Population coding of tone stimuli in auditory cortex: dynamic rate vector analysis.
Population coding of tone stimuli in auditory cortex: dynamic rate vector analysis.
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DOI：
10.1111/j.1460-9568.2009.06954.x
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发表时间：
2009-11
期刊：
影响因子：
--
通讯作者：
Harris KD
中科院分区：
文献类型：
--
作者：
Bartho P;Curto C;Luczak A;Marguet SL;Harris KD
即使是时间上非结构化的刺激的神经表征也可以表现出复杂的时间动态。在许多系统中，神经元群体代码显示出“渐进分化”，即在刺激呈现期间，群体对不同刺激的反应进一步分开。在这里，我们分析了大鼠的听觉皮层群体的反应，延长音。在发病时（高达300毫秒），紧张性反应涉及大量的神经元的强烈兴奋，在持续的反应（500毫秒后）整体放电率下降，但大多数细胞仍然表现出统计学显着差异的放电率。由不同的音调频率引起的人口矢量轨迹迅速扩大沿着一个最初相似的轨迹在第一个几十毫秒后的音调开始，后来发散到较小的幅度固定点对应于持续的反应。对同一音调的起始和持续反应之间的角度差异大于同一刺激时期不同音调之间的角度差异。没有明确的正交化的反应，发现随着时间的推移，从人口活动的刺激的可预测性也下降，在此期间相比，发病。人口活动是否随着时间的推移而变得越来越稀疏的问题取决于这个术语的精确数学意义。我们的结论是，听觉皮质人口的反应，音调不同，在许多其他系统中的报告，与渐进分化没有看到持续的刺激。持续的声音刺激通常不是行为上的突出：我们假设，我们观察到的动态，而不是允许动物保持这种声音的表示，在低能量成本。
Neural representations of even temporally unstructured stimuli can show complex temporal dynamics. In many systems, neuronal population codes show “progressive differentiation,” whereby population responses to different stimuli grow further apart during a stimulus presentation. Here we analyzed the response of auditory cortical populations in rats to extended tones. At onset (up to 300 ms), tone responses involved strong excitation of a large number of neurons; during sustained responses (after 500 ms) overall firing rate decreased, but most cells still showed a statistically significant difference in firing rate. Population vector trajectories evoked by different tone frequencies expanded rapidly along an initially similar trajectory in the first tens of ms after tone onset, later diverging to smaller amplitude fixed points corresponding to sustained responses. The angular difference between onset and sustained responses to the same tone was greater than between different tones in the same stimulus epoch. No clear orthogonalization of responses was found with time, and predictability of the stimulus from population activity also decreased during this period compared to onset. The question of whether population activity grew more or less sparse with time depended on the precise mathematical sense given to this term. We conclude that auditory cortical population responses to tones differ from those reported in many other systems, with progressive differentiation not seen for sustained stimuli. Sustained acoustic stimuli are typically not behaviorally salient: we hypothesize that the dynamics we observe may instead allow an animal to maintain a representation of such sounds, at low energetic cost.
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