Tsinghua Laboratory of Brain and Intelligence and School of Biomedical Engineering, McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
Tsinghua Laboratory of Brain and Intelligence and School of Biomedical Engineering, McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China.
J Neurosci. 2024 Oct 23;44(43):e0159242024. doi: 10.1523/JNEUROSCI.0159-24.2024.
Neural decoding is a tool for understanding how activities from a population of neurons inside the brain relate to the outside world and for engineering applications such as brain-machine interfaces. However, neural decoding studies mainly focused on different decoding algorithms rather than different neuron types which could use different coding strategies. In this study, we used two-photon calcium imaging to assess three auditory spatial decoders (space map, opponent channel, and population pattern) in excitatory and inhibitory neurons in the dorsal inferior colliculus of male and female mice. Our findings revealed a clustering of excitatory neurons that prefer similar interaural level difference (ILD), the primary spatial cues in mice, while inhibitory neurons showed random local ILD organization. We found that inhibitory neurons displayed lower decoding variability under the opponent channel decoder, while excitatory neurons achieved higher decoding accuracy under the space map and population pattern decoders. Further analysis revealed that the inhibitory neurons' preference for ILD off the midline and the excitatory neurons' heterogeneous ILD tuning account for their decoding differences. Additionally, we discovered a sharper ILD tuning in the inhibitory neurons. Our computational model, linking this to increased presynaptic inhibitory inputs, was corroborated using monaural and binaural stimuli. Overall, this study provides experimental and computational insight into how excitatory and inhibitory neurons uniquely contribute to the coding of sound locations.
神经解码是一种用于理解大脑内神经元群体的活动如何与外部世界相关联的工具，同时也可用于脑机接口等工程应用。然而，神经解码研究主要集中在不同的解码算法上，而不是不同的神经元类型，不同类型的神经元可能使用不同的编码策略。在这项研究中，我们使用双光子钙成像技术评估了雄性和雌性小鼠背外侧下丘脑中兴奋性和抑制性神经元的三种听觉空间解码器（空间图、对侧通道和群体模式）。我们的研究结果揭示了兴奋性神经元的聚类，它们对相似的两耳强度差（ILD），即小鼠的主要空间线索，有较强的偏好，而抑制性神经元则表现出随机的局部 ILD 组织。我们发现，在对侧通道解码器下，抑制性神经元的解码变异性较低，而在空间图和群体模式解码器下，兴奋性神经元的解码准确性较高。进一步的分析表明，抑制性神经元对中线以外的 ILD 的偏好以及兴奋性神经元异质的 ILD 调谐解释了它们的解码差异。此外，我们还发现抑制性神经元的 ILD 调谐更尖锐。我们的计算模型将这一结果与增加的突触前抑制性输入联系起来，并通过单耳和双耳刺激得到了验证。总的来说，这项研究为兴奋性和抑制性神经元如何独特地编码声音位置提供了实验和计算上的见解。
