A Neurophysiological Assessment of Selective Attention Before and After Cognitive Remediation in Patients with Severe Closed Head Injury

Abstract

Auditory event-related potentials (ERPs) were recorded in a binaural listening task to assess neurophysiological correlates of selective attention before and after an intensive computer-dispensed cognitive remediation program (6 months) administered to 21 patients with severe closed head injuries (CHI). With a double-blind procedure, they were compared to a control group of 22 patients with CHI, matched for age (X = 28), sex, and education (X = 11 years), who did not receive cognitive remediation. Analyses of covariance were applied to control for coma duration (X = 57 days), posttrauma interval (X = 6.4 years), and severity of neuropsychological deficits. Error rates were not sensitive to treatment and speed of stimulation effects, but neurophysiological measures were. Distraction of both stimulus and response sets was manifested in all subjects (Ss) at pretest by relatively large P3a amplitudes to task-irrelevant tones at inattention and by an absence of attention modulation of N1 to task-relevant tones. Coma and severity of neuropsychological deficits correlated significantly with P3b amplitude, which indexes target discrimination and template-matching in short-term memory. All Ss improved capacity to follow instructions and efficiency of stimulus processing, as shown respectively by reduced N1 latencies at slow speed and increased P1-N1-P2 amplitudes at fast speed of stimulation at retest. Nd amplitudes at 200-ms latency also discriminated the treatment effect between the two groups, with the experimental group showing larger Nd-200 amplitude for the left ear after cognitive remediation. The pattern of modulations between ERP and Nd measures and between speed conditions at retest indicates that these modulations are not due to improved attentional selectivity but possibly to increased motivation or attentional effort and improved tonal stimulus processing after cognitive remediation. © 1989, Sage Publications. All rights reserved.