Categorisation of ‘perceptual’ and ‘premotor’ neglect patients across different tasks: is there strong evidence for a dichotomy?

Abstract

The aim of the presented studies was to investigate whether classifications of neglect patients into perceptual (i.e. identifying a patient as suffering from mainly attentional/space representation deficits) and premotor (judging the main impairment to be related towards actions into contralesional space) categories is consistent across different line bisection assessment techniques that have, in the past, been designed to tease these potentially overlapping aspects of hemispatial neglect apart.Twelve patients with hemispatial neglect and three control groups were tested with the Overhead Task, adapted from Nico [Neuropsychologia 34 (1996) 471] in which patients were asked to bisect lines that were mirror reversed, the Pulley Device Technique, adapted from Bisiach et al. [Neurology 40 (1990) 1278] in which they had to perform a movement opposite to the direction of the transaction mark that bisected the line and the Landmark Test, adapted from Milner et al. [Neuropsychologia 30 (1992) 515] in which they had to manually point to the half of a centrally pre-bisected line that, to them, appeared shorter. The specific question was whether these three tasks would categorise the same set of patients in the same way?Most patients could be classified into either the premotor or perceptual category in each task, but no consistent categorisation emerged across the three techniques. Just 1 out of the 12 patients, was consistently classified across all three tasks. It seemed that despite the fact that all tasks essentially required a line bisection response, the perceptual and motor differences between the tasks were still great enough to result in inconsistent classifications. The Landmark Task classified the majority of patients into the perceptual neglect category, while the Overhead and Pulley Device Techniques tended to identify more patients as suffering from a premotor deficit (albeit not the same set of patients).

Right hemisphere control of visuospatial attention in near space

“…This pattern suggests important functional differences between bisection and landmark tasks, consistent with dissociations between these tasks reported both in neuropsychological patients (e.g., Harvey et al, 2002;Ishiai et al 1998) and healthy adults (e.g., Varnava, Dervinis, & Chambers, 2013). The meta-analysis of Jewell and McCourt (2000) found much larger effect sizes for pseudoneglect measured using landmark than manual (overt) bisection.…”

Cognitive Rehabilitation Interventions for Neglect and Related Disorders: Moving from Bench to Bedside in Stroke Patients

“…Harvey, Kramer-McCaffery, Dow, Murphy, and Gilchrist (2002) reported data from subjects with neglect tested on three tasks: the overhead task (Nico, 1996), the pulley test (Bisiach, Geminiani, et al, 1990), and the landmark test (Milner, Brechmann, & Pagliarini, 1992) known to distinguish between sensory-attentional and motor-intentional neglect; they found that the same patients were not consistently classified with these measures. Furthermore, there is only preliminary evidence, in one case study, that subtype-defined patterns of performance are stable across time (Barrett, Crucian, Schwartz, & Heilman, 1999).…”

Near and far space: Understanding the neural mechanisms of spatial attention

“…If a task requires a directional motor response (like line bisection or item cancellation tasks do) then perceptual and motor effects may be confounded (Bisiach et al, 1990;Bisiach, 1993); an error could reflect an impairment in orienting visual attention towards contralesional space or in making movements towards such locations. Much research has been conducted to try and dissociate the contribution of perceptual and motor effects (Bisiach et al, 1990;Harvey et al, 2002a), and various tasks have been designed to try and overcome this confounding such as landmark and pulley device tasks (see Harvey, 2004 for a review). We feel that it is important to examine perceptual visuospatial processes using a task that does not rely on a potentially confounding motor response, and visual search is one such task.…”