Behav Brain Res. 2014 Jan 1;258:166-78. doi: 10.1016/j.bbr.2013.10.021.
Previous studies in both humans and animals have documented improved performance following discrimination training. This enhanced performance is often associated with cortical response changes. In this study, we tested the hypothesis that long-term speech training on multiple tasks can improve primary auditory cortex (A1) responses compared to rats trained on a single speech discrimination task or experimentally naïve rats. Specifically, we compared the percent of A1 responding to trained sounds, the responses to both trained and untrained sounds, receptive field properties of A1 neurons, and the neural discrimination of pairs of speech sounds in speech trained and naïve rats. Speech training led to accurate discrimination of consonant and vowel sounds, but did not enhance A1 response strength or the neural discrimination of these sounds. Speech training altered tone responses in rats trained on six speech discrimination tasks but not in rats trained on a single speech discrimination task. Extensive speech training resulted in broader frequency tuning, shorter onset latencies, a decreased driven response to tones, and caused a shift in the frequency map to favor tones in the range where speech sounds are the loudest. Both the number of trained tasks and the number of days of training strongly predict the percent of A1 responding to a low frequency tone. Rats trained on a single speech discrimination task performed less accurately than rats trained on multiple tasks and did not exhibit A1 response changes. Our results indicate that extensive speech training can reorganize the A1 frequency map, which may have downstream consequences on speech sound processing.
先前在人类和动物身上的研究都记录了经过辨别训练后表现的提高。这种性能的提升通常与皮质反应的变化有关。在这项研究中，我们测试了这样一个假设，即与仅接受单一语音辨别任务训练或未经实验训练的大鼠相比，经过多任务的长期语音训练可以改善初级听觉皮层（A1）的反应。具体来说，我们比较了 A1 对训练声音的反应比例、对训练和未训练声音的反应比例、A1 神经元的感受野特性，以及在经过语音训练和未经训练的大鼠中语音对的神经辨别能力。语音训练导致了对辅音和元音声音的准确辨别，但并没有增强 A1 反应强度或这些声音的神经辨别能力。语音训练改变了在六个语音辨别任务中接受训练的大鼠的音调反应，但没有改变在单一语音辨别任务中接受训练的大鼠的音调反应。广泛的语音训练导致了更宽的频率调谐、更短的起始潜伏期、对音调的驱动反应减少，并且导致频率图向有利于语音最响亮的频率范围的转移。接受训练的任务数量和训练天数都强烈预测了 A1 对低频音调的反应比例。接受单一语音辨别任务训练的大鼠比接受多任务训练的大鼠表现得更不准确，并且没有表现出 A1 反应的变化。我们的结果表明，广泛的语音训练可以重组 A1 的频率图，这可能对语音处理产生下游影响。
