Neurophotonics Center, Boston University, Boston, 02215, MA, USA.
Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA.
Commun Biol. 2023 Jul 19;6(1):751. doi: 10.1038/s42003-023-05126-0.
Cortical representations supporting many cognitive abilities emerge from underlying circuits comprised of several different cell types. However, cell type-specific contributions to rate and timing-based cortical coding are not well-understood. Here, we investigated the role of parvalbumin neurons in cortical complex scene analysis. Many complex scenes contain sensory stimuli which are highly dynamic in time and compete with stimuli at other spatial locations. Parvalbumin neurons play a fundamental role in balancing excitation and inhibition in cortex and sculpting cortical temporal dynamics; yet their specific role in encoding complex scenes via timing-based coding, and the robustness of temporal representations to spatial competition, has not been investigated. Here, we address these questions in auditory cortex of mice using a cocktail party-like paradigm, integrating electrophysiology, optogenetic manipulations, and a family of spike-distance metrics, to dissect parvalbumin neurons' contributions towards rate and timing-based coding. We find that suppressing parvalbumin neurons degrades cortical discrimination of dynamic sounds in a cocktail party-like setting via changes in rapid temporal modulations in rate and spike timing, and over a wide range of time-scales. Our findings suggest that parvalbumin neurons play a critical role in enhancing cortical temporal coding and reducing cortical noise, thereby improving representations of dynamic stimuli in complex scenes.
支持许多认知能力的皮质代表来自由几种不同细胞类型组成的基础电路。然而，细胞类型特异性对基于率和基于时间的皮质编码的贡献还没有被很好地理解。在这里，我们研究了 Parvalbumin 神经元在皮质复杂场景分析中的作用。许多复杂场景包含在时间上高度动态的感官刺激，并且与其他空间位置的刺激竞争。Parvalbumin 神经元在皮质中平衡兴奋和抑制以及塑造皮质时间动态方面起着至关重要的作用；然而，它们在基于时间的编码中对复杂场景进行编码的特定作用，以及时间表示对空间竞争的稳健性，尚未得到研究。在这里，我们使用鸡尾酒会样范式在小鼠听觉皮层中解决这些问题，整合了电生理学、光遗传学操作和一系列尖峰距离度量，以剖析 Parvalbumin 神经元对基于率和基于时间的编码的贡献。我们发现，通过快速时间调制在率和尖峰时间方面的变化，以及在广泛的时间尺度上，抑制 Parvalbumin 神经元会降低皮质在鸡尾酒会样环境中对动态声音的区分能力。我们的研究结果表明，Parvalbumin 神经元在增强皮质时间编码和减少皮质噪声方面起着关键作用，从而改善了复杂场景中动态刺激的表示。
