L30-32: Intro Flashcards
What are the two most basic subdivision of memory?
Short term (working) and long term
How does the neural activity mediating short- and long term memory differ?
Short: info is sustained for as long as the neural activity keeps going, and comepletely disapears when the activity is interrupted
Long: neural and synaptic plasticity stores info that can be reactivated by partial or associated cues (does not rely on sustained neural activity)
How can long-term memory be further subdivided?
- Non-declarative (implicit): memories that are expressed through performance independently of consciousness
- Declarative (explicit): consious memory for facts and events
Define semantic memory.
Schematic organization of our factual knowledge of the world, e.g., objects –> inanimate/ANIMATE –> mammals/BIRDS –> flyring/FLIGHTLESS –> penguin
Define episodic memory.
Events
Define sensitization, and provide an example.
An increase in response to the habituated stimulus when it is paired with an aversive stimulus (e.g., a shock)
Example: Aplysia gill withdrawal
Describe reinforcement learning.
Rats get food when they press the lever, cats can escape box and gets fish when they press button ect.
Describe the role of dopamine and other reward signals in learning and memory
Dopamine: reward system
If reward is predicted, and no reward is given –> VTA DA decrease with unexpected lack of reward, and vise versa for unexpected reward
Describe the involvement of different brain structures in procedural learning and memory.
Corticobasal ganglia loops
Basal ganglia: striatum
Describe differences between motor skill learning, motor sequence learning and motor adaptation.
- Motor skill learning: refers to every task learned that require the motor system, subdivided into:
- Motor sequence learning: focus on the incremental aquisition of movements into a well executed behavior
Motor adaption; focus on the process of compensating for environmental changes
Define habituation, and provide an example.
A reduced response when the same stimulus is repeated multiple times. Example: Aplysia gill withdrawal
Define classical conditioning, and provide examples.
An innate reflex is modifed by associating its normal triggering stimulus to an unrelated stimulus that reliably predicts the trigger
Response: Involuntary
Timing of stimulus: precedes the response
Timing of response: after stimulus
Role of learner: passive
Examples:
- Pavlov’s dogs: rings a bell every time they get food –> associates bell ring with food –> saliva when bell rings
- eye-blink conditioning (repeated puff of air + tone untill tone itself elicits reflex (blinking))
Define operant conditioning, and provide examples.
The probability of a behavioral response is altered by associating the response with a reward (reinforcement) or a punishment.
- Nature of response: voluntary (usually), but can be both in/voluntary
- Timing of stimulus: after the desired response
- Timing of response: before the stimulus
- Role of learner: active
Examples: - Skinners box (animals learn to associate pressing a lever with receiving a food pellet)
- Edward Thorndike’s puzzelbox (cats learn to press the level in a box to escape and receive fish)
Describe different stages of human motor learning.
1) cognitive phase: What is it that I have to do? - frontal cortex
2) association phase: proper motor learning - cerebellum, BG, preMC, parietal cortex
3) autonomous phase: little attention necessary - PMC, cerebellum, brain stem, spinal cord
Describe the role of the cerebellum in motor adaptation.
Feedforward: compares the motor signals being sent to the muscles from the cortex with the somatosensory info from the limbs –> ensures that the ongoing movements are produced in a coordinated manner
Describe the idea of internal feed-forward models in motor learning.
Error based:
- Prediction is important in motor learning, as the motor commands to the muscles and sensory signals from the limbs take time to travel back and forth (50-150 ms). This delay would make it impossible to rely on feedback ==> feedforward
Describe the underlying molecular mechanisms of sensitization (Aplysia gill withdrawal: short-term).
Lasts app. 1 hour
- Recruitment of additional circuit elements (modulatory interneurons) that strengthen the synaptic transmission in the gill withdrawal circuit
- Tail shock activates sensory neurons –> modulatory interneurons are activated –> release serotonin –> GPCR on the presynaptic sensory neurons of the siphon activated –> adenylyl cyclase activated –> cAMP production increased –> cAMP bind to the regulatory subunits of PKA –> catalytic subunits of PKA are liberated –> K+ channels are phospharylated and deactivated –> prolonged presynaptic AP –> more Ca2+ channels are activated by prolonged AP –> more glutamate release to motor neuron –> increased sensory response
Describe the underlying molecular mechanisms of habituation.
Transmission at the glutamatergic synapse between the sensory and motor neurons is depressed at the PREsynaptic level due to a reduction in the number of synaptic vesicles available for release:
- when rates of release are high, the NT vesicles deplete rapidly –> depression
Describe the underlying molecular mechanisms of sensitization (Aplysia gill withdrawal: long-term).
Lasts up to several weeks
-the same mechanisms that underlie short-term –> PKA also phosphorylate the transcribtional activator CREB –> binds to cAMP response elements (CREs) in regulatory regions of nuclear DNA –> increased rate of transcription of downstream genes ==> multiple consequences, e.g.,
- –> activation of ubiquitin hydrolase –> degradation of the regulatory subunits of PKA –> long-lasting increase of free catalytic PKA subunits –> PKA is consistently active without serotonin release
Describe the underlying molecular mechanisms of classical conditioning.
Delay (eyeblink):
- cerebellar cortex:
Particularly dependent on the interpositus nucleus and the cerebellar cortex
Trace (eyeblink)
- also dependent on the cerebellar cortex, but moreover dependent on the hippocampus
Describe the underlying molecular mechanisms of operant conditioning.
Goal directed:
- depends on hippocampus, and the caudate (associative loop)
Habitual learning:
- depends on the putamen (sensory-motor loop)
Describe the differnce between delay conditioning and trace conditioning.
In delay conditioning the conditioned stimulus (CS, e.g., the tone in eyeblink) is still present when the unconditioned stimulus (US, e.g., the puff in eye blink) start, and they both terminate at the same time, whereas in the trace, there is a brief interval between the CS and the US (CS must leave some kind of memory trace)
What types of memories are delay- and trace conditioning, respectively?
Delay: nondecalrative (hippocampus is not involved)
Trace: declarative (hippocampus is involved, and only participants aware of CS-US contingencies showed trace conditioning)
How can declarative memory be subdivided?
- Episodic:
- Semantic:
- Spatial:
How can nondeclarative memory be subdivided?
- Procedural (skill learning): tasks either motor or cognitive (e.g., reading)
- Priming: change in response to a stimulus/in the ability to identify a stimulus following prior exposure to that stim
- Conditioning
- Nonassociative learning: habituation or sensitazation
