The Japanese journal of neuropsychology

Full Text of this Article
in Japanese PDF (556K)

ArticleTitle	A Study on the mechanism of auditory extinction -Dichotic listening test and dichotic discrimination test-
Language	J
AuthorList	Chie Yoshikawa¹⁾, Tsuneo Harashima²⁾, and Akiyoshi Katada³⁾
Affiliation	1) Department of Speech/Language and Audiology, International University of Health and Wealfare 2) Institute of Disability Sciences, University of Tsukuba 3) Kinjo University
Publication	Japanese Journal of Neuropsychology: 18 (4), 230-238, 2002
Received	Jun 13, 2002
Accepted	Aug 30, 2002
Abstract	Patients with unilateral brain lesions who are free from any sensory impairment sometimes fail to respond to stimuli to the ear contralateral to the lesion, when tested under conditions of double simultaneous auditory stimulation. This has been called auditory extinction. There have been many reported cases of auditory extinction, but few studies have referred to the mechanism of this phenomenon. In a previous paper (Yoshikawa et al, 2001), however, we reported subjects who couldn't recall any words presented to the ear contralateral to the lesion in a dichotic listening test could nonetheless recognize words in a dichotic monitoring test. We thus demonstrated that a difference exists between reproduction and reconfirmation in auditory extinction. In the present study we aimed to investigate the level at which auditory extinction occurs, using a dichotic test requiring identification and another dichotic test requiring discrimination. Six brain damaged patients were tested with the dichotic listening test, which involved two attention conditions; divided attention (condition D) and focused attention (condition F). Afterward, they underwent the dichotic discrimination test, which required discrimination between stimuli in a dichotic situation. On the dichotic listening test under condition D, none of patients responded correctly to stimuli to the ear contralateral to the lesion. Under condition F, there were also no correct responses on the dichotic listening test for the ear contralateral to the lesion, but three of the six patients could discriminate stimuli from both ears in the dichotic discrimination test. We suggest that in these patients auditory extinction was not affected by conscious attention and the stimulus from the lesion side was not extinguished at the discrimination level but at the identification level.
Keywords	auditory extinction, dichotic listening, auditory discrimination