Enhancing the Sensitivity of a Sustained Attention Task to Frontal Damage: Convergent Clinical and Functional Imaging Evidence

Abstract

Despite frequent reports of poor concentration following traumatic brain injury, studies have generally failed to find disproportionate time-on-task decrements using vigilance measures in this patient group. Using a rather different definition, neuropsychological and functional imaging research has however linked sustained attention performance to right prefrontal function--a region likely to be compromised by such injuries. These studies have emphasised more transitory lapses of attention during dull and ostensibly unchallenging activities. Here, an existing attention measure was modified to reduce its apparent difficulty or 'challenge'. Compared with the standard task, its capacity to discriminate traumatically head-injured participants from a control group was significantly enhanced. Unlike existing functional imaging studies, that have compared a sustained attention task with a no-task control, in study 2 we used positron emission tomography to contrast the two levels of the same task. Significantly increased blood flow in the dorsolateral region of the right prefrontal cortex was associated with the low challenge condition. While the results are discussed in terms of a frontal system involved in the voluntary maintenance of performance under conditions of low stimulation, alternative accounts in terms of strategy application are considered.

A right hemisphere role in cognitive reserve

“…Furthermore, the NA-sensitive SART test, sensitive to variations in NA availability (Bellgrove, et al, 2006,Greene, et al, 2009) and associated with right dFPLC-parietal activation (Manly, et al, 2003,O'Connor, et al, 2011 has also been shown to be selectively impaired by lesions to the right inferior frontal gyrus (Molenberghs, et al, 2009), which further cements the associations observed. Finally when NA is pharmacologically up-regulated, the dominant alterations in neural activation include the right dorsolateral prefrontal cortex (Chamberlain, et al, 2007,Grefkes, et al, 2010.…”

“…As described above, there are at least three different supramodal attentional systems for selection, control and vigilance respectively, but it is only the latter which has a strong linkage to NA activity and a clear right hemisphere fronto-parietal neural basis as shown in many studies (Manly, et al, 2003,Paus, et al, 1997,Sturm, et al, 1999. This network monitors and modulates activity in subcortical regions governing arousal to match current task demands (Critchley, et al, 2002,Foucher, et al, 2004.…”

Do sleep difficulties exacerbate deficits in sustained attention following traumatic brain injury?

“…However, studies using traditional vigilance tests have often failed to fi nd disproportionate defi cits (see Manly et al, 2003 ). Robertson, Manly, Andrade, Baddeley, and Yiend ( 1997 ) developed a new computerized measure designed to be more sensitive to transient lapses in attention than traditional vigilance and continuous performance tests; the Sustained Attention to Response Test (SART).…”

Awareness of deficits in traumatic brain injury: A multidimensional approach to assessing metacognitive knowledge and online-awareness

“…These included: National Adult Reading Test (NART) (Nelson, 1982;Nelson & Willison, 1991), Hospital Anxiety and Depression Scale (HADS) (Zigmond & Snaith, 1983), Frenchay Aphasia Screening Test (FAST) (Enderby et al, 1987), and Frontal Assessment Battery (FAB) (Dubois et al, 2000). (Robertson et al, 1996) and the Sustained Attention to Response Task (Robertson et al, 1997, Manly et al, 2003, Dockree et al, 2006. Participants undertook three tasks of sustained attention: the Fixed SART, Random SART and the DART.…”