ORCID Profile
0000-0001-6686-7262
Current Organisation
KU Leuven
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Cambridge University Press (CUP)
Date: 22-03-2021
DOI: 10.1017/S1355617721000242
Abstract: Mental fatigue, ‘brain fog’, and difficulties maintaining engagement are commonly reported issues in a range of neurological and psychiatric conditions. Traditional sustained attention tasks commonly measure this capacity as the ability to detect target stimuli based on sensory features in the auditory or visual domains. However, with this approach, discrete target stimuli may exogenously capture attention to aid detection, thereby masking deficits in the ability to endogenously sustain attention over time. To address this, we developed the Continuous Temporal Expectancy Task (CTET) where in iduals continuously monitor a stream of patterned stimuli alternating at a fixed temporal interval (690 ms) and detect an infrequently occurring target stimulus defined by a prolonged temporal duration (1020 ms or longer). As such, sensory properties of target and non-target stimuli are perceptually identical and differ only in temporal duration. Using the CTET, we assessed stroke survivors with unilateral right hemisphere damage ( N = 14), a cohort in which sustained attention deficits have been extensively reported. Stroke survivors had overall lower target detection accuracy compared with neurologically healthy age-matched older controls ( N = 18). Critically, stroke survivors performance was characterised by significantly steeper within-block performance decrements, which occurred within short temporal windows (˜3 ½ min), and were restored by the break periods between blocks. These findings suggest that continuous temporal monitoring taxes sustained attention processes to capture clinical deficits in this capacity over time, and outline a precise measure of the endogenous processes hypothesised to underpin sustained attention deficits following right hemisphere stroke.
Publisher: Elsevier BV
Date: 02-2022
Publisher: Society for Neuroscience
Date: 26-03-2008
DOI: 10.1523/JNEUROSCI.5247-07.2008
Abstract: The parietal regions implicated in spatially selective attention differ between patient lesion studies and functional imaging of the intact brain. We aimed to resolve this discordance. In a voxel-based lesion-symptom mapping study in 20 ischemic stroke patients, we applied the same cognitive subtraction approach as in 23 healthy volunteers who underwent functional magnetic resonance imaging (fMRI) using identical tasks and stimuli. An instructive central cue directed attention to one visual quadrant. After a brief delay, a grating appeared in that quadrant together with an irrelevant grating in an uncued quadrant. Subjects had to discriminate the orientation of the grating in the cued quadrant. Patients with a right inferior parietal lesion were significantly more impaired during contralesional versus ipsilesional orienting when stimuli were bilateral and symmetrical than when stimuli occupied diagonally opposite quadrants or two quadrants within the same hemifield. In one area, the lesion-volume map overlapped with the activity map obtained in healthy volunteers: the lower bank of the middle third of the right intraparietal sulcus (IPS). In an additional 37 healthy fMRI subjects, we disentangled the effects of symmetry, bilaterality, and spatial configuration between stimuli on activity in the volume of overlap. Only the axis of configuration between stimuli had a significant effect, with highest activity when the configuration axis was horizontal. This constitutes converging evidence from patients and cognitively intact subjects that the lower bank of the middle third of the right IPS critically contributes to attentive selection between competing stimuli in a spatially anisotropic manner.
Publisher: Oxford University Press (OUP)
Date: 14-05-2011
DOI: 10.1093/BRAIN/AWR085
Abstract: Based on lesion mapping studies, the inferior parietal lobule and temporoparietal junction are considered the critical parietal regions for spatial-attentional deficits. Lesion evidence for a key role of the intraparietal sulcus, a region featuring prominently in non-human primate studies and human functional imaging studies of the intact brain, is still lacking, probably due to the exceptional nature of isolated intraparietal sulcus lesions. We combined behavioural testing and functional imaging in two patients with a focal intraparietal sulcus lesion sparing the inferior parietal lobule and temporoparietal junction to examine the critical contribution of the intraparietal sulcus to spatial attention. Case H.H. had a focal ischaemic lesion (1.8 cm3) that was confined to the posterior segment of the left intraparietal sulcus, whereas Case N.V. had a partially reversible lesion of the middle segment of the right intraparietal sulcus extending into the superior parietal lobule (13.8 cm3). The performance of these cases was contrasted with five cases with a classical inferior parietal lesion, as well as with a group of 31 age-matched controls. In the behavioural study, the patients performed an orientation discrimination task on a peripheral target (eccentricity 7.6°) that was preceded by a central spatial cue. We manipulated both the cue validity (17% trials with an invalid spatial cue) and the presence of a competing distracter in the visual field contralateral to the target (17% double stimulation trials). The ability of the patients with an intraparietal sulcus lesion to reorient their spatial focus of attention and to select between competing stimuli was impaired for contralesional targets compared with controls, similarly to what we saw in the inferior parietal group. Furthermore, we could observe that the deficit in Case N.V. resolved with regression of the lesion. To further evaluate the correspondence between spatial-attentional deficits and the intraparietal sulcus lesions, we ascertained the functional integrity of the inferior parietal lobule and temporoparietal junction in Case H.H. using event-related functional magnetic resonance imaging with the same task as in the behavioural study. The intraparietal sulcus lesion of this patient did not affect the task-related activation of the inferior parietal lobule or temporoparietal junction. Additionally, a resting-state functional magnetic resonance imaging study in Case H.H. and 62 controls revealed that the lesion in Case H.H. did not affect the topology of the ventral attention network nor the strength of its main inter- and intrahemispheric connections. Our findings demonstrate that the human superior parietal cortex critically contributes to spatially selective attention.
Publisher: SAGE Publications
Date: 16-07-2021
DOI: 10.1177/15459683211032977
Abstract: Background/Objective. This study aims to investigate how complex visuospatial neglect behavioural phenotypes predict long-term outcomes, both in terms of neglect recovery and broader functional outcomes after 6 months post-stroke. Methods. This study presents a secondary cohort study of acute and 6-month follow-up data from 400 stroke survivors who completed the Oxford Cognitive Screen’s Cancellation Task. At follow-up, patients also completed the Stroke Impact Scale questionnaire. These data were analysed to identify whether any specific combination of neglect symptoms is more likely to result in long-lasting neglect or higher levels of functional impairment, therefore warranting more targeted rehabilitation. Results. Overall, 98/142 (69%) neglect cases recovered by follow-up, and there was no significant difference in the persistence of egocentric/allocentric (X 2 [1] = .66 and P = .418) or left/right neglect (X 2 [2] = .781 and P = .677). Egocentric neglect was found to follow a proportional recovery pattern with all patients demonstrating a similar level of improvement over time. Conversely, allocentric neglect followed a non-proportional recovery pattern with chronic neglect patients exhibiting a slower rate of improvement than those who recovered. A multiple regression analysis revealed that the initial severity of acute allocentric, but not egocentric, neglect impairment acted as a significant predictor of poor long-term functional outcomes (F [9,300] = 4.742, P .001 and adjusted R 2 = .098). Conclusions. Our findings call for systematic neuropsychological assessment of both egocentric and allocentric neglect following stroke, as the occurrence and severity of these conditions may help predict recovery outcomes over and above stroke severity alone.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2011.12.016
Abstract: According to a longstanding view, inferior as opposed to superior parietal cortex critically contributes to the spatial attentional deficits encountered following unilateral parietal ischemic lesions. We review the evidence on which this view is based and contrast it with more recent structural lesion evidence concerning the critical role of the intraparietal sulcus in spatial attention deficits. In a classical spatial cueing paradigm, focal lesions of the posterior and of the middle segment of the intraparietal sulcus give rise to a pathological invalidity effect that is indistinguishable from that seen after classical inferior parietal lesions. When a competing distracter is added to a target stimulus, the deleterious consequences of focal IPS lesions are again very similar to those classically observed following inferior parietal lesions. The deficit could not be accounted for by functional effects at a distance affecting inferior parietal cortex. These single-case lesion data establish the critical role of the posterior and the middle IPS segment in spatially selective attention and are in line with a vast amount of functional imaging evidence in the intact brain pointing to the prominent role of the intraparietal sulcus in spatial attention, along with inferior parietal cortex under specific circumstances. Functional imaging has also provided hints about the differences in functional contribution between inferior and superior parietal cortex. These hypotheses await further confirmation based on lesion evidence.
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2009.06.012
Abstract: The Sustained Attention to Response task is a classical neuropsychological test that has been used by many centres to characterize the attentional deficits in traumatic brain injury, ADHD, autism and other disorders. During the SART a random series of digits 1-9 is presented repeatedly and subjects have to respond to each digit (go trial) except the digit '3' (no-go trial). Using voxel-based lesion symptom mapping (VLSM) in a consecutive series of 44 ischemic unifocal non-lacunar hemispheric stroke patients we determined the neuroanatomy of 4 SART parameters: commission and omission error rate, reaction time variability and post-error slowing. Lesions of the right inferior frontal gyrus significantly increased commission error rate. Lesions of the middle third of the right inferior frontal sulcus (IFS) reduced post-error slowing, a measure of how well subjects can utilize errors to adjust cognitive resource allocation. Omissions and reaction time variability had less localising value in our s le. To conclude, commission errors and post-error slowing in the SART mainly probe right inferior frontal integrity.
Publisher: Elsevier BV
Date: 11-2021
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Celine Gillebert.