Article

Unilateral spatial neglect is a neurological disorder characterized by impaired
orienting of attention to stimuli located in the contralesional space, typically
following right-hemisphere damage. Neuropsychological investigations in the past
two decades have demonstrated that neglect is caused by deficits affecting a
widespread cortico-subcortical fronto-parietal network controlling spatial attention, but usually sparing early sensory pathways. As a consequence, certain
residual abilities in sensory processing remain intact and still take place for
stimuli in the neglected space, such as the extraction and organization of
coherent or meaningful object features. Moreover, these residual abilities can
alleviate inattention symptoms when contralesional stimuli are perceptually or
biologically salient. Here we review recent studies suggesting that the emotional
content of stimuli may also be processed despite impaired attention towards
contralesional space, and that such processing may act to enhance attention and
partly reduce neglect for these stimuli, relative to similar but emotionally
neutral stimuli. For example, faces with emotional expressions, voices with
emotional prosody, as well as pictures of scenes or even spiders have been found
to be less severely extinguished from awareness in conditions of bilateral
stimulations, and/or lead to fewer omissions in search tasks with multiple
distracters. Gaze cues and reward learning might also produce similar effects.
Altogether, these findings suggest that emotionally significant information is
not only extracted from stimuli at neglected locations through spared pathways,
but can also induce emotional biases in attention that partly counteract the
abnormal spatial biases caused by fronto-parietal damage. We discuss results from
neuropsychology and neuroimaging research suggesting that specific mechanisms for
emotional attention might exist, centered on the amygdala and other limbic
regions, and that these mechanisms can operate partly independent from other
circuits controlling spatial and object-based attention. Although we are only beginning to understand these interactive effects of emotion and attention and to
identify their neuroanatomical substrates, we believe that a deeper knowledge of
such mechanisms and their conditions of optimal operation will help develop or
improve therapeutic strategies in neglect patients.
CI - Copyright (c) 2012 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS