Redefining the tonotopic core of rat auditory cortex: Physiological evidence for a posterior field
Redefining the tonotopic core of rat auditory cortex: Physiological evidence for a posterior field
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DOI：
10.1002/cne.10412
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发表时间：
2002-11-25
影响因子：
2.5
通讯作者：
Semple, MN
中科院分区：
文献类型：
--
作者：
Doron, NN;Ledoux, JE;Semple, MN
以前的生理学研究已经在大鼠中发现了一种强直有组织的初级听觉皮质野(AI)。之前的一些研究表明，老鼠和其他哺乳动物一样，可能在人工智能周围有额外的领域。因此，我们在Spraogue-Dawley大鼠中记录了整个AI过程中单个神经元的细胞外反应，并继续向后验证后场(P)的存在，并比较两个区域的神经元特性。声学刺激，包括音调、带通噪声、宽带噪声和时间调制刺激，通过密封系统以两种方式传送。与以前的发现一致，人工智能的特征是从高频到低频(从40 kHz到1 khz)从前到后的可调性进展。AI后缘的频率反转标志着进入第二个核心调控区P，在更靠后的地方，逐渐遇到更高的频率，直到细胞不再对音调反应的点(约8 kHz)。然而，带通噪声在P中是一种有效的刺激，能够表征高达15 kHz的细胞。与人工智能相比，P组反应区域的频率调谐相对较宽，反应潜伏期往往更长且更具变异性，反应幅度更多地是刺激水平的非单调函数。在这两个领域，大多数神经元都受到双耳影响。大鼠的多个听觉皮质区域的存在与其他哺乳动物的听觉皮质组织是一致的。此外，P相对于AI在大鼠中的反应特性也与在其他哺乳动物中发现的相似。最后，生理数据表明，核心听觉皮质(颞区TE1)不仅由AI组成，而且至少由另外两个亚区P和前场(A)组成。此外，我们对TE1的生理特征表明，它比以前的解剖学特征所暗示的要大。
Previous physiological studies have identified a tonotopically organized primary auditory cortical field (AI) in the rat. Some of this prior research suggests that the rat, like other mammals, may have additional fields surrounding AI. We, therefore, recorded in the Sprague-Dawley rat extracellular responses of single neurons throughout AI, and continued posteriorly to verify the existence of a posterior field (P) and to compare the neuronal properties in the two regions. Acoustic stimuli, including tones, bandpass noise, broadband noise, and temporally modulated stimuli, were delivered dichotically via sealed systems. Consistent with previous findings, AI was characterized by an anterior-to-posterior tonotopic progression from high to low frequencies (ranging from > 40 kHz to < 1 kHz). A frequency reversal at the posterior border of AI marked entry into a second core tonotopic region, P, with progressively higher frequencies encountered further posteriorly, up to a point (approximately 8 kHz) where cells were no longer tone responsive. Nevertheless, bandpass noise was an effective stimulus in P, enabling characterization of cells up to 15 kHz. Compared with AI, the frequency tuning of response areas was relatively broader in P, the response latency was often longer and more variable, and the response magnitude was more commonly a nonmonotonic function of stimulus level. In both fields, most neurons were binaurally influenced. The presence of multiple auditory cortical fields in the rat is consistent with auditory cortical organization in other mammals. Moreover, the response properties of P relative to AI in the rat also resemble those found in other mammals. Finally, the physiological data suggest that core auditory cortex (temporal area TE1) is composed not only of AI as previously thought, but also of at least two other subdivisions, P and an anterior field (A). Furthermore, our physiological characterization of TE1 reveals that it is larger than suggested by previous anatomical characterizations.