Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.
University College London, London, United Kingdom.
J Neurophysiol. 2020 Apr 1;123(4):1536-1551. doi: 10.1152/jn.00587.2019. Epub 2020 Mar 18.
Contrast gain control is the systematic adjustment of neuronal gain in response to the contrast of sensory input. It is widely observed in sensory cortical areas and has been proposed to be a canonical neuronal computation. Here, we investigated whether shunting inhibition from parvalbumin-positive interneurons-a mechanism involved in gain control in visual cortex-also underlies contrast gain control in auditory cortex. First, we performed extracellular recordings in the auditory cortex of anesthetized male mice and optogenetically manipulated the activity of parvalbumin-positive interneurons while varying the contrast of the sensory input. We found that both activation and suppression of parvalbumin interneuron activity altered the overall gain of cortical neurons. However, despite these changes in overall gain, we found that manipulating parvalbumin interneuron activity did not alter the strength of contrast gain control in auditory cortex. Furthermore, parvalbumin-positive interneurons did not show increases in activity in response to high-contrast stimulation, which would be expected if they drive contrast gain control. Finally, we performed in vivo whole-cell recordings in auditory cortical neurons during high- and low-contrast stimulation and found that no increase in membrane conductance was observed during high-contrast stimulation. Taken together, these findings indicate that while parvalbumin-positive interneuron activity modulates the overall gain of auditory cortical responses, other mechanisms are primarily responsible for contrast gain control in this cortical area. We investigated whether contrast gain control is mediated by shunting inhibition from parvalbumin-positive interneurons in auditory cortex. We performed extracellular and intracellular recordings in mouse auditory cortex while presenting sensory stimuli with varying contrasts and manipulated parvalbumin-positive interneuron activity using optogenetics. We show that while parvalbumin-positive interneuron activity modulates the gain of cortical responses, this activity is not the primary mechanism for contrast gain control in auditory cortex.
对比增益控制是神经元对感觉输入对比度的系统调整。它在感觉皮质区域中广泛观察到，并被提议为一种典型的神经元计算。在这里，我们研究了来自 PV 阳性中间神经元的分流抑制（一种参与视觉皮层增益控制的机制）是否也构成了听觉皮层对比增益控制的基础。首先，我们在麻醉雄性小鼠的听觉皮层中进行了细胞外记录，并在改变感觉输入对比度的同时光遗传地操纵 PV 阳性中间神经元的活性。我们发现，PV 阳性中间神经元的激活和抑制都会改变皮质神经元的整体增益。然而，尽管整体增益发生了这些变化，我们发现操纵 PV 阳性中间神经元的活性并没有改变听觉皮层对比增益控制的强度。此外，尽管它们驱动对比增益控制，但 PV 阳性中间神经元在高对比度刺激下并没有表现出活性增加。最后，我们在高对比度和低对比度刺激期间在听觉皮层神经元中进行了体内全细胞记录，并且没有观察到在高对比度刺激期间膜电导增加。总之，这些发现表明，尽管 PV 阳性中间神经元的活性调节了听觉皮质反应的整体增益，但其他机制主要负责该皮质区域的对比增益控制。我们研究了听觉皮层中的对比增益控制是否由 PV 阳性中间神经元的分流抑制介导。我们在呈现具有不同对比度的感觉刺激时，在小鼠听觉皮层中进行了细胞外和细胞内记录，并使用光遗传学来操纵 PV 阳性中间神经元的活性。我们表明，虽然 PV 阳性中间神经元的活性调节皮质反应的增益，但这种活性不是听觉皮层对比增益控制的主要机制。
