Recent neuroimaging studies of memory retrieval have reported the activation of a medial and left

1
Attribute-based modulation in medial temporal
activation during recollection of personal
experiences D. R. Addis1,2, M. Moscovitch1, A.
P. Crawley2, and M. P. McAndrews1,2 1 Department
of Psychology, University of Toronto, Toronto,
Ontario 2 Toronto Western Research Institute,
University Health Network, Toronto, Ontario

• Methods
• Participants
• 6 male and 6 female participants (20 40 years)
• Pre-Scan Interview
• Participants retrieved and described 20 specific
  and 20 general AMs.
• A title was provided for each memory, to be
  later used as a cue in the scanner.
• Each memory was rated on a five point scale for
  level of detail, emotionality and personal
  significance.
• Scanning Protocol
• AM tasks General and Specific AMs
• Retrieve a general or specific AM in response to
  a visually presented AM title (6 sec)
• Rate AM for either level of detail, emotionality
  or personal significance (4 sec)
• Rest (6 sec)

• Results
• Contrast 1 AMs (general specific) Control
  tasks
• AM retrieval resulted in increased activation of
  a predominantly medial and left lateralised
  memory network.

• Introduction
• Recent neuroimaging studies of memory retrieval
  have reported the activation of a medial and left
  lateralised memory network that includes
  hippocampus, parahippocampus, posterior
  cingulate, precuneus, and medial frontal
  regions1.
• The retrieval of autobiographical memories (AMs)
  appears to preferentially activate the
  hippocampus as part of this network1.
• It remains unclear why the hippocampus exhibits
  preferential activation during AM retrieval.
• Maguire Mummery1 found that temporally specific
  AMs activated the hippocampus to a greater extent
  than personal facts. A more direct test of
  temporal specificity would be to compare unique,
  specific AMs to general, repeated AMs.
• Maguire et al.2 reported that remembered AMs
  elicited greater left hippocampal activation than
  known AMs. Thus, attributes contributing to the
  re experiencing of AMs, such as detail,
  emotionality and personal significance, may
  modulate hippocampal engagement.
• We conducted an event related fMRI study,
  testing three hypotheses

• Parametric Modulation Level of Emotionality
• Level of Emotionality modulated activation of
  hippocampus bilaterally, bilateral anterior
  cingulate, L thalamus, L precuneus and L inferior
  parietal lobule.

• Parametric Modulation Level of Personal
  Significance
• Level of Personal Significance modulated
  activation of the
• L hippocampus, L medial frontal lobe, L superior
  frontal gyrus, R anterior cingulate, L
  parahippocampal gyrus,
• R temporal pole and bilateral parietal lobules.

• Contrast 2 General AMs Specific AMs
• No differences in hippocampal activation evident.
  
• Retrieval of General AMs resulted in increased
  activation of R insula and R parahippocampal
  gyrus.
• Retrieval of Specific AMs resulted in increased
  activation of the R ventrolateral prefrontal
  cortex and R temporal pole.

• Conclusions
• We replicated previous findings of a
  predominantly medial and left lateralised
  memory retrieval network.
• There were no differences in hippocampal
  activation between the retrieval of memories for
  repeated, general AMs and temporally specific
  AMs, suggesting that this is not an important
  determinant of the level of hippocampal
  activation.
• Hippocampal activation was modulated by the level
  of detail, emotionality and personal
  significance. This indicates that attributes of
  AMs contributing to re experiencing are
  significant predictors of hippocampal activation.
  
• Other brain regions also correlated with the
  level of
• re experiencing, though the regions differed
  depending on the particular attribute, suggesting
  the activation of different memory networks of
  which the hippocampus is a key structure.

• Parametric Modulation Level of Detail
• Level of detail modulated activation of R
  hippocampus, bilateral medial frontal lobe,
  bilateral anterior cingulate, L superior/middle
  temporal gyrus, bilateral precuneus and R
  supramarginal gyrus.

References 1 Maguire, E.A., Mummery, C.J.
(1999). Differential modulation of a common
memory network revealed by PET. Hippocampus, 9,
54 61. 2 Maguire, E.A., Vharga-Khadem, F.
Mishkin, M. (2001). The effects of bilateral
hippocampal damage on fMRI regional activations
and interactions during memory retrieval. Brain,
124, 1156 1170.