging the presynaptic action potential
-so more calcium enters
-Thus more neurotransmitters are released.
What is long-term potentiation (LTP)
Long-term Potentiation (LTP): long-term increase in the excitability of a neuron caused by repeated high-frequency activity of input
What is Associative long-term potentiation?
Associative Long-term potentiation:
-LTP in which concurrent stimulation of weak and strong synapse to a given neuron strengthens the weak ones
Describe all the features of Long-term potentiation, including where it occurs.
Long Term Potentiation
-A large amount of studies demonstrated that LTP is indeed a valid model of “memory storage”
LTP is observed when postsynaptic neuron is persistently depolarized after a high-frequency burst of presynaptic neural firing
-LTP has a number of properties that make it as suitable as Physiological substrate of memory
-It is ASSOCIATIVE, in that it depends on the co-occurrence of presynaptic activity and postsynaptic depolarization.
LTP occurs prominently in the HIPPOCAMPUS, a structure that is important for memory
-
What does the Induction of LTP (long term potentiation) involve?
The Induction of LTP: is known to be mediated postsynaptically and to involve the N-methlyl D-asparteate (NMDA) receptor, which permits the influx of calcium into postsynaptic cell.
How is LTP maintained?
LTP is maintained by an increase in the number of alpha-amino-3-hydroxy-5-methyl 4-isoxazolepropionate (AMPA; non-NMDA) receptors in postsynaptic cell and also possibly by increase transmitter release
Discuss the differences in synapse before and after long-term potentiation occurs
Before long term potentiation: no change, structures (synaptic vesicles, terminal button, dendritic spine and active zone are normal)
After long-term potentiation: CHANGES in synapse occur
-genearte perforated (hole) synapse
How are axons affected after long term potentiation (LTP)? REVIEW
Before LTP: axon normal shape
After LTP: change in axon
What is hippocampus structure composed of?
Hippocampus structure:
Schaefer collaterals
-mossy fibers
-Perforant path
-entorhinal cortex, fornix or sensory cortex
Describe the connections seen in hippocampus
Connections in Hippocampus:
-entorhinal cortex connects to the hippocampus via axons called Perforant path
-Mossy fibers from the dentate gyrus synapses on CA3
-CA3 cells synapse via Schaffer collateral cells in CA1 region
-Both CA3 and CA1 cells have output fibers to the fornix
Where does Long-term Potentiation occur? What kind of receptors are used for excitatory transmission?
Long Term potentiation (LTP) occurs in CA1 when multiple synapses are active at the same time that the CA1 cell is depolarized
-Recall that GLUTAMATE receptors are responsible for Excitatory transmission in hippocampus
What is the Mechanism of LTP?
Mechanism of LTP:
- Glutamate is released from synapse
-Na+ ions pass through the AMPA receptor causing EPSPs
-CA1 neurons also have post synaptic N-methyl-D-Aspartate (NMDA) receptors
-These conduct Ca++ ions when cell is depolarized
-Thus Ca++ entering the NMDA receptor indicates that presynaptic and postsynaptic elements are active at the same time.
What occurs in the Induction of LTP? how is LTP induction prevented? What causes LTP to be blocked? What will happen after LTP occurs
Induction of LTP;
Rise in postsynaptic CA++ linked to LTP
-LTP induction is prevented if NMDA receptors are INHIBITED
-Rise in Ca++ activates 2 protein kinases:
-Protein Kinase C
-Calcium-calmodulin-dependent protein kinase II (CaMKII)
-Inhibition of either of these kinases Blocks long term potentiation
-Following LTP, a single axon may form multiple new synapses on a single postsynaptic neuron
What is Long Term Depression (LTD) ?
Long Term Depression (LTD);
-LTD occurs in CA1 when it is only Weakly depolarized by other inputs
- Inward calcium levels are Lower, activating a different enzymatic response
-Thus, LTP and LTD are two responses of the same system
Explain how LTD, LTP and Memory are correlated. What causes a reduction in learning for rats
LTD, LTP and Memory
-LTP and LDP are mechanisms of synaptic plasticity
-They may contribute to formation of Declarative memory
-Recordings from inferotermporal cortex slices from humans shows the Same kind of interplay of LTP and LTD
- Rats with damage to hippocampus show reduced learning in Morris water maze
-Injecting an NMDA-blocker into rats produces the same reduction of learning
Describe the model of LTP and LTD. What mediates LTP?
Current model of LTP and LTD:
on The post-synaptic membrane, you will have Glutamate binds to NMDA receptor.
-Calcium will pass through NDMA receptor and either have brief and large excitatory signals when protein kinases ar activated; or have prolonged and moderate excitatory activity when protein phosphates are activated.
LTP mediated by the number of NMDA and AMPA receptors
