PSYC 444 Lecture Notes - Lecture 8: Long-Term Memory, Short-Term Memory, Explicit Memory
14 May 2018
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PSYC 444 – LECTURE 8
COGNITIVE FUNCTIONS OF SLEEP: MEMORY
SLEEP TO FORGET- SLEEP TO REMEMBER
Sleep helps consolidate memories
• You learn better after having slept
• You remember better after a night (even a nap) of sleep
During sleep, you extract what is important, or the gist of the experience
• Create associations with previously learned material
• Transfer from short to long term memory
o Engrams become more stable
• More salient events are more likely to be kept in memory
o Dependent on individual factors, such as motivation
Memory must be flexible, as it is disadvantageous for one memory to influence all other memories
• Each memory is distinctive yet integrated into a larger network
MEMORY: TEMPORAL SCALE
Types of memory by duration
• Sensory memory: milliseconds to 1-2s
• Short term memory: few dozen seconds; needs conscious effort
• Long term memory: days, weeks, months, years
This scale is fairly uncontroversial
Sensory memory: touch, hearing, seeing, etc.
• Do not remember much, as input from sensory organs are not that important
If something attracts attention, it is more likely to be held in short term memory
• No subconscious effort
If experience is important for X number of reasons, it will be kept in long term memory
• Example reason is emotional significance
• Some may be things we want to remember and others not
o Example: remembering an annoying song from childhood
LONG-TERM MEMORY
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Declarative (explicit) memory: accessible to consciousness
Episodic memory: what, where and when component of memory
• Specific events, in context
Semantic memory: common knowledge; facts
• Example: The Earth is round
• Potentially accessible to memory if called upon, but not constantly aware
Non-declarative (implicit) memory: somewhat inaccessible- though not always true
• Implicit memories are hard to explain, such as teaching a child how to walk
• The more attention paid to execution of a skill, the worse the performance
• For example: riding a bike or playing an instrument
Patient HM had both hippocampi removed
• Subsequently, he lost the ability to make new declarative, but non-declarative, memories (procedural)
• It was concluded that there must be some separation between the two types of memories
EXPLICIT/DECLARATIVE MEMORY
Episodic: etal tie trael; hat, here ad hen
• Importance of context
• Possibly unique to primates
o Keep in mind that it is difficult to test and question non-priates’ delaratie eor
• Includes autobiographic memory
o Example: last spring in Florence, I saw the Duomo
• Same networks used to imagine the future
o Picture yourself in a future situation by drawing on past experiences
o Both are accessible to consciousness
o Advantages: able to avoid danger and predators; mental simulation
Semantic: facts and concepts
• General knowledge of the world
• Example: Florence is a city in Italy where Renaissance started
IMPLICIT/NON-DECLARATIVE MEMORY
• Generally not accessible to consciousness
• Includes procedural memory: how to do things
o Example: riding a bicycle, writing, playing musical instrument
• Includes conditioning and priming
Not long after the experience, there is good memory. However, memory declines as the experience is interpreted.
Meories a e releared through rehearsal, akig it aessile for a loger period of tie
• If the rehearsal is negative, it becomes problematic
o Impacts how well things are remembered (negative bias)
• Example: rumination and depression
HIPPOCAMPUS AND AMYGDALA
The hippocampus is very interconnected; there are projections everywhere
• The hippocampus is a very small structure but it is very important for identity
The amygdala, in a reductionist sense, is the fear center
• This is because fear is the most salient emotion
o However, more generally, it is the emotion center. In real life, we are not just motivated by fear but positive affects as well.
• Largely interconnected with other brain regions
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MEMORY CONSOLIDATION
Process of transferring newly learned information from short to long term memory
• Long term is not infallible and may be forgotten eventually, but it is more likely to be consolidated
• Consolidation may take many days; memories get gradually strengthened and weakened
Our etal apait to tie-trael perits reosolidatio
• Recalling the memory and being exposed to the memory again and again strengthens memory for whatever event is being recalled
LONG-TERM STORAGE: NEUROPHYSIOLOGY
On the level of the neuron, memory consolidation begins with long-term potentiation (LTP)
If two neurons fire at the same time, which occurs more often during learning, then the response becomes more salient and is activated with a larger amplitude.
• Strengthening the synapse creates stable memories
• Hebb: neurons that fire together, wire together
MEMORY CONSOLIDATION
In animals, there is evidence of neural replay during sleep
In humans, this replay is likely taking place via involvement of the hippocampus
What is the role of mental activity in sleep? Do dreams reflect memory consolidation?
Dreams are usually not an accurate reflection of actual memories
• Exception: those with PTSD and brain damage do have dreams of full episodic memories
In animals, the neural signature repeats itself
• Experience never gets fully replayed. Thus, there must be something else involved
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find more resources at oneclass.com
Document Summary
You remember better after a night (even a nap) of sleep. During sleep, you extract what is important, or the gist of the experience. Engrams become more stable: more salient events are more likely to be kept in memory. Memory must be flexible, as it is disadvantageous for one memory to influence all other memories. Each memory is distinctive yet integrated into a larger network. Short term memory: few dozen seconds; needs conscious effort. Do not remember much, as input from sensory organs are not that important. If something attracts attention, it is more likely to be held in short term memory. If experience is important for x number of reasons, it will be kept in long term memory. Some may be things we want to remember and others not. Episodic memory: what, where and when component of memory. Potentially accessible to memory if called upon, but not constantly aware. Non-declarative (implicit) memory: somewhat inaccessible- though not always true.
