Centre for Neuroscience, Indian Institute of Science, Bengaluru, India.
IISc Mathematics Initiative, Indian Institute of Science, Bengaluru, India.
PLoS Biol. 2022 Jun 14;20(6):e3001666. doi: 10.1371/journal.pbio.3001666. eCollection 2022 Jun.
Gamma oscillations (30 to 80 Hz) have been hypothesized to play an important role in feature binding, based on the observation that continuous long bars induce stronger gamma in the visual cortex than bars with a small gap. Recently, many studies have shown that natural images, which have discontinuities in several low-level features, do not induce strong gamma oscillations, questioning their role in feature binding. However, the effect of different discontinuities on gamma has not been well studied. To address this, we recorded spikes and local field potential from 2 monkeys while they were shown gratings with discontinuities in 4 attributes: space, orientation, phase, or contrast. We found that while these discontinuities only had a modest effect on spiking activity, gamma power drastically reduced in all cases, suggesting that gamma could be a resonant phenomenon. An excitatory-inhibitory population model with stimulus-tuned recurrent inputs showed such resonant properties. Therefore, gamma could be a signature of excitation-inhibition balance, which gets disrupted due to discontinuities.
伽马振荡（30 到 80 赫兹）被假设在特征绑定中发挥重要作用，这是基于这样的观察：连续的长条在视觉皮层中引起的伽马振荡比带有小间隙的条更强。最近，许多研究表明，具有几个低级特征不连续性的自然图像不会引起强烈的伽马振荡，这对它们在特征绑定中的作用提出了质疑。然而，不同不连续性对伽马的影响尚未得到很好的研究。为了解决这个问题，我们在两只猴子观看具有 4 种属性不连续性的光栅时记录了它们的尖峰和局部场电位：空间、方向、相位或对比度。我们发现，尽管这些不连续性对尖峰活动只有适度的影响，但在所有情况下，伽马功率都大幅降低，这表明伽马可能是一种共振现象。具有刺激调谐递归输入的兴奋性-抑制性群体模型表现出这种共振特性。因此，伽马可能是兴奋-抑制平衡的特征，由于不连续性而被破坏。
