NEUR 362 Notes: Neurobiology of Memory

Short-term memory

1) Limited capacity (3-4 items)

2) Fades quickly unless rehearsed

3) Can't be regained

Long-term memory

Memories that stay in short-term memory long enough get "consolidated" into long-term memory

Short-term memory duration

seconds to hours

Long-term memory duration

hours to months

Long-lasting memory duration

months to lifetime

Working memory

Temporary storage for information while we are actively working on it or attending to it

What is a common test for working memory?

Delayed response task

Delayed response task

psychological or cognitive experiment that tests working memory and a subject's ability to remember and use information after a delay period

presenting a stimulus, removing it, waiting for a period, and then requiring the subject to respond based on the remembered information

Dorsolateral prefrontal cortex

region of the brain in the frontal lobe that is crucial for executive functions such as working memory, planning, and cognitive flexibility

Declarative (explicit) memory

type of long-term memory containing information that is conscious and known

List the two main subdivisions of Declarative (explicit) memory.

1) Episodic (events)

2) Semantic (facts)

Episodic memory

Memory of specific personal events and experiences

Semantic (facts) memory

Memory of general facts, concepts, and knowledge

Semantic vs Episodic: Which is context-free?

semantic

Semantic vs. Episodic: Which is personal and contextual?

episodic

Non-declarative (implicit) memory

retention without conscious recollection of learning the

skills and procedures to do things

Perceptual priming (Perceptual learning)

prior encounter with a stimulus unconsciously improves the ability to identify or process it later

Example of perceptual priming

Image identification

Image identification (priming)

After repeatedly being shown a degraded or incomplete image, a person will be able to identify it faster and more accurately on subsequent viewings, even if they don't remember seeing the specific image before

Procedural memory/motor skills

Type of long-term, implicit memory that allows people to perform tasks without conscious thought

The "how-to" memory that stores learned skills, which are executed automatically through practice and repetition

Example of procedural memory

Riding a bike

Typing

Associative learning

Process where an individual learns to connect two stimuli or a stimulus and a response, allowing them to predict future events and guide their behavior

List two examples of associative learning.

1) Classical conditioning

2) Operant conditioning

Classical conditioning

An automatic, unconscious response becomes associated with a specific stimulus

(Neural stimulus paired with Unconditioned stimulus to become Conditioned stimulus to elicit a Conditioned response)

Operant conditioning

Learning occurs through the consequences of a behavior.

Actions followed by reinforcement become more likely to be repeated, while those followed by punishment become less likely.

Non-associative learning

Fundamental form of learning involving a change in a response to a single stimulus upon repeated exposure

Associative learning -> one stimulus or multiple stimuli?

multiple stimuli

Non-associative learning -> one stimulus or multiple stimuli?

one stimulus

List the two main types of non-associative learning.

1) Habituation

2) Sensitization

Habituation

response to a repeated stimulus decreases

Sensitization

response to a repeated stimulus increases

H.M. 1953

bilateral medial temporal lobe removal

What could H.M. still learn (and retain)?

1) New motor skills

2) Perceptual learning

3) Working memory

4) Classical conditioning

Which brain area corresponds to Declarative Memory (Facts, Events)

Medial Temporal Lobe

Medial Temporal Lobe

Crucial brain region located on the inner surface of the temporal lobes that is essential for memory, especially for forming new long-term, declarative memories for facts and events

Includes the hippocampus, the amygdala, and the parahippocampal gyrus, and plays a vital role in memory functions like encoding, consolidation, and retrieval

Hippocampus and Spatial Memory

Helps form a mental/cognitive map of an environment, which is crucial for navigation

Place cells

fire when an organism is in a specific location

Where are place cells located in the brain?

Hippocampus

Grid cells

provide a coordinate system with a hexagonal grid-like firing pattern that helps with navigation and distance estimation

Where are grid cells located?

Entorhinal cortex (near the hippocampus)

Posterior Hippocampus and Spatial Memory

The posterior hippocampus is the region of the brain that stores a spatial representation of the environment

Studies on London taxi drivers show that the ____________________ __________________________ is enlarged in experienced drivers compared to non-drivers

posterior hippocampus

The longer a taxi driver has been licensed . . .

the larger their posterior hippocampus tends to be

Which brain area corresponds to Procedural Memory (Non-declarative)?

Basal ganglia

Which brain area corresponds to Classical Conditioning (Non-declarative)?

Cerebellum

Which brain area corresponds to Perceptual Memory? (Non-declarative)

(Visual and Temporal) Cortex

Cortex and Perceptual Memories

Perception vs Memory

Perception

immediate processing of sensory information

Recall

retrieval of stored information