Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Institute of Neuroscience of Castilla y León, 37007 Salamanca, Spain.
J Neurosci. 2012 Dec 5;32(49):17762-74. doi: 10.1523/JNEUROSCI.3190-12.2012.
The ability to detect unexpected sounds within the environment is an important function of the auditory system, as a rapid response may be required for the organism to survive. Previous studies found a decreased response to repetitive stimuli (standard), but an increased response to rare or less frequent sounds (deviant) in individual neurons in the inferior colliculus (IC) and at higher levels. This phenomenon, known as stimulus-specific adaptation (SSA) has been suggested to underpin change detection. Currently, it is not known how SSA varies within a single neuron receptive field, i.e., it is unclear whether SSA is a unique property of the neuron or a feature that is frequency and/or intensity dependent. In the present experiments, we used the common SSA index (CSI) to quantify and compare the degree of SSA under different stimulation conditions in the IC of the rat. We calculated the CSI at different intensities and frequencies for each individual IC neuron to map the neuronal CSI within the receptive field. Our data show that high SSA is biased toward the high-frequency and low-intensity regions of the receptive field. We also find that SSA is better represented in the earliest portions of the response, and there is a positive correlation between the width of the frequency response area of the neuron and the maximum level of SSA. The present data suggest that SSA in the IC is not mediated by the intrinsic membrane properties of the neurons and instead might be related to an excitatory and/or inhibitory input segregation.
在环境中检测意外声音的能力是听觉系统的一个重要功能，因为生物体可能需要快速做出反应才能生存。以前的研究发现，在下丘脑中（IC）和更高水平的个别神经元中，对重复刺激（标准）的反应减少，但对罕见或不太频繁的声音（偏差）的反应增加。这种现象称为刺激特异性适应（SSA），被认为是变化检测的基础。目前，尚不清楚 SSA 在单个神经元感受野内如何变化，即尚不清楚 SSA 是神经元的独特特性还是取决于频率和/或强度的特征。在本实验中，我们使用常见的 SSA 指数（CSI）来量化和比较 IC 中不同刺激条件下 SSA 的程度在大鼠的。我们为每个个体 IC 神经元计算了不同强度和频率下的 CSI，以绘制感受野内神经元 CSI 的图谱。我们的数据表明，高 SSA 偏向感受野的高频和低强度区域。我们还发现 SSA 在反应的最早部分表现得更好，并且神经元的频率响应区域的宽度与 SSA 的最大水平之间存在正相关关系。目前的数据表明，IC 中的 SSA 不是由神经元的固有膜特性介导的，而是可能与兴奋性和/或抑制性输入分离有关。
