Lecture 9: Memory

Question 1

What are the key definitions of learning and memory?

Answer 1

Learning is the acquisition of new information, while memory is the outcome of learning, involving cellular and circuitry changes in the nervous system.

Question 2

What are the three stages of memory processing?

Answer 2

1. Encoding: Acquisition and consolidation of information.
2. Storage: Retention of memory traces.
3. Retrieval: Accessing stored memory traces.

Question 3

What is amnesia, and what are its two main types?

Answer 3

Amnesia is memory loss, typically caused by brain damage:

Retrograde amnesia: Loss of memories before the lesion.
Anterograde amnesia: Inability to form new memories after the lesion.

Question 4

Amnesia

What is Ribot’s law?

Answer 4

In retrograde amnesia, the most recent memories are the most vulnerable and the first to be lost.

Question 5

Who was H.M., and why is he significant in memory research?

Answer 5

H.M. had bilateral hippocampal lesions, causing severe anterograde amnesia. He demonstrated the importance of the hippocampus for forming new long-term memories.

Question 6

Sensory memory

What is sensory memory, and what are its two main types?

Answer 6

Sensory memory holds brief sensory traces:

Echoic memory: Auditory memory lasting ~10 seconds.
Iconic memory: Visual memory lasting 300–500ms.

Question 7

Sensory memory

What is the Sperling paradigm, and how does it demonstrate sensory memory?

Answer 7

Participants were shown a matrix of letters and asked to report them:

Whole report: Only ~4 items remembered.
Partial report: With a cue, participants recalled 9–12 items, showing a high-capacity sensory memory trace.

Question 8

Sensory memory

How does echoic memory differ from iconic memory?

Answer 8

Echoic memory (auditory) lasts longer (~10 seconds) compared to iconic memory (visual), which lasts only 300–500ms.

Question 9

Short term and working memory

What is the modal model of memory by Atkinson & Shiffrin?

Answer 9

A hierarchical model where:

Sensory memory → short-term memory via attention.
Short-term memory → long-term memory via rehearsal.

Question 10

Long-term memory without short-term memory

What evidence challenges the serial processing of the modal model?

Answer 10

Patients like K.F. showed impaired short-term memory but normal long-term memory, proving that long-term memory can form independently of short-term memory. left parietooccipital damage

Question 11

What is the double dissociation in short-term and long-term memory?

Answer 11

Damage to left parieto-occipital cortex (e.g., K.F.) impairs short-term memory but spares long-term memory.

Damage to hippocampus (e.g., H.M.) impairs long-term memory but spares short-term memory.

Question 12

What is the difference between a single dissociation and a double dissociation?

Answer 12

Single dissociation: Damage to brain area X impairs task A but not task B. This suggests area X is involved in task A but does not prove independence.

Double dissociation: Damage to area X impairs task A but not task B, and damage to area Y impairs task B but not task A. This strongly indicates the two tasks rely on independent systems.

Question 13

What is the difference between working memory and short-term memory?

Answer 13

Working memory extends short-term memory by allowing for manipulation (e.g., summing a list) in addition to maintenance.

Question 14

What is the difference between working memory and short-term memory?

Answer 14

Working memory extends short-term memory by allowing for manipulation (e.g., summing a list) in addition to maintenance.

Question 15

What are the components of Baddeley and Hitch’s working memory model?

Answer 15

1. Central executive: Controls attention and coordination.
2. Phonological loop: Verbal working memory via acoustic rehearsal.
3. Visuospatial sketchpad: Visual and spatial memory.

Question 16

Non-Declarative Memory

What is non-declarative memory, and what types of learning does it include?

Answer 16

Non-declarative memory is implicit, influencing behavior without conscious awareness. It includes:

Procedural memory (skills).
Priming.
Conditioning.

Question 17

How is procedural memory studied, and what brain areas are involved?

Answer 17

Using tasks like the serial reaction time task:

Early learning: Premotor cortex, SMA, basal ganglia, cerebellum.
Later learning: Reduced activity in these areas.

Question 18

How does the serial reaction time task show procedural learning?

Answer 18

Participants respond faster to structured sequences even without awareness, showing implicit learning.

Question 19

How does procedural memory relate to patients with amnesia?

Answer 19

Procedural memory is intact in patients like H.M., proving it does not rely on the medial temporal lobe.

Question 20

Priming

What is priming, and what are its three main types?

Answer 20

Priming is the improved processing of a stimulus due to prior exposure:

Perceptual priming.
Conceptual priming.
Semantic priming.

Question 21

What is perceptual priming, and which brain regions are involved?

Answer 21

Perceptual priming improves processing of forms or shapes. It relies on sensory cortices and can last hours to months.

Question 22

How does perceptual priming function in patients with anterograde amnesia?

Answer 22

Patients like H.M. show normal perceptual priming despite no explicit memory of prior exposure.

Question 23

What is conceptual priming, and how is it tested?

Answer 23

Conceptual priming involves exposure to semantically related concepts. It is tested with tasks like category-association tests.

Question 24

What is semantic priming, and what brain regions are involved?

Answer 24

Semantic priming occurs when a word (e.g., “dog”) facilitates recognition of a related word (e.g., “cat”). It involves the lateral temporal lobe and Broca’s area.

Question 25

How do conceptual and semantic priming differ from perceptual priming?

Answer 25

Conceptual and semantic priming are modality-independent and rely on higher-level association areas rather than sensory cortices.

Question 26

Declarative Memory

What is declarative memory, and what are its two main types?

Answer 26

Declarative memory is explicit, conscious memory. Types include:

Episodic memory: Events and their context.
Semantic memory: World knowledge and facts.

Question 27

What role does the medial temporal lobe (MTL) play in declarative memory?

Answer 27

The MTL, including the hippocampus, is critical for encoding new declarative memories but is less involved in their long-term storage.

Question 28

What brain circuits support the phonological loop and visuospatial sketchpad in working memory?

Answer 28

• Phonological loop: Relies on brain regions involved in auditory processing (e.g., Broca’s area, left parietal cortex).

Visuospatial sketchpad: Relies on occipital and parietal cortex regions for visual and spatial rehearsal.

Question 29

How do the central executive and subordinate systems interact in working memory?

Answer 29

the central executive allocates attention and resources to the phonological loop and visuospatial sketchpad, coordinating memory maintenance and manipulation.

Question 30

Non-Declarative long-term memory

What evidence shows that non-declarative memory is intact in amnesia patients?

Answer 30

Patients like H.M. show intact procedural learning (e.g., mirror tracing) and priming despite severe anterograde amnesia.

Question 31

What is an example of perceptual priming, and how does it work?

Answer 31

Completing a word-fragment task (e.g., “_u_dy”) after prior exposure to “study.” Perceptual priming improves processing through the same sensory modality.

Question 32

perceptual priming

What is a double dissociation in priming and episodic memory?

Answer 32

Patients with occipital lobe damage (e.g., M.S.) lose visual priming but have intact episodic memory, whereas patients like H.M. lose episodic memory but retain priming.

Question 33

Declarative Memory: Hippocampus and MTL

What are the two types of declarative memory, and what brain structures are involved?

Answer 33

Episodic memory: Encoded by the hippocampus and surrounding medial temporal lobe (MTL).

Semantic memory: Relies on the anterior temporal lobe (not the hippocampus).

Question 34

What evidence highlights the hippocampus’s role in encoding episodic memories?

Answer 34

Damage to the CA1 region of the hippocampus impairs the formation of new episodic memories, as seen in patient R.B..

Question 35

How does semantic dementia differ from hippocampal amnesia?

Answer 35

In semantic dementia, there is damage to the anterior temporal lobe, leading to loss of semantic knowledge but sparing episodic memory.

Question 36

What does the subsequent memory paradigm reveal about memory encoding?

Answer 36

Greater activity in the hippocampus during encoding predicts later successful recall, showing the hippocampus’s role in memory formation.

Question 37

How do episodic and familiarity-based recognition differ, and which brain regions support them?

Answer 37

Episodic recollection (detailed memory) depends on the hippocampus.

Familiarity-based recognition (feeling of knowing) relies on the perirhinal cortex.

Question 38

What brain regions are reactivated during memory retrieval?

Answer 38

Sensory areas activated during encoding (e.g., visual or auditory cortices) are reactivated during retrieval, along with the hippocampus.

Question 39

How can false memories be experimentally induced?

Answer 39

By presenting misleading cues or edited photographs (e.g., a fake childhood event), participants may create false episodic memories.

Question 40

How do brain activations differ for true vs. false memories?

Answer 40

True memories activate both the hippocampus and sensory cortex, while false memories rely on frontoparietal regions (top-down mechanisms).

Question 41

Episodic Memory Consolidation

What does the standard theory of memory consolidation propose?

Answer 41

Initially, the hippocampus binds distributed neocortical information. Over time, repeated retrieval strengthens intracortical connections, making the hippocampus unnecessary.

Question 42

What does the multiple trace theory suggest about memory consolidation?

Answer 42

The hippocampus remains involved in episodic memory retrieval, even for remote memories. Repeated retrieval creates new traces in the hippocampus.

Question 43

How does Ribot’s law relate to theories of memory consolidation?

Answer 43

Ribot’s law (recent memories are lost first) supports the idea that recent memories rely on the hippocampus, while older memories are more consolidated in the neocortex.

Question 44

Synaptic Plasticity and Memory

What is Hebb’s law, and how does it relate to learning and memory?

Answer 44

Hebb’s law states, “Cells that fire together, wire together.” It explains how simultaneous activation strengthens synaptic connections, forming the basis of learning.

Question 45

What is long-term potentiation (LTP)?

Answer 45

LTP is a long-lasting increase in synaptic strength following a high-frequency burst of stimulation, reflecting the cellular mechanism of learning.

Question 46

What are two key properties of long-term potentiation (LTP)?

Answer 46

1. Specificity: Only stimulated pathways are potentiated.
2. Associativity: Weak inputs are potentiated when paired with strong inputs (associative learning).

Question 47

What is long-term depression (LTD), and how does it differ from LTP?

Answer 47

LTD is a weakening of synapses caused by low-frequency stimulation, in contrast to the strengthening seen in LTP.

Question 48

How does LTP explain “one-shot learning”?

Answer 48

LTP can occur after a single high-frequency burst, enabling rapid and long-lasting learning.

Question 49

How are forward models related to motor control and learning?

Answer 49

Forward models predict the sensory consequences of movements, allowing the brain to compare predictions with actual feedback to correct errors.

Question 50

What role does the cerebellum play in forward models?

Answer 50

The cerebellum generates precise temporal predictions of motor outcomes, enabling real-time error correction and motor learning.

Question 51

How does stress influence memory?

Answer 51

Acute stress can enhance memory formation.

However, chronic stress or high cortisol levels impair memory over time, showing a complex relationship between stress and memory.

Question 52

What is emotional tagging in memory?

Answer 52

Emotional events enhance memory for neutral information occurring around the same time. The amygdala modulates hippocampal activity to prioritize emotional memories.

Question 53

Why is population coding of movement direction significant?

Answer 53

Population coding allows the brain to predict movement direction with high accuracy using signals from 30–50 neurons.