Lecture 9: Memory Flashcards
What are the key definitions of learning and memory?
Learning is the acquisition of new information, while memory is the outcome of learning, involving cellular and circuitry changes in the nervous system.
What are the three stages of memory processing?
- Encoding: Acquisition and consolidation of information.
- Storage: Retention of memory traces.
- Retrieval: Accessing stored memory traces.
What is amnesia, and what are its two main types?
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.
Amnesia
What is Ribot’s law?
In retrograde amnesia, the most recent memories are the most vulnerable and the first to be lost.
Who was H.M., and why is he significant in memory research?
H.M. had bilateral hippocampal lesions, causing severe anterograde amnesia. He demonstrated the importance of the hippocampus for forming new long-term memories.
Sensory memory
What is sensory memory, and what are its two main types?
Sensory memory holds brief sensory traces:
Echoic memory: Auditory memory lasting ~10 seconds.
Iconic memory: Visual memory lasting 300–500ms.
Sensory memory
What is the Sperling paradigm, and how does it demonstrate sensory memory?
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.
Sensory memory
How does echoic memory differ from iconic memory?
Echoic memory (auditory) lasts longer (~10 seconds) compared to iconic memory (visual), which lasts only 300–500ms.
Short term and working memory
What is the modal model of memory by Atkinson & Shiffrin?
A hierarchical model where:
Sensory memory → short-term memory via attention.
Short-term memory → long-term memory via rehearsal.
Long-term memory without short-term memory
What evidence challenges the serial processing of the modal model?
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
What is the double dissociation in short-term and long-term memory?
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.
What is the difference between a single dissociation and a double dissociation?
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.
What is the difference between working memory and short-term memory?
Working memory extends short-term memory by allowing for manipulation (e.g., summing a list) in addition to maintenance.
What is the difference between working memory and short-term memory?
Working memory extends short-term memory by allowing for manipulation (e.g., summing a list) in addition to maintenance.
What are the components of Baddeley and Hitch’s working memory model?
- Central executive: Controls attention and coordination.
- Phonological loop: Verbal working memory via acoustic rehearsal.
- Visuospatial sketchpad: Visual and spatial memory.
Non-Declarative Memory
What is non-declarative memory, and what types of learning does it include?
Non-declarative memory is implicit, influencing behavior without conscious awareness. It includes:
Procedural memory (skills).
Priming.
Conditioning.
How is procedural memory studied, and what brain areas are involved?
Using tasks like the serial reaction time task:
Early learning: Premotor cortex, SMA, basal ganglia, cerebellum.
Later learning: Reduced activity in these areas.
How does the serial reaction time task show procedural learning?
Participants respond faster to structured sequences even without awareness, showing implicit learning.
How does procedural memory relate to patients with amnesia?
Procedural memory is intact in patients like H.M., proving it does not rely on the medial temporal lobe.
Priming
What is priming, and what are its three main types?
Priming is the improved processing of a stimulus due to prior exposure:
Perceptual priming.
Conceptual priming.
Semantic priming.
What is perceptual priming, and which brain regions are involved?
Perceptual priming improves processing of forms or shapes. It relies on sensory cortices and can last hours to months.
How does perceptual priming function in patients with anterograde amnesia?
Patients like H.M. show normal perceptual priming despite no explicit memory of prior exposure.
What is conceptual priming, and how is it tested?
Conceptual priming involves exposure to semantically related concepts. It is tested with tasks like category-association tests.
What is semantic priming, and what brain regions are involved?
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.
How do conceptual and semantic priming differ from perceptual priming?
Conceptual and semantic priming are modality-independent and rely on higher-level association areas rather than sensory cortices.
Declarative Memory
What is declarative memory, and what are its two main types?
Declarative memory is explicit, conscious memory. Types include:
Episodic memory: Events and their context.
Semantic memory: World knowledge and facts.
What role does the medial temporal lobe (MTL) play in declarative memory?
The MTL, including the hippocampus, is critical for encoding new declarative memories but is less involved in their long-term storage.
What brain circuits support the phonological loop and visuospatial sketchpad in working memory?
- 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.
How do the central executive and subordinate systems interact in working memory?
the central executive allocates attention and resources to the phonological loop and visuospatial sketchpad, coordinating memory maintenance and manipulation.
Non-Declarative long-term memory
What evidence shows that non-declarative memory is intact in amnesia patients?
Patients like H.M. show intact procedural learning (e.g., mirror tracing) and priming despite severe anterograde amnesia.
What is an example of perceptual priming, and how does it work?
Completing a word-fragment task (e.g., “_u_dy”) after prior exposure to “study.” Perceptual priming improves processing through the same sensory modality.
perceptual priming
What is a double dissociation in priming and episodic memory?
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.
Declarative Memory: Hippocampus and MTL
What are the two types of declarative memory, and what brain structures are involved?
Episodic memory: Encoded by the hippocampus and surrounding medial temporal lobe (MTL).
Semantic memory: Relies on the anterior temporal lobe (not the hippocampus).
What evidence highlights the hippocampus’s role in encoding episodic memories?
Damage to the CA1 region of the hippocampus impairs the formation of new episodic memories, as seen in patient R.B..
How does semantic dementia differ from hippocampal amnesia?
In semantic dementia, there is damage to the anterior temporal lobe, leading to loss of semantic knowledge but sparing episodic memory.
What does the subsequent memory paradigm reveal about memory encoding?
Greater activity in the hippocampus during encoding predicts later successful recall, showing the hippocampus’s role in memory formation.
How do episodic and familiarity-based recognition differ, and which brain regions support them?
Episodic recollection (detailed memory) depends on the hippocampus.
Familiarity-based recognition (feeling of knowing) relies on the perirhinal cortex.
What brain regions are reactivated during memory retrieval?
Sensory areas activated during encoding (e.g., visual or auditory cortices) are reactivated during retrieval, along with the hippocampus.
How can false memories be experimentally induced?
By presenting misleading cues or edited photographs (e.g., a fake childhood event), participants may create false episodic memories.
How do brain activations differ for true vs. false memories?
True memories activate both the hippocampus and sensory cortex, while false memories rely on frontoparietal regions (top-down mechanisms).
Episodic Memory Consolidation
What does the standard theory of memory consolidation propose?
Initially, the hippocampus binds distributed neocortical information. Over time, repeated retrieval strengthens intracortical connections, making the hippocampus unnecessary.
What does the multiple trace theory suggest about memory consolidation?
The hippocampus remains involved in episodic memory retrieval, even for remote memories. Repeated retrieval creates new traces in the hippocampus.
How does Ribot’s law relate to theories of memory consolidation?
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.
Synaptic Plasticity and Memory
What is Hebb’s law, and how does it relate to learning and memory?
Hebb’s law states, “Cells that fire together, wire together.” It explains how simultaneous activation strengthens synaptic connections, forming the basis of learning.
What is long-term potentiation (LTP)?
LTP is a long-lasting increase in synaptic strength following a high-frequency burst of stimulation, reflecting the cellular mechanism of learning.
What are two key properties of long-term potentiation (LTP)?
- Specificity: Only stimulated pathways are potentiated.
- Associativity: Weak inputs are potentiated when paired with strong inputs (associative learning).
What is long-term depression (LTD), and how does it differ from LTP?
LTD is a weakening of synapses caused by low-frequency stimulation, in contrast to the strengthening seen in LTP.
How does LTP explain “one-shot learning”?
LTP can occur after a single high-frequency burst, enabling rapid and long-lasting learning.
How are forward models related to motor control and learning?
Forward models predict the sensory consequences of movements, allowing the brain to compare predictions with actual feedback to correct errors.
What role does the cerebellum play in forward models?
The cerebellum generates precise temporal predictions of motor outcomes, enabling real-time error correction and motor learning.
How does stress influence memory?
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.
What is emotional tagging in memory?
Emotional events enhance memory for neutral information occurring around the same time. The amygdala modulates hippocampal activity to prioritize emotional memories.
Why is population coding of movement direction significant?
Population coding allows the brain to predict movement direction with high accuracy using signals from 30–50 neurons.
