Article

Portions of the posterior parietal cortex (PPC) play a role in working memory
(WM) yet the precise mechanistic function of this region remains poorly
understood. The pure storage hypothesis proposes that this region functions as a
short-lived modality-specific memory store. Alternatively, the internal attention
hypothesis proposes that the PPC functions as an attention-based storage and
refreshing mechanism deployable as an alternative to material-specific rehearsal.
These models were tested in patients with bilateral PPC lesions. Our findings
discount the pure storage hypothesis because variables indexing storage capacity
and longevity were not disproportionately affected by PPC damage. Instead, our
data support the internal attention account by showing that (a) normal
participants tend to use a rehearsal-based WM maintenance strategy for recall
tasks but not for recognition tasks; (b) patients with PPC lesions performed
normally on WM tasks that relied on material-specific rehearsal strategies but
poorly on WM tasks that relied on attention-based maintenance strategies and
patient strategy usage could be shifted by task or instructions; (c) patients'
memory deficits extended into the long-term domain.
These findings suggest that
the PPC maintains or shifts internal attention among the representations of items
in WM.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS