Nakamoto Kyle T, Shackleton Trevor M, Magezi David A, Palmer Alan R
Medical Research Council Institute of Hearing Research, University Park, Nottingham, United Kingdom; Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio; and
Medical Research Council Institute of Hearing Research, University Park, Nottingham, United Kingdom;
J Neurophysiol. 2015 Mar 15;113(6):1819-30. doi: 10.1152/jn.00472.2014. Epub 2014 Dec 24.
Responses of neurons to binaural, harmonic complex stimuli in urethane-anesthetized guinea pig inferior colliculus (IC) are reported. To assess the binaural integration of harmonicity cues for sound segregation and grouping, responses were measured to harmonic complexes with different fundamental frequencies presented to each ear. Simultaneously gated harmonic stimuli with fundamental frequencies of 125 Hz and 145 Hz were presented to the left and right ears, respectively, and recordings made from 96 neurons with characteristic frequencies >2 kHz in the central nucleus of the IC. Of these units, 70 responded continuously throughout the stimulus and were excited by the stimulus at the contralateral ear. The stimulus at the ipsilateral ear excited (EE: 14%; 10/70), inhibited (EI: 33%; 23/70), or had no significant effect (EO: 53%; 37/70), defined by the effect on firing rate. The neurons phase locked to the temporal envelope at each ear to varying degrees depending on signal level. Many of the cells (predominantly EO) were dominated by the response to the contralateral stimulus. Another group (predominantly EI) synchronized to the contralateral stimulus and were suppressed by the ipsilateral stimulus in a phasic manner. A third group synchronized to the stimuli at both ears (predominantly EE). Finally, a group only responded when the waveform peaks from each ear coincided. We conclude that these groups of neurons represent different "streams" of information but exhibit modifications of the response rather than encoding a feature of the stimulus, like pitch.
本文报道了在氨基甲酸乙酯麻醉的豚鼠下丘（IC）中，神经元对双耳谐波复合刺激的反应。为了评估谐波线索的双耳整合以进行声音分离和分组，测量了对分别呈现给每只耳朵的具有不同基频的谐波复合体的反应。将基频分别为125Hz和145Hz的同时门控谐波刺激分别呈现给左耳和右耳，并在IC中央核中对96个特征频率>2kHz的神经元进行记录。在这些单元中，70个在整个刺激过程中持续反应，并被对侧耳的刺激所兴奋。同侧耳的刺激根据对放电率的影响，产生兴奋（EE：14%；10/70）、抑制（EI：33%；23/70）或无显著影响（EO：53%；37/70）。神经元根据信号水平在不同程度上对每只耳朵的时间包络进行锁相。许多细胞（主要是EO）以对侧刺激的反应为主导。另一组（主要是EI）与对侧刺激同步，并被同侧刺激以相位方式抑制。第三组与双耳的刺激同步（主要是EE）。最后，一组仅在每只耳朵的波形峰值重合时做出反应。我们得出结论，这些神经元组代表不同的信息“流”，但表现出反应的改变，而不是像音高那样编码刺激的特征。
