Dynamic attentional modulation of vision across space and time after right hemisphere stroke and in ageing

Abstract

IntroductionAttention modulates the availability of sensory information to conscious perception. In particular, there is evidence of pathological, spatial constriction of the effective field of vision in patients with right hemisphere damage when a central task exhausts available attentional capacity. In the current study we first examined whether this constriction might be modulated across both space and time in right hemisphere stroke patients without neglect. Then we tested healthy elderly people to determine whether non-pathological ageing also leads to spatiotemporal impairments of vision under conditions of high attention load.MethodsRight hemisphere stroke patients completed a task at fixation while attempting to discriminate letters appearing in the periphery. Attentional load of the central task was modulated by increasing task difficulty. Peripheral letters appeared simultaneously with the central task or at different times (stimulus onset asynchronies, SOAs) after it. In a second study healthy elderly volunteers were tested with a modified version of this paradigm.ResultsUnder conditions of high attention load right hemisphere stroke patients have a reduced effective visual field, over a significantly extended ‘attentional blink’, worse for items presented to their left. In the second study, older participants were unable to discriminate otherwise salient items across the visual field (left or right) when their attention capacity was loaded on the central task. This deficit extended temporally, with peripheral discrimination ability not returning to normal for up to 450 msec.ConclusionsDynamically tying up attention resources on a task at fixation can have profound effects in patient populations and in normal ageing. These results demonstrate that items can escape conscious detection across space and time, and can thereby impact significantly on visual perception in these groups.

The effects of motivational reward on the pathological attentional blink following right hemisphere stroke

“…As the purpose of this study was to explore the effects of reward on the pathological AB, the parameters of the task were adjusted so that they would reliably demonstrate an effect in the patient group, enabling us to identify any reward-related response. Even though a number of patients had apparently recovered from their neglect at the time of their participation, they still manifested an attentional blink, in keeping with previous observations that attentional deficits often persist after apparent recovery from neglect on standard clinical tasks (Russell, Malhotra, Deidda, & Husain, 2013). In comparison to the findings of Husain and colleagues the post-T1 target processing deficit of patients was of much shorter duration (starting to recover from 750 ms) and we note that the patients who participated in the current study manifested much less of a spatial bias on cancellation tasks than did those in the previous study, all of whom failed to locate any targets on the left side of space on standard clinical tests (Husain et al, 1997).…”

“…The authors proposed that, in addition to a spatial bias, neglect has a non-lateralised, temporal component which when present, may exacerbate spatial neglect (Husain & Rorden, 2003). Further work has shown that, although there is evidently a link between poor temporal selection and biases in spatial attention, the presence of neglect is not a necessary prerequisite for a pathological AB (Correani & Humphreys, 2011;Rizzo, Akutsu, & Dawson, 2001;Russell, Malhotra, Deidda, & Husain, 2012;Shapiro, et al, 2002).…”

Sensorimotor and cognitive factors associated with the age-related increase of visual field dependence: a cross-sectional study

“…Furthermore, it should be pointed out, that UFOV 3 is not only a test assessing inhibition of distracters, attention, and processing in the peripheral visual field, but is in itself also a more difficult, cognitively demanding task. Research has revealed visual processing impairments in old adults when attentional load is increased in central tasks as well (Russell et al 2013). It should be noted therefore that, with age, cognitive load affects perception in a general manner.…”

Posterior kortikal atrofi

“…Dette gjelder ikke utelukkende lange og vanskelige ord, men også korte ord, enkeltbokstaver og tall. Fenomenet kalles «innsnevret funksjonelt synsfelt» og innebaerer at man ikke klarer å holde oversikten over hele synsfeltet (7,8).…”