Kang HiJee, Babola Travis A, Kanold Patrick O
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 20215.
Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 20215.
bioRxiv. 2024 Oct 8:2024.06.17.599418. doi: 10.1101/2024.06.17.599418.
Sensory information is represented by small varying neuronal ensembles in sensory cortices. In the auditory cortex (AC) repeated presentations of the same sound activate differing ensembles indicating high trial-by trial variability in activity even though the sounds activate the same percept. Efficient processing of complex acoustic signals requires that these sparsely distributed neuronal ensembles actively interact in order to provide a constant percept. Thus, the differing ensembles might interact to process the incoming sound inputs. Here, we probe interactions within and across ensembles by combining 2-photon Ca imaging and holographic optogenetic stimulation to study how increased activity of single cells level affects the cortical network. We stimulated a small number of neurons sharing the same frequency preference alongside the presentation of a target pure tone, further increasing their tone-evoked activity. We found that other non-stimulated co-tuned neurons decreased their tone-evoked activity when the frequency of the presented pure tone matched to their tuning property, while non co-tuned neurons were unaffected. Activity decrease was greater for non-stimulated co-tuned neurons with higher frequency selectivity. Co-tuned and non co-tuned neurons were spatially intermingled. Our results shows that co-tuned ensembles communicated and balanced their total activity across the larger network. The rebalanced network activity due to external stimulation remained constant. These effects suggest that co-tuned ensembles in AC interact and rapidly rebalance their activity to maintain encoding homeostasis, and that the rebalanced network is persistent.
感觉信息由感觉皮层中变化的小神经元集群来表征。在听觉皮层（AC）中，相同声音的重复呈现会激活不同的集群，这表明即使声音激活相同的感知，每次试验的活动仍存在很大差异。复杂声学信号的有效处理要求这些稀疏分布的神经元集群积极相互作用，以提供恒定的感知。因此，不同的集群可能相互作用以处理传入的声音输入。在这里，我们通过结合双光子钙成像和全息光遗传学刺激来探究集群内部和集群之间的相互作用，以研究单细胞水平上增加的活动如何影响皮层网络。我们在呈现目标纯音的同时刺激了一小部分具有相同频率偏好的神经元，进一步增加它们的音调诱发活动。我们发现，当呈现的纯音频率与它们的调谐特性匹配时，其他未受刺激的共调谐神经元会降低它们的音调诱发活动，而非共调谐神经元则不受影响。对于频率选择性更高的未受刺激的共调谐神经元，活动降低幅度更大。共调谐和非共调谐神经元在空间上相互交织。我们的结果表明，共调谐集群在更大的网络中进行通信并平衡它们的总活动。由于外部刺激而重新平衡的网络活动保持恒定。这些效应表明，听觉皮层中的共调谐集群相互作用并迅速重新平衡它们的活动以维持编码稳态，并且重新平衡的网络是持久的。
