The influence of traumatic brain injury on the allocation of vertical spatial attention

ABSTRACT

Objective: Research on impairments of spatial attention has primarily investigated hemispatial neglect in brain-lesioned patients, revealing decrements in the allocation of attention to right versus left egocentric or allocentric hemispace. Whereas head trauma might injure those parts of the brain that allocate vertical attention, little is known about the influence of trauma on the allocation of visuospatial attention in vertical space. Thus, the goal of this study was to learn if chronic moderate-to-severe traumatic brain injury (m/sTBI) alters the allocation of vertical visuospatial attention as assessed by the Attention Network Task (ANT). The ANT assesses the influence of Posner-type spatial cues and distractors using an Eriksen flanker task.

Methods: 12 chronic m/sTBI patients and 12 demographically-matched neurologically-healthy controls (HCs) completed a version of the ANT wherein trials were coded for cue and target locations above and below central visual fixation. Trial-wise reaction times (RT) and accuracy were subjected to mixed-model ANOVAs and planned contrasts.

Results: These data were subject to secondary analyses, which revealed that across groups, median RTs were significantly faster when targets occurred above than below the central visual fixation (p < .01); however, only HCs’ error rates differed as a function of target altitude. Unlike controls, m/sTBI survivors did not exhibit the anticipated upward error-rate attentional bias.

Conclusions: As alteration of spatial attention can be a major cause of disability, present findings suggest that m/sTBI survivors exhibit this loss of normal upward attentional bias. Future studies are need to learn if these patients might benefit from treatment.

KEYWORDS:

• Traumatic brain injury
• attention network task
• altitudinal attention
• vertical attention bias

Disclosure statement

The information in this manuscript and the manuscript itself is new and original and has never been published whether electronically or in print.

Notes

1. This study represents a re-analysis of data from the same participants reported previously in a Ph.D. dissertation by Sozda (2012).

2. ERP findings will be reported in a separate paper.

3. Time since injury was not significantly correlated between RT or error rates. Given this, and our small sample size, we chose not to use time since injury as a covariate in the following analyses.

4. Though debate exists regarding whether accuracy and RT should be combined, we also conducted a 2-group X 2-altitude analysis of the inverse efficiency score (IES; Bruyer & Brysbaert, 2011). This revealed a marginally-significant (F[1,11] = 4.15, p = .054) interaction, with HCs showing a significant altitudinal effect and TBIs not, further supporting our assertion of differential vertical-attention bias in healthy (t[11] = 4.58, p < .001) vs. TBI participants (t[11] = 1.70, p > .10).

Additional information

Funding

The authors acknowledge the support, in part, by a 2011 American Psychological Association Dissertation Research Award to Christopher N. Sozda.