Lecture 17 Flashcards
What is an unconditioned stimulus?
A stimulus that has inherent value, like food or a painful shock
What is an unconditoned response?
A bhevaioural response that is largely innate, hard wire (unlearned, undoncitioned)
What is a conditioned stimulus?
A stimulus that was initially perceived as neutral but now is perceived as predictive of an US
What is a conidtionned response?
A behavioural response that occurs in response to a CS, the behaviour is often similar to the UR that was eleiced by the US during training
What is reinforcement learning?
Learning from the consequences of your own actions, from the receipt of reinforcement or punishment
What determines the likelihood of you repeating an action?
Whether it was previously reinforced or punished
How do instrumental behaviours start off as?
Flexible, volitional exploratory behaviours
What type of conditioning is reinforcement learning?
instrumental conditional conditioning
How does operant conditioning contrasts classical pavlovian learning?
operant conditioning requires that the animal can move and make decisions that influence their environment
What is a reinforcing stimulus?
An appetitive stimulus. When it follows a particular behaviour, it increases the likelihood the animal will repeat the behaviour.
What does reinforcement do?
Make it more likely for the behaviour to occur?
What does the process of reinforcement strengthen?
A connection between neural circuits involved in perception (sight of the lever) and those involved in movement (the act of lever pressing)
What is a punishing stimulus?
An aversive stimulus
What happens when an aversive stimulus follows a particular behaviour?
It decreases the likelihood the animal will repeat the bheaviour
What are the two major pathways between sesnory association cortex and motor association cortex?
Direct transcortical connection and the basal ganglia
What are direct transcortical connections?
Connections from one area of the cerebral cortex to another
What are direct transcortiocal connections involved in?
acquiring complex motor sequences that involve deliberation or instruction
What does the basal ganglia integrate?
Sensory and motor information from throughout the brain
What is the basal ganglia important for?
Habit formation
What happens at first in regards to the basal ganglia?
Then?
At first it’s a passive observer but then as behaviours are repeated again and again, the basal ganglia begins to learn what to do
What happens eventually in regards to the basal ganglia?
It takes over most of the details of the process, leaving the transcortical circuits free to do something else
What is the strength of cortical inputs to the basal ganglia regulated by?
Dopamine signaling
What is the major input nucleus of the basal ganglia?
The striatum (or neostriatum)
Where do the dopamine neurons in the midbrain project to? What do they signal?
They project to the striatum.
They signal reinforcement and punishment
What do the amount of dopamine in the striatum correspond to?
The motivation and the value of moving in and engaging with the environemnt.
What do the transient fluctuations in dopamine signaling seem to drive?
Learning by signaling how unexpectadly good or bad the current moment is
What do the different areas of the striatum process?
Different types of information
What do the different areas of the striatum regulate?
People’s priorities
What happens when action sequences and thought patterns are repeated again and again?
They become more and more habitual, more ingrained and automatic
What disrupts reinforcement learning and habit learning?
Basal ganglia leasoning
What doesn’t basal ganglia lesioning affect?
Perceptual learning or stimulus-stimulus learning
What happens when doctors cut out Henry Gustav Molaisons hippocampus bilaterly to cure his epilepsy?
It worked (no more epilepsy) but he lost the ability to form new explicit memories (severe anterograde amnesia)
What else did Henry Gustabe Molaison who had a bilateral hippocampus removal suffer from?
He suffered from a graded retrograde amnesia as well
What is permanent anterograde amnesia aused by brain damange, usually from chronic alcholism?
Korsakoff’s syndrome
What is permanent anterograde amnesia aused by brain damange, usually from chronic alcholism?
Korsakoff’s syndrome
What are Korsakoff’s patients unable to do?
Form new memories but can still remember old ones that before the brain damage occured
What is confabulation?
Reporting of memories of events that did not take place without intention to deceive
Where is confabulation seen?
In people with Korsakoff’s syndrome
What happens when there’s no functional hippocampus?
Animals cannot form new episodic or semantic memories - but their short term, working memory is generally fine
They usually live in the moment
What is the hippocampus involved with?
Converting short term memories into explicit long-term memories (memory consolidation)
What are the two learning stages?
Short term memory and long term memory
What is 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
What is reflected by a unique patter of neural activity during any given moment?
The constellantion of sensory input, thought processes and emotion you are currently experiencing
What is generally thought in regards to the memories and the hippocampus?
Memories are not stored in the hippocampus.
The hippocampus forms a hub, node or index that is capable of both representing and reactivating the sensory system that initia;;y encoded any given event/expereience
What is memory encoding?
Cortical sensory systems sending stuff to the hippocampus
Whats memory retrieval?
The hippocampus sending stuff to the cortical sensory systems
What happens over time in humans?
Memory gradually becomes less and less dependant on the hippocampus
What is happening in the years that memories are dependant on the hippocampus?
Hippocampal activity 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 did rodents need a functional hippocampus to remember?
Why?
Newly learned spatial information but not information learned 30 days ago.
Memories are consolidated and stored in the cerebral cortex during this time
What is anterograde amnesia?
Inability to learn new information or retain new information after brain injury.
Memory for events that occured before the injry remain largely intact
What is retrograde amnesia?
Referes to the inability to remember events that occured ‘before’ the brain injury
Is complete amnesia in either direction rare?
Yes
Does nondeclarative learning ability remain intact when there’s damage to the hippocampus or to regions of that supply its inputs?
Yes
What happens when amnesic patients are trained and tested?
We find that they are capable of three of the four major types of learning
But they don’t explicitly remember anything about WHAT they have learned
What do basal ganglia lesioning disreput?
Response learning
What does hippocampal lesions disrupt?
Place learning
