Visual feedback explains why propointing is better than antipointing in spatial neglect.

Rossit et al. (2011) showed that neglect patients perform normally in a propointing task but not in an antipointing task which requires pointing towards the mirrored position of a target. It is assumed that antipointing relies on information from the perceptual pathway of our visual brain. Therefore, this finding supports the notion that neglect is a disorder that primarily affects perceptual spatial representations within the brain leaving spatial maps used for visuomotor guidance intact. Alternatively, performance of patients might be compromised in both tasks, but only obviously so in tasks in which online corrections are made more difficult. It can be argued that online-corrections via visual feedback are less effective in antipointing because a direct comparison between hand and target is not possible in this condition. Secondly, it is also known that neglect patients have a pronounced egocentric bias which is assumed to be associated with a deviation of the perceived body midline. Since the midline is used to compute the end-position in the antipointing task this could also explain why patients are worse in antipointing. We investigated the influence of visual feedback on pro- and antipointing and the effect of providing a visual reference line for the antipointing task in right-brain damaged patients with neglect (n = 20), right-brain damaged patients without neglect (n = 23) and in a group of healthy participants (n = 22). The withdrawal of visual feedback had a stronger effect on propointing compared to antipointing. This effect was stronger in neglect patients than in patients without neglect or healthy controls. The introduction of a reference line reduced errors in antipointing performance, particularly in neglect patients with a strong egocentric bias. The results support our alternative account and challenge the hypothesis that the spatial disorder in neglect affects primarily perceptual maps within the visual system.

Effects of acupuncture and computer-assisted cognitive training for post-stroke attention deficits: study protocol for a randomized controlled trial.

BACKGROUND: A majority of stroke survivors present with cognitive impairments. Attention disturbance, which leads to impaired concentration and overall reduced cognitive functions, is strongly associated with stroke. The clinical efficacy of acupuncture with Baihui (GV20) and Shenting (GV24) as well as computer-assisted cognitive training in stroke and post-stroke cognitive impairment have both been demonstrated in previous studies. To date, no systematic comparison of these exists and the potential beneficial effects of a combined application are yet to be examined. The main objective of this pilot study is to evaluate the effects of computer-assisted cognitive training compared to acupuncture on the outcomes of attention assessments. The second objective is to test the effects of a combined cognitive intervention that incorporates computer-assisted cognitive training and acupuncture (ACoTrain). METHODS/DESIGN: An international multicentre, single-blinded, randomised controlled pilot trial will be conducted. In a 1:1:1 ratio, 60 inpatients with post-stroke cognitive dysfunction will be randomly allocated into either the acupuncture group, the computer-assisted cognitive training group, or the ACoTrain group in addition to their individual rehabilitation programme. The intervention period of this pilot trial will last 4 weeks (30 minutes per day, 5 days per week, Monday to Friday). The primary outcome is the test battery for attentional performance. The secondary outcomes include the Trail Making Test, Test des Deux Barrages, National Institute of Health Stroke Scale, and Modified Barthel Index for assessment of daily life competence, and the EuroQol Questionnaire for health-related quality of life. DISCUSSION: This trial mainly focuses on evaluating the effects of computer-assisted cognitive training compared to acupuncture on the outcomes of attention assessments. The results of this pilot trial are expected to provide new insights on how Eastern and Western medicine can complement one another and improve the treatment of cognitive impairments in early stroke rehabilitation. Including patients with different cultural backgrounds allows a more generalisable interpretation of the results but also poses risks of performance bias. Using standardised and well-described assessments, validated for each region, is pivotal to allow pooling of the data. TRIAL REGISTRATION: Clinical Trails.gov ID: NCT02324959 (8 December 2014).