Dividing attention across space and tasks: a study in acute stroke patients
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1
Ghent University, Belgium
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2
University of Padova, Italy
Objective
After a unilateral stroke the processing of contralesional hemispace can be heterogeneously affected by a number of factors. Detecting the presence of neglect is modulated by task demands and thus greatly depends on the tasks adopted. Previous studies have shown that in chronic right hemisphere stroke patients, computer-based dual-tasks detect neglect much more sensitively than the conventional paper-and-pencil tests (Bonato, 2010 et al.; Bonato et al., 2012; Bonato et al., 2013). We aimed to study the level of awareness for contralesional items after attention has been divided across tasks, space, or both tasks and space using the same tasks in the acute stage after stroke, before compensatory strategies can be learned.
Participants and Methods
A sample of 21 (left and right hemisphere damaged) stroke patients was tested within the first week of lesion onset in order to maximize the detection of across hemispheric attentional imbalances. Both classic neglect paper-and-pencil tasks as well as a specifically designed computer-based task were administered. The computer-based task included a spatial detection task where patients had to verbally report the position of targets (presented either left, right, or on both sides).
This design allows target presentation within contralesional hemispace to occur either in isolation or concurrently with another target in ipsilesional hemispace, therefore maximally triggering, within the same task, competitive mechanisms for awareness. Three different task versions encompassing the mere focusing on target position (single task) or the parallel processing of additional, visual or auditory, features (duals task) were administered.
Results
Our results show that the dividing of attention either proactively, to perform a concurrent task, or reactively, to process a concurrent ipsilesional target, had a detrimental effect on contralesional hemispace awareness, not only after right but also after left hemispheric stroke. This approach allowed to more sensitively detect and characterize contralesional awareness deficits (neglect and extinction) than classical clinical tests, where no divided attention processes have to be implemented.
The core spatial awareness deficits characterizing the acute phase were exacerbated by the need to split attention across space and tasks. The severity of contralesional omissions found in the presence of a ipsilesional target and under divided attention conditions confirms that the more cognitive control is required directly by a spatial task or by a concurrent (even non-spatial) one, the worse patients' awareness of contralesional hemispace becomes.
Conclusion
The divided-attention procedure we adopted here has a number of methodological strengths, including the possibility to assess neglect and extinction within the same task, which in turn allows a direct comparison between the two phenomena. Possibly, this the first time that a spatial monitoring task measuring spatial awareness in a context of cognitive control/divided attention is implemented in acute, unselected patients. Our divided attention approach went much further than the current gold standard for measuring these deficits (paper-and-pencil tests and DSS, respectively). Besides the high sensitivity described earlier, the very strong methodological advantage is related to trigger competitive mechanisms. A second yet important additional feature is that this approach avoids the recruitment of -potentially confounding- motor involvement, allowing to focus on pure awareness.
References
Bonato, M., Priftis, K., Marenzi, R., Umiltà, C., & Zorzi, M. (2010). Increased attentional demands impair contralesional space awareness following stroke. Neuropsychologia, 48, 3934-3940.
Bonato, M., Priftis, K., Marenzi, R., Umiltà, C., & Zorzi, M. (2012). Deficits of contralesional awareness: A case study on what paper-and-pencil tests neglect. Neuropsychology, 26, 20-36.
Bonato, M., Priftis, K., Umiltà C., & Zorzi, M. (2013). Computer-based testing unveils severe neglect in apparently intact patients. Behavioural Neurology, 25, 1-3.
Keywords:
neglect,
extinction,
Acute stroke patients,
compter-based task,
Attentional load,
spatial attention
Conference:
13th National Congress of the Belgian Society for Neuroscience , Brussels, Belgium, 24 May - 24 May, 2019.
Presentation Type:
Poster presentation
Topic:
Behavioral/Systems Neuroscience
Citation:
Naert
L,
Fias
W and
Bonato
M
(2019). Dividing attention across space and tasks: a study in acute stroke patients.
Front. Neurosci.
Conference Abstract:
13th National Congress of the Belgian Society for Neuroscience .
doi: 10.3389/conf.fnins.2019.96.00003
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Received:
01 May 2019;
Published Online:
27 Sep 2019.
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Correspondence:
Ms. Lien Naert, Ghent University, Ghent, Belgium, lhnaert.naert@ugent.be