Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA.
J Neurosci. 2010 Feb 24;30(8):3058-66. doi: 10.1523/JNEUROSCI.3766-09.2010.
Descriptions of how attention modulates neuronal responses suggest that the strength of its effects depends on stimulus conditions. Attention to an isolated stimulus in the receptive field of an individual neuron typically produces a moderate enhancement of the cell's response, but neuronal responses are often strongly modulated when attention is shifted between multiple stimuli that lie within the receptive field. However, previous reports have not compared these stimulus effects under equivalent conditions, so differences in task difficulty could have been responsible for much of the difference. Consequently, the quantitative effects of stimulus conditions have remained unknown, and it has not been possible to address the question of whether the differences that have been observed could be explained by a single mechanism. We measured the attentional modulation of the responses of 70 single neurons in area MT of two rhesus monkeys using a task designed to keep attention stable across different stimulus configurations. We found that attentional modulation was indeed much stronger when more than one stimulus was within the receptive field. Nevertheless, the broad range of attentional modulations seen across the different conditions could be readily explained by single mechanism. The neurophysiological data from all stimulus conditions were well fit by a model in which attention acts via a response normalization mechanism (Lee and Maunsell, 2009). Collectively, these results validate previous impressions of the effects of stimulus configuration on attentional modulation, and add support to hypothesis that attention modulation depends on a response normalization mechanism.
描述注意力如何调节神经元反应的研究表明，其影响的强度取决于刺激条件。将注意力集中在单个神经元的感受野中的单个刺激上，通常会适度增强细胞的反应，但当注意力在感受野内的多个刺激之间转移时，神经元的反应通常会受到强烈的调节。然而，以前的报告并没有在等效条件下比较这些刺激效应，因此任务难度的差异可能导致了大部分差异。因此，刺激条件的定量影响仍然未知，也不可能解决已经观察到的差异是否可以用单一机制来解释的问题。我们使用一种旨在保持不同刺激配置下注意力稳定的任务，测量了两只恒河猴的 MT 区 70 个单个神经元的反应的注意力调节。我们发现，当有多个刺激在感受野内时，注意力的调节确实要强得多。尽管如此，不同条件下广泛的注意力调节可以用单一机制来很好地解释。所有刺激条件的神经生理学数据都非常符合这样一个模型，即注意力通过响应归一化机制发挥作用（Lee 和 Maunsell，2009）。总的来说，这些结果验证了之前对刺激配置对注意力调节影响的印象，并为注意力调节取决于响应归一化机制的假说提供了支持。
