Intro to Long-term Memory Flashcards
Long-term memory
Declarative
memory
memories we can declere-memories we are awear we know
- Episodic memories
- Semantic memories
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.
ex:my last birthday party
Semantic memories:
Consciously retrieved knowledge of autobiographical and non-personal concepts or “facts.” Semantic
memories are derived from experience but are largely retrievable
without reconstructing specific details about the contexts from
which they were extracted.
ex: the capital of italy is rome
Can Nonhumans Have Episodic Memory?
Some researchers believe that animals cannot maintain episodic memories; others hold the opposite view:
○ Birds may be able to remember specific events and how long ago they happened
○ Do we think this is episodic memory?
- **the thing is we have no way of knowing if they have a concioness that allows them to be able to revisit their past/relive events that they were a part of **
Can Nonhumans Have 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.
● Later, the scrub jays were given the opportunity to retrieve the food
● If the delay was short, scrub jays preferentially retrieved the worms. If the delay was longer, scrub jays retrieved the nuts. It was as though they anticipated the quick spoilage of worms.
● Some believe that this behaviour is evidence that the scrub jays possess episodic memory
They seemed to remember what food they hid, where they had hid it, and how long since they hid it (when)
the worm and nuts were taken out so the smell wasnt a variable
the simple answer is yes but there is more to it
Amnesia
● “The amnesic syndrome: a profound impairment in the ability to store and retrieve consciously experienced, long-term memories in the context of otherwise relatively
spared cognition. The prototypical amnesic syndrome is caused by acquired, stable damage to the extended hippocampal network.”
● Episodic memory is most severely impaired..
they can talk to u (sematic memory)
Causes of Amnesia
Multiple etiologies can cause amnesia
○ stroke
○ virus (e.g., encephalitis)
○ anoxia/hypoxia (reduced or complete loss of oxygen)
○ traumatic brain injury
○ surgical resections (for tumors or epilepsy)
Causes of Amnesia
● Many of these illnesses, diseases or injuries affect the whole brain but the
hippocampus (as we will see) is especially sensitive. For example in anoxia, the hippocampus is more vulnerable due to its high metabolic demand (it constantly needs a lot of oxygen). Other cellular properties can lead to toxicity effects in the hippocampus following anoxia.
● The hippocampus is also vulnerable to seizure activity
Types of Amnesia
Many forms of amnesia are permanent but there are temporary variants, which involve profound memory loss for a short period of time
types of amnesia
Transient global amnesia
- Causes unclear but several candidates
- short lived (which is rare)
- affects episodic memory
type of amnesia
Psychogenic amnesia (extends to loss of identity)
- affects episodic memory
- short-term
- they lose their identity - dont know who they are
- Linked to psychological factors (e.g., stress)
Clive Wearing
- his memory was destryoed because of a virus but he could still play the piano
Patient H.M
● Seizures originated in medial temporal lobes (MTL) including hippocampus (H)
● 1953: William Scoville removed MTL (hypocamps) bilaterally
H.M. Post Surgery
● IQ unchanged (118)
● Relatively intact short-term memory
● Relatively intact perception attention, language
● But…complained of severe (long-term) memory loss
● Referred to Brenda Milner, neuropsychologist
Episodic vs. Semantic Memory in Amnesia
- When H.M. was asked about his past (before his surgery) he could remember facts about himself and the world BUT could not remember any specific events.( - had trouble with episodic memory)
● Suggests that damage to the hippocampus affects episodic memory but less so semantic memory?
○ Depends on whether you are examining pre- versus post-amnesia information and what types of tests you use!
Anterograde domain (anterograde amnesia)
Memories derived from experiences that occurred after the onset of amnesia-driving
Retrograde domain
(retrograde amnesia)
Memories derived from experiences that occurred prior to the onset of amnesia.
a single patient can have BOTH
retrograde and anterograde amnesia (many do!)
Anterograde and Retrograde Amnesia
in anterograde amnesia they have problems with creating new episodic and sematic memory
Anterograde and Retrograde Amnesia
● Patterns of loss in anterograde amnesia( loss of memory after the time of injury) is relatively undisputed amongst scholars.
● But scholars differ in their opinions on retrograde amnesia for many reasons.
● We use the term “relative” sparing to denote that though semantic memory is much better than episodic memory but not always intact
Dissociation does not preclude association
Semantic and episodic memory can dissociate to some extent following a brain injury. However, in the healthy brain, they often interact
Example 1: When you are cooking a recipe for the second time, you may remember some of the ingredients and steps (semantic memory) but you may also have an episodic memory of that first instance, which helps you refine your memory of the steps
Anatomy of Declarative Memory
The medial temporal lobes in humans
contain the hippocampus and nearby cortical areas, including the entorhinal cortex, the perirhinal cortex, and the parahippocampal cortex (called “medial temporal lobes” or ”MTL”)
in adults the demage usually is around the hypocanpus and medial temporal lobes
The Hippocampus
● Much research points to the role of the hippocampus in episodic memory especially.
● Began with H.M.
● Similar pattern observed in many other patients
● What other evidence points to a role of the hippocampus in episodic memory?
Episodic Memory and the Hippocampus
● Taken together, there is strong evidence from patient work and fMRI that the hippocampus (and MTL) are involved in episodic memory
But what exact role does the hippocampus play?
Even within episodic memory, though researchers agree that the
hippocampus is important for new learning (anterograde).
There is disagreement about the role (extent) of the hippocampus in old episodic memories (retrograde)
in other words!!!
ask professor if this is right
reserchers agree that the hipocanpus plays a role in the episodic antegrade amnesia (memory )after injury
BUT
reserchers are not in agreement as how much the hipocampus playes a role in episodic retograde amnesia (memory before injury)
