Eaton R C, Canfield J G, Guzik A L
Department of Biology (EPO), University of Colorado at Boulder 80309, USA.
Brain Behav Evol. 1995;46(3):165-79. doi: 10.1159/000113269.
We present a neural model for how the Mauthner system could compute the direction of a transient sound stimulus originating on either the left or right side of a fish. This computation results in an initial orientation of an escape response away from the side of the stimulus. Our idea is based on the phase model of underwater sound localization by fishes. If the phase model is applicable to the Mauthner system, then the problem of sound localization can be reduced to a logical operator, the EXCLUSIVE-NOR (or XNOR). We show how this can be solved by the Mauthner system using afferents that convey separate inputs of sound pressure transduced by the swimbladder (rarefaction and compression) and particle displacement (left and right) from the inner ear. In our model, both pressure components are responsible for bringing the Mauthner cell to threshold. Mauthner firing is gated by the inhibitory PHP neurons receiving specific combinations of pressure and displacement that implement the XNOR logic. We refer to this as the XNOR model. This model is experimentally verifiable and makes specific predictions about the expected acoustic response characteristics of the Mauthner and PHP neurons. Our model places a component of PHP function into a new neuroethological context and may provide insights into the central neurophysiological mechanisms of directional hearing in fishes. In particular, we show how the XNOR model can be applied to predict the activity of diverse neural elements involved in acoustic localization by fishes.
我们提出了一种神经模型，用于解释莫特纳尔系统如何计算源自鱼类左侧或右侧的瞬态声音刺激的方向。这种计算会产生一种逃避反应的初始定向，使鱼远离刺激源所在的一侧。我们的想法基于鱼类水下声音定位的相位模型。如果相位模型适用于莫特纳尔系统，那么声音定位问题就可以简化为一个逻辑运算符——异或非（XNOR）。我们展示了莫特纳尔系统如何利用传入神经来解决这个问题，这些传入神经传递由鱼鳔转换的声压（稀疏和压缩）以及来自内耳的粒子位移（左和右）的单独输入。在我们的模型中，两个压力分量都负责使莫特纳尔细胞达到阈值。莫特纳尔细胞的放电由抑制性PHP神经元控制，这些神经元接收实现异或非逻辑的压力和位移的特定组合。我们将此称为异或非模型。该模型可以通过实验验证，并对莫特纳尔细胞和PHP神经元的预期声学反应特性做出具体预测。我们的模型将PHP功能的一个组成部分置于一个新的神经行为学背景中，并可能为鱼类定向听觉的中枢神经生理机制提供见解。特别是，我们展示了异或非模型如何应用于预测鱼类声学定位中涉及的各种神经元件的活动。
