Lecture 6: Learning

Question 1

What is memory?

Answer 1

A process where info is stored, consolidated and retrieved

Question 2

What is the multi-store model think about how memories are made?

Answer 2

Sensory input is stored in sensory memory, which if salient enough is input into short-term memory. Once this information is encoded through rehearsal, it gets stored into long-term memory from where you can retrieve it.

Question 3

What are the different types of memory and how long does the memory last?

Answer 3

Short-term memory: seconds
Working memory: seconds-hours
Long-term memory: hours to months
Long-lasting memory: months to years

Question 4

Working memory is moderately correlated with: (2)

Answer 4

fluid intelligence and overall g score

Question 5

How is memory assembled?

Answer 5

From pieces (similar to William James’s theory), we build mental representations of it which is influenced by our goals, expectation, knowledge and schemas.

Question 6

What is ironic about arousing memories?

Answer 6

We tend to be more confident about them, but our ability to remember them over time becomes inaccurate.

Question 7

What modulates our inaccurate memories?

Answer 7

1. Inconsistent information

2. False memories

Question 8

A memory trace/engram is:

Answer 8

A subset of cells representing a memory which were active during the original experience. All of the cells are connected, if you activate one, you will activate them all.

Question 9

Which cells are more likely to be included in the engram? (2)
How do we know?

Answer 9

Cells that are most amenable to change and likely to be excited at the time of memory formation. Also those that are overexpressing CREB.

Neurons overexpressing CREB are more active during fear memory training. Killing these neurons after the fear training impairs the fear memory.

Question 10

What is the process that increases the likelihood that a memory will be remembered?

Answer 10

LTP

Question 11

Gene-expression alters behavior. What is gene-expression regulated by?

Answer 11

Regulated by transcription factors, which are activated by events associated with learning (I.e., CREB - cyclic AMP-response element binding protein)

Question 12

What events associated with learning activate CREB? (2)

Answer 12

1. Neurotrophins

2. NMDA receptors

Question 13

How do linked memories work?

Answer 13

When Event 2 happens shortly after Event 1, the cells that were excited by Event 2 are still very excitable and so the second memory gets formed in very similar cells. Meaning memories close in space/time will get coded together and when one gets changed, the other one can as well.

Question 14

What was a criticism levelled at Lashley for his experiment of finding the engram?

Answer 14

Lashley assumed that memory was in cortex (not subcortical areas including the striatum and did not consider others like hippocampus).

Question 15

What was the case of patient H.M?

Answer 15

Hippocampus and adjoining areas in the medial temporal lobe were removed to treat epilepsy. After this surgery he had anterograde amnesia for declarative memory.

Question 16

What is retrograde amnesia?

Answer 16

inability to access old memories, may not be incomplete, with older memories being accessible while more recent memories are not

Question 17

Define declarative memory? What are the types?

Answer 17

things that you know that you can tell others (hippocampus involved). Types include episodic and semantic.

Question 18

Define non-declarative memory (which remains partially intact after hippocampus lesion).

Answer 18

Things that you know that you can show by doing (no hippocampus involved).

Question 19

What are the types of non-declarative memory and what brain structures are involved? (3)

Answer 19

1. Skill learning (basal ganglia, motor cortex and cerebellum)
2. Priming (cortex)
3. Conditioning (cerebellum)

Question 20

Due to H.M, what theory was hypothesized?

Answer 20

The Gateway hypothesis, that the hippocampus was involved in recent events but not in remote events that are stored as memories in the cortex. This theory says that memories become more semantic over time.

Question 21

What is the recognition test after image encoding? How was this confirmed by fMRIs?

Answer 21

It tests whether you remember (episodic) or know the interacting images (semantic). Items remembered at 10 minutes and 1 week had different signatures than items remembered at 10 minutes but known at 1 week because change from RR to RK over time corresponded to reduced activation of part of the hippocampus.

Question 22

What is the evidence against standard consolidation theory?

Answer 22

1. Patients with damage to the hippocampus showed retrograde amnesia years before injury
2. remote memories can be affected by hippocampus lesion

Question 23

What is the multiple-trace theory?

Answer 23

Everytime a richly detailed (episodic) memory is recalled, a new memory trace is constructed in the hippocampus.

Question 24

What do the standard vs multiple-trace theories predict?

Answer 24

STD vs MTT

1. Lower memory score for recent memory for semantic and episodic information
2. Same memory score for remote memory for partial/complete HPC lesion and controls for semantic/episodic info

MTT

1. Same memory score for remote memory for partial/complete HPC lesion and controls for semantic remote information
2. No memory for remote episodic information for complete HPC lesion.

Question 25

What are the cells in the HPC related to spatial navigation and the environment?

Answer 25

1. Place cell
2. Place-by-direction cell
3. Head direction cell
4. Grid cell

Question 26

What is non-declarative memory?

Answer 26

Memory that cannot be reported, often no awareness when memory is being used and involuntary.

Question 27

What is procedural memory?

Answer 27

Individuals with anterograde amnesia can still learn tasks such as mirror tracing which is a visual and motor test that involves learning a new motor skill. The task requires you to move a pencil to trace the diagram of a star while looking at your hand only as a reflection in a mirror.

Question 28

What brain structures are involved in skill learning? What is the sequence?

Answer 28

Cortex, basal ganglia and cerebellum.

Neocortex -> basal ganglia (moderated by dopamine from the substantia nigra) -> ventral thalamus -> premotor cortex

Question 29

What disease occurs due to dysfunction in basal ganglia?

Answer 29

Parkinsons, due to changes in input from the substantia nigra.

Question 30

What brain structure is involved in recognition memories?

Answer 30

Perirhinal cortex.

Question 31

How do animal studies show that the perirhinal cortex is involved in recognition, while the hippocampus is involved in spatial memory?

Answer 31

Lesions to the perirhinal cortex prevent animal from recognizing something as novel and they are unable to choose the reward that is under the novel box. While lesions to the HPC show that the animal does not choose the box in the same location as where the reward was.

Question 32

What are PFC cells involved with in memory?

Answer 32

PFC cells maintain representation of food by firing during the delay period (when the food is hidden). Or in other words, responsible for object permanence.

Question 33

What’s the difference between recall/retrieval and reconsolidation.

Answer 33

They are reverse processes.

Question 34

How can we treat memory dysfunction?

Answer 34

Activation of certain brain areas (e.g. entorhinal cortex) using electrodes can modestly facilitate spatial memory.

Question 35

What is neuroprosthesis?

Answer 35

Use of direct electrical stimulation (via implanted devices) to affect behaviour

Question 36

How do we erase a fear memory?

Answer 36

By killing/silencing the group of cells that were initially engineered to have a lot of CREB expression.

Question 37

How do we create false memories?

Answer 37

One study used a transgenic mouse model where active (engram) cells will express light sensitive receptors.
First, animals is placed in a safe context A (afterward, engram A cells express light-sensitive receptors).
Second, animals is placed in fear context B (unsafe), BUT during this time, Engram A cells are activated with light (so those animals have a reactivation of the safe context while they’re being conditioned).
The result, is that when returned to Context A, animal freezes in context A (even though it was safe)
We turned the safe memory of context A into a fear memory by manipulating the engram cells.

Question 38

How do we modify memory? What about pharmacologically?

Answer 38

While the memory is active you do a drug intervention, therefore reconsolidation is affected and gets stored differently in long-term memory. Since the amygdala adds emotional valence to memories if it is damaged or B-adrenergic receptors that are reactive to stress are blocked by a drug intervention, over time, the emotional saliency will go away.

Question 39

What is extinction?

Answer 39

The reduction in a conditioned response to a conditioned stimulus following repeated, unreinforced presentation of that stimulus.

Question 40

What factors modulate extinction? (7)

Answer 40

1. Age
2. Sex
3. Genetics
4. Stress
5. Neuroticism
6. Brain morphology
7. Life events

Question 41

What neural structures are implicated in extinction (inhibition)?

Answer 41

1. Prefrontal Cortex

2. Dorsal Anterior Cingulate Cortex

Question 42

What is the Morris Water Maze testing?

Answer 42

Spatial memory; Animal is placed in a pool of water. To escape it must find a submerged platform (takes several trials (useful in testing LTM). As the animal learns the platform location, they complete the trails faster.

Question 43

How do animals overexposing NMDA receptors perform on the Morris Water Maze task?

Answer 43

Have slightly better memories than controls for the location of the platform, even when it’s removed in what’s called a probe trial.

Question 44

What is the novel object recognition task?

Answer 44

It’s a non-aversive way to test memory. During the training phase, the animal exposed to a set of ID objects. In phase 2, the animal is allowed to explore. In phase 3, animal is returned to the chamber, once object replaced with a novel object.

Question 45

How do transgenic animals perform on the NOR task?

Answer 45

If they’re missing the gene that they had played a role in recognition, the animals showed deficits in hippocampus and perirhinal related memory (what’s involved in object recognition) and performed poorly on the NOR task.

Question 46

What is the T-maze, Y-maze task?

Answer 46

It is a non-invasive working memory task. We measure the ability of animals to maintain spatial information and know which places it has been to before. Will animals visit new places? Signals good memory, avoiding old locations)