Gabbiani F, Metzner W, Wessel R, Koch C
Computation and Neural Systems Program, California Institute of Technology, Pasadena 91125, USA.
Nature. 1996 Dec 12;384(6609):564-7. doi: 10.1038/384564a0.
Animals acquire information about sensory stimuli around them and encode it using an analogue or a pulse-based code. Behaviourally relevant features need to be extracted from this representation for further processing. In the electrosensory system of weakly electric fish, single P-type electroreceptor afferents accurately encode the time course of random modulations in electric-field amplitude. We applied a stimulus estimation method and a signal-detection method to both P-receptor afferents and their targets, the pyramidal cells in the electrosensory lateral-line lobe. We found that although pyramidal cells do not accurately convey detailed information about the time course of the stimulus, they reliably encode up- and downstrokes of random modulations in electric-field amplitude. The presence of such temporal features is best signalled by short bursts of spikes, probably caused by dendritic processing, rather than by isolated spikes. Furthermore, pyramidal cells outperform P-receptor afferents in signalling the presence of temporal features in the stimulus waveform. We conclude that the sensory neurons are specialized to acquire information accurately with little processing, whereas the following stage extracts behaviourally relevant features, thus performing a nonlinear pattern-recognition task.
动物获取周围感觉刺激的信息，并使用模拟编码或基于脉冲的编码对其进行编码。行为相关特征需要从这种表征中提取出来以便进一步处理。在弱电鱼的电感觉系统中，单个P型电感受器传入神经精确地编码电场幅度随机调制的时间进程。我们将一种刺激估计方法和一种信号检测方法应用于P感受器传入神经及其靶标，即电感觉侧线叶中的锥体细胞。我们发现，尽管锥体细胞不能准确地传达有关刺激时间进程的详细信息，但它们可靠地编码电场幅度随机调制的上升和下降。这种时间特征的存在最好由短脉冲串发出信号，这可能是由树突处理引起的，而不是由单个脉冲发出信号。此外，在发出刺激波形中时间特征的存在信号方面，锥体细胞比P感受器传入神经表现得更好。我们得出结论，感觉神经元专门用于在几乎不进行处理的情况下准确获取信息，而接下来的阶段提取行为相关特征，从而执行非线性模式识别任务。
