Final Material Flashcards
What is learning and how does it relate to memories?
- The process by which experiences change our nervous system and hence our behavior
- We refer to these changes as memories (memory traces or memory engrams)
What are the different forms memories can take?
- Transient or durable
- Explicit or implicit
- Personal or impersonal
Assessing memories is known as ____?
Memory retrieval
What’s the cellular basis of long-term memory?
- Neuronal plasticity
- Physical changes in neurons that support long term learning and memory
What’s neuronal plasticity?
The ability of the nervous system to change and adapt
Why do we say the brain is plastic?
- Because it’s easily changed and easily molded into whatever it wants
- The brain is constantly changing structure and shape according to its environment
What are some physical changes that can occur in the brain?
- Rearrangement of proteins within the brain and within cells
- Seizures, anesthesia and sleep can all dramatically change/disrupt the ongoing patterns of activity in the brain -> leading to ppl not remembering moment around this event
What do researchers typically measure to identify neuronal plasticity?
- Intrinsic excitability
- Synaptic strength
What’s intrinsic excitability?
- the number of action potentials a neuron exhibits in response to an influx of positive current
- the neuron can change the dynamic, change the excitability of neurons (expression of ion channels in the membrane that cause action potentials)
What’s synaptic strength?
the amount of positive (or negative) current that enters the postsynaptic neuron when a presynaptic cell has an action potential
What’s synaptic plasticity?
A change in the strength of the synaptic connection between two neurons
What is intrinsic excitability determined by?
Determined by the number and type of ion channels (leak channels and voltage-gated channels) expressed by the neuron
If a neuron starts making fewer potassium leak channels, what will happen to the resting membrane potential and to the neuron?
- The resting membrane potential will be slightly depolarized
- The neuron will be more excitable in general (i.e., it will exhibit more action potentials in response to the same excitatory synaptic input)
Enduring changes in synaptic strength are referred to as what?
- Long term potentiation (LTP)
- Long term depression (LTD)
How do we measure whether a cell is more excitable than another?
By sticking a metal wire in the cell and injecting a positive current to see how many and how frequent the action potentials will be in comparison to other cells
What are excitatory postsynaptic potentials (EPSPs)?
Membrane depolarizations that are driven by neurotransmitter release and postsynaptic receptor activation
What’s the difference between Long term potentiation (LTP)
and Long term depression (LTD)?
LTP is a stronger synapse and LDP is a weaker synapse
Synaptic plasticity can involve what kind of synaptic changes?
Both pre and postsynaptic changes
What are some presynaptic changes that can occur with synaptic plasticity?
The amount of voltage-gated calcium channels on presynaptic membrane influences how many vesicles will be released following an action potential
What are some postsynaptic changes that can occur with synaptic plasticity?
The amount of neurotransmitter receptors influences the sensitivity of the postsynaptic cell to neurotransmitter
What will happen if you stimulate a lot of the presynaptic side?
It’ll trigger a lot of action potentials -> not useful
Where should we measure to see if the synapse got stronger or not?
If we do something to make the synapse stronger, we would stimulate again and measure the postsynaptic response to see if synapse got stronger or not
What happens to the subthreshold EPSPs
in recorded cell before and after LTP induction?
After the LTP induction in the recorded cell, the subthreshold EPSPs gets more positive or stronger
What happens to calcium voltage-gated channels with LTP induction?
They increase in number
What’s habituation?
Reduced physiological or behavioural responding to a repeated stimulus
What’s sensitization?
Increased sensitivity to a stimulus
How does habituation occur in the sea slug aplysia that has a simple nervous system?
- If its siphon is lightly touched, its gill withdraws reflexively to protect it and survive
- Repeated light touching of the siphon will reduce the magnitude of the reflex until the Aplysia completely ignores this stimulus because they believe it isn’t threatening anymore
How does sensitization occur in the sea slug aplysia that has a simple nervous system?
The sea slug’s response to an electrical shock often becomes greater with additional exposures
Does the sensory neuron of the sea slug’s siphon become less sensitive to touch with habituation?
No, it depolarizes the same amount
Has the excitability of the sensory neuron of the sea slug’s siphon changed with habituation?
Yes, fewer action potentials (1 vs 2) occur when the siphon is touched
Has the synaptic connection weakened between the sensory and motor neurons of the sea slug’s siphon with habituation?
Yes, could be due to:
- Less presynaptic vesicles docking
- Vesicles having less glutamate in them
- Presynaptic voltage-gated calcium channels not opening as easily or for as long
- Fewer postsynaptic glutamate receptors
- Postsynaptic glutamate receptors being less sensitive to glutamate or not opening as much or for as long
Has the motor neuron of the sea slug’s siphon become less excitable with habituation?
No, it spikes the same amount when depolarized
Has the synaptic connection weakened between the motor neuron and the sea slug’s gill?
No, the gill is as sensitive to an action potential in the motor neuron as before
How can cell excitability and synaptic strength be measured?
They can be directly measured in brain slice recordings
How are brain slice recordings conducted?
- As soon as we kill the animal, the brain loses oxygen and sugar
- Goal is to take the brain out within a few minutes and then slice the brain very thin so the oxygen and sugar can fuse within a slice and keep the brain part healthy
- Putting ice cold saline in circulatory system of an animal in the heart to get a nice clean brain and being able to take the brain out and take a slice of it because the body is freezing
How can you stop a cell from getting an action potential?
By constantly hyperpolarizing it
What could long-term potentiation do to dendrite spines?
It may convert thin spines into mushroom-shaped spines
What are the 3 components of a deep neural network used in artificial intelligence for pattern recognition?
- Structure
- Objective function
- Learning function
What’s the structure component of a deep neural network used in artificial intelligence for pattern recognition?
Number of nodes and layers as well as how each node gets activated
What’s the objective function component of a deep neural network used in artificial intelligence for pattern recognition?
- The goal
- Ex: to label things in the input or to predict what the next input will be or to identify the best action given the input
What’s the learning function component of a deep neural network used in artificial intelligence for pattern recognition?
Method of adjusting the strength of each connection to better achieve the objective function
What are the different layers of the deep neural network?
Input layer -> hidden layer 1 -> hidden layer 2 -> hidden layer 3 -> output layer
Describe long-term potentiation (LTP)
- Long-term increase in the strength of the connection between two neurons (i.e., increased synaptic strength)
- Synaptic strengthening occurs when synapses are active while the membrane of the postsynaptic cell is depolarized
What does repeated high-frequency (tetanic) stimulation of the inputs to a neuron do to LTP?
It induces it
On which part of the synapse is LTP often initiated?
LTP is often initiated on the postsynaptic side (with more neurotransmitter receptors)
Describe long-term depression (LTD)
Long-term decrease in the strength of the connection between two neurons (i.e., decreased synaptic strength)
What often causes LTD?
- Persistent low-frequency stimulation of the inputs to a quiet neuron
- Commonly used is 1 Hz stimulation for 10 minutes
On which part of the synapse is LTD often initiated?
LTD is often initiated on the postsynaptic side (with less neurotransmitter receptors)
What can drive presynaptic modifications with long-term potentiation?
- Retrograde signaling of nitric oxide
- Ex: could cause creation of more vesicles of neurotransmitters
What can drive presynaptic modifications with long-term depression?
- Retrograde endocannabinoid signaling
- Ex: could cause less calcium-influx per action potential
What kind of stimulation often produces LTP?
High frequency stimulation (~100 Hz) for 1 second, repeated a few times every 10 seconds
What kind of stimulation often produces LTD?
- Low frequency stimulation (1Hz) over 5-10 minutes
- The same number of stimulations as LTP delivered at a slow rate
What needs to happen with the release of neurotransmitter for LTP to occur?
The release of neurotransmitter must coincide with a substantial depolarization of the postsynaptic cell (normally associated with an action potential)
What does low and high frequency axon stimulation do to postsynaptic neurons?
- High frequency axon stimulation often causes postsynaptic neurons to spike (summation of EPSPs brings the neuron across threshold)
- Low frequency stimulation on its own is often not sufficient to get a postsynaptic neuron to spike
NMDA receptors play a large role in what?
In learning and memory
What’s an NMDA receptor?
- an ionotropic glutamate receptor that has a large ion pore
- a coincidence detector
- a neurotransmitter- and voltage-dependent ion channel
- When the receptor binds glutamate and opens, magnesium ions try to pass through its pore, but they get stuck in it and block all current flow
How does the NMDA receptor function?
- When the postsynaptic membrane is at the resting potential, Magnesium (Mg2+) blocks the ion channel, preventing calcium (Ca2+) from entering
- When the membrane is depolarized, the magnesium ion is evicted
- Thus, the attachment of glutamate to the binding site causes the ion channel to open, allowing calcium ions to enter the dendritic spine
How does glutamate interact with the NMDA receptor?
- If a molecule of glutamate binds with the NMDA receptor, the calcium channel can’t open because the magnesium ion blocks the channel (cell at rest)
- However, depolarization of the membrane evicts the magnesium ion and unblocks the channel. Now glutamate can open the ion channel and permit the entry of calcium ions
When does the magnesium ion blockage occur in a NMDA receptor?
When the membrane potential is below threshold (< -40mV), such as when the cell is at rest
What happens if the NMDA receptor membrane is depolarized (more positive than -40 mV) because of synaptic inputs?
Then magnesium ions will not try to enter though the NMDA receptor, and thus they won’t clog the pore
When will Sodium (Na+) and Calcium (Ca2+) ions enter a cell through NMDA receptors?
Only when these receptors are bound to glutamate and magnesium (Mg2+) is not clogging the pore
Current flow through the NMDA channel is gated by what?
Both glutamate and membrane voltage
What’s an AMPA receptor?
- The glutamate receptor that mediates most excitatory fast synaptic currents in the brain
- It’s ionotropic and opens upon glutamate binding
- It lets in sodium ions which cause EPSPs (excitatory postsynaptic potentials) that depolarizes neurons
Most glutamate synapses in the brain have what kind of receptors?
AMPA and NMDA receptors
What’s Type II calcium-calmodulin kinase (CaMKII)?
- An enzyme that’s activated by calcium influx through NMDA receptors
- It plays a role in the intracellular signaling cascade that establishes long-term potentiation, by increasing the number of postsynaptic AMPA receptors (in excitatory glutamatergic synapses)
What are the 4 different types of learning?
- Perceptual learning
- Motor learning
- Relational learning
- Stimulus-response learning
What’s perceptual learning?
- Learning to recognize stimuli as distinct entities
- Brain will make up patterns by paying attention to and attaching meaning to stimuli
- Putting effort drives learning
- Ex: learning foreign language
What’s motor learning?
- Learning to make skilled, choreographed movements
- Actively think about it and focus on it
- Doing the action repeatedly
- Procedural learning
What’s relational learning?
- Learning relationships among individual stimuli across space and time
- Stimulus-Stimulus learning
What’s stimulus-response learning?
- Learning to perform a particular behavior when a particular stimulus is present
- “Given what you see what’s the best movement or action to take?”
- Includes classical and instrumental conditioning
How does effort coincide with learning?
A good part of learning is automatic but it also focuses on how much effort you put into it
What does the size of the dendritic spine (size of synapse) correlate with?
How strong the synapse is
What happens to the dendritic spine after long-term potentiation?
It grows in size
Describe associative long-term potentiation?
- The increase in synaptic strength that occurs in weak synapses when they are active right around the time when stronger inputs caused the postsynaptic neuron to spike
- If the weak stimulus and strong stimulus are applied at the same time, the synapses activated by the weak stimulus will be strengthened
- If the activity of strong synapses is sufficient to trigger an action potential in the neuron, the dendritic spike will depolarize the membrane of dendritic spines, priming NMDA receptors so that any weak synapses active at that time will become strengthened
- Pairing 2 inputs together (associating)
What’s Hebb’s rule?
- Hypothesis proposed by Donald Hebb that the cellular basis of learning involves the strengthening of synaptic connections that are active when the postsynaptic neuron fires an action potential
- “What fires together, wires together” (more strongly than before)
- The synaptic connection does have to initially exist
What’s an example of classical conditioning on neurons?
- When you hear a tone, the synapse isn’t strong enough to cause you to blink
- Weak synapse so not enough to depolarize the neuron and cause an action potential
- When a 1000-Hz tone is presented just before the puff of air to the eye, synapse T (from neuron in auditory system) is strengthened
- If we pair a tone with an air puff, we get action potentials in both these synapses and overtime, the weaker synapse will get stronger and stronger
Where is it much easier to induce synaptic plasticity?
In the hippocampus
What’s a dendritic spike?
When the action potential occurs, all the dendrites will be depolarized a bit
What are the 2 types of memory?
- Unconscious memory (implicit memory, nondeclarative memory)
- Consciously accessible memory (explicit memory, declarative memory)
Describe unconscious memories
- Implicit and nondeclarative
- Memories that influence behavior in an automatic, involuntary manner
- Relates to automatic adjustments to perceptual, cognitive, and motor systems that occur beneath the level of conscious awareness
How do we probe unconscious memories?
We say “show me”
What are examples of unconscious memories?
- Procedural memories (how to ride a bike)
- Perceptual memories (how to tell identical twins apart, unconsciously)
- Stimulus-response memories (salivating in response to a tone)
Describe consciously accessible memories
- Explicit and declarative
- Memories of events and facts that we can think and talk about
How do we probe consciously accessible memories?
We say “tell me”
What 2 types of memories are consciously accessible memories comprised of?
- Episodic memory
- Semantic memory
What’s episodic memory?
- “Episodes” of your life
- Personal experiences associated with a time and place
- Autobiographical memory that involves contextual information and is learned all at once
What’s semantic memory?
- Encyclopedic memory of facts and general information, often acquired gradually over time
- This knowledge need not be associated with the time or place in which we learned the information
What kind of memory is perceptual learning associated with?
- Implicit memory (unconscious)
- The basis of recognition & categorization
- Detecting the sensory irregularities in your environment
- Largely dependent on the neocortex – sensory association areas/cortexes
What kind of memory is motor (procedural) learning associated with?
- Implicit memory (unconscious)
- The basis of motor skills (bike riding, ball throwing, etc.…)
- Involves different brain areas involved in movement
What kind of memory is relational (stimulus-stimulus) learning associated with?
- Explicit and accessible memory (conscious)
- The basis of declarative memory (episodic and semantic)
- Largely dependent on the hippocampus and neocortex (visual association cortex)
What kind of memory is stimulus-response learning associated with?
- Implicit (unconscious) and Explicit (conscious) memory
- The basis of classical (Pavlovian) and instrumental (operant) conditioning
- Involves different brain areas depending on the stimulus and response
What’s a sensory memory?
- Perceptual memory (exactly what you perceive) that lasts only a couple seconds or less
- Allows an individual to retain the experience of the sensation slightly longer than the original stimulus
- Occurs in each of the senses
- Ex: people often reflexively say “what?” when they hear something while distracted, but then they quickly realize they did hear what was said
What’s short-term memory?
- Lasts for seconds to minutes
- Only a small fraction of sensory information enters short-term memory
- Memory capacity of short-term memory is limited to a few items (e.g. digits in a phone number or letters in a name)
- Length of short-term memory can be extended through rehearsal or thinking about something more
- Ex: might be able to remember phone number longer if you repeat it to yourself until you write it down
What’s long-term memory?
- Persists after getting distracted and even after a nap
- Information that’ll be retained from short-term memory is consolidated (thought about over and over) into long-term memory
- Long-term memories can be retrieved throughout a lifetime and strengthened with increased retrieval
How long do visual sensory memories last vs auditory sensory memories?
Visual memories last for hundreds of milliseconds and auditory information could last for 2 seconds
What’s the function of perceptual learning?
- Enables us to recognize and identify object or situations
- Pattern recognition system
- With it we can recognize changes/variations in familiar stimuli and respond to those changes
- Involves changes in the strength of connections between neurons and changes in excitability in primary and association sensory cortices
What’s the function of motor learning?
- Involves learning to make a sequence of coordinated movements
- We get feedback from our movements from our joints, vestibular system, eyes, ears, etc., then use this information to improve and optimize our movements
- Rapid component to motor learning as well as a slower process called between-session learning
What’s between-session learning?
Process where improvements in motor behavior are seen following a period of memory consolidation (in part during sleep)
What parts of the brain are involved with motor learning?
- Cerebellum
- Thalamus
- Basal ganglia
- Motor cortex
What’s visual agnosia?
- Damage to regions of brain involved in visual perception not only impair ability to recognize visual stimuli but also disrupt people’s memory of visual properties of familiar stimuli
- Damage to the ventral stream
- Trouble perceiving the world -> they can see but can’t make sense of it
What happens to people with visual agnosia’s drawings?
They are able to copy drawings line by line by looking at the image (can’t see it as a whole), but as soon we take the picture away and they have to draw from memory, they can’t draw it as well
Activation in what part of the brain occurs when someone looks at a picture that involves movement?
- Activation occurs in dorsal stream of parietal lobe
- They have the perceptual realization and tap into parietal cortex to identify the movement
What’s an unconditioned stimulus and an unconditioned response?
US: a stimulus that has inherent value, like food or a painful shock. Some stimuli in our environment trigger innate reflexive behaviours (ex: painful stimuli, fear from loud noises, food in mouth causing salivation, blinking when things fly toward your face)
UR: a behavioural response that is largely innate, hard-wired (unlearned, unconditioned)
What’s a conditioned stimulus and a conditioned response?
CS: a stimulus that was initially perceived as neutral (e.g., a tone) but now is perceived as predictive of an US. Conditioned responses are there to prepare for the stimulus (associating a tone with puff in the eye -> blinking when you hear tone)
CR: a behavioural response that occurs in response to a CS. The behaviour is often similar to the UR that was elicited by the US during training
What’s a key aspect of classical conditioning (pavlovian learning) regarding the animal and its environment?
- The animal has no control over its environment
- The animal can react to things (and we measure these reactions to infer learning), but the animal’s actions do not influence the course of events
What are synonyms of operant conditioning?
- Instrumental conditioning
- Reinforcement learning
What’s reinforcement learning (operant/instrumental conditioning)?
- Learning from the consequences of your actions, from the receipt of reinforcement or punishment
- The likelihood of you repeating an action depends on whether it was previously reinforced or punished
- Animals are always exploring their environment and sometimes their actions have consequences
- Instrumental behaviours start off as flexible, volitional exploratory behaviours
What’s the difference between classical (Pavlovian) and operant conditioning?
- In contrast to Classical (Pavlovian) learning, operant conditioning requires that the animal can move and make decisions that influence their environment (i.e., decisions that have consequences)
- When we’re looking at how the animal reacts to something to figure out what happens next -> instrumental task
- If we don’t need to look at animal to know what happens next -> pavlovian classical conditioning
What’s a reinforcing stimulus?
- Appetitive stimulus
- When it follows a particular behavior, it increases the likelihood the animal will repeat the behaviour
- Reinforcement makes the behavior more likely to occur
What’s a punishing stimulus?
- Aversive stimulus
- When it follows a particular behavior, it decreases the likelihood the animal will repeat the behaviour
- Punishment makes the behavior less likely to occur
The process of reinforcement strengthens the connection between what 2 neural circuits?
Strengthens a connection between neural circuits involved in perception (sight of the lever) and those involved in movement (the act of lever pressing)
Can instrumental conditioning be internal?
- Yes, you can be thinking thoughts and then do a behaviour and in your head and can decide whether this was good or this was bad
- Perceptual system doesn’t have to be something you see it could be generated by your own thoughts
What is drug addiction associated with?
- Instrumental conditioning
- When people start taking drugs, they’re initially in control and it’s acting as a reinforcement system, people think they’re consciously making this decision to take drugs
- What happens unconsciously is the dependency to this reinforcement system and people are often caught off guard about their addiction to it
- This builds up naturally in these neural circuits
What are 2 major pathways between the sensory association cortex and the motor association cortex (to go from perceptions to movements)?
- Direct transcortical connections
- Basal ganglia
How is the basal ganglia important for habit formation and instrumental conditioning?
- It integrates sensory and motor information from throughout the brain
- At first the basal ganglia is a passive “observer”
- As behaviors are repeated again and again, the basal ganglia begins to learn what to (actions become more and more habitual, more ingrained and automatic)
- Different circuits within the basal ganglia become involved in the action selection and action execution processes
- Eventually, the basal ganglia takes over most of the details of the process, leaving the transcortical circuits free to do something else
- At this point, we don’t need to consciously think about what we are doing
The strength of cortical inputs to the basal ganglia is regulated by what kind of signaling?
Dopamine signaling
What’s the major input nucleus of the basal ganglia and what is it comprised of?
- The striatum (or neostriatum)
- Consists of the caudate, putamen, and nucleus accumbens
Working memory involves what part of the brain?
Involves the whole cerebral cortex
What’s the importance of direct transcortical connections for instrumental conditioning?
- Connections from one area of the cerebral cortex to another
- Involved in acquiring complex motor sequences that involve deliberation or instruction
What’s the function of dopamine input to the striatum?
- Dopamine neurons in the midbrain (substantia nigra and ventral tegmental area) project to the striatum and seem to signal reinforcement and punishment
- The overall amount of dopamine in the striatum seems to correspond to motivation and the value of moving in and engaging with the environment
- Transient fluctuations in dopamine signaling seem to drive learning by signaling how unexpectedly good or bad the current moment is
- People think the overall dopamine levels relates to the animal’s ability to engage with the environment (when dopamine levels are low, animals aren’t engaging with environment and aren’t seeking rewards)
What are the different parts of the striatum?
- Caudate
- Putamen
- Nucleus accumbens (ventral striatum)
What kind of information does the nucleus accumbens process?
- It receives input from limbic areas such as the hippocampus, amygdala, and parts of PFC
- It seems to regulate people’s priorities (“I’m craving this thing or obsessing over this thing”)
What kind of information does the most dorsal lateral (caudate and putamen) part of the striatum get?
It’s getting motor sensory information that’s related to planning sequences of motor actions
What do lesions of the basal ganglia disrupt?
- Reinforcement learning and habit learning
- Don’t strongly affect perceptual learning or stimulus-stimulus learning
What was Henry Gustav Molaison’s (HM) condition and what treatment was given to him?
- He had epilepsy
- Doctors cut out his hippocampus bilaterally to cure his epilepsy
- It worked, but he lost the ability to form new explicit memories (severe anterograde amnesia)
- He also suffered from a graded retrograde amnesia (events that occurred within 1 or 2 years were lost as well as some events that happened even longer ago than that)
- He still had a brief working memory and a high IQ, but he could not learn new words or names or learn to navigate a new space
- Every day he woke up, he thought he was late for high school or football practice -> everyday he woke up, he thought he was a kid
- As soon as he was distracted, he would forget what he was doing (couldn’t remember what he was saying, what he was doing, what he ate that day or the day before)
What happens if you lesion the hippocampus bilaterally?
- You disrupt the animal’s ability to create/store memories
- Makes it so that you can remember things from 2 years ago (will forget the last year)
What’s Korsakoff’s syndrome?
- Permanent anterograde amnesia caused by brain damage, usually resulting from chronic alcoholism
- Caused by severe lack of vitamin B1
- Tends to be found in homeless alcoholics
- Patients are unable to form new memories but can still remember old ones before the brain damage occurred
- Confabulation is common for these patients -> if they think they know something but they don’t due to this syndrome, they make up an event
- Similar to what we see in split brain patients -> people think this is related to damage in one side of the brain
What’s confabulation?
Reporting of memories of events that did not take place without intention to deceive
What happens to animals/humans without a functional hippocampus?
- Animals cannot form new episodic or semantic memories
- Their short-term, working memory is generally fine
- They can also remember previously learned semantic information if it was consolidated prior to the hippocampal damage
- But generally live in the moment (in the present)
- They don’t really reminisce about previous episodes in their life, nor do they imagine future possibilities
What’s memory consolidation and where does it occur in the brain?
- Process of converting short-term memories into explicit long-term memories
- The hippocampus is not the location of either short-term or long-term memories but works with memory consolidation
- The hippocampus “turns the past into the future”
Describe the simplest model of the memory process
Sensory information enters short-term memory, rehearsal keeps it there, and eventually, the information makes its way into long-term memory, where it is permanently stored
Are memories stored in the hippocampus?
- It’s generally thought that memories are not stored in the hippocampus, but that the hippocampus forms a hub, node, or index that is capable of both representing and reactivating the sensory systems that initially encoded any given event/experience
- The hippocampus is creating some kind of snapshot
What’s memory retrieval (pattern completion)?
Partial cue (ex: ”what did you have for lunch”) processed in cerebral cortex and then goes in hippocampus which reactivates the entire cerebral cortex to relive this event (imagined -> see the sandwich, taste the sandwich, feel how you felt)
How does memory gradually becomes less and less dependent on the hippocampus, meaning the memory will still be there if you lose your hippocampus?
- A prominent theory is that hippocampal activity (during recall events and during sleep) is “training” the cortex, causing a reorganization of the synaptic weights in the cortex so that intra-cortical connections can support memory recall on their own
What’s the Semantic Transformation Theory?
- Some people argue that the cortex only contains semantic information (facts) - In this model, all memory starts off as episodic memory, which is always dependent on hippocampal nodes interacting with the cortex
- Over time, as facts emerge from repeated episodic experiences, these semantic memories are permanently stored in the cortex in a hippocampal-independent manner
What happens to the hippocampus when you’re asleep, spaced out or not paying attention?
It is replaying events (10x as fast), which is somehow training the cortex
