Memory: Episodic Memory and Non-declarative Memory

Episodic Memory

memory for experiences situated in a spatiotemporal context

Can mentally time travel and re experience and episodic memory

Semantic Memory

Memory for general world knowledge, facts, ideas, meanings, and concepts that are independent of personal experience.

How is episodic memory measured? 

Participants study a series of items, complete a distractor task, and then take a memory test.

What are the two essential phases of a laboratory episodic memory task?

A study phase, when information is learned, and a test phase, when memory is assessed.

How does a recall test measure memory?

Participants produce items they remember—for example, saying any words they remember from the study phase.

How does a recall test measure memory?

Participants produce items they remember—for example, saying any words they remember from the study phase.

How does a recognition test measure memory?

Participants identify whether an item is old (previously studied) or new (not previously studied).

Why are these episodic memory tests considered tests of declarative memory?

Participants consciously report what they remember.

What kinds of stimuli can be used in episodic memory experiments?

Virtually anything, including words, pictures, sounds, and objects.

Although the task has study and test phases, when is behavioral memory performance measured?

During the test phase.

What two failures could explain an incorrect response on a memory test?

Encoding failure: the information was not successfully learned. Retrieval failure: the information was stored but could not be successfully accessed during the test.

How can inattention lead to an encoding failure?

If someone does not attend to a stimulus during study, they may fail to encode it into memory.

Why does an incorrect test response alone not identify the cause of a memory failure?

It cannot distinguish whether the person failed to encode the information or failed to retrieve it.

Damage to which brain structure can cause severe episodic memory impairment?

The hippocampus, which is necessary for forming new episodic memories.

Who was patient H.M.?

A patient who underwent surgery to treat epilepsy that damaged medial temporal lobe structures, including the hippocampus, resulting in severe memory impairment.

What is retrograde amnesia?

Difficulty remembering information or events from before the injury or damage.

How does the fictional portrayal of losing all past memories differ from typical retrograde amnesia?

A complete loss of one’s entire past while all other abilities remain normal is not the typical clinical pattern. Retrograde amnesia is usually more selective.

Can a concussion cause retrograde amnesia?

Yes. It can cause loss of memories from before the injury, particularly events near the time of injury.

What is anterograde amnesia?

Difficulty forming lasting new memories after the injury or damage.

What pattern of memory deficits commonly follows hippocampal damage?

Severe anterograde amnesia with more limited, often temporally graded retrograde amnesia.

What does “temporally graded retrograde amnesia” mean?

Recent memories from before the damage are more affected than older memories.

What did H.M.’s preserved and impaired abilities show?

He retained his identity and much previously learned personal information but had severe difficulty forming new declarative memories, such as learning new names.

What role does the hippocampus play in long-term memory?

It helps encode and establish new episodic memories rather than serving as the permanent storage site for all memories.

Does the hippocampus only support encoding and never retrieval?

No. It also contributes to episodic retrieval. Older, well-established knowledge can be less dependent on it.

How can researchers test whether hippocampal activity during study supports episodic memory encoding?

Measure brain activity during study, then test which items participants remember later.

What is the hypothesis about hippocampal activity during study?

• hippocampal activity during study differentiates which stimuli will later be remembered at test 

What is “back coding” in a subsequent memory study?

Using later memory-test performance to label each earlier study item as later remembered or later forgotten.

How is cognitive subtraction used in this study?

Compare study-phase brain activity for later-remembered items minus later-forgotten items.

What finding supported the hypothesis about hippocampal encoding activity?

The hippocampus was more active during study for items participants later remembered than for items they later forgot.

What is the subsequent memory effect?

Greater brain activity during study for items that are subsequently remembered than for items that are subsequently forgotten.

Does the subsequent memory effect compare activity during study or during the memory test?

During study; the later test determines how the study items are grouped.

Is the hippocampus engaged during the memory test as well as during study?

Yes. Hippocampal neurons can respond during recognition of previously encountered items.

How does signal detection theory classify recognition-memory responses?

By crossing an item’s actual status (old or new) with the participant’s response (“old” or “new”).

What represents objective status versus subjective judgment in a recognition task?

Objective: whether the item was actually studied. Subjective: whether the participant judges it to be old or new.

What is a hit?

An old item correctly identified as “old.”

What is a miss?

An old item incorrectly identified as “new.”

What is a false alarm?

A new item incorrectly identified as “old.”

What is a correct rejection?

A new item correctly identified as “new.”

How did Rutishauser et al. measure hippocampal activity in humans?

Using implanted electrodes to record single-neuron firing in the hippocampus.

Human iEEG and single unit recording

What does the neural-response graph plot?

Normalized firing rate on the y-axis and time in milliseconds on the x-axis.

What three conditions are compared in the graph?

Hits: correctly recognized old items. Correct rejections: correctly identified new items. Study: items presented during initial learning.

How did firing rates differ across the three conditions shown?

Firing was greater for hits than for correct rejections or study presentations.

What do these findings suggest about the hippocampus?

It contributes to recognizing previously encountered items during retrieval, in addition to its role in encoding.

What information makes up an episodic memory?

An item or event, where it occurred (spatial context), and when it occurred (temporal context).

What is the binding hypothesis of hippocampal function?

The hippocampus binds or associates an item with its context, helping form an episodic memory.

What did Davachi et al. investigate in their human fMRI study?

Whether hippocampal activity during word encoding predicts later memory for the word alone or the word together with its source.

IV

• Task, 2 conditions

• Memory, 3 conditions

What were the two study-task conditions?

Imagery: imagine a place described by the word, such as a dirty place. Silent reading: read the word silently, such as “happy.”

Why were two different study tasks needed?

To give each word a distinguishable source or encoding context that participants could later remember.

What two judgments did participants make during the test?

Item recognition: is the word old or new? Source recognition: was it studied using imagery or silent reading?

What were the two factors used to compare brain activity?

Study task: imagery or reading. Later memory outcome: remembered with source, remembered without source, or forgotten. Memory outcome was determined from test performance.

What was the neural dependent variable, and when was it measured?

fMRI BOLD signal during study, even though items were grouped using later test performance.

How were study items back-coded into three memory categories?

Remembered with source: word recognized and task correctly identified. Remembered without source: word recognized but task not correctly remembered. Forgotten: studied word judged “new.”

What would “no memory sensitivity” mean for a brain region?

Similar study-phase activity across all three later-memory outcomes.

What would item sensitivity look like?

Greater study-phase activity for later-recognized words than forgotten words, regardless of whether their source was remembered.

What would associative/source sensitivity look like?

Greater study-phase activity for words later remembered with their source than words remembered without their source.

What did Davachi et al. find in the hippocampus?

Greater activity during study for words later remembered with their task source; simply recognizing the word did not show the same enhancement.

How do these findings support the binding hypothesis?

Hippocampal encoding activity predicted memory for the association between an item and its context, supporting a role in binding the components of an episode.

What does BIC stand for, and who proposed the model?

Binding Items in Context, associated with Diana et al.

Which medial temporal lobe (MTL) regions are central to the BIC model?

The hippocampus, perirhinal cortex (PRC), and parahippocampal cortex (PHC).

What is the role of the perirhinal cortex (PRC) in the BIC model?

It supports memory for items and is associated with the ventral “what” pathway.

What is the role of the parahippocampal cortex (PHC) in the BIC model?

It supports memory for context and is associated with the dorsal “where” pathway.

What is the hippocampus’s role in the BIC model?

It binds items to their contexts.

What did Davachi et al. find about PRC activity during study?

Greater activity for items later remembered with or without their task source than for items later forgotten.

Why does this PRC finding support a role in item memory?

PRC activity predicted whether the item itself would be remembered, regardless of whether its context was also remembered.

What are forms of non declarative memory? 

1. Procedural memory 

2. perceptual learning

3. classical conditioning

4. Nonassociative learning 

Non declarative memory

• Memories you can't declare or articulate

1. Procedural memory 

• Motor and cognitive skills memory 

How to test for procedural memory

• The mirror tracing task - make participant sit in front of mirror and trace something by looking in the mirror. Learning is shown by improved performance with practice.

What did H.M.’s performance on mirror tracing demonstrate?

He made fewer errors with repeated practice, despite having no explicit memory of previously completing the task. This shows procedural learning can occur without declarative memory.

What is perceptual learning?

Previous experience with a stimulus facilitates its subsequent processing.

How does the Gollin partial-picture test assess perceptual learning?

Participants identify incomplete pictures that become progressively more complete. Prior exposure allows identification at an earlier, less complete stage.

How do people without prior exposure perform on the Gollin partial-picture test?

They generally need a more complete version of the picture before identifying it.

What happens when amnesic patients repeatedly see the same pictures in the Gollin test?

They identify them earlier, even without explicitly remembering seeing them before.

classical conditioning

Classical conditioning is a type of unconscious, automatic learning where a neutral stimulus becomes associated with a natural stimulus to trigger an involuntary response.

What is an unconditioned stimulus (US)?

A stimulus that produces a response without prior learning, such as food producing salivation.

What is an unconditioned response (UR)?

The naturally occurring response to the US, such as salivation in response to food.

What is a conditioned stimulus (CS)?

An initially neutral stimulus that acquires the ability to elicit a response through pairing with a US.

How is classical conditioning established in the bell-and-food example?

A bell (CS) is repeatedly paired with food (US), which naturally produces salivation (UR).

What is a conditioned response (CR)?

The learned response to the CS—for example, salivating to the bell after it has been paired with food.

What can preserved classical conditioning in amnesic patients demonstrate?

They can learn some stimulus associations, such as a cue predicting a shock, without explicitly remembering the pairings.

What is nonassociative learning?

A change in response to a stimulus through experience, without learning an association between separate stimuli.

What is habituation?

A decrease in response following repeated presentations of a stimulus.

What is sensitization?

An increase in responsiveness following stimulation, especially strong or repeated stimulation.

Can patients with amnesia show habituation and sensitization?

Yes. These forms of nonassociative learning can remain intact.

What do these preserved abilities in amnesia reveal about memory systems?

Nondeclarative learning can occur despite impaired declarative memory, showing that these forms of memory rely on partly different brain systems.

Is the hippocampus necessary for all nondeclarative memory?

No. Many forms are supported by other brain systems, although some forms of conditioning can involve the hippocampus.