Mechanisms of speech sound discrimination learning in the rat auditory and association cortices

黄素蛋白自发荧光成像显示，合成共振峰和元音除在初级听觉皮层(AI)外，还在前(AAF)和背(DAF)听区引起显著反应，而摩擦辅音在AI、DAF和腹侧听区(VAF)引起显著反应。电刺激AAF可引起DAF的荧光反应，电刺激AI可引起DAF和VAF的荧光反应。AAF对共振峰的反应明显，波形包络变化快，而AI反应依赖于声音的频谱。这些发现表明，语音辨别存在双重途径。

Flavoprotein autofluorescence imaging showed that synthetic formants and vowels evoked prominent responses in the anterior(AAF) and dorsal(DAF) auditory field in addition to the primary auditory cortex(AI), while fricative consonants evoked responses in the AI, DAF and ventral auditory field(VAF). Electrical stimulation to AAF elicited fluorescence responses in DAF while that to AI evoked responses in DAF and VAF. AAF responded markedly to formants with fast change of waveform envelopes, while AI responses depended on spectrum of sounds. These findings suggest that there are dual pathways for speech sound discrimination.