PSYC 333 - Lecture 7: Episodic and Semantic Memory

Episodic memories

Consciously retrieved memories of unique events, bound by event specific contextual details, such as the time and place in which the experiences occurred.

Semantic memories

Consciously retrieved knowledge of autobiographical and non-personal concepts or 'facts.' Largely retrievable without reconstructing specific details about the contexts from which they were extracted.

Declarative memory

Memory where we can declare our memory; 'what we know is what we know' but we can't put it into facts.

Episodic memories (simplified)

Unique events in time and place (ex. recalling your last birthday, first date).

Semantic memories (simplified)

Knowledge or facts (ex. capital of France, I have 2 sisters).

Double dissociation

Damage to region A, loss of function A, but not B; Damage to region B, loss of function B, but not A.

Single dissociation

Damage to region A, loss of function A, but not B.

Can Nonhumans Have Episodic Memory?

Some researchers believe that non-human animals cannot maintain episodic memories; others hold the opposite view.

Scrub jays and episodic memory

Scrub jays hid either worms (which spoil over time) or nuts (which do not spoil quickly) in different parts of a sand-filled ice tray. Short delay, they retrieved worms, long delay, they retrieved nuts, almost anticipating the worms to spoil. Some say this is evidence of episodic memory because they knew where they hit the food, what food they hid, and how long it had been since they hid it. But others are not convinced because we can't communicate with them to confirm.

Importance of double dissociation

It helps to clarify the relationship between different cognitive functions and the brain regions responsible for them.

What's important to remember about damage?

Damage is usually partial, affecting certain functions while leaving others intact.

Amnesic syndrome

A profound impairment in the ability to store and retrieve consciously experienced, long-term memories, even though most other thinking abilities (like lang, problem-solving, and attention) are relatively unaffected.

- main deficit is memory

What memory is most severely impaired by amnesia?

Episodic

Causes of Amnesia

Stroke, virus (e.g., encephalitis), anoxia (complete loss of O2)/hypoxia (reduced O2), traumatic brain injury, and surgical resections (tumors or epilepsy).

Temporary: Transient global amnesia

A temporary form of amnesia that lasts a few hours with unclear causes.

Permanent: Psychogenic amnesia

A form of amnesia that extends to loss of identity and can last for hours, days, months, or years, linked to psychological factors like stress

Clive Wearing

A case of permanent amnesia where the individual has a 7-second memory, only recognizes his wife, and recalls details from childhood.

Henry Molaison (H.M.)

The most studied mind in history, who experienced severe long-term memory loss after bilateral removal of the medial temporal lobes (specifically the hippocampus).

H.M. Post Surgery

After surgery, H.M. had unchanged IQ, relatively intact short-term memory, perception, attention, and language, but severe long-term memory loss.

Episodic vs. Semantic Memory in Amnesia

H.M. could remember semantic facts about himself and the world but could not recall any specific events (episodes) from his past.

Why can Clive feel emotion but can't remember things?

Storing emotions and storing memory happen simultaneously but are stored differently and can influence each other.

Metabolic demand of the hippocampus

The hippocampus constantly needs a lot of oxygen, making it more vulnerable during anoxia.

Brenda Milner

The neuropsychologist who referred to H.M. after his surgery due to severe long-term memory loss.

Anterograde domain

Memories derived from experiences that occurred after the onset of amnesia-driving.

Retrograde domain

Memories derived from experiences that occurred prior to the onset of amnesia.

Hippocampal atrophy

The reduction in size or volume of the hippocampus, often associated with memory impairment.

Developmental cases of amnesia

Cases where amnesia occurs due to early-life damage or reduction in size of hippocampus, affecting memory differently than in adults.

Episodic memory impairment in developmental amnesia

B/c damage happened at birth, all new information is new, leaving no old memories to lose, so it's just semantic memory

ex. Mirror drawing test shows how episodic memory is affected

Plasticity in the brain

The ability of the brain to change and adapt, particularly in response to damage or learning.

Episodic vs. Semantic memory in adults

In adults, episodic memory is often impaired across the board, while semantic memory may remain intact post-injury

Why do developmental cases have severe episodic memory impairment, but good semantic memory?

Hippocampus is essential for episodic memory so that events can be linked to a time and place. Semantic can be supported through other areas of the brain as the brain is more adaptable when younger and can compensate

Standard Consolidation Theory (for relation btwn episodic memory and hippocampus)

A theory suggesting that the hippocampus is involved in the encoding of memories, but its involvement fades over time as memories are consolidated in the cortex.

Consolidation

The process of strengthening the stability of stored information.

Multiple Trace Theory

A theory proposing that while the hippocampus is involved in the encoding of episodic and semantic memories, over time it remains involved ONLY in episodic memory retrieval.

Episodic Memory Trace - of Multiple Trace Theory

A new memory created each time an episodic memory is retrieved, involving a connection between the hippocampus and cortex.

Temporally graded amnesia

better recall for old childhood memories than recent events, associated with SCT

Flat Amnesia

A type of amnesia where there is no difference in the recall of old and new memories, often associated with multiple trace theory.

Example of Cooking

When cooking a recipe for the second time, one may recall ingredients (semantic memory) but will also have an episodic memory of the first instance, helping to refine your memory of the steps.

Example of Professor Falling

Recalling a memory of a professor tripping, you include specific episodic details (her loud scream), but also use general knowledge (semantic) to fill in gaps.

Semantic and Episodic interaction in a healthy brain

In a healthy brain, semantic and episodic memories often interact, despite their potential to dissociate following a brain injury