Chapter 24

Question 1

Define declarative and non declarative memory.

Answer 1

Declarative memory: Memory of facts and events.

Non-declarative memory: Several categories, e.g., procedural memory (memory for skills, habits, and behaviors).

Question 2

What are the brain structures thought to be involved in the following forms of memory:

1) Declarative memory
2) Procedural memory
3) Skeletal musculature
4) Emotional responses?

Answer 2

1) Medial temporal lobe; diencephalon
2) Striatum
3) Cerebellum
4) Amygdala

Question 3

What is the role of consciousness with declarative and non-declarative memory?

Answer 3

Generally, declarative memories are accessed consciously. However, non-declarative memories generally operate without conscious recollection.

Question 4

What are the other common names for declarative and non-declarative memory?

Answer 4

Declarative memory is known as explicit memory.

Non-declarative memory is known as implicit memory.

Question 5

How does the formation of procedural memories occur?

Answer 5

1) Through non-associative learning: A change in behavioral response that occurs over time in response to a single type of stimulus. Subcategories: Habituation and sensitization.
2) Through associative learning: Behavior is altered by the formation of associations between events; this is in contrast to a changed response to a single stimulus in non-associative learning. Subcategories: Classical conditioning and instrumental conditioning.

Question 6

What is habituation?

Answer 6

A form of non-associative learning, which is about learning to ignore a stimulus that lacks meaning. For example, a train goes by your apartment every hour, and over time you no longer notice it.

Question 7

What is sensitization?

Answer 7

A form of non-associative learning, which intensifies one’s response to all stimuli during a strong sensory stimulus (such as a blackout in a city). Response to stimuli that previously evoked little or no reaction is also intensified.

Question 8

What is associative learning in general?

Answer 8

In associative learning, behavior is altered by the formation of associations between events; this is in contrast to a changed response to a single stimulus in non-associative learning.

Question 9

What is classical conditioning?

Answer 9

A form of associative learning which involves combining an unconditional stimulus (US), that requires no training/conditioning to yield a response, with a conditional stimulus (CS), that requires training/conditioning before yielding a response.

In Pavlov’s experiment, the US was the sight of a piece of meat, and the dog’s response was salivation.
The CS was an auditory stimulus, such as the sound of a bell.

After repeatedly pairing the CS with the US, eventually the CS (auditory stimulus) was enough to trigger salivation alone, without the US. This learned response to the conditioned stimulus was called the conditioned response.

Question 10

What is instrumental conditioning?

Answer 10

A form of associative learning in which an individual learns to associate a response, a motor act, with a meaningful stimulus, typically a reward such as food.

An example of this is a rat in a box with a food dispensing lever. The rat learns from accidentally bumping the lever that food comes out of it, and after a few times it will press the lever until it is no longer hungry.

Question 11

What is the difference between classical conditioning and instrumental conditioning?

Answer 11

In classical conditioning, the subject learns that one stimulus (CS) predicts another stimulus (US).

In instrumental conditioning, the subject learns that a certain behavior is associated with a particular consequence.

Because motivation plays a large role in instrumental conditioning, the underlying neural circuits are considerably more complex than those involved in simple classical conditioning.

Question 12

How is declarative memory divided into subcategories?

Answer 12

• Long-term memory
• Short-term memory
• Working memory.

Question 13

What is long-term memory?

Answer 13

Long-term memories are those that you can recall days, months, or years after originally stored.

Question 14

What is short-term memory?

Answer 14

Short-term memories are more temporary, and vulnerable to disruption.

Question 15

What is working memory?

Answer 15

Working memory is sharply limited in capacity and requires rehearsal.

Question 16

How can sensory information affect the retaining of temporary/working memory information?

Answer 16

There are reports of humans with cortical lesions who have normal memory for information coming from one sensory system (e.g., seeing a list of numbers) but a profound deficit for information that comes through another sensory system (e.g., hearing a list of numbers).

Question 17

What is memory consolidation?

Answer 17

The process of facts and events stored in memory being converted into long-term memories.

Question 18

What is amnesia?

Answer 18

A serious loss of memory and/or the ability to learn.

Question 19

What is dissociated amnesia?

Answer 19

Amnesia that is not accompanied by any other cognitive deficit.

Question 20

What is retrograde amnesia?

Answer 20

Events for a period of time prior to the trauma (that caused amnesia) are forgotten, but memories from the distant past and period following the trauma are intact.

Question 21

What is anterograde amnesia?

Answer 21

Events prior to trauma can be remembered, but there are no memories for the period following the trauma.

Question 22

What is transient global amnesia?

Answer 22

A sudden onset of anterograde amnesia (memories for a period following the trauma), which only lasts for a period of minutes to days, often accompanied by retrograde amnesia for recent events preceding the attack.

A characterization of this could involve a person appearing disoriented and asking the same questions repeatedly, but being conscious and having normal working memory.

Question 23

What part of the brain is working memory based on?

Answer 23

Research in both animals and humans suggests that working memory is a capability of neocortex found in numerous locations in the brain.

Question 24

What is the role of the prefrontal cortex in human characteristics? Why?

Answer 24

It is often assumed to be involved in the characteristics that separate humans from animals, because it is so well developed in humans. However, its function is relatively poorly understood.

Question 25

What is a delayed-response task and what does it say about working memory?

Answer 25

In a delayed-response task, a monkey was shown food being placed in a well below one of two identical covers in a table. A delay period followed, during which the animal was not shown the table, and finally the animal was shown the table again and allowed to choose the well. Since large prefrontal lesions seriously degraded performance in this task, it was suggested that the frontal lobe is important for learning and memory.

Question 26

How does the Wisconsin card-sorting test work?

Answer 26

Cards containing various numbers of colored symbols must first be sorted by color. After a string of correct responses is made, the sorting category is changed to shape. People with prefrontal lesions have great difficulty on this task when the sorting category is changed; they continue to sort according to a rule that no longer applies. They appear to have a working memory deficit that limits their ability to make use of recent information to change their behavior. As such, it is suggested that the prefrontal cortex plays a role in working memory and learning. This is supported by human brain imaging experiments.

Question 27

What is LIP, and where is it located?

Answer 27

LIP stands for Lateral Intraparietal Cortex (area LIP), which is buried in the intraparietal sulcus.

Question 28

What is LIP involved in?

Answer 28

Guiding eye movements; electrical stimulation here elicits saccades in monkeys. The responses of many neurons in area LIP of monkeys suggest that they are also involved in a type of working memory. The responses in LIP area are specific to vision.

Question 29

What is a delayed-saccade test?

Answer 29

A test in which an animal fixates on a point on a computer screen and a target is briefly flashed at a peripheral location. After the target goes off, there is a variable length delay, at the end of which the fixation point disappears, and the animal's eyes make a saccadic movement to the remembered location of the target.

Question 30

What is an engram or memory trace?

Answer 30

An engram or memory trace is the location of a memory in the brain.

Question 31

What were Karl Lashley's findings related to memory? What were his incorrect and correct conclusions?

Answer 31

He induced large lesions in the brains of rats, and the rats started making mistakes in a maze game after getting the lesions. Lashley's INCORRECT conclusion was that all cortical areas contribute equally to all memories. However, his CORRECT conclusion was that all of the cortex participates inn memory storage, and that an engram can be widely distributed in the brain.

Question 32

What were Donald Hebb's findings related to memory?

Answer 32

He suggested that internal representations of objects consist of all the cortical cells that are activated by the external stimulus (e.g., the circle in figure 24.11). This group of simultaneously active neurons is called a cell assembly. "Neurons that fire together wire together". If onnly a fraction of the assembly were activated by a later stimulus, the powerful reciprocal connections in the memory would cause the whole assembly to become active again, thus recalling the entire internal representation of the external stimulus.

Question 33

What was Donald Hebb's important twofold message about the engram?

Answer 33

(1) It could be widely distributed among the connections that link the cells of the assembly (2) It could involve the same neurons that are involved in sensation and perception Destruction of just some of the cells would not be expected to eliminate the memory; this could possibly explain Lashley's results.

Question 34

Where do declarative memories need to go through in order to end up in the neocortex?

Answer 34

Decades of research suggests that they must pass through structures in the medial temporal lobes. A variety of experiments indicate that structures in the MEDIAL TEMPORAL LOBE are particularly important for the consolidation and storage of declarative memories.

Question 35

What is the medial temporal lobe known for, and where is it?

Answer 35

The temporal lobe is located under the temporal bonne. The medial temporal lobe contains the temporal neocortex, which may be a site of long-term memory storage, and a group of structures interconnected with neocortex that are critical for the formation of declarative memories.

Question 36

Where is the hippocampus?

Answer 36

It is a folded structure situated medial to the lateral ventricle.

Question 37

What are the 3 areas ventral to the hippocampus?

Answer 37

1) Entorhinal cortex, which occupies the medial bank of the rhinal sulcus (PART 1 of Rhinal Cortex) 2) Perirhinal cortex, which occupies the lateral bank of the rhinal sulcus (PART 2 of Rhinal Cortex) 3) Parahippocampal cortex, which lies lateral to the rhinal sulcus.

Question 38

Explain the 6 steps of information flow through the medial temporal lobe.

Answer 38

1) Sensory information 2) Cortical association areas 3) Parahippocampal and rhinal cortical areas 4) Hippocampus (CAN CONTINUE TO 2 FROM HERE) 5) Fornix 6) Thalamus, hypothalamus

Question 39

What is the fornix?

Answer 39

A major output pathway from the hippocampus which loops around the thalamus before terminating in the hypothalamus.

Question 40

What can happen when the human temporal lobe is electrically stimulated?

Answer 40

This can occasionally produce sensations such as hallucinations or recollections of past experiences. This is consistent with reports that epileptic seizures of the temporal lobes can evoke complex sensations, behaviors, and memories. However, these complex sensations were only reported by a minority of patients in the study, and all had an abnormal cortex associated with their epilepsy. Still, consequences of temporal lobe stimulation and temporal lobe seizures can be qualitatively different from other areas of the neocortex.

Question 41

How does the temporal lobe relate to memory?

Answer 41

In some experiments, neurons of the temporal lobe were activated when pictures of certain actors were shown. It is likely that the temporal lobe is indeed particularly important for learning and memory.

Question 42

Explain briefly the case of H.M. and temporal lobectomy&amnesia.

Answer 42

H.M. experienced minor epileptic seizures from the age of 10, perhaps from a bicycle accident suffered at the age of 9. At the age of 27, H.M. had an operation in which an 8cm length of medial temporal lobe was bilaterally excised, including cortex, the underlying amygdala, and the anterior two-thirds of the hippocampus. This was a last ditch attempt to alleviate the seizures. This had little effect on perception, intelligence, or personality, but caused profound and debilitating anterograde amnesia. For 50 years, doctors who worked with him had to reintroduce themselves each time they met with him. H.M. would forget events almost as quickly as they occurred.

Question 43

What was the nature of H.M.'s amnesia?

Answer 43

Anterograde amnesia with some degree of retrograde amnesia. He retained some childhood memories but little to no memory for events just before the surgery. He could learn a very small number of declarative facts after the surgery, such as John Kennedy and the floor plan of the home he moved to after surgery. He was also able to learn new procedural memories, such as new tasks, e.g., looking at his hand in a mirror. He was able to learn them even without having recollection of the specific experiences in which he was taught to do them.

Question 44

What can we conclude from H.M.'s case?

Answer 44

The medial temporal lobe is critical for memory consolidation but not for the retrieval of memories. Medial temporal structures do not store all memories even though engrams for some things may be located there. Working memory does not seem to rely on the medial temporal lobe. The formation and retention of procedural memories use brain structures distinct from those involved in declarative memory consolidation and perhaps storage.

Question 45

How does a delayed non-match to sample (DNMS) task work?

Answer 45

A monkey first displaces a sample object to obtain a food reward. After a delay, two objects are shown, and recognition memory is tested by having the animal choose the object that does not match the sample. With delays between a few seconds to 10 minutes, the monkey correctly displaces the non-matching stimulus on about 90% of the trials.

Question 46

What has been learned of amnesia as it relates to medial temporal lesions?

Answer 46

Anterograde amnesia does appear in monkeys with medial temporal lesions. Furthermore, the most severe memory deficits seem to result from damage to the perirhinal cortex. The anterograde amnesia resulting from perirhinal lesions is not specific to information from a particular sensory modality, reflecting the convergence of input from association cortex of multiple sensory systems.

Question 47

Do selective amygdala lesions have effect on recognition memory?

Answer 47

No.

Question 48

Do lesions of the hippocampus alone produce amnesia?

Answer 48

Yes, but only relatively mild amnesia.

Question 49

Where is a critical transformation of the information coming from the association cortex made?

Answer 49

Together with the hippocampus, the cortex in and around the rhinal sulcus evidently performs this critical transformation.

Question 50

In addition to consolidation, what role do medial temporal structures play?

Answer 50

They MAY play a role in the storage of memories for a long or short time.

Question 51

Are lesions to the medial temporal lobe the only lesions that produce amnesia?

Answer 51

No. Lesions to interconnected areas elsewhere in the brain can also produce amnesia.

Question 52

What role does the hippocampus play in memory?

Answer 52

1) It appears it plays a critical role in binding sensory information for memory consolidation 2) Particularly in rodents, it appears that the hippocampus supports spatial memory of the location of objects of behavioral importance.

Question 53

How do rats without a hippocampus perform in a radial arm maze?

Answer 53

They learn to go down the arms of the maze and eat the food placed at the end of each arm. However, they never learn to do this efficiently: they visit some arms multiple times, and leave other arms containing food unexplored. It seems that they learn the procedural memory part of going down the arms, but cannot seem to remember which arms they have already visited. However, a variation of this test shows that rats with hippocampus lesions are able to learn to avoid arms that never contain food, even though they never become efficient in searching through the ones that may contain it.

Question 54

What is the Morris water maze and how does it show that memory operates?

Answer 54

A pool of cloudy water has one slightly submerged platform. The rat is placed in the pool, and it will eventually find the platform, and escape water. Normal rats are quick to learn the spatial location of the platform, but rats with bilateral hippocampal damage never seem to figure out the game or remember the location of the platform.

Question 55

How do hippocampal neurons aid in spatial navigation and memory?

Answer 55

There are neurons in the hippocampus that selectively respond when a rat is in a particular location in its environment. When a rat is in a corner, a certain neural cell starts firing. When it moves out, the cell stops firing. Other hippocampal cells have other place fields. These neurons are called place cells.

Question 56

How to place fields work?

Answer 56

Their responses are, at least under some conditions, based on visual input. Blindfolded rats whose mazes are turned around have their place cells activated in a way that corresponds to the new appearance of the maze.

Question 57

What are grid cells?

Answer 57

They are neurons in the entorhinal cortex that are also spatially selective, like place cells. However, they respond when the animal is at multiple locations that form a hexagonal grid. Cells in different portions of entorhinal cortex differ in the spacing between "hotspots" in the grid, but the sensitivity grid for each cell tiles the environment the rodent is in.

Question 58

What place provides input to the hippocampus?

Answer 58

The entorhinal cortex.

Question 59

How does hippocampus function in relation to odors?

Answer 59

Some neurons in the hippocampus became selectively responsive for certain pairs of odors in lab rat experiments. The neurons were also particular about which odor was at which port

Question 60

What are the 3 key conclusions about the hippocampus?

Answer 60

1) It seems to be critical for memory consolidation of facts and events. 2) It seems to be especially important for spatial memory. 3) In human hippocampal neurons, there is sometimes surprising selectivity for people or objects we are familiar with. 4) Hippocampal cells appear to form associations between sensory stimuli even when the information is not about space.

Question 61

What are the key components of declarative memory formation?

Answer 61

1) Hippocampus 2) Cortical areas around the hippocampus 3) Diencephalon 4) Neocortex 5) More

Question 62

What is the standard model of memory consolidation?

Answer 62

In this model, information comes through neocortex areas associated with sensory systems and is then sent to the medial temporal lobe for processing (especially the hippocampal system). Changes in synapses create a memory trace via a process of synaptic consolidation. After synaptic consolidation, or perhaps overlapping it with time, systems consolidation occurs in which engrams are moved gradually over time into distributed areas of the neocortex.

Question 63

What is the multiple trace model of consolidation?

Answer 63

A theory according to which engrams involve neocortex, but even old memories also involve the hippocampus. The term "multiple trace" refers to the way the model allows for retrograde amnesia resulting from hippocampal damage to sometimes be graded in time. Hypothesis: Each time an episodic memory is retrieved, it occurs in a context different from the initial experience and the recalled information combines with new sensory input to form a new memory trace involving both the hippocampus and neocortex. This creation of multiple memory traces presumably gives the memory a more solid foundation and makes it easier to recall. Because retrieval requires the hippocampus, complete loss of the hippocampus should cause retrograde amnesia for all episodic memories no matter how old. With partial damage, intact memories are the ones with multiple traces.

Question 64

What is reconsolidation of memories?

Answer 64

According to rat studies, it seems that re-activating a consolidated memory brings it up for processing again, and makes it vulnerable to being wiped out e.g., by ECS. In human studies, a reminder of past events may make the memories susceptible to change and reconsolidation.

Question 65

How was the striatum shown to be part of the procedural memory system?

Answer 65

In rats, lesions in the hippocampal system, maze performance was degraded on the standard maze test but relatively unaffected in the one with lights. Lesions to the striatum impaired performance of the light task but had little effect on the standard task.

Question 66

How do Huntington's and Parkinson's patients show the role of the striatum in procedural memory?

Answer 66

Huntington's disease focuses on the Striatum and kills neurons throughout the brain. These people generally have motor dysfunction, but the difficulty in learning the stimulus-response habit does not correlate with the severity of the motor deficits, suggesting that it is an independent consequence of the disease. In Parkinson's, the substantia nigra inputs to the striatum are degenerated. Parkinson's patients have great difficulty learning how a certain deck of cards predicts the weather in a weather forecasting task, but performed at normal levels on the declarative memory questionnaire.

Question 67

1. If you try to recall how many windows there are in your house by mentally walking from room to room, are you using declarative memory, procedural memory, or both?

Answer 67

Mainly declarative memory, a recollection of the number of windows in the room is a fact you are trying to uncover. However, you might also argue that procedural memory of habits of walking through the rooms in your house would also be accessed.

Question 68

2. What kind of experiment might you conduct to find the place in the brain that people use to hold a phone number in mind?

Answer 68

Monitor the activity of neurons in e.g., the hippocampus and the neocortex. See which neurons light up when the participants are asked to recall the numbers.

Question 69

3. In what brain areas have neural correlates of working memory been observed?

Answer 69

Rather than a single system, the working memory is a capability of neocortex found in numerous locations of the brain, for instance frontal and parietal cortex.

Question 70

4. What structures in the medial temporal lobe are thought to be involved in memory?

Answer 70

1) Hippocampus 2) Rhinal sulcus (Entorhinal cortex + Perirhinal cortex) 3) Parahippocampal cortex

Question 71

5. Why did Lashley conclude that all cortical areas contribute equally to learning and memory? Why was this conclusion later called into question?

Answer 71

The severity of memory deficits correlated with the size of the lesions but apparently not with their location. However, Lashley's lesions were large, each damaging multiple brain areas possibly involved in learning or remembering the maze task. Furthermore, the rats may have solved the maze in several different ways, and the loss of one memory might have been compensated by another.

Question 72

6. What arguments can you think of for and against the idea that Wilder Penfield's electrical brain stimulation evoked memories?

Answer 72

For: The patients reported complex sensations, and they seemed to be describing memories in some cases. Against: Only few patients described complex sensations. Furthermore, the brain stimulation could have evoked sensory sensations that in turn triggered memories by association. Some patients also said they saw themselves, which is not something we normally experience.

Question 73

7. What evidence is there that declarative and non-declarative memory use distinctly different circuits?

Answer 73

H.M., who lost his medial temporal lobe in surgery, was unable to form new memories but was able to learn new tasks, i.e., form new procedural memories. Parkinson's and Huntington's may also provide some insight here.

Question 74

8. In the famous amnesic known as H.M., what types of memory were lost after temporal lobe surgery? What kinds were preserved?

Answer 74

H.M. suffered anterograde amnesia and some degree of retrograde amnesia. However, he could still learn procedural memories and his working memory was not destroyed.

Question 75

9. What are place and grid cells? Where have they been observed?

Answer 75

Place cells light up when e.g., a rat is in a certain position to its environment. Grid cells light up in specific areas of the environment, forming a grid. They've been observed in rats and to a limited degree in humans.

Question 76

10. What evidence indicates that long-term memories are stored in the neocortex?

Answer 76

H.M. experienced only a certain degree of retrograde amnesia when his medial temporal lobe was removed.

Question 77

11. The multiple trace model of memory consolidation was proposed to deal with what concern(s) about the standard model of memory consolidation?

Answer 77

The standard model of memory consolidation assumed decades-long systems consolidation process in order to account for extended retrograde amnesia.

Question 78

12. Where is it thought that procedural memories are stored?

Answer 78

The striatum.