Abstract
In recent years, evidence has emerged to suggest abnormal temporal dynamics of attentional processing in stroke patients, especially those presenting with neglect symptoms. However, there has been little profiling of the nature and extent of such temporal anomalies. In addition, many paradigms currently used to measure the time required to deploy visual attention in stroke require a psychomotor response, and may therefore confound performance outcomes. Thus, the aim of this systematic review was to identify and evaluate studies that have employed non-motor psychophysical paradigms to characterize the temporal deployment of visual attention in space. A total of 13 non-motor psychophysical studies were identified, in which stimulus exposure times were manipulated to measure the time course of attentional deployment. Findings suggest that prolonged attentional deployment thresholds are more likely to occur with lesions within more ventral areas of the fronto-parietal network, irrespective of whether patients presented with neglect. Furthermore, this deficit was greater following right-hemispheric lesions, suggesting a dominant role for the right-hemisphere in facilitating efficient deployment of attention. These findings indicate that area and hemisphere of lesion may serve as putative markers of attentional deployment efficiency. In addition, findings also provide support for using non-motor psychophysical paradigms as a more rigorous approach to measuring and understanding the temporal dynamics of attention.
Highlights
The concept of attention has been broadly understood as being the behavioral process of concentrating on a particular task or information at hand, while filtering other ongoing activities within the perceptual environment (James, 1890)
It is worth noting that the common neural regions that are implicated in neglect and its associated exogenous deficit are the same regions associated with the Ventral Attention Network (Husain and Kennard, 1996; Vallar, 2001; Mort et al, 2003; Umarova et al, 2011)
Application of the above selection criteria led to identification of a total of 13 studies involving stroke patients
Summary
The concept of attention has been broadly understood as being the behavioral process of concentrating on a particular task or information at hand, while filtering other ongoing activities within the perceptual environment (James, 1890). Exogenous attention has been defined as the allocation of attention that is driven by salient external sensory stimuli, and is neuroanatomically underpinned by more ventrally located fronto-parietal networks known. Endogenous attention, on the other hand, has been referred to as the allocation of attention that is driven by an individual’s expectations, goals and knowledge, and is underpinned by more dorsal fronto-parietal tracts (i.e., Dorsal Attention Network; Corbetta and Shulman, 2002; Shomstein, 2012). In the case of unilateral spatial neglect, a common disorder of attention post-stroke, this phenomenon is known to be associated with an exogenous deficit in attending to salient stimuli within contralesional space, resulting in a lack of awareness to this side of visual hemi-space (Samuelsson et al, 1997; Mort et al, 2003; He et al, 2007; Bartolomeo et al, 2012). It is worth noting that the common neural regions that are implicated in neglect and its associated exogenous deficit (i.e., right temporo-parietal junction, right inferior parietal lobule, and inferior prefrontal gyrus) are the same regions associated with the Ventral Attention Network (Husain and Kennard, 1996; Vallar, 2001; Mort et al, 2003; Umarova et al, 2011)
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