Kuwada S, Yin T C, Syka J, Buunen T J, Wickesberg R E
J Neurophysiol. 1984 Jun;51(6):1306-25. doi: 10.1152/jn.1984.51.6.1306.
We studied the monaural and binaural response properties of 82 low-frequency inferior colliculus (IC) neurons that display a clear sensitivity to changes in interaural phase. Most cells (60%) are excited by sound delivered to either ear, the remainder being excited only by stimulation of one ear; 70% of the neurons receive their stronger or sole excitatory input from the contralateral ear. A monotonic relation between spike discharge and sound pressure level (SPL) is seen in 65% of the monaural response areas, i.e., the range of stimulus frequencies and intensities effective in eliciting a response, while 30% show a nonmonotonic response pattern. In 33% of the cases there is a significant shift in the most effective frequency as a function of SPL. Most discharge patterns are classified as sustained (69%) and the remainder as onset. However, there is considerable variability within these patterns and often two types of discharges are present at different points in the same response area of a single cell. The sustained responses show a broad range of latencies, while onset patterns show a tighter distribution and shorter first spike latencies. Thus, IC neurons showing sensitivity to changes in interaural phase can differ in laterality preferences, response area characteristics, discharge patterns, and latency parameters. Given the diversity of inputs to the IC from lower brain stem structures, this heterogeneity is not surprising. For most neurons excited by stimulation to either ear, the characteristic frequencies, discharge patterns, and first spike latencies are similar, suggesting that the monaural inputs to a binaural cell are of the same type. A neuron's most effective frequencies at a particular SPL for monaural and binaural stimulation are, in general, the same. In some cases a neuron's monaural and binaural response areas can show remarkable similarities, suggesting that certain monaural features are intimately related to the binaural response. In 18% of the IC cells, phase locking to the monaural stimulating frequency is seen. When both inputs are phase locked, a simple coincidence model can predict the interaural phase or delay at which the maximal binaural discharge occurs.
我们研究了82个低频下丘（IC）神经元的单耳和双耳反应特性，这些神经元对耳间相位变化表现出明显的敏感性。大多数细胞（60%）对传递到任一耳朵的声音产生兴奋反应，其余细胞仅对一只耳朵的刺激产生兴奋反应；70%的神经元从对侧耳朵接受更强或唯一的兴奋性输入。在65%的单耳反应区域中，即有效引发反应的刺激频率和强度范围，可观察到放电频率与声压级（SPL）之间呈单调关系，而30%表现出非单调反应模式。在33%的情况下，最有效频率随声压级发生显著变化。大多数放电模式被归类为持续型（69%），其余为起始型。然而，这些模式存在相当大的变异性，并且在单个细胞的同一反应区域的不同点通常会出现两种放电类型。持续反应表现出广泛的潜伏期，而起始模式表现出更紧密的分布和更短的首次放电潜伏期。因此，对耳间相位变化敏感的IC神经元在偏好的耳侧性、反应区域特征、放电模式和潜伏期参数方面可能存在差异。鉴于来自脑干下部结构的IC输入的多样性，这种异质性并不令人惊讶。对于大多数因任一耳朵刺激而兴奋的神经元，其特征频率、放电模式和首次放电潜伏期相似，这表明双耳细胞的单耳输入是同一类型。通常，神经元在特定声压级下对单耳和双耳刺激的最有效频率相同。在某些情况下，神经元的单耳和双耳反应区域可能表现出显著的相似性，这表明某些单耳特征与双耳反应密切相关。在18%的IC细胞中，可观察到对单耳刺激频率的相位锁定。当两个输入都发生相位锁定时，一个简单的符合模型可以预测最大双耳放电发生时的耳间相位或延迟。
