Department of Physiology and the W. M. Keck Foundation Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA.
IEEE Trans Neural Syst Rehabil Eng. 2012 Jan;20(1):85-93. doi: 10.1109/TNSRE.2011.2166807. Epub 2011 Dec 27.
Intracortical microstimulation (ICMS) has promise as a means for delivering somatosensory feedback in neuroprosthetic systems. Various tactile sensations could be encoded by temporal, spatial, or spatiotemporal patterns of ICMS. However, the applicability of temporal patterns of ICMS to artificial tactile sensation during active exploration is unknown, as is the minimum discriminable difference between temporally modulated ICMS patterns. We trained rhesus monkeys in an active exploration task in which they discriminated periodic pulse-trains of ICMS (200 Hz bursts at a 10 Hz secondary frequency) from pulse trains with the same average pulse rate, but distorted periodicity (200 Hz bursts at a variable instantaneous secondary frequency). The statistics of the aperiodic pulse trains were drawn from a gamma distribution with mean inter-burst intervals equal to those of the periodic pulse trains. The monkeys distinguished periodic pulse trains from aperiodic pulse trains with coefficients of variation 0.25 or greater. Reconstruction of movement kinematics, extracted from the activity of neuronal populations recorded in the sensorimotor cortex concurrent with the delivery of ICMS feedback, improved when the recording intervals affected by ICMS artifacts were removed from analysis. These results add to the growing evidence that temporally patterned ICMS can be used to simulate a tactile sense for neuroprosthetic devices.
皮层内微刺激 (ICMS) 有望成为神经假体系统中提供感觉反馈的一种手段。各种触觉感觉可以通过 ICMS 的时间、空间或时空模式进行编码。然而，ICMS 的时间模式在主动探索期间对人工触觉的适用性以及时间调制的 ICMS 模式之间可分辨的最小差异尚不清楚。我们在一项主动探索任务中对恒河猴进行了训练，在该任务中，它们将 ICMS 的周期性脉冲串（10 Hz 次频的 200 Hz 脉冲串）与具有相同平均脉冲率但周期性失真的脉冲串（可变瞬时次频的 200 Hz 脉冲串）区分开来。无规律脉冲串的统计数据来自伽马分布，其平均脉冲间隔等于周期性脉冲串的平均脉冲间隔。猴子可以将具有变异系数为 0.25 或更高的周期性脉冲串与无规律脉冲串区分开来。当从分析中去除受 ICMS 伪影影响的记录间隔时，从记录的运动皮层神经元群体活动中提取的运动运动学重建得到了改善。这些结果增加了越来越多的证据，表明时间模式的 ICMS 可用于模拟神经假体设备的触觉。
