Objectives: There is increasing evidence of non-motor, sensory symptoms, mainly involving the spatial domain, in cervical dystonia (CD). These manifestations are likely driven by dysfunctional overactivity of the parietal cortex during the execution of a sensory task. Few studies also suggest the possibility that visuospatial attention might be specifically affected in patients with CD. Therefore, we asked whether non-motor manifestations in CD might also comprise impairment of higher level visuospatial processing. Methods: To this end, we investigated visuospatial attention in 23 CD patients and 12 matched healthy controls (for age, gender, education, and ocular dominance). The patients were identified according to the dystonia pattern type (laterocollis vs. torticollis). Overall, participants were right-handers, and the majority of them was right-eye dominant. Visuospatial attention was assessed using a line bisection task. Participants were asked to bisect horizontal lines, using their right or left hand. Results: Participants bisected more to the left of true center when using their left hand to perform the task than when using their right hand. However, overall, torticollis patients produced a significantly greater leftward deviation than controls. Conclusions: These data are consistent with preliminary findings suggesting the presence of biased spatial attention in patients with idiopathic cervical dystonia. The presence of an attentional bias in patients with torticollis seem to indicate that alterations of attentional circuits might be implicated in the pathophysiology of this type of CD. (JINS, 2018, 24, 23–32)

The attentional blink (AB) is a well-established paradigm in which identification of a target T2 is reduced shortly after presentation of an earlier target T1. An important question concerns the importance of backward masking during the AB. While task switching has been found to be a strong modulator mediating the AB without any masking of T2, the present study investigated whether spatial switching could similarly produce an AB without masking. Using a spatial AB paradigm in which items appeared at different locations; we found (a) a significant AB without backward masking of T2 but no AB when no distractors followed T2, (b) no evidence for Lag 1 sparing. These findings show that when there is a spatial switch between the targets, presenting the distractor following T2 at the same location than T2 (backward masking) is not a necessary condition for the AB to occur, but T2 has to be followed by surrounding distractors (appearing at different locations than T2). This pattern of data confirms that spatial switching is a robust modulator of the AB, but to a less extent than task switching.

A space-based dissociation has been observed in clinical hemineglect, wherein neglect can be specific to either peripersonal or extrapersonal space. This same dissociation might occur in pseudoneglect, where both space-based and visual field differences have been observed. Upper and bottom visual field differences were examined within-subjects (N = 39), by presenting the greyscales task in both peripersonal and extrapersonal space. The leftward bias was strongest in the bottom visual field; however, no space-based differences were observed. It appears that perceptual biases differ between the upper and bottom visual fields, but this is not related to space-based perceptual biases. (JINS, 2010, 16, 210–214.)

These studies provide evidence for slowed spatial orienting of attention in autism. A group of well-defined adult autistic subjects and age-matched normal controls performed a traditional spatial cueing task in which attention-related response facilitation is indexed by speed of target detection. To address the concern that motor impairment may interfere with interpretation of response time measures in those with neurologic abnormality, we also used a new adaptation of the traditional task that depended on accuracy of response (target discrimination) rather than speed of response. This design allowed separation of time to process and respond to target information from the time to move and engage (orient) attention. Results from both tasks were strikingly similar. Normal subjects oriented attention very quickly, and showed maximal performance facilitation at a cued location within 100 ms. Autistic subjects oriented attention much more slowly and showed increasing benefits of a spatial cue with increasing cue-to-target delays. These results are consistent with previous reports that patients with autism, the majority of whom have developmental abnormalities of the cerebellum, as well as those with acquired damage to the cerebellum, are slow to shift attention between and within modalities. This paper also addresses the variability in behavioral findings in autism, and suggests that many of the apparently contradictory findings may actually reflect sampling differences in patterns of brain pathology. (JINS, 1996, 2, 541–550.)

Recent investigations have distinguished between ophthalmokinetic and melokinetic factors of unilateral neglect. The aim of our study was to investigate the possible dissociation between melokinetic (premotor) and perceptual factors, avoiding any overt oculokinctic components. We asked four blindfolded left neglect patients to set a dichotic sound in central position, by moving a handle controlling the difference of intensity between the sounds delivered to the left and to the right cars. Two conflicting conditions were used. In the congruent condition, the sound moved in the same direction as the hand movement; in the noncongruent condition, it moved in the opposite direction. One patient performed as if suffering from melokinetic neglect, and another as if suffering from perceptual neglect. The behavior of the other two subjects did not lend itself to a clearcut interpretation. (JINS, 1996, 2, 419–425.)

Various factors influence the degree of leftward error (pseudoneglect) that typifies the performance of normal individuals in line bisection tasks. This experiment reveals that the eye through which stimuli are viewed also exerts a modulating influence on spatial attention, as indexed by significant alterations in the magnitude of pseudoneglect. Using a forced-choice tachistoscopic line bisection protocol, 24 participants (12 male; 12 female) bisected horizontally oriented lines (22.6° w × 0.39° h) presented to central vision in 3 conditions: left uniocular viewing (L), right uniocular viewing (R), and binocular viewing (B). Perceived line midpoint, a measure of bisection accuracy, deviated significantly leftward of veridical ( p < .05) in all viewing conditions, confirming a tonic asymmetry of visuospatial attention in normal young observers. In addition, a significant influence of viewing condition was found (p < .05) where pseudoneglect was greatest in the L condition, followed by the B and R conditions, respectively. Analysis of the slopes of the psychometric functions revealed significantly greater bisection precision in the binocular versus uniocular viewing conditions (p < .05). The results are interpreted to suggest that phasic effects on spatial attention can be produced by uniocular viewing via asymmetric retinotectal projections. The results are consistent with activation–orientation theories of attentional asymmetry. (JINS, 2001, 7, 391–395.)

Attentional modulations of event-related brain potentials (ERPs) were measured when subjects were cued to attend to a visual quadrant or to a ring-shaped region of visual space to detect infrequently presented targets within the attended region. Spatial attention directed to quadrants was reflected in modulations of sensory-evoked P1 and N1 components at lateral posterior sites and enhanced negativities (Nds) at midline electrodes that started around 150 ms poststimulus. When attention was directed to ring-shaped regions, no modulations of P1 and N1 amplitudes were found, and Nd effects observed at midline electrodes were delayed by about 50 ms. These findings indicate that behavioral effects observed both when attention is directed to contiguous regions and to general areas of visual space may be caused by different underlying processes. Intraperceptual “sensory gating” mechanisms operating in a way suggested by the notion of an attentional “zoom-lens” may be responsible for the selection of single regions, quadrants, or hemifields. When relevant regions are more complex, spatial selectivity will affect primarily postperceptual processes.