Memories

Question 1

Entorhinal cortex

Answer 1

EC is the main interface between the hippocampus and cortex. EC-hippocampus system plays important role in autobiographical/declarative/episodic memories and in particular spatial memories including memory formation, memory consolidation, and memory optimization in sleep.

Question 2

Dentate gyrus

Answer 2

Part of the hippocampal formation. Thought to contribute to the formation of new memories, as well as possessing other functional roles.

Question 3

Perirhinal cortex

Answer 3

Cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36. Lesions to this area in monkeys and rats lead to the impairment of visual recognition memory/disruption of object-recognition abilities.

Question 4

Posterior cingulate cortex

Answer 4

Imaging studies indicate that this area plays a prominent role in episodic memory retrieval.

Question 5

Medial Temporal Circuitry

Answer 5

Areas belonging to the Hippocampus proper: Dentate Gyrus, CA3, CA1, and Subiculum. Adjacent MTL cortices: Entorhinal, perirhinal, parahippocampal. These interact with one another (see diagram in slides for more info)

Question 6

Hippocampus

Answer 6

Found in the medial temporal lobe. Plays major role in consolidation of information from short-term to long term memory and spatial navigation.

Question 7

EC-hippocampus system

Answer 7

Plays an important role in autobiographical/declarative/episodic memories and in particular spatial memories including memory formation, memory consolidation, and memory optimization in sleep.

Question 8

Retrograde amnesia

Answer 8

Loss of access to memories that occurred, or information that was learned, before and injury. Often graded: very recent memories are more affected than ones from youth. “Ribot” gradient.

Question 9

Anterograde amnesia

Answer 9

Loss of ability to create new memories after the event that caused the amnesia, while long-term memories from before the event remain intact. Irreversible.

Question 10

“Ribot” gradient

Answer 10

States that there is a time gradient in retrograde amnesia, so that recent memories are more likely to be lost than more remote ones (look at diagram)

Question 11

Case of HM

Answer 11

Patient whose hippocampus, parahippocampal gyrus, and amygdala were surgically removed to try to cure his epilepsy had severe anterograde amnesia.

Question 12

Case of Clive Wearing

Answer 12

Contracted Herpesviral encephalitis - virus attacked hippocampus. Anterograde amnesia where memory only lasts between 7 and 30 seconds. Consciousness restarts every 20 seconds. Yet he still has procedural memory: he can play piano and conduct even though he has no recollection of his musical education.

Question 13

Alzheimer’s Disease

Answer 13

Atrophy of the brain. Memory loss - difficulty in remembering recently learned facts/inability to acquire new information. Subtle problems with executive functions - attentiveness, planning, flexibility, abstract thinking, impairments in semantic memory - can also be symptoms of AD.

Question 14

Korsakoff’s syndrome

Answer 14

Characterized by anterograde amnesia; during the late stages there is also retrograde. Caused by lack of thiamine in brain. Onset linked to chronic alcohol abuse and/or severe malnutrition, which causes damage to medial thalamus and hypothalamus; generalized cerebral atrophy.

Question 15

Areas involved in memory coding

Answer 15

Medial Temporal Lobe - Different features are bound into an episodic representation.
Dorsolateral PFC - Organizes material to be remembered.
Ventrolateral PFC - Elaborative processing of MTL representations to ensure traces are distinct.

Question 16

Areas involved in memory retrieval

Answer 16

MTL - Comparison of retrieval cue and stored representations using pattern completion.
Anterior PFC - Higher-level mnemonic control operations
Dorsolateral PFC - Monitoring and verification of retrieved information
Ventrolateral PFC - Strategic search of MTL stored representation; maintenance of retrieved information

Question 17

Two kinds of memory

Answer 17

Long-term and short-term
Long-term has declarative/explicit and nondeclarative/implicit memory: focus on declarative in class.
Declarative memory concerns both events/episodic memory and facts/semantic memory.

Question 18

Episodic memory

Answer 18

Memory for personally experienced events that occurred in particular place at specific time
Specific events - the first time doing something
General events - the general feeling of doing something, such as stepping into the ocean
Personal facts - biographical, etc
Flashbulb memories - critical autobiographical memories about a major event

Question 19

Effects of lesions on episodic memory

Answer 19

1. Large lesions of bilateral hippocampi, amygdala, rhinal cortex produce severe amnesia.
2. Circumscribed lesions of CA1 of hippocampus produce anterograde amnesia.
3. Korsakoff’s patients with diffuse damage to medial thalamus, hypothalamus show varied amnesia.
4. Alzheimer’s patients show early signs of amnesia, with first lesions in Medial Temporal Lobe

Question 20

Retrieval of episodic memories - neuroimaging

Answer 20

1. Hippocampal activations during episodic encoding.
2. Left frontal during encoding, right during retrieval
3. Posterior cingulate/precuneus - successful retrieval of remembered episodes.
4. Ventral parietal cortex - episodic memory retrieval tasks, such as old/new recognition memory tasks, consistently activate VPC

Question 21

What different areas are basically responsible for (memory)

Answer 21

Medial Temporal regions - bind different components (temporarily)
Frontal areas control encoding and retrieval of memories
Posterior association areas store components of memories.

Question 22

Semantic memory

Answer 22

A structured record of facts, concepts, and skills that we have acquired. General knowledge about world, without autobiographical context. Episodic memory can be thought of as a map that ties together items in semantic memory.

Question 23

Effects of lesions on semantic memory

Answer 23

1. Modality-specific visual agnosia after left temporal damage.
2. Semantic dementia - failure to name objects, concepts, and people. Graded deterioration of knowledge

Question 24

Semantic memory - neuroimaging

Answer 24

Activation in left inferior frontal, inferior temporal, temporal pole for semantic judgments to words and pictures
Left inferior temporal activations for animal and tool names, temporal pole for people naming
Activations may reflect the object’s interaction with the world - tool naming activates motor regions, for example.

Question 25

Working/short term memory

Answer 25

Ability to maintain and manipulate information for short periods of time in order to guide behavior. Temporary retention of an item of information for the prospective attainment of a goal.

Question 26

Working memory processes - three main components in the original model

Answer 26

Central executive supervises and controls information flow to and from slave systems
Slave systems are the phonological loop and the visuo-spatial sketchpad. In 2000 added a third slave system - episodic buffer
Phonological - related to sound - limited ability to pay attention
Visuo-spatial sketch pad - visualizing the spatial relationship between objects (used in sports for example)
Episodic buffer - added to explain why patients with amnesia can remember passages from a book.

Question 27

Effects of lesions on working memory

Answer 27

Auditory-verbal maintenance deficit following left ventral parietal lesions
Visual-spatial maintenance deficit following right ventral parietal lesion
Frontal patients impaired on manipulating information in working memory such as card sorting and selection without repetition.
Lesions of the dorsolateral prefrontal cortex especially impair working memory performance, as it is involved both in WM and in correcting performance.

Question 28

N-back task

Answer 28

Measures working memory, the ability to hold information on-line for current task.

Question 29

Working memory - neuroimaging

Answer 29

Right ventral parietal, ventral frontal, and premotor cortex activated during spatial maintenance
Dorsolateral prefrontal cortex activated in n-back task when manipulation required.
Parietal cortex involved with spatial maintenance
Modality-specific, passive stores in posterior parietal and temporal cortex
Common executive processes in the frontal cortex

Question 30

Memory and emotion

Answer 30

Amygdala influences memory, Emotion can enhance memory and make it more powerful and long-lasting. Used MRI to measure neural activity during retrieval of emotional and neutral pictures after a retention interval of 1 yr. Recognition performance was better for emotional than neutral pictures. Successful retrieval of emotional pictures elicited greater activity than successful retrieval of neutral pictures in the amygdala, entorhinal cortex, and hippocampus. Recalling September 11th, for example, leads to more reaction in people who were downtown at the time.

Question 31

Imagining the future

Answer 31

Patients with hippocampal lesions cannot imagine new events