Tonic and phasic alertness training: a novel behavioral therapy to improve spatial and non-spatial attention in patients with hemispatial neglect

Joseph M Degutis

doi:10.3389/fnhum.2010.00060

Abstract

Hemispatial neglect is a debilitating disorder marked by a constellation of spatial and non-spatial attention deficits. Patients’ alertness deficits have shown to interact with lateralized attention processes and correspondingly, improving tonic/general alertness as well as phasic/moment-to-moment alertness has shown to ameliorate spatial bias. However, improvements are often short-lived and inconsistent across tasks and patients. In an attempt to more effectively activate alertness mechanisms by exercising both tonic and phasic alertness, we employed a novel version of a continuous performance task (tonic and phasic alertness training, TAPAT). Using a between-subjects longitudinal design and employing sensitive outcome measures of spatial and non-spatial attention, we compared the effects of 9 days of TAPAT (36 min/day) in a group of patients with chronic neglect (N = 12) with a control group of chronic neglect patients (N = 12) who simply waited during the same training period. Compared to the control group, the group trained on TAPAT significantly improved on both spatial and non-spatial measures of attention with many patients failing to exhibit a lateralized attention bias at the end of training. TAPAT was effective for patients with a range of behavioral profiles and lesions, suggesting that its effectiveness may rely on distributed or lower-level attention mechanisms that are largely intact in patients with neglect. In a follow-up experiment, to determine if TAPAT is more effective in improving spatial attention than an active treatment that directly trains spatial attention, we trained three chronic neglect patients on both TAPAT and search training. In all three patients, TAPAT training was more effective in improving spatial attention than search training suggesting that, in chronic neglect, training alertness is a more effective treatment approach than directly training spatial attention.

Highlights

The neglect syndrome is a common consequence of lateralized brain injury in which patients fail to respond to stimuli on the side of space opposite their lesion (Buxbaum et al, 2004; Bartolomeo, 2007; Adair and Barrett, 2008)
Experiment 2 Given these improvements in spatial attention following only 9-days of TAPAT training, we examined whether these effects are comparable to directly training spatial attention
Summary We demonstrate that 9 days of training on a continuous performance task that promotes tonic and phasic alertness significantly improves spatial and non-spatial attention in neglect

Summary

Introduction

The neglect syndrome is a common consequence of lateralized brain injury in which patients fail to respond to stimuli on the side of space opposite their lesion (Buxbaum et al, 2004; Bartolomeo, 2007; Adair and Barrett, 2008). Researchers have examined neglect patients’ non-spatial impairments which may include deficits in sustaining attention (Hjaltason et al, 1996; Robertson et al, 1997b) and in the moment-to-moment engagement and disengagement of attention (Husain et al, 1997). These non-spatial impairments have been shown to modulate patients’ spatial deficits and paradoxically, may be more fundamental to the neglect syndrome than patients’ spatial symptoms (Lazar et al, 2002; Husain and Rorden, 2003). Compared to patients with similar stroke pathology and other forms of cognitive impairment, patients with neglect score significantly lower on established measures of

Methods

Results

Discussion

Conclusion