Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
Neuron. 2012 Feb 23;73(4):803-13. doi: 10.1016/j.neuron.2012.01.006.
The effect of attention on firing rates varies considerably within a single cortical area. The firing rate of some neurons is greatly modulated by attention while others are hardly affected. The reason for this variability across neurons is unknown. We found that the variability in attention modulation across neurons in area MT of macaques can be well explained by variability in the strength of tuned normalization across neurons. The presence of tuned normalization also explains a striking asymmetry in attention effects within neurons: when two stimuli are in a neuron's receptive field, directing attention to the preferred stimulus modulates firing rates more than directing attention to the nonpreferred stimulus. These findings show that much of the neuron-to-neuron variability in modulation of responses by attention depends on variability in the way the neurons process multiple stimuli, rather than differences in the influence of top-down signals related to attention.
注意力对单个皮质区域内的发射率的影响变化相当大。一些神经元的发射率受到极大的调制，而另一些神经元则几乎不受影响。这种跨神经元的可变性的原因尚不清楚。我们发现，猴 MT 区中跨神经元的注意力调制的可变性可以很好地用跨神经元的调谐归一化的强度的可变性来解释。调谐归一化的存在也解释了神经元内注意力效应的惊人的不对称性：当两个刺激物在神经元的感受野中时，将注意力引导到优势刺激物会比引导到非优势刺激物更能调节发射率。这些发现表明，注意力对反应的调制的神经元间的大部分可变性取决于神经元处理多个刺激的方式的可变性，而不是与注意力相关的自上而下信号的影响的差异。
