310 Ch 7 Episodic and Semantic Memory
association cortex
other cortical areas - meaning they are involved in associating information within and across modalities - helps us link the words dog with the visual image of a dog and with semantic information about what dogs are like and linguistic information about how to pronounce and recognize the spoken word itself
metamemory
our knowledge of, and ability to think about, our own memories
typing in an old password
proactive interference
transient global amnesia
transient or temporary disruption of memory
Proactive interference
where old information can disrupt new learning
Depth of processing effect
Deeper processing at encoding of new information improves the ability to remember that information later
Source amnesia
Occurs when we remember information but cannot remember the source at all
Creating false memories in the lab
Researchers pasted childhood pictures of adult participants into a photograph of a hot air balloon ride. When prompted to recall details for he trip, about half the participants claimed they could remember the episode - even though none had ever been in a hot air balloon
free recall
Simply asked an open ended question and you supply the answer from memory
amnesia
memory loss
anterograde amnesia
patients lose the ability to form memories for events that occurred after the injury
memories
the facts we know and the autobiographic events we remember
Shared features of semantic and episodic memory
- Can be communicated flexibly, in different formats than the one in which they were originally acquired - Both consciously accessible
Are there different brain substrates for episodic and semantic memory?
- hippocampus is critical for the acquisition of new autobiographical or episodic information but not for new semantic information - Semantic learning depends on medial temporal areas, including the entorhintal cortex and perirhinal cortex
Sensory agnosias
- some are caused by damage to the corresponding areas of sensory cortex
Anterograde amnesia
A severe loss of the ability to form new episodic and semantic memories
Functional amnesia
A sudden, massive retrograde memory loss that seems to result from psychological causes, in contrast to organic amnesia, which arises from obvious physical causes, such as brain injury - lose memory for specific episodes in their lives or may even lose their identity. This very rare form of amnesia seems to result from psychological trauma rather than any physical cause
Consolidation period
A time window during which new memories are vulnerable and easily lost
The radial arm maze experiment
After many trials in which the rat is allowed to explore the maze until it finds food located at the end of the "goal arm", it will eventually learn to run straight to the goal arm, indicating it has semantic memory for where the food is located in the maze
Electroconvulsive therapy
Electroconvulsive shock is administered to provide temporary relief from certain kinds of mental illness, particularly severe depression.
Multiple trace theory
Episodic memories are encoded by an ensemble of hippocampal and cortical networks, and the cortical networks never, in normal circumstances, become fully independent of the hippocampal networks. In this view, individuals with hippocampal damage effectively lose all their episodic memories.
Associative visual agnosia
Have difficulty recognizing and naming objects, even though they an see the objects. If shown a pen or cup, may be unable to name it or say what it is used for, though she may be able to name the object based on feel if it is placed in her hand
retrograde amnesia
Loss of memories for events that occurred before the injury.
Tactile agnosia
May be able to recognize an object by sight or description but not by feel.
Semantic memories
Memories for facts and general knowledge about the world, as well as for personal information such as your own name and your favourite food - it is not tagged in time and space
False memoreis
Memories of events that never actually happened
Successful retrieving is governed by two key principles:
Memory retrieval is better when study and test conditions match More cues mean better recall
Three basic principles that govern how successfully a new episodic or semantic memory is encoded, or stored in memory
Mere exposure to information does not guarantee memory Memory is better for information that relates to prior knowledge Deeper processing at encoding improves recognition later
Passive forgetting
Occurs as a function of time: older information is more likely to be forgotten than more recently acquired information. Here, people tested in the 1980s could correctly recognize the names of more TV shows that had aired in the prior year than of shows that had aired a decade previously
Direct forgetting
Occurs when information is forgotten on demand
Two kinds of forgetting
Passive forgetting and directed forgetting
Anterograde amnesia in patient E.P
Shown a complex picture, a healthy control participant can generally copy it accurately and can do a reasonably good job if asked to draw the figure form memory 15 minutes later. Patient E.P could also copy the drawing well but asked to draw it form memory after the delay, he had essentially forgotten everything about it.
The medial temporal lobe in humans
The medial portion of the temporal lobe contains the hippocampus, the amygdala, and several other cortical areas. Damage limited to the hippocampus was sufficient to disrupt memory.
Cued recall
You are given some kind of promote or clue to the correct answer
Recognition
You pick out the correct answer from a list of possible options
hippocampus
a brain structure located in the medial temporal lobe that is important for new memory formation
Basal forebrain
a collection of structures that lie at the base of the forebrain - includes nucleus basal is and medial septal nuclei, which contain neurson that produce the neuromodulator acetylcholine and distribute it throughout the brain
Damage to basal forebrain, the dienecephalon, or the fornix can result in __
amnesia
diencephalon
area near the core of the brain just above the brainstem - includes the thalamus, hypothalamus, mammillary bodies
Memory retrieval is better when study and test conditions match
- Deep processing during encoding may help only if the test requires deep processing. If the test instead involves the physical attributes or sounds of a word, superficial processing may be preferable - Physical context on memory retrieval is important - recall is slightly better if the retrieval conditions are similar to the encoding conditions - No effect on performance when finals were administered in the same room where the course had been taught or in a novel classroom
What distinguishes episodic from semantic memory?ea form which several arms branch off like the spokes of a wheel. The toy of the ma
- Episodic memoreis concern specific events that occurred at a particular place and time - Semantic memories involve factual information: you do not need to remember where and when you learn this information - Episodic memory is always autobiographical: it must have happened to you - Semantic memory can be personal or general factual information - Episodic memory is acquired in a single exposure: the event itself - Semantic memories can be acquired in a single exposure too, particularly if the information is sufficiently interesting or important. But, it weight take you several exposures to memorize a fact. - Repeated exposures can strengthen semantic memory, but repeated exposure to very similar events may weaken episodic memory
Electroconvulsive shock training with rats
- If shock given 20 seconds after the end of training, the rats' memory of the conditioned response was severely disrupted - If the shock was given an hour or more after training, there was little disruption - Intermediate delays produced intermediate levels of disruption - The consolidation period for this type of learning in rats appears to extend for a few minutes; older memories are relatively stable and difficult to disrupt; more recent memories are highly vulnerable to disruption
The medial temporal lobes and memory storage
- Medial temporal lobes in humans contain the hippocampus, the amygdala, and nearby cortical areas, including the entorhinal cortex and peripheral cortex - most widely studied role of hippocampus is in storage of new episodic and semantic memory
Mere exposure to information does not guarantee memory
- Sheer repetition of either verbal or visual information isn't enough to ensure its being remembered.
Passive forgetting curves
- Suggest that if you can still remember a fact or event after a few months,t hen the odds are good that you'll remember it permanently (or at least for a very long time)
Korsakoff's disease and the diencephalon
- consistently damages two areas of the diencephalon: the mammillary bodies and part of the thalamus - develop same kind of anterograde amnesia and time graded retrograde amnesia observed in HM - may confabulate
Animals with broad lesions of the hippocampal region
- difficulty learning new information - impaired at episodic-like learning that involves memory of unique events set in a particular scene
More cues mean better recall
- free recall is harder than cued recall, which in turn is harder than recognition.
Memory is better for information that relates to prior knowledge
- new information is easier to remember if you can relate it to things you already know
Individuals with frontal cortex damage
- prone to source amnesia - an inability to remember where and when an event occurred
TGA
- starts suddenly, persists for several hours, and then gradually dissipates over the course of a d ay or so - during amnesic episode, shows severe anterograde amnesia, some degree of retrograde amnesia for events that occurred within the preceding decade or so
Electroconvulsive shock
A brief pulse of electricity passed through the brain via electrodes on each side of the head
declarative memory
A broad class of memories, both semantic and episodic, that can typically be verbalized or explicitly communicated in some other way
nondeclarative memory
A broad class of memory hat includes skill memory and other types of learning that do not fall under the heading of episodic or semantic memory and that are not always consciously accessible or easy to verbalize
explicit memory
A category of memory that includes semantic memory and episodic memory and consists of memories of which the person is aware: you know that you know the information
Korsakoff's disease
A condition caused by a deficiency in thiamine that sometimes accompanies chronic alcohol abuse
Retrograde and anterograde amnesia
A healthy adult may be able to recall most of what happened today and will recall progressively less about events that happened weeks, months, years ago. In contrast, a persons tin bilateral hippocampal damage may suffer anterograde amnesia, a loss of the ability to form new episodic and semantic memories since the injury, as well as retrograde amnesia, or emery loss for events that occurred days or weeks before the injury. If the brain damage extends beyond the hippocampus into nearby cortex, retrograde amnesia may be much more severe and may extend back for decades longer
Category sensitive neurons in the human brain
A patient with electrodes implanted in the right hippocampus was shown photos of famous celebrities and landmarks. Great response of the neuron to pictures of Steve Carell but not to photos of other celebrities such as Bill Clinton or Whoopi Goldberg
The standard consolidation theory
An episodic memory consists of many components, such as sight, sound, texture, and other features, stored ins sensory and association cortex. Initially, the hippocampal region helps link these components into single episodic memory. Over time, the components become linked to one another directly, and hippocampal involvement is no longer required
The effects of organization on memory
An experimenter read aloud to participants a short story describing scene. Participants who heard the paragraph alone (no picture) recalled a few items, but participants who saw the picture in and then heard the paragraph (picture before story) recalled more items. Participants who saw the picture only after hearing the paragraph performed no better than those who had never seen the picture
Effects of ECT on memory
Before ECT, patients with depression show a forgetting curve similar to that of non depressed adults. After the patients undergo ECT, retrieval of recent memories is temporarily disrupted. Many of the disrupted episodic and semantic memories return with time. Only the memories for a short period before and after the ECT are gone forever
The subsequent memory paradigm
Brain imaging (fMRI) records activity while participants make categorization judgements on a series of words. Later, participants are given a recognition test; typically, they correctly recognize some but not all of the previously viewed words. Some areas of the brain, including the left medial temporal lobe and left prefrontal cortex, are more active during initial viewing of words that will subsequently be remembered compared with initial viewing of words that will subsequently be forgotten
implicit memory
Memory that occurs without the learner's awareness
Directed forgetting
Occurs when we intentionally try to suppress memory. Here, participants' memory was worse for studied word pairs they and been instructed to forget than for pairs they'd been instructed to remember or control pairs they hadn't seen since the original study phase
Misattribution
Occurs when we remember information but mistakenly associate it with an incorrect source
What does the ability to form new facts and even memories depend on?
On the medial temporal lobes, but many other kinds of memory and cognitive function do not
The depth of processing effect
Participants were shown words and asked either to generate a mental image of a place described by the word (image condition) or to imagine pronouncing the word backwards (pronounce condition) Laater when shown a second list and asked whether or not each word had been previously viewed, participants recognized many more words from the "image" condition than from the "pronounce" condition. fMRI scans conducted during the encoding phase of this task revealed several brain areas that were significantly more active during the "image" condition than during the "pronounce" condition
False memory for studied words
People were first asked to learn lists of words organized around an unstated theme (sweet). Later, participants were generally accurate at recognizing the studied words and at rejecting (failing to recognize) novel, unrelated words. But they would also claim to recognize the unstudied theme words
Frontal cortex
Regions of cortex that lie within the frontal lobes, may help determine what information we store (and remember) and what information we don't store (and therefore forget)
Transfer-appropriate processing effect
Retrieval is more likely to be successful if the cues available at recall are similar to those that were available at encoding E.g. if you are initially shown a series of pictures of objects and then later are given a recognition test in which some of the objects are presented as pictures and some as words, most people show better recognition if the format is the same at encoding as at testing: if objects presented as words are tested as words, and objects presented as pictures are tested as pictures
Episodic like memory in birds
Scrub jays were permitted to cache worms and nuts int eh compartments of sand filled ice cube trays. Four hours later, the birds tended to dig int he compartments where they had buried worms (their favourite food) But after a delay of 124 hours, during which time the worms would have rotted, the birds went after the nuts instead. This suggests that the birds remembered what they had buried where and how long ago - an episodic like memory
agnosia
Selective disruption of the ability to process a particular kind of semantic information
Different regions of the cerebral cortex that are specialized to process particular kinds of sensory information
Somatosensory cortex in the parietal lobe Visual cortex in the occipital lobe Auditory cortex in the temporal lobe
Semantic memory and the cerebral cortex
Some areas of the cerebral cortex specialize in processing specific kinds of sensory information; these include areas in the parietal lobe, occipital lobe, and superior temporal lobe. Many of the remaining cortical areas are association areas that link information within and across modalities, forming a basic substrate for semantic information
Standard consolidation theory
The hippocampus and related medial temporal lobe structures are required for the initial storage and retrieval of an episodic memory but that their contribution diminishes over time until the cortex is capable of retrieving the memory without hippocampal help
Auditory agnosia for speech
They can hear sounds and echo them, but they are unable to understand the meaning of spoken words, though they can often recognize written words
cryptomnesia
When a person mistakenly thinks that his thoughts are novel or original when he's actually remembering information he learned from somewhere else
confabulation
When questioned about past events, many individuals with basal forebrain damage will respond with highly detailed but false memories
Interference
When two memories overlap in content, the strength of either or both memories may be reduced
radial arm maze
a maze with a central area from which several arms branch off like the spokes of a wheel. The top of the maze is open so that a rat placed in the maze can see out and use landmarks in the room, such as the placement of windows or posters, to help navigate
Episodic memory
a memory for a specific autobiographical event - includes information about the spatial and temporal context: where and when the event occurred
Why could basal forebrain damage lead to amnesia?
although the hippocampus is undamaged, it can't work effectively without neuromodulation from the basal forebrain telling it when to store new information
fornix
arch like fiber bundle in the basal forebrain and diencephalon
Thalamus
consists of several nuclei, many of which help relay sensory information from sensory receptors to the appropriate areas of sensory cortex
sensory cortex
cortical areas that specialize in one kind of sensory information
Directed forgetting
fMRI images show the hippocampus to be less active while people were actively truing to forget than while they were actively trying to remember. Several prefrontal areas, however, were more active while participants were trying to forget
hypothalamus
important role in regulating involuntary functions such as heartbeat, appetite, temperature control, and the wake/sleep cycle
trouble remembering old password when you just recently change it to a new one
retroactive interference
Ribot gradient
retrograde memory loss is worse for events that occurred shortly before the injury than for events that occurred in the distant past
mnemonics
techniques that make information easier to memorize - using acronyms, rhymes, etc
medial temporal lobes
the inner or medical surfaces of the temporal lobes, which contain the hippocampus, the amygdala, and several nearby cortical areas
temporary failure of memory
the memory is inaccessible at the moment but may resurface later tip of the tongue phenomenon
dissociative fugue
type of functional amnesia patients lose all memory of their identity
dissociative amnesia
type of functional amnesia patients lose memory of a specific, traumatic event
Retroactive interference
where new information can disrupt old learning