Cognitive Neuroscience (2) – Lectures
Lecture 7: Memory: Varieties & Mechanisms
Tuesday 9 december – Van de Vijver
What is memory?
Three phases:
1. Encoding: the nervous system acquires information from new experiences, formation of
‘memory traces’.
2. Storage: retention of memory traces over time.
3. Retrieval: accessing of stored memory traces and using this information to guide behavior
and plan future actions.
Memory trace (engram): alterations to the nervous system from experiences (changes in the strength
and/or number of connections between neurons).
Memory systems
Case 1: Clive Wearing
• Herpes simplex virus encephalitis
• Severe damage to the medial temporal lobe
Case 2: Henry Molaison, patient H.M.
• Severe form of epilepsy
• Operated in 1957, removal of part of medial temporal lobe
• Bilateral damage to…
o Amygdala
o Entorhinal cortex
o Large part of hippocampus
Amnesia = severe memory loss due to brain damage (caused by damage to the temporal lobe).
• Anterograde amnesia = information acquired after damage
• Retrograde amnesia = information acquired before damage
1
,Which part of the medial temporal lobe are important for storing memories?
Study:
Rhesus monkeys
Lesions, 4 groups:
• No damage (control group)
• Only damage to hippocampus (H)
• Damage to hippocampus + some surrounding cortex (H+)
• Damage to hippocampus + more surrounding cortex (H++)
Delayed-nonmatch-to-sample task (after the operation!)
Monkeys learn over repeated exposures that the reward is always under the new sample.
It is not only by hippocampus damage; also other surrounding regions in the medial temporal lobe
are necessary for storing memories.
Back to case 2: Henry Molaison (patient H.M.)
There is a difference between two types of memory.
H.M.: no problems with immediate (working) memory (tested with digit span task).
• When he did a declarative memory task, he completely failed.
Patient K.F.: motor cycle accident, damage to left parieto-occipital cortex.
• Failed at the working memory task, no impairment in declarative memory task.
Double dissociation
= one experimental variable affects one system but not the
other, whereas another experimental variable affects the
other system but not the first.
2
,Memory systems
Working memory: maintenance and manipulation of information for a brief period of time.
Long-term memory: retention of information for longer periods.
Declarative/explicit memory: conscious memory for events and facts (temporal lobe)
Nondeclarative/implicit/procedural memory: memories that are expressed through performance
independently of consciousness.
Case 3: Patient M.S.
• Epilepsy
• Removal of part of right occipital lobe
• Task:
o Read aloud 24 words twice.
o Implicit test: 24 old/24 new words briefly
shown, identify word.
▪ No faster response for old words for
patient M.S.
o Explicit test: 24 old/ 24 new words, indicate
whether seen before in the study (respond
faster for words they have seen before).
▪ Amnesia patients are not faster for
old words.
• M.S.: selective impairment in visual implicit memory.
Differences between patients and lesions help identify memory systems and relevant brain areas.
BUT: only when areas are damaged that are specifically involved in one function.
• Other brain areas do play a role in multiple memory functions.
Declarative memory:
• Episodic memory (events)
• Semantic memory (facts)
The declarative memory is very dependent on the medial temporal lobe.
3
, Nondeclarative memory:
• Priming
• Skill learning
• Conditioning
Priming
Priming
= change in the processing of a stimulus due to a previous encounter with the same or a related
stimulus, in the absence of conscious awareness of the first encounter.
Example
Find the tilted T
Is it tilted left of right?
When the same display is repeated, you see that reaction times
are faster than when people are presented with new stimuli.
• Perceptual priming
Direct priming: the prime and the target are the same.
Indirect priming: the prime and the target are different (semantic relationship).
4
Lecture 7: Memory: Varieties & Mechanisms
Tuesday 9 december – Van de Vijver
What is memory?
Three phases:
1. Encoding: the nervous system acquires information from new experiences, formation of
‘memory traces’.
2. Storage: retention of memory traces over time.
3. Retrieval: accessing of stored memory traces and using this information to guide behavior
and plan future actions.
Memory trace (engram): alterations to the nervous system from experiences (changes in the strength
and/or number of connections between neurons).
Memory systems
Case 1: Clive Wearing
• Herpes simplex virus encephalitis
• Severe damage to the medial temporal lobe
Case 2: Henry Molaison, patient H.M.
• Severe form of epilepsy
• Operated in 1957, removal of part of medial temporal lobe
• Bilateral damage to…
o Amygdala
o Entorhinal cortex
o Large part of hippocampus
Amnesia = severe memory loss due to brain damage (caused by damage to the temporal lobe).
• Anterograde amnesia = information acquired after damage
• Retrograde amnesia = information acquired before damage
1
,Which part of the medial temporal lobe are important for storing memories?
Study:
Rhesus monkeys
Lesions, 4 groups:
• No damage (control group)
• Only damage to hippocampus (H)
• Damage to hippocampus + some surrounding cortex (H+)
• Damage to hippocampus + more surrounding cortex (H++)
Delayed-nonmatch-to-sample task (after the operation!)
Monkeys learn over repeated exposures that the reward is always under the new sample.
It is not only by hippocampus damage; also other surrounding regions in the medial temporal lobe
are necessary for storing memories.
Back to case 2: Henry Molaison (patient H.M.)
There is a difference between two types of memory.
H.M.: no problems with immediate (working) memory (tested with digit span task).
• When he did a declarative memory task, he completely failed.
Patient K.F.: motor cycle accident, damage to left parieto-occipital cortex.
• Failed at the working memory task, no impairment in declarative memory task.
Double dissociation
= one experimental variable affects one system but not the
other, whereas another experimental variable affects the
other system but not the first.
2
,Memory systems
Working memory: maintenance and manipulation of information for a brief period of time.
Long-term memory: retention of information for longer periods.
Declarative/explicit memory: conscious memory for events and facts (temporal lobe)
Nondeclarative/implicit/procedural memory: memories that are expressed through performance
independently of consciousness.
Case 3: Patient M.S.
• Epilepsy
• Removal of part of right occipital lobe
• Task:
o Read aloud 24 words twice.
o Implicit test: 24 old/24 new words briefly
shown, identify word.
▪ No faster response for old words for
patient M.S.
o Explicit test: 24 old/ 24 new words, indicate
whether seen before in the study (respond
faster for words they have seen before).
▪ Amnesia patients are not faster for
old words.
• M.S.: selective impairment in visual implicit memory.
Differences between patients and lesions help identify memory systems and relevant brain areas.
BUT: only when areas are damaged that are specifically involved in one function.
• Other brain areas do play a role in multiple memory functions.
Declarative memory:
• Episodic memory (events)
• Semantic memory (facts)
The declarative memory is very dependent on the medial temporal lobe.
3
, Nondeclarative memory:
• Priming
• Skill learning
• Conditioning
Priming
Priming
= change in the processing of a stimulus due to a previous encounter with the same or a related
stimulus, in the absence of conscious awareness of the first encounter.
Example
Find the tilted T
Is it tilted left of right?
When the same display is repeated, you see that reaction times
are faster than when people are presented with new stimuli.
• Perceptual priming
Direct priming: the prime and the target are the same.
Indirect priming: the prime and the target are different (semantic relationship).
4
