| |
Abstract:
While many studies have shown that dorsolateral prefrontal
cortex (DLPFC) is involved in aspects of working memory processing,
the precise role of this region remains unclear. Recently, it has
been suggested that this area is involved in manipulation of
information held in working memory. Here we addressed this question
directly using event-related functional magnetic resonance imaging.
Each trial was constructed as follows: During a study phase, four
consonants were presented sequentially. These stimuli had to be
held in working memory during a retention phase which lasted
several seconds. Following a cue the subject was required to
re-order the consonants in one of several pre-specified ways. In a
'no manipulation condition' the order was the same as in the study
phase. In an 'easy manipulation condition' and a 'hard manipulation
condition' the order of two or four of the consonants had to be
changed, respectively. Data analyses were carried out using
Statistical Parametric Mapping (Wellcome Department of Cognitive
Neurology, London). Specific comparisons were made between trials
where re-ordering information within working memory was required
and trials where no re-ordering was required. Consistent with the
hypothesis above, the DLPFC was shown to be preferentially
activated during the manipulation conditions.
|
