Metzen Michael G, Hofmann Volker, Chacron Maurice J
Computational Systems Neuroscience Laboratory, Department of Physiology, McGill University, Montreal, QC, Canada.
Front Neurosci. 2020 Feb 5;14:79. doi: 10.3389/fnins.2020.00079. eCollection 2020.
When confronted with a highly variable environment, it remains poorly understood how neural populations encode and classify natural stimuli to give rise to appropriate and consistent behavioral responses. Here we investigated population coding of natural communication signals with different attributes (i.e., amplitude and duration) in the electrosensory system of the weakly electric fish . Our results show that, while single peripheral neurons encode the detailed timecourse of different stimulus waveforms, measures of population synchrony are effectively unchanged because of coordinated increases and decreases in activity. A phenomenological mathematical model reproduced this invariance and shows that this can be explained by considering homogeneous populations whose responses are solely determined by single neuron firing properties. Moreover, recordings from downstream central neurons reveal that synchronous afferent activity is actually decoded and thus most likely transmitted to higher brain areas. Finally, we demonstrate that the associated behavioral responses at the organism level are invariant. Our results provide a mechanism by which amplitude- and duration-invariant coding of behaviorally relevant sensory input emerges across successive brain areas thereby presumably giving rise to invariant behavioral responses. Such mechanisms are likely to be found in other systems that share anatomical and functional features with the electrosensory system (e.g., auditory, visual, vestibular).
当面对高度可变的环境时，神经群体如何编码和分类自然刺激以产生适当且一致的行为反应，目前仍知之甚少。在此，我们研究了弱电鱼电感觉系统中具有不同属性（即幅度和持续时间）的自然通信信号的群体编码。我们的结果表明，虽然单个外周神经元编码不同刺激波形的详细时间进程，但由于活动的协同增加和减少，群体同步性测量实际上没有变化。一个现象学数学模型重现了这种不变性，并表明这可以通过考虑其反应仅由单个神经元放电特性决定的同质群体来解释。此外，来自下游中枢神经元的记录显示，同步传入活动实际上被解码，因此很可能被传输到更高的脑区。最后，我们证明了在生物体水平上相关的行为反应是不变的。我们的结果提供了一种机制，通过这种机制，行为相关感觉输入的幅度和持续时间不变编码在连续的脑区中出现，从而可能产生不变的行为反应。这种机制可能存在于与电感觉系统具有相同解剖和功能特征的其他系统中（例如听觉、视觉、前庭系统）。
