Cortical representation of auditory space: Information-bearing features of spike patterns
Cortical representation of auditory space: Information-bearing features of spike patterns
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DOI：
10.1152/jn.00491.2001
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发表时间：
2002-04-01
影响因子：
2.5
通讯作者：
Middlebrooks, JC
中科院分区：
文献类型：
--
作者：
Furukawa, S;Middlebrooks, JC
先前的研究表明，皮层神经元的棘波模式作为声源位置的函数而系统地变化，因此单个神经元的响应可以在360度方位角上发出声源位置的信号。本研究考察了可能传递与声源位置相关的信息的棘波模式的特定特征。分析是基于在α-氯醛糖麻醉的猫的皮层A2区记录的良好隔离的单个单位的反应。刺激是扬声器在水平面上发出的80ms噪声脉冲串；源方位角范围为360度，20度阶跃。在八个试验的样本中，平均得到了尖峰模式。竞争人工神经网络(ANN)通过识别棘波模式来识别声源位置；ANN使用学习矢量量化学习规则进行训练。通过联合刺激-反应概率矩阵计算由棘波模式传递的有关刺激位置的信息。以不同的方式处理尖峰模式，以分离特定的特征。包含所有尖峰计数信息和精确度为100微秒的尖峰计时的全尖峰模式传递了最多与刺激相关的信息。传输的信息对尖峰计时的干扰很敏感，其范围类似到4ms，当尖峰计时信息被完全消除时，平均减少了类似到35%。在每种模式中除第一个尖峰以外的所有尖峰都被消除的情况下，传输的信息平均只减少了类似于11%。在许多情况下，这种情况基本上没有显示传输的信息丢失。从棘波模式中提取了三个一维特征。在这些特征中，尖峰潜伏期传输的信息比通过尖峰计数或潜伏期分散测量传输的信息多60%。与平均8次试验相比，单次试验记录的棘波模式所传递的信息大大减少。然而，在平均和非平均反应的比较中，潜伏期传递的信息减少了类似于29%，而尖峰计数传递的信息减少了79%。尖峰计数显然对声源位置很敏感，可以传递有关声源位置的信息。然而，目前的结果表明，第一次刺激后尖峰的时间携带了大量，可能是大部分与位置相关的信息，出现在尖峰模式中。结果表明，任何完整的听觉空间皮质表征模型都必须包含神经元反应模式的时间特征。
Previous studies have demonstrated that the spike patterns of cortical neurons vary systematically as a function of sound-source location such that the response of a single neuron can signal the location of a sound source throughout 360degrees of azimuth. The present study examined specific features of spike patterns that might transmit information related to sound-source location. Analysis was based on responses of well-isolated single units recorded from cortical area A2 in alpha-chloralose-anesthetized cats. Stimuli were 80-ms noise bursts presented from loudspeakers in the horizontal plane; source azimuths ranged through 360degrees in 20degrees steps. Spike patterns were averaged across samples of eight trials. A competitive artificial neural network (ANN) identified sound-source locations by recognizing spike patterns; the ANN was trained using the learning vector quantization learning rule. The information about stimulus location that was transmitted by spike patterns was computed from joint stimulus-response probability matrices. Spike patterns were manipulated in various ways to isolate particular features. Full-spike patterns, which contained all spike-count information and spike timing with 100-mus precision, transmitted the most stimulus-related information. Transmitted information was sensitive to disruption of spike timing on a scale of more than similar to4 ms and was reduced by an average of similar to35% when spike-timing information was obliterated entirely. In a condition in which all but the first spike in each pattern were eliminated, transmitted information decreased by an average of only similar to11%. In many cases, that condition showed essentially no loss of transmitted information. Three unidimensional features were extracted from spike patterns. Of those features, spike latency transmitted similar to60% more information than that transmitted either by spike count or by a measure of latency dispersion. Information transmission by spike patterns recorded on single trials was substantially reduced compared with the information transmitted by averages of eight trials. In a comparison of averaged and nonaveraged responses, however, the information transmitted by latencies was reduced by only similar to29%, whereas information transmitted by spike counts was reduced by 79%. Spike counts clearly are sensitive to sound-source location and could transmit information about sound-source locations. Nevertheless, the present results demonstrate that the timing of the first poststimulus spike carries a substantial amount, probably the majority, of the location-related information present in spike patterns. The results indicate that any complete model of the cortical representation of auditory space must incorporate the temporal characteristics of neuronal response patterns.