Division for Memory and Cognitive Function, Research Center for Advanced Medical Science, Comprehensive Research Facilities for Advanced Medical Science, Dokkyo Medical University, Tochigi, 321-0293, Japan.
Department of Physiology, Osaka Metropolitan University Graduate School of Medicine, Osaka, 545-8585, Japan.
Mol Brain. 2023 May 3;16(1):38. doi: 10.1186/s13041-023-01019-9.
Characterization of inter-regional interactions in brain is essential for understanding the mechanism relevant to normal brain function and neurological disease. The recently developed flexible micro (μ)-electrocorticography (μECoG) device is one prominent method used to examine large-scale cortical activity across multiple regions. The sheet-shaped μECoG electrodes arrays can be placed on a relatively wide area of cortical surface beneath the skull by inserting the device into the space between skull and brain. Although rats and mice are useful tools for neuroscience, current μECoG recording methods in these animals are limited to the parietal region of cerebral cortex. Recording cortical activity from the temporal region of cortex in mice has proven difficult because of surgical barriers created by the skull and surrounding temporalis muscle anatomy. Here, we developed a sheet-shaped 64-channel μECoG device that allows access to the mouse temporal cortex, and we determined the factor determining the appropriate bending stiffness for the μECoG electrode array. We also established a surgical technique to implant the electrode arrays into the epidural space over a wide area of cerebral cortex covering from the barrel field to olfactory (piriform) cortex, which is the deepest region of the cerebral cortex. Using histology and computed tomography (CT) images, we confirmed that the tip of the μECoG device reached to the most ventral part of cerebral cortex without causing noticeable damage to the brain surface. Moreover, the device simultaneously recorded somatosensory and odor stimulus-evoked neural activity from dorsal and ventral parts of cerebral cortex in awake and anesthetized mice. These data indicate that our μECoG device and surgical techniques enable the recording of large-scale cortical activity from the parietal to temporal cortex in mice, including somatosensory and olfactory cortices. This system will provide more opportunities for the investigation of physiological functions from wider areas of the mouse cerebral cortex than those currently available with existing ECoG techniques.
脑区间相互作用的特征对于理解与正常大脑功能和神经疾病相关的机制至关重要。最近开发的灵活微（μ）脑电描记术（μECoG）设备是一种用于检查多个区域皮质大范围活动的突出方法。片状μECoG 电极阵列可以通过将设备插入颅骨和大脑之间的空间，放置在颅骨下的皮质表面相对较宽的区域上。虽然大鼠和小鼠是神经科学的有用工具，但这些动物的当前 μECoG 记录方法仅限于大脑皮层的顶叶区域。由于颅骨和周围颞肌解剖结构造成的手术障碍，记录来自皮层颞区的皮层活动已被证明很困难。在这里，我们开发了一种片状的 64 通道 μECoG 设备，该设备可用于访问小鼠的颞叶皮层，并确定了决定 μECoG 电极阵列适当弯曲刚度的因素。我们还建立了一种手术技术，将电极阵列植入覆盖从桶状皮层到嗅觉（梨状）皮层的大脑皮层广泛区域的硬膜外空间，这是大脑皮层的最深区域。使用组织学和计算机断层扫描（CT）图像，我们证实 μECoG 设备的尖端到达大脑皮层的最腹侧部分，而不会对脑表面造成明显的损伤。此外，该设备同时在清醒和麻醉的小鼠中记录来自大脑皮层背侧和腹侧部分的躯体感觉和气味刺激诱发的神经活动。这些数据表明，我们的 μECoG 设备和手术技术使我们能够在小鼠中从顶叶到颞叶皮层记录大范围的皮层活动，包括躯体感觉和嗅觉皮层。与现有的 ECoG 技术相比，该系统将为研究来自比当前可用技术更大范围的小鼠大脑皮层的生理功能提供更多机会。
