Lecture 16 Flashcards
What does learning refer to?
The process by which experiences change our nervous system and hence our behaviour
What do refer to the changes of our nervous system as?
Memories
What can memories be?
Transient or durable
Explicit or implicit
Personal or impersonal
What is accesing memory known as?
Memory retreival
What is the cellular basis of long term memory?
Neuronal plasticity
What does neuronal plasticity refer to?
The ability of the nervous system to change and adapt
To identify neuronal plasticity what do researchers typically measure?
Intrinsic excitability and synaptic strength
What is intrinsic excitability?
The number of action potentials a neuron exhibits in response to an influx of positive current
What is synaptic stength?
The amount of positive or negative current that enters the post synaptic neuron when a presynaptic cell has an action potential
What is the change in strength of the synaptic connection between neurons called?
Synaptic plasticity
How is intrisic excitability determined?
By the number and type of ion channels expressed by the neurons
What are enduring changes in synaptic strength referred to as?
Long term potentiation or long term depression
What are EPSP?
Excitatory post synaptic potentials.
Membrane depolarizations that are driven by neurotransmitter release and postsynaptic receptor activation
What can synaptic plasticity involved?
Pre and post synaptic changes
On the presynaptic side, what does the amount of voltage gated calcium channels on the presynaptic membrane influence?
How many vesicles will be released following an action potential
On the post synaptic side, what does the amount of neurotransmitter receptors influence?
The sensitivity of the postsynaptic cell to neurotransmitter
What is habituation?
Reduced physiological or behavioural responding to a repeated stimulus
What is sensitization?
Increased sensitivity to a stimulus?
In regards to habituation, does the sensory neuron become less sensitive to touch?
No it depolarizes the same amount
In regards to habituation, has the excitability of the sensory neuron changed?
Yes, fewer action potentials occur when the siphon is touched
In regards to habituation, has the synaptic connection weakened between the sensory and motor neurons?
Yes
In regards to habituation, has the motor neuron become less excitable?
No, it spikes the same amount when depolarized
What do the deep neural nets used in artificial intelligence for pattern recognition have a:
- Structure
- Objective function
- Learning function
What are the structure of deep neural nets?
Number of nodes and layers as well as how each node gets activated
What is objective function?
The goal
What is the learning function?
Method of adjusting the stength of each connection to better acheive the objective function
What does long term potentiation increase?
The stength of the connection between two neurons
What does repeated high - frequency (tetanic) stimulation of the inputs to a neuron induce?
LTP
What side is LTP often initiated by?
The post synaptic side
Does long term depression increase or decrease the strength of the connection between two neurons?
Decrease
What does the persisitent low frequency stimulation of the inputs to a quiet neuron cause?
LTD
What side is the LTD often initiated by?
The postsyanptic side
What are LTP and LTD functions of?
The number of times the synapse was activated as well as whether the postsynaptic neuron fired at those precise times
What has to happen for LTP to occur?
The release of neurotransmitter must coincide with a substantial depolarization of the post synaptic cell
What often causes post synaptic neurons to spike?
High frequency axon stimulation
What is not sufficent to get a post synaptic neuron to spike?
Low frequency axon stimulation
What do NMDA receptors play a large role in?
Learning and memory
Where are NMDA receptors located?
In almost every glutamatergic synapse in the brain
What is the NMDA receptor?
An ionotropic glutamate receptor that has a large ion pore
What happens when NMDA receptor binds to glutamate and opens?
Magneisum ions (Mg2+) try to pass through its pore, but they get stuck in it and block all current flow
When does the Mg2+ blockage of the NMDA receptors occur?
When the membrane potential is below threshold
What happens when the membrane is depolarized because of other synaptic inputs?
Mg2+ ions will not try to enter through the NMDA recepter, and they won’t clug the pre
What is an AMPA receptor?
The glutamate receptor that mediates most excitatory fast synaptic currents in the brain
Is an AMPA receptor ionotropic or metabotropic? What does it open up?
ionotropic, glutamate binding
What does an AMPA receptor let in? What do they cause?
Sodium ions, EPSPs, that depolarize neurons
What do most glutamate synapses in the brain have?
AMPA and NMDA receptors
What is an NMDA receptor?
An ionotropic glutamate receptor that only passes current upon glutamate binding when the membrane potential is slightly depolariaed
What happens when the glutamate binds when the cell is hyperpolarize?
The pore will get blocked by Mg2+
What do open unblocked NMDA receptors allow?
Sodiym and calcium ions through
What is an CaMKII?
A type II calcium-calmodulin kinase, an enzyme
What is CaMKII activated by?
A calcium influx through NMDA receptors.
What does CaMKII play a role in?
Intracellular signalling cascade that establish long term potentiation by increasing the number of postsynaptic AMPA receptors
How can LTP also be expressed?
Through changes on the presynaptic side of things
How do LTP’s initiate the process?
Postsynaptic neurons
What is associative long term potentiation?
Increase in synaptic strength that occurs in weak synapses when they are active right around the time when stronger inputs cause the post synaptic neuron to spike
What’s hebb’s rule?
Fire together, wire tigeth : cellular basis of learning involves the strengthening of synaptic connections that are active when the post synaptic neurons fires an action potential
What are the types of learning?
Perceptual
Motor
Relational
Stimulus/response
What is perceptual learning?
Learning to recognize stimuli as distinct entities
What is motor learning?
Learning to make skilled, choreographed movements, procedural learning
What is relational learning?
Learning relationships among individual stimuli (stimulus-stimulus learning)
What is stimulus/response learning?
What does it include?
Learning to perform a particular behaviour when a particular stimulus is present .
Classical and instrumental conditioning
What is unconsious memory? What does it entail?
Implicit/non declarative memory
What do unconscious memories relate to?
Automatic adjustments to perceptual, cognitive and motor systems that occur beaneath the level of consiousness awareness
How do we prob memories in the unconscious memory? Give the three examples
We say show me
Procedural memories (like how to ride a bike)
Perceptual memroies (how to tell identical twins apart)
Stimulus response memories (salivating in response to a tone)
What is consciously accesible memory?
Exp0licit memory, declarative memory
Memories of events and facts that we can think and talk about
How do we probe consciously accesible memory?
Say “tell me”
What does consciously accesible memory include?
Episodic memory and sematic memory
What is episodic memory?
Personal experience associated with a time and place. Autobiographical memory that involves contextual information and is learned all at once
What is sematic memory?
encyclopedic memory of facts and general information.
What type of memory is perceptual learning?
implicit memory
What is perceptual learning the basis of?
The basis of recognition and categorization
What is perceptual learning dependant on?
On the neocortex - sensory association areas
What type of memory is motor/procedural learning?
Implicit
What is motor learning the basis of?
Motor skills
What does motor learning involve?
Different parts of brain areas involved in movement
What is relational learning/stimulus- stiumulus learning type of memory?
Explicit
What is stimulus response learning memory type?
implicit and explicit
What is relational/stimulus-stimulus learning the basis of?
Declarative memory (episodic and semantic)
What is relational/stimulus to stimulus learning dependant on?
On the hippocampus and neocortex
What is stimulus - response learning the basis of?
clasical (pavlovian) and instrumental (operant) conditioning
What areas does stimulus response learning involve?
Different brain areas depedning on the stimulus and response
What is sensory memory?
Perceptual memory; lasts inly a couple seconds or less
What does sensory memory allow an individual to?
An individual to retain the experience of the sensantion slightly longer than the original stimulus =
Where does sensory memory occur?
In each of the senses
How long does short - term memory last?
Lasts for a seconds to minutes
Is a large fraction of short term memory sensory information?
No, only a small fraction
What is the memory capacity of short term memory limited to?
A few items, such as the ligits in a phone number or the letters in a name
How can the length of short term memory be extended?
Through rehearsal
What does long term memory do?
persist
How long thereafeter can long term memories be retrieved?
Throughout a lifetime
How is long term memory strengthened?
With increased retrieval
What are the different types of learning?
Perceptual
Motor
Relational
Stimulus - response
What is perceptual learning?
Learning to recognize stimuli as distinct entities
What is motor learning?
learning to make skilled, choreographed movements, procedural learning
What is relational learning?
learning relationships among individual stimuli.
Stimulus-stimulus learning
What is stiumulus- response learning?
learning to perform a particular behaviour when a particular stimulus is present
What does stimulus response learning include?
Classical and instrumental conditioning
What does perceptual learning enable us to do?
Recognize and identify objects or situations
What type of recognition is perceptual learning?
Pattern recognition
What can we do through perceptual learning?
Recognize changes or variations in familiar stimuli and respond to these changes
What does perceptual learning involve?
Changes in the strength of connections between neurons in primary and association sensory cortices
What is a visual agnosia?
Damage to regions of brain involved in visual perception not only impair ability to recognize visual stimuli but also disrupt peoples vissual memory of visual properties of familiar stimuli
What is motor learning involved in?
Learning to makie a sequence of coordinated movements
What information do we use in order to improve and optimize our movements?
The feedback from our joints, vestibular system, eyes, ears, etc..
What parts of the brain are involved in motor learning?
The cerebellum, the thalamus, the basal ganglia and the motor cortex
What is between session learning?
Where improvements in motor behaviour are seen following a period of the memory consoldiation (in part during sleep)
