1. Learning and Memory

2. Lecture Outline Hypotheses of learning and memory Short-term memory
Long-term memory
Learning and synaptic plasticity

3. Lecture Outline Hypotheses of learning and memory
Multiple memory processes
Multiple memory traces
Multiple memory systems
Short-term memory
Long-term memory
Learning and synaptic plasticity

4. Why are learning and memory important?
To be able to adapt to changes in the environment
Learning
Acquire and process information from the environment.
Changes the nervous system
Memory
Ability to retain this information.

5. Hypothesized Memory Processes
Incoming information
Performance
Retrieval
Working memory
Short-term storage
Encoding
Long-term storage
Consolidation
Sensory buffers
Sight
Sound
Smell
Touch
Loss of information 

6. Multiple Trace Hypothesis of Memory
High
Low
Input

7. Multiple Memory Systems Hypothesis
Memory can be divided into categories that reflect the type of information being remembered.
Each system primarily employs a distinct brain region.
Declarative  Hippocampus
Procedural  Basal Ganglia
Emotional  Amygdala
‘Working With’ Memory  Prefrontal Cortex

10. Sensory memory Large capacity, but rapid decay.
High
Large capacity, but rapid decay.
Sensory association areas involved.
Example: Your mother is lecturing you and you aren’t paying attention, however, if asked, you can repeat the last sentence she said.
Low
Input

11. Short-term memory (Working memory)
Lasts for seconds to minutes.
Severely limited capacity.
magical 7 ± 2 – digits, letters, etc.
Available to conscious awareness.
Prefrontal cortex involved.
Example: remember a phone number. between looking it up and dialing.
High
Low
Input

12. Intermediate-term Memory
Lasts for hours and days.
May be transferred to LTM through rehearsal.
Example: remembering where you parked your car.
High
Low
Input

13. STM and Forgetting Decay theory
memory fades away with time, unless there is rehearsal.
Interference theory
memory for other material interferes with information we are trying to remember.

14. Decay Theory of Forgetting
memory fades away with time.
unless there is rehearsal.
Rehearsal
100%
Amount of information
Day 1 Day Day Day 30
Example: reviewing notes after class.

15. Interference Theory of Forgetting
Better recall when presentation of information is spaced.
Massed
Spaced
Example: studying versus cramming.

16. Interference Theory of Forgetting
Better recall for items presented first (primacy) and last (recency) in a list.
BOOK
CAP
HAWK
BALL
LETTER
BIRD
CAN
SHIRT
LION
DOOR

17. Mechanisms of Primacy and Recency
Memory system has enough resources to transfer items at the beginning of a list into LTM.
Recency:
Items at the end of the list are still in STM and are therefore available for recall.
1. BOOK
2. CAP
3. HAWK
4. BALL
5. LETTER
6. BIRD
7. CAN
8. SHIRT
9. LION
10. DOOR

18. Hypothesized Memory Processes
Performance
Retrieval
Incoming information
Working memory
Long-term storage
Sight
Sound
Short-term storage
Sensory buffers
Encoding
Consolidation
Smell
Attention
Rehearsal
Touch

19. Factors Affecting Primacy and Recency
A distractor task at the end of a list interfered with recency, but not primacy.
Interrupts rehearsal.
A faster presentation rate interfered with primacy, but not recency.
Increases load and effects transfer of information from STM to LTM.
Changing the length of delay between training and testing interfered with both primacy and recency.

20. Effect of Delay on Primacy and Recency

21. Consolidation Hippocampus and amygdala involved.
Memories are subject to modification during reactivation and reconsolidation.
Memories are more likely to reflect how person perceived the event, rather than what actually happened.
Confidence is not correlated with accuracy.
Implications for eyewitness accounts, repressed memories of abuse.

22. Story so far…
Learning and memory involves multiple processes, traces and systems.
Processes
Encoding, consolidation and retrieval.
Traces
Sensory, short-, intermediate- and long-term.
Systems
Declarative, procedural, emotional, ‘working-with’.

23. Long-term memory Declarative Non-declarative Episodic Semantic
Procedural
Perceptual
Conditioning
Non-associative
High
Low
Lasts for months and years.
Takes a long time to consolidate.
Input

24. Declarative memory Knowledge we have conscious access to.
Often referred to as explicit memory.
Episodic
Personal experiences / events etc.
Canoeing on Lake Winnipeg, surfing in San Diego.
Often referred to as autobiographical memory.
Semantic
Conceptual knowledge
“Where is Lake Winnipeg, where is San Diego?”
“How do you canoe, how do you surf?”

25. Classical Conditioning
association between stimulus-stimulus.
hippocampus is involved.
Unconditioned stimulus (US)
stimulus (puff of air) that produces UR.
Unconditional response (UR)
reflex (eye blink) to US.
Conditional stimulus (CS)
an arbitrary stimulus (tone) paired closely in time with an US.
Conditioned response (CR)
behaviour (blinking) now occurs in response to CS (without need for US).
How general is this effect?

26. Mechanism for Classical Conditioning: Hebbian learning
If a synaptic connection is repeatedly active at the same time a post-synaptic neuron fires, then this will lead to changes in the structure or chemistry that strengthen the connection.

27. Non-declarative Memory
Performance informed by implicit knowledge.
Perceptual memory
Priming
Procedural memory
Operant / instrumental conditioning
Emotional memory
Conditioned fear response
Non-associative memory
Habituation / sensitization

28. Perceptual Memory: Priming
An alteration of response to a stimulus as a result of prior exposure.

29. Perceptual Memory: Priming
Can last for hours.
Not dependent on level of processing.
Reduced (but not eliminated) when presentation and test modalities are different.
Perceptual short-term memory involves the sensory association cortices.

30. Procedural Memory: Instrumental / Operant Conditioning
Pressing a button provides a reward.
Increases the likelihood that the animal will press the button again.

31. Procedural Memory: Instrumental / Operant Conditioning
Association between stimulus-response.
Stimuli following a behaviour can be either:
Reinforcing: perceived as positive.
Punishing: perceived as negative.
Basal ganglia are involved.

32. Procedural Memory: Motor Learning
Series of connected movements that become automatic with practice.
Other examples: how to tie a shoe lace, ride a bike, drive a manual transmission, play piano.

33. Emotional Memory: Conditioned Fear
Association between stimulus-valence (pleasant-unpleasant).
Amygdala is involved.
Little Albert
Conditioned to fear rats – hammer hitting metal.
Extended to other furry animals and objects.

34. Emotional Memory: Conditioned Fear
Nothing lasts forever!
If CS is repeated without US often enough, then the CR disappears (extinction).

35. Non-associative Memory: Habituation
Ignore incoming information that is not relevant.
Most basic form of learning.
Even worms can do it.
Tap response
C. elegans

36. Memory can be subdivided into multiple categories
involve distinct brain regions.
Short-term memory
Prefrontal cortex, sensory association areas
Declarative long-term memory
Hippocampus
Procedural long-term memory
Basal ganglia, motor association areas, cerebellum
Emotional long-term memory
Amygdala

37. Long-term potentiation
A long-term increase in the excitability of a neuron to a particular synaptic input caused by repeated high-frequency activity of that input.
EPSP’s are summated as successive EPSP’s occur and before past EPSP’s have dissipated.

38. Synaptic plasticity Presynaptic density Synaptic structure
LTP strengthens existing synapses and creates new ones.
Important for recovery of function post stroke.
Presynaptic density
Synaptic structure
Before LTP
After LTP
Before LTP
After LTP

39. Take Home Message Memory is multifaceted.
Many processes, traces, systems and brain regions involved.

40. Review Questions 1) In classical conditioning, an organism
A) learns the consequences of a specific behavior.
B) identifies and categorizes objects.
C) shows a species-typical behavior in response to a previously unimportant stimulus.
D) is able to recognize objects by the sounds they make.
E) forms an association between a response and a stimulus.
2) You are listening to a song on the radio while doing your homework. The phone rings. Your mother has called to tell you that your favorite uncle has died after being hit by a car. Three months later, you again hear the same song and suddenly feel very sad. In this example, the unconditional response is
A) the voice of your mother as she relays the bad news.
B) listening to the song.
C) your feeling about the song prior to the phone call.
D) your feeling about your uncle before he died.
E) feeling sad when your mother calls with the bad news.

41. Review Questions
3) The ________ states that a weak synapse will be strengthened if its activation occurs at the same time that the postsynaptic neuron fires.
A) perforant path hypothesis
B) law of effect
C) all-or-none principle
D) Hebb rule
E) law of summation
4) The ability to recall a series of events is referred to as
A) serial memory.
B) spatial learning.
C) perceptual learning.
D) episodic learning.
E) observational learning.
5) Intense electrical stimulation of axons within the hippocampal formation results in
A) long-term potentiation of postsynaptic neurons.
B) axoaxonic inhibition of presynaptic neurons.
C) recurrent inhibition of the stimulated axons.
D) long-term potentiation of presynaptic neurons.
E) B and C are correct.