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Abstract:
Recent functional imaging studies of spatial working memory
have activated a right-lateralized network which bears similarities
to the areas typically damaged in spatial neglect. Moreover, many
tests for neglect often involve an overlooked spatial working
memory component. We tested two neglect patients in cancellation
tasks, manipulating whether their marks were visible (providing a
permanent reminder of which items had been visited) or invisible
(so that spatial working memory must represent which items have
been cancelled). If deficient spatial memory contributes to
neglect, perseverations should increase and/or cancellations
decline (ie. stronger neglect) with invisible marks; but the
opposite result (stronger neglect with visible marks) would be
expected if patients' initial visible marks on the right make that
side even more salient, as commonly argued. When the items to be
cancelled were homogenous (ie. distinguishable only by their
location), both patients showed stronger neglect and more
perserverations with invisible marks, consistent with a spatial
working memory impairment. One patient was tested in a further
condition with reduced spatial memory load for invisible marks, by
making each item to be cancelled unique (each was a different
familiar object); this eliminated his perseveration errors, which
had primarily been on the right. These results suggest that spatial
working memory deficits may be an exacerbating component of
neglect. [Supported by HFSPO Fellowship to EW]
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