Cold Spring Harbor Laboratory, Watson School of Biological Sciences, Cold Spring Harbor, New York 11724, USA.
J Neurophysiol. 2009 Nov;102(5):2638-56. doi: 10.1152/jn.00577.2009. Epub 2009 Aug 12.
Acoustic processing requires integration over time. We have used in vivo intracellular recording to measure neuronal integration times in anesthetized rats. Using natural sounds and other stimuli, we found that synaptic inputs to auditory cortical neurons showed a rather long context dependence, up to > or =4 s (tau approximately 1 s), even though sound-evoked excitatory and inhibitory conductances per se rarely lasted greater, similar 100 ms. Thalamic neurons showed only a much faster form of adaptation with a decay constant tau <100 ms, indicating that the long-lasting form originated from presynaptic mechanisms in the cortex, such as synaptic depression. Restricting knowledge of the stimulus history to only a few hundred milliseconds reduced the predictable response component to about half that of the optimal infinite-history model. Our results demonstrate the importance of long-range temporal effects in auditory cortex and suggest a potential neural substrate for auditory processing that requires integration over timescales of seconds or longer, such as stream segregation.
声处理需要时间整合。我们使用在体细胞内记录来测量麻醉大鼠听觉皮层神经元的整合时间。使用自然声音和其他刺激，我们发现听觉皮层神经元的突触输入表现出相当长的上下文依赖性，长达 > 或 = 4 秒（tau 约为 1 秒），尽管声音诱发的兴奋性和抑制性电导本身很少持续超过 100 毫秒。丘脑神经元只表现出更快的适应形式，衰减常数 tau < 100 毫秒，这表明这种持久的形式起源于皮层的突触前机制，如突触抑制。将对刺激历史的了解限制在几百毫秒内，将可预测的反应分量减少到最佳无限历史模型的一半左右。我们的结果表明了听觉皮层中长程时间效应的重要性，并为听觉处理提供了一个潜在的神经基础，该处理需要在几秒钟或更长的时间尺度上进行整合，例如流分离。
