Castelló María E, Nogueira Javier, Trujillo-Cenóz Omar, Caputi Angel A
Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Unidad Asociada de la Facultad de Ciencias, Universidad de la República. Montevideo, Av Italia 3318, 11600, Uruguay; Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República. Montevideo, Uruguay.
Departamento de Neuroanatomía Comparada, Instituto de Investigaciones Biológicas Clemente Estable, Unidad Asociada de la Facultad de Ciencias, Universidad de la República. Montevideo, Uruguay.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Nov;151(3):370-380. doi: 10.1016/j.cbpa.2007.04.012. Epub 2007 Apr 22.
Pulse gymnotids extract information about the environment using the pulsed discharge of an electric organ. Cutaneous electroreceptor organs transduce and encode the changes that objects imprint on the self-generated transcutaneous electric field. This review deals with the role of a neural circuit, the fast electrosensory path of pulse gymnotids, in the streaming of self generated electrosensory signals. The activation of this path triggers a low-responsiveness window slightly shorter than the interval between electric organ discharges. This phenomenon occurs at the electrosensory lateral line lobe where primary afferent terminals project on the somata of spherical neurons. The main subservient mechanism of the low-responsiveness window rely on the intrinsic properties of spherical neurons (dominated by a voltage dependent, low-threshold, non-inactivating and slowly-deactivating K(+) conductance) determining the cell to respond with a single spike followed by a long refractory period. Externally generated signals that randomly occur within the interval between self-generated discharges are likely blocked by the low responsiveness window. Repetitive signals, as those emitted by conspecifics with a slightly lower rate, occur progressively at longer delays beyond the duration of the low responsiveness window. Transient increases of the discharge rate relocate the interference within the low-responsiveness window. We propose that this combination of sensory filtering and electromotor control favors the self-generated signals in detriment of other, securing the continuity of the electrolocation stream.
脉冲电鱼利用电器官的脉冲放电来提取有关环境的信息。皮肤电感受器器官将物体在自身产生的跨皮肤电场中留下的变化进行转换和编码。本综述探讨了一种神经回路——脉冲电鱼的快速电感觉通路——在自身产生的电感觉信号流中的作用。该通路的激活会触发一个低反应性窗口，其持续时间略短于电器官放电的间隔时间。这种现象发生在电感觉侧线叶，初级传入神经末梢投射到球形神经元的胞体上。低反应性窗口的主要辅助机制依赖于球形神经元的内在特性（由电压依赖性、低阈值、非失活且缓慢失活的钾离子电导主导），这使得细胞以单个尖峰响应，随后是较长的不应期。在自身产生的放电间隔内随机出现的外部产生的信号很可能被低反应性窗口阻断。重复信号，比如同种个体以略低频率发出的信号，会在低反应性窗口持续时间之后以越来越长的延迟逐渐出现。放电率的瞬时增加会将干扰重新定位到低反应性窗口内。我们提出，这种感觉过滤和电动控制的组合有利于自身产生的信号，而不利于其他信号，从而确保电定位流的连续性。
