remembering and forgetting of
verbal experiences as
predicted by brain activity
Anthony D. Wagner, Daniel L.
Schacter, Michael Rotte, Wilma
Koutstaal, Anat Maril, Anders M.
Dale, Bruce R. Rosen, Randy L.
By: Andrea Ching
What is memory encoding?
Memory encoding refers to the processes
by which an experience is transformed into
an enduring memory trace.
Memorability of an event is influenced
by the cognitive operations during the
initial encoding of the event.
Left pre-frontal cortex involved in verbal
Left pre-frontal cortex activation greater
in semantic relative to non-semantic
Medial temporal regions
No medial temporal activation
Novel stimuli > familiar stimuli
Twelve normal, right handed subjects
Seven men, five women
Aged 18-29 years
Blocked design experiment
Trials from each encoding condition are
presented sequentially inseparable from
each other during the scan
Comparison between activation during
semantic vs non-semantic processing
Novelty of the words are equivalent in
semantic and non-semantic blocks.
During semantic and nonsemantic blocks, 20
words were visually presented: 10 abstract
and 10 concrete nouns; half in uppercase and
half in lowercase letters.
Each word was presented for 1 s followed by
1 s of fixation between words.
Memory was assessed using a yes-no
recognition procedure after 20 to 40 minutes
Reaction times were longer for semantic
Subsequent memory was superior
following semantic (85% recognized)
than following non-semantic
Greater Activation during
Thirteen normal, right-handed subjects
Six men and seven women
Aged 18-35 years
Event-related fMRI was used while
participants performed a single incidental
Word and fixation events presented in a
continuous series of 120 intermixed trials.
Semantic decision during word trials(abstract
Recognition test (High or low confidence).
fMRI data analysis: four encoding trial
High confidence hits
Low confidence hits
Word processing relative to fixation
resulted in greater activation
High confidence hits to misses
Multiple left prefrontal regions
Left parahippocampal gyrus
Magnitude of activation is greater in
Subsequently remembered events are processed
longer during learning
Reaction times for high confidence hits and
miss trials were matched
Greater activation in left prefrontal and temporal
regions in subsequently remembered items
Left parahippocampal gyrus is more
active in later remembered events even
though both were equally novel
Extends beyond novelty detection
more general encoding mechanism
Principal neocortical input to
important role in memory formation
Verbal experience may be more memorable
when semantic and phonological attributes
are processed via the left prefrontal regions.
Organization in working memory serves as
input to the parahippocampal gyrus and the
medial temporal memory system.
Left prefrontal and temporal processes will
tend to produce more memorable verbal
Were able to identify many brain
regions that were involved in
Small sample size
Instead of words they could use
Age, sex differences
Wagner AD, Schacter DL, Rotte M,
Koutstaal W, Maril A, Dale AM,
Rosen BR, Buckner RL (1998)
Building memories: remembering
and forgetting of verbal
experiences as predicted by brain
activity. Science, 281(5350), 1188