Processing Temporal Modulations in Binaural and Monaural Auditory Stimuli by Neurons in the Inferior Colliculus and Auditory Cortex
Processing Temporal Modulations in Binaural and Monaural Auditory Stimuli by Neurons in the Inferior Colliculus and Auditory Cortex
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DOI：
10.1007/s10162-009-0177-8
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发表时间：
2009-12-01
影响因子：
2.4
通讯作者：
Filipovic, Blagoje
中科院分区：
文献类型：
--
作者：
Fitzpatrick, Douglas C.;Roberts, Jason M.;Filipovic, Blagoje
处理刺激流中的动态变化是感觉系统的主要任务。在听觉系统中，对于诸如振幅调制的单耳信号，下丘（IC）和听觉皮层之间的时间整合窗口的增加是众所周知的，但是双耳信号的类似增加尚未被证明。为了研究双耳时间处理在这些大脑水平的限制，我们使用了双耳节拍刺激，这会导致波动的耳间相位差，而记录从神经元在未麻醉的兔子。我们发现，双耳拍频（BBF）的神经同步的截止频率之间的IC和听觉皮层下降，这种下降与组延迟的增加。这些特征表明，与IC相比，皮层中的时间整合窗口增加，补充了单耳信号所见的时间整合窗口。对振幅调制的响应的可比测量结果表明，在皮层水平的单耳和双耳的时间整合窗口在定量和定性上是相似的，这表明内在的膜特性和传入突触的皮层神经元支配的动态处理。与BBF同步的上限和皮层神经元的带通调谐特性与人类心理物理学密切匹配。
Processing dynamic changes in the stimulus stream is a major task for sensory systems. In the auditory system, an increase in the temporal integration window between the inferior colliculus (IC) and auditory cortex is well known for monaural signals such as amplitude modulation, but a similar increase with binaural signals has not been demonstrated. To examine the limits of binaural temporal processing at these brain levels, we used the binaural beat stimulus, which causes a fluctuating interaural phase difference, while recording from neurons in the unanesthetized rabbit. We found that the cutoff frequency for neural synchronization to the binaural beat frequency (BBF) decreased between the IC and auditory cortex, and that this decrease was associated with an increase in the group delay. These features indicate that there is an increased temporal integration window in the cortex compared to the IC, complementing that seen with monaural signals. Comparable measurements of responses to amplitude modulation showed that the monaural and binaural temporal integration windows at the cortical level were quantitatively as well as qualitatively similar, suggesting that intrinsic membrane properties and afferent synapses to the cortical neurons govern the dynamic processing. The upper limits of synchronization to the BBF and the band-pass tuning characteristics of cortical neurons are a close match to human psychophysics.