Effects of damage to auditory cortex on the discrimination of speech sounds by rats.
The intensity of a noise-induced startle response can be reduced by the presentation of an otherwise neutral stimulus immediately before the noise ("prepulse inhibition" or PPI). We used a form of PPI to study the effects of damage to auditory cortex on the discrimination of speech sounds by rats. Subjects underwent control surgery or treatment of the auditory cortex with the vasoconstrictor endothelin-1. This treatment caused damage concentrated in primary auditory cortex (A1). Both before and after lesions, subjects were tested on 5 tasks, most presenting a pair of human speech sounds (consonant-vowel syllables) so that the capacity for discrimination would be evident in the extent of PPI. Group comparisons failed to reveal any consistent lesion effect. At the same time, the analysis of individual differences in performance by multiple regression suggests that some of the temporal processing required to discriminate speech sounds is concentrated anteroventrally in the right A1. These results also confirm that PPI can be adapted to studies of the brain mechanisms involved in the processing of speech and other complex sounds.
Floody
Owen R
OR
Department of Psychology, Bucknell University, Lewisburg, Pennsylvania 17837, United States. ofloody@bucknell.edu
Ouda
Ladislav
L
Porter
Benjamin A
BA
Kilgard
Michael P
MP
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D001303:Auditory Cortex / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology*; D003463:Cues; D005260:Female; D009433:Neural Inhibition / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000502:physiology; D012044:Regression Analysis; D013018:Sound Spectrography / Q000379:methods; D013067:Speech Perception / Q000502:physiology*