| |
Abstract:
This study had two aims: 1) to assess whether the
preferential role for dorsolateral prefrontal cortex (PFC) in the
manipulation of letter stimuli (D'Esposito et al., in press)
generalizes to spatial stimuli; and 2) to test the proposal of
Courtney et al. (1997) that a region proximal to the frontal eye
fields (FEF) plays a privileged role in spatial working memory. Our
delayed-response task featured a Corsi block-like array of 10
squares in which 6 squares were highlighted in a random sequence.
The Forward condition required maintenance of the chronological
sequence of locations; the Manipulation condition required
reordering the sequence of locations into a spatially defined order
(top-to-bottom, bottom-to-top, left-to-right, or right-to-left).
The Guided Saccade condition required saccades to highlighted
squares in the array, but no memory, and the Free Saccade condition
required self-paced, self-directed saccades in the absence of the
array. Results: 1) Dorsolateral, but not ventrolateral, PFC was
associated with a spatial manipulation effect. 2) There was no
evidence of reliably greater Memory than Guided Saccade activity in
peri-FEF regions; peri-FEF activity was reliably greater, in
contrast, during Guided than Free saccades. These data suggest that
behavioral factors mediating saccade generation, rather than
mnemonic factors, may be principally responsible for differential
peri-FEF activity observed in spatial working memory
experiments.
|
