Disentangling neglect and hemianopia

doi:10.1016/0028-3932(91)90065-G

Neuropsychologia

Volume 29, Issue 10, 1991, Pages 1019-1027

https://doi.org/10.1016/0028-3932(91)90065-G Get rights and content

Abstract

In this paper we report findings which question the diagnosis of a hemianopia in B.Q., a 66-year-old lady who shows unilateral spatial neglect following a lesion to the right parietal lobe. The presence of a hemianopia has been indicated following two independent assessment of B.Q.'s visual fields. We examined B.Q.'s performance on a visuo-spatial task in which single or double stimuli were displayed left and right of a central fixation point. B.Q. failed to report left stimuli when the fixation point was continuously displayed (OVERLAP CONDITION). This performance is consistent with the suggestion of a left hemianopia as indicated by perimetric field testing. In a further condition the fixation point was extinguished prior to stimuli onset (GAP CONDITION). B.Q. consistently responded to left stimuli in the gap condition and also showed improved performance to right stimuli. Eye movements were recorded on a separate testing session, in which B.Q. showed a normal saccadic response to left targets in the gap condition, but not during the overlap condition. These results suggest that B.Q.'a failure to report left stimuli during field plotting is due to her neglecting left stimuli and not because she has a visual field defect. By using a testing procedure which reduces the severity of neglect B.Q. is able to respond to left stimuli. Reducing the severity of B.Q.'s neglect also abolishes the apparent hemianopia. Standard field plotting techniques which use a consistently displayed fixation point may not be appropriate for the testing of neglect patients' visual fields.

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Cited by (92)

Visual and motor neglect: Clinical and neurocognitive aspects
2021, Revue Neurologique
Citation Excerpt :
Presumably, in these cases the mere presence of the fixation point induces a stimulus competition with left-sided targets, which are therefore neglected. In one of these patients, removal of the fixation point just before target presentation was able to restore perception of left-sided targets [53]. The possibility of neglect-related pseudohemianopia should be kept in mind, especially with the now commonly used automated perimetry, where a trained perimetrist has less opportunity to interact with the patients and to observe their performance.
Attention allows us to prioritize the processing of external information according to our goals, but also to cope with sudden, unforeseen events. Attention processes rely on the coordinated activity of large-scale brain networks. At the cortical level, these systems are mainly organized in fronto-parietal networks, with functional and anatomical asymmetries in favor of the right hemisphere. Dysfunction of these right-lateralized networks often produce severe deficit of spatial attention, such as visual neglect. Other brain-damaged patients avoid moving the limbs contralateral to their brain lesion, even in the absence of sensorimotor deficits (motor neglect). This paper first summarizes past and current evidence on brain networks of attention; then, it presents clinical and experimental findings on visual and motor neglect, and on the possible mechanisms of clinical recovery.
Keeping an eye on visual search patterns in visuospatial neglect: A systematic review
2020, Neuropsychologia
Citation Excerpt :
Because of this, there is a possibility that some patients with neglect were incorrectly classified. Further to this, visual field defects, such as homonymous hemianopia, are frequently observed with neglect (Kooistra and Heilman, 1989; Müller-Oehring et al., 2003; Walker et al., 1991). While perimetry or confrontation tests can easily detect patients with hemianopia only, assessing hemianopia in patients with neglect remains a challenge since both patients with hemianopia and patients with neglect will fail to report contralesional stimuli.
Patients with visuospatial neglect exhibit a failure to detect, respond, or orient towards information located in the side of space opposite to their brain lesion. To extend our understanding of the underlying cognitive processes involved in neglect, some studies have used eye movement measurements to complement behavioural data. We provide a qualitative synthesis of studies that have used eye-tracking in patients with neglect, with a focus on highlighting the utility of examining eye movements and reporting what eye-tracking has revealed about visual search patterns in these patients. This systematic review includes twenty studies that met the eligibility criteria. We extracted information pertaining to patient characteristics (e.g., age, type of stroke, time since stroke), neglect test(s) used, type of stimuli (e.g., static, dynamic), eye-tracker specifications (e.g., temporal and spatial resolution), and eye movement measurements (e.g., saccade amplitude, fixation duration). Five key themes were identified. First, eye-tracking is a useful tool to complement pen-and-paper neglect tests. Second, the lateral asymmetrical bias in eye movement patterns observed during active exploration also occurred while at rest. Third, the lateral asymmetrical bias was evident not only in the horizontal plane but also in the vertical plane. Fourth, eye movement patterns were modulated by stimulus- and task-related factors (e.g., visual salience, local perceptual features, image content, stimulus duration, presence of distractors). Fifth, measuring eye movements in patients with neglect is useful for determining and understanding other cognitive impairments, such as spatial working memory. To develop a fuller, and a more accurate, picture of neglect, future research would benefit from eye movement measurements.
Ipsilesional deficit of selective attention in left homonymous hemianopia and left unilateral spatial neglect
2019, Neuropsychologia
Patients with homonymous hemianopia may present a subtle ipsilesional deficit, recently referred to as ‘sightblindness’ in addition to the contralesional visual field defect. We recently demonstrated that this deficit could be worse in right brain-damaged patients with left hemianopia than in left brain-damaged patients with right hemianopia, confirming right hemisphere dominance for visuo-spatial and attentional capacities. In the present study we investigate whether this ipsilesional deficit could be attentional in nature and to what extent it is comparable in right brain-damaged (RBD) patients with left hemianopia and in RBD patients with left neglect. The study was also conducted in RBD patients with neither left hemianopia nor left neglect signs in order to test if a right hemisphere lesion per se could be responsible for subtle ipsilesional attentional deficit. To reach this aim, we tested selective attentional capacities in both visual fields of 10 right brain-damaged patients with left neglect (LN), 8 right brain-damaged patients with left homonymous hemianopia (LHH), 8 right brain-damaged patients with no signs of left neglect or left hemianopia (RBD controls), and 17 healthy age-matched participants (Normal controls).
A lateralized letter-detection task was used to test if right-brain damaged patients with LN or LH may present a deficit of selective attention in their right, ipsilesional visual field, in comparison to Normal and RBD controls. Participants were asked to detect a target letter in either a single large stimulus (low attentional load) or a small stimulus surrounded by flankers (high attentional load). Stimuli were displayed either in the left or in the right visual field. Accuracy and reaction times were recorded.
Results on accuracy showed that both LN and LH patients exhibited lower correct responses than Normal controls in their ipsilesional right visual field, suggesting an attentional deficit in their ipsilesional, supposed healthy visual field. More specifically, LH patients exhibited a specific deficit for processing single large stimuli, but not for processing flanked stimuli, relative to normal controls. LN patients exhibited lower correct responses for processing all types of stimulus than normal controls, but also than right brain damaged controls, in both visual fields suggesting a non-lateralized deficit not only due to the right hemisphere lesion. Furthermore, this deficit is more pronounced for flanked small stimuli, requiring higher attentional load.
The present results bring further evidence that patients with left homonymous hemianopia or left unilateral neglect both present a weaker but significant ipsilesional deficit in addition to their well-known massive contralesional deficit. The presence of a specific attentional deficit in the right ipsilesional visual field of left hemianopic and left neglect patients is discussed regarding the hypothesis of hemispheric specialization for selective spatial attention and may have clinical implications for both conditions.
Attention in action: Evidence from on-line corrections in left visual neglect
2012, Neuropsychologia
It is widely accepted that the posterior parietal cortex is critical for the on-line control of action and optic ataxia patients are unable to correct their movements in-flight to changes in target position. The current study investigated on-line correction in patients with left visual neglect, right brain damaged patients without neglect and healthy controls. Participants were asked to reach towards a central target that could jump unexpectedly, at movement onset, to the right or left sides of space. In response to the jump, participants were asked either to follow the target or to stop their movement. Neglect patients were able to correct their ongoing movements smoothly and accurately towards right and left target jumps. They did so even when told to stop their movement, indicating that these corrections occurred automatically (i.e., without instruction). However, the timing of corrections to the left was delayed in neglect patients and this produced a drastic increase in movement time. To our surprise, we also found that neglect patients were impaired at stopping their ongoing reaches, when compared to the control groups, in response to either left or right jump trials. We suggest that the ‘automatic pilot’ system for the hand is spared in neglect, but its processing speed is unilaterally slowed due to a deficit in orienting of attention to the contralesional side. We relate these findings to the breakdown of a system that combines information for attention, perception and action. Damage to this system may not only slow corrective movements to the contralesional side, but also produce non-lateralized deficits in interrupting an ongoing reach.
The imbalance of oculomotor capture in unilateral visual neglect
2010, Consciousness and Cognition
Visual neglect has been associated with an imbalance in the level of activity in the saccadic system: activity in the contralesional field is suppressed, which makes target selection unlikely. We recorded eye movements of a patient with hemispatial neglect and a group of healthy participants during an oculomotor distractor paradigm. Results showed that the interfering effects of a distractor were very strong when presented in her ipsilesional visual field. However, when the distractor was presented in her contralesional field, there were no interfering effects when the target was presented in her ipsilesional field. These findings could not be explained by the presence of a visual field defect as revealed by the results of two hemianopic patients. Our results are in line with an imbalance in the level of activity in the saccadic system in visual neglect because visual elements presented in the contralesional field did not compete for saccadic selection.
Bilateral impairment of concurrent saccade programming in hemispatial neglect
2010, Neuropsychologia
When healthy observers make a saccade that is erroneously directed toward a distracter stimulus, they often produce a corrective saccade within 100 ms after the end of the primary saccade. Such short inter-saccadic intervals indicate that programming of the secondary saccade has been initiated prior to the execution of the primary saccade and hence that the two saccades have been programmed concurrently. Here we show that concurrent saccade programming is bilaterally impaired in left spatial neglect, a strongly lateralized disorder of visual attention resulting from extensive right cerebral damage. Neglect patients were asked to make saccades to targets presented left or right of fixation while disregarding a distracter presented in the opposite hemifield. We examined those experimental trials on which participants first made a saccade to the distracter, followed by a secondary (corrective) saccade to the target. Compared to healthy and right-hemisphere damaged control participants the proportion of secondary saccades directing gaze to the target instead of bringing it even closer to the distracter was bilaterally reduced in neglect patients. In addition, the characteristic reduction of secondary saccade latency observed in both control groups was absent in neglect patients, whether the secondary saccade was directed to the left or right hemifield. This pattern is consistent with a severe, bilateral impairment of concurrent saccade programming in left spatial neglect.

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View full text

Disentangling neglect and hemianopia

Abstract

Neuropsychologia

Brain Res.

Neuropsychologia

Neuropsychologia

Neuropsychologia

Human saccadic eye movements in the absence of the geniculostriate projection

Brain

Neglect and related disorders

Hemispace and hemispatial neglect

Posterior parietal lobe of the primate brain

Physiological Rev.