The spatial distribution of visual attention in hemineglect and extinction patients

Smania, Nicola; Martini, M.; Gambina, Giuseppe; Tomelleri, Giampaolo; Palamara, Anna Teresa; Natale, Elena; Marzi, Carlo Alberto

doi:10.1093/brain/121.9.1759

Cited by 158 publications

(103 citation statements)

References 36 publications

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“…These results suggest that the temporal dynamics of attentional processing may be enhanced compared to normal performance for ipsilesional stimuli, whereas it is significantly prolonged for stimuli appearing to the left. This suggestion of an atypically good performance on the right is consistent with previous investigations, which demonstrated 'hyperattention' toward stimuli on the right at the expense of stimuli to the left (De Renzi, Gentilini, Faglioni, & Barbieri, 1989;Di Pellegrino, Basso & Frassinetti, 1997;Gainotti, D'Erme, & Bartolomeo, 1991;Ladavas, Petronio, & Umiltà, 1990;Smania, Martini, Gambina, Tomelleri, Palamara, Natale, & Marzi, 1998).…”

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confidence: 91%

Time and neglect: Abnormal temporal dynamics in unilateral spatial neglect

Becchio

Bertone²

2006

Neuropsychologia

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Temporality enters our immediate experience as passage and becoming: the role time plays in the construction of a world of enduring entities tends to go unnoticed. This paper examines the relation between time and ontology in the context of unilateral neglect, a neuropsychological syndrome in which patients fail to perceive or respond to stimuli in the contralateral hemifield, behaving as if that half of space does not exist. Traditional models characterize neglect exclusively in spatial terms. Based on recent investigations suggesting abnormal temporal dynamics, here we highlight the impact of time factors on the presentation of the disorder. Neglect patients do not simply miss the presence of stimuli on the left: they also ignore the past as well as the future of neglected stimuli. We claim that, if this occurs, it is because time, and not only space, is impaired. Torino, 05/05/2006Dear Editor, We modified the manuscript in an attempt to achieve the top standard required for publication in Neuropsychologia. Reviewer 1The reviewers have answered most of my concerns to my satisfaction. However, there is still a onesentence paragraph on page 3, and the formatting appears to need revision on page 17.We would like to thank the reviewer for her/his careful review of our manuscript. We have now integrated the one-sentence paragraph on page 3. Formatting on page 17 has been revised.On page 10, there is a typing mistake: the word "that" should be replaces by "than" in the second to last paragraph.We apologize for the typing mistake. As requested we have now replaced "that". These bewildering behavioural manifestations clearly exhibit a spatial gradient: the patient behaves as if half of the space does not exist, failing to report, react or search for stimuli located in the space contralateral to the lesion. The spatial nature of neglect is manifest and, understandably, interest in research has focused on spatial mechanisms (Halligan, Fink, Marshall, & Vallar, 2003).Here, we intend to focus on a dimension that, although less evident, is nevertheless no less important in the presentation of the disorder: time.Compared with spatial cognition, little is known about the neuropsychology of time. In this paper we first summarize the results of recent investigations suggesting abnormal temporal dynamics in neglect. Next, we consider some of the empirical and theoretical issues raised by this evidence: do the temporal abnormalities observed in neglect reflect the impairment of a unique mechanism or do they arise in relation to different timing systems? Do temporal deficits in neglect relate to spatial distortions? A final concern relates to the contribution of temporal deficits to neglect per se, i.e. to the loss of awareness for contralateral stimuli and events characteristically observed in neglect patients. It is impossible for us -wrote Kant in the Critique of Pure Reason (1787) -to represent things outside space and time and this is because things appear to us as spatiotemporally connoted. Whereas previous work f...

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confidence: 91%

Time and neglect: Abnormal temporal dynamics in unilateral spatial neglect

Becchio

Bertone²

2006

Neuropsychologia

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“…In a study employing simple RTs to lateralized visual stimuli, Smania et al [101] produced evidence for preserved endogenous orienting in neglect. In this study, neglect patients had faster RTs for both hemi®elds when the side of stimulus presentation was predictable as compared to the case when stimuli were presented randomly.…”

Section: Impaired Orienting Of Attention In Neglect: Exogenous Vs Enmentioning

confidence: 99%

Orienting of attention in left unilateral neglect

Bartolomeo

Chokron

2002

Neuroscience & Biobehavioral Reviews

286

137

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After right posterior brain damage, patients may ignore events occurring on their left, a condition known as unilateral neglect. Although de®cits at different levels of impairment may be at work in different patients, the frequency and severity of attentional problems in neglect patients have been repeatedly underlined. Recent advances in the knowledge of the mechanisms of spatial attention in normals may help characterizing these de®cits. The present review focuses on studies exploring several aspect of attentional processing in unilateral neglect, with particular reference to the dichotomy between`exogenous', or stimulus-related, and`endogenous', or strategy-driven, orienting of attention. A large amount of neuropsychological evidence suggests that a basic mechanism leading to left neglect behavior is an impaired exogenous orienting toward left-sided targets. In contrast, endogenous processes seem to be relatively preserved, if slowed, in left unilateral neglect. Other component de®cits, such as a general slowing of the operations of spatial attention, might contribute to neglect behavior. These results are presented and discussed, and their implications for hemispheric specialization in attentional orienting and for the mechanisms of visual consciousness are explored. q

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“…Evidence for this lateralized bias is the failure of neglect patients to be aware of a contralesional stimulus when an ipsilesional stimulus competes for attentional resources (Driver and Vuilleumier, 2001;Geeraerts et al, 2005) and their facilitated processing of right compared to left items (Smania et al, 1998). Since the planning of eye movements is closely linked to spatial attention (Shepherd et al, 1986), saccadic eye movements of neglect patients should be particularly affected by their spatial orienting bias.…”

Section: Introductionmentioning

confidence: 99%

A non-spatial bias favouring fixated stimuli revealed in patients with spatial neglect

Ptak

Schnider

Golay

et al. 2007

Brain

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The cardinal feature of spatial neglect is severely impaired exploration of the contralesional space, a failure resulting in unawareness of many contralesional stimuli. This deficit is exacerbated by a reflexive attentional bias toward ipsilesional items. Here we show that, in addition to these spatially lateralized failures, neglect patients also exhibit a severe bias favouring stimuli presented at fixation. We tested neglect patients and matched healthy and right-hemisphere damaged patients without neglect in a task requiring saccade execution to targets in the left or right hemifield. Targets were presented alone or simultaneously with a distracter that appeared in the same hemifield, in the opposite hemifield, or at fixation. We found two fundamental biases in saccade initiation of neglect patients: irrelevant distracters presented in the preserved hemifield tended to capture gaze reflexively, resulting in a large number of saccades erroneously directed toward the distracter. Additionally, distracters presented at fixation severely disrupted saccade initiation irrespective of saccade direction, leading to disproportionately increased latencies of left and right saccades. This latency increase was specific to oculomotor responses of neglect patients and was not observed when a manual response was required. These results show that, in addition to their failure to inhibit reflexive glances toward ipsilesional items neglect patients exhibit a strong oculomotor bias favouring fixated stimuli. We conclude that impaired initiation of saccades in any direction contributes to the deficits of spatial exploration that characterize spatial neglect.

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The spatial distribution of visual attention in hemineglect and extinction patients

Cited by 158 publications

References 36 publications

Time and neglect: Abnormal temporal dynamics in unilateral spatial neglect

Time and neglect: Abnormal temporal dynamics in unilateral spatial neglect

Orienting of attention in left unilateral neglect

A non-spatial bias favouring fixated stimuli revealed in patients with spatial neglect

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