Department of Experimental Otology, Institute of AudioNeuroTechnology (VIANNA), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany. Cluster of Excellence 'Hearing4all', Hannover, Germany.
J Neural Eng. 2019 Jun;16(3):036002. doi: 10.1088/1741-2552/ab0944. Epub 2019 Feb 21.
Intracortical microstimulation (ICMS) is widely used in neuroscientific research. Earlier work from our lab showed the possibility to combine ICMS with neuronal recordings on the same shank of multi-electrode arrays and consequently inside the same cortical column in vivo. The standard stimulus pulse shape for ICMS is a symmetric, biphasic current pulse. Here, we investigated the role of the leading-phase polarity (cathodic- versus anodic-leading) of such single ICMS pulses on the activation of the cortical network.
Local field potentials (LFPs) and multi-unit responses were recorded in the primary auditory cortex (A1) of adult guinea pigs (n = 15) under ketamine/xylazine anesthesia using linear multi-electrode arrays. Physiological responses of A1 were recorded during acoustic stimulation and ICMS. For the ICMS, the leading-phase polarity, the stimulated electrode and the stimulation current where varied systematically on any one of the 16 electrodes while recording at the same time with the 15 remaining electrodes.
Cathodic-leading ICMS consistently led to higher response amplitudes. In superficial cortical layers and for a given current amplitude, cathodic-leading and anodic-leading ICMS showed comparable activation patterns, while in deep layers only cathodic-leading ICMS reliably generated local neuronal activity. ICMS had a significantly smaller dynamic range than acoustic stimulation regardless of leading-phase polarity.
The present study provides in vivo evidence for a differential neuronal activation mechanism of the different leading-phase polarities, with cathodic-leading stimulation being more effective, and suggests that the waveform of the stimulus should be considered systematically for cortical neuroprosthesis development.
皮层内微刺激（ICMS）广泛应用于神经科学研究。我们实验室早期的工作表明，有可能在同一多电极阵列的同一叉上进行 ICMS 与神经元记录相结合，从而在体内进行同一皮层柱内的实验。ICMS 的标准刺激脉冲形状是对称的双相电流脉冲。在这里，我们研究了这种单脉冲 ICMS 的前导相极性（阴极领先与阳极领先）对皮层网络激活的作用。
在成年豚鼠（n=15）的初级听觉皮层（A1）中，使用线性多电极阵列，在氯胺酮/甲苯噻嗪麻醉下记录局部场电位（LFPs）和多单位反应。在声学刺激和 ICMS 期间记录 A1 的生理反应。对于 ICMS，系统地改变前导相极性、刺激电极和刺激电流，同时在 15 个剩余电极中的任何一个上进行记录。
阴极领先的 ICMS 始终导致更高的响应幅度。在浅层皮层中，对于给定的电流幅度，阴极领先和阳极领先的 ICMS 显示出可比的激活模式，而在深层中只有阴极领先的 ICMS 可靠地产生局部神经元活动。无论前导相极性如何，ICMS 的动态范围都明显小于声学刺激。
本研究提供了体内证据，证明不同前导相极性具有不同的神经元激活机制，阴极领先刺激更有效，并表明应系统地考虑刺激波形，以促进皮质神经假体的发展。
