| |
Abstract:
Experiment:
Scalp topography of event-related potential (ERP) effects
This experiment contrasted the scalp topography of
event-related potential (ERP) effects associated with the
recollection of words presented in two different classes of study
episode. In one class words were 'deeply' processed while in the
other class words were 'shallowly' processed. ERPs were recorded at
test from 16 healthy young adult subjects performing a word-stem
(e.g. UNC__) cued recall task. The deeply studied items were
recalled more often than the shallowly studied items, replicating
numerous previous behavioural studies. ERP topographic analyses
revealed that at least two different neural populations contributed
to ERP effects associated with the recollection of study episodes.
One population gave rise to a posterior left>right positivity,
closely resembling the 'left parietal old/new effect' commonly
observed in other tasks, e.g. recognition. The other neural
population generated a sustained positivity which was more
extensive over the right than the left hemi-scalp late in the
recording epoch. Subtle differences in the topography of these ERP
effects were also observed as a function of depth of study
processing. This finding suggests that differential encoding during
study episodes leads to the engagement of different brain regions
when information from the episodes is subsequently recollected.
However, because of the overall similarity of ERP effects
associated with the recollection of each class of study episode, we
conclude that common memory functions contributed to recollection
in each case.
|
