Massoudi Roohollah, Van Wanrooij Marc M, Van Wetter Sigrid M C I, Versnel Huib, Van Opstal A John
Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
Eur J Neurosci. 2014 May;39(9):1538-50. doi: 10.1111/ejn.12532. Epub 2014 Mar 20.
We characterised task-related top-down signals in monkey auditory cortex cells by comparing single-unit activity during passive sound exposure with neuronal activity during a predictable and unpredictable reaction-time task for a variety of spectral-temporally modulated broadband sounds. Although animals were not trained to attend to particular spectral or temporal sound modulations, their reaction times demonstrated clear acoustic spectral-temporal sensitivity for unpredictable modulation onsets. Interestingly, this sensitivity was absent for predictable trials with fast manual responses, but re-emerged for the slower reactions in these trials. Our analysis of neural activity patterns revealed a task-related dynamic modulation of auditory cortex neurons that was locked to the animal's reaction time, but invariant to the spectral and temporal acoustic modulations. This finding suggests dissociation between acoustic and behavioral signals at the single-unit level. We further demonstrated that single-unit activity during task execution can be described by a multiplicative gain modulation of acoustic-evoked activity and a task-related top-down signal, rather than by linear summation of these signals.
我们通过比较在被动声音暴露期间的单单元活动与在针对各种频谱-时间调制宽带声音的可预测和不可预测反应时任务期间的神经元活动，来表征猴子听觉皮层细胞中与任务相关的自上而下信号。尽管动物没有经过训练去关注特定的频谱或时间声音调制，但它们的反应时间显示出对不可预测调制起始的明显声谱-时间敏感性。有趣的是，对于具有快速手动反应的可预测试验，这种敏感性不存在，但在这些试验中较慢反应时又重新出现。我们对神经活动模式的分析揭示了听觉皮层神经元与任务相关的动态调制，该调制与动物的反应时间锁定，但对频谱和时间声学调制不变。这一发现表明在单单元水平上声学信号和行为信号之间存在分离。我们进一步证明，任务执行期间的单单元活动可以通过声诱发活动的乘法增益调制和与任务相关的自上而下信号来描述，而不是通过这些信号的线性总和来描述。
