Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
Brain Stimul. 2022 May-Jun;15(3):881-888. doi: 10.1016/j.brs.2022.05.015. Epub 2022 May 27.
Intracortical microstimulation (ICMS) of somatosensory cortex can partially restore the sense of touch. Though ICMS bypasses much of the neuraxis, prior studies have found that conscious detection of touch elicited by ICMS lags behind the detection of cutaneous vibration. These findings may have been influenced by mismatched stimulus intensities, which can impact temporal perception.
Evaluate the relative latency at which intensity-matched vibration and ICMS are perceived by a human participant.
One person implanted with microelectrode arrays in somatosensory cortex performed reaction time and temporal order judgment (TOJ) tasks. To measure reaction time, the participant reported when he perceived vibration or ICMS. In the TOJ task, vibration and ICMS were sequentially presented and the participant reported which stimulus occurred first. To verify that the participant could distinguish between stimuli, he also performed a modality discrimination task, in which he indicated if he felt vibration, ICMS, or both.
When vibration was matched in perceived intensity to high-amplitude ICMS, vibration was perceived, on average, 48 ms faster than ICMS. However, in the TOJ task, both sensations arose at comparable latencies, with points of subjective simultaneity not significantly different from zero. The participant could discriminate between tactile modalities above chance level but was more inclined to report feeling vibration than ICMS.
The latencies of ICMS-evoked percepts are slower than their mechanical counterparts. However, differences in latencies are small, particularly when stimuli are matched for intensity, implying that ICMS-based somatosensory feedback is rapid enough to be effective in neuroprosthetic applications.
皮层内微刺激（ICMS）可以部分恢复触觉。虽然 ICMS 绕过了大部分的神经轴，但先前的研究发现，由 ICMS 引起的触觉的意识检测滞后于皮肤振动的检测。这些发现可能受到刺激强度不匹配的影响，而刺激强度会影响时间感知。
评估由人类参与者感知到匹配强度的振动和 ICMS 的相对潜伏期。
一名植入感觉皮层微电极阵列的人员进行了反应时间和时间顺序判断（TOJ）任务。为了测量反应时间，参与者报告他何时感知到振动或 ICMS。在 TOJ 任务中，振动和 ICMS 依次呈现，参与者报告哪个刺激先出现。为了验证参与者可以区分刺激，他还进行了模态辨别任务，在该任务中，他指出自己感觉到了振动、ICMS 还是两者都有。
当振动的感知强度与高振幅的 ICMS 匹配时，振动的感知速度比 ICMS 平均快 48ms。然而，在 TOJ 任务中，两种感觉的潜伏期相当，主观同时性的点与零没有显著差异。参与者可以在高于机会水平的触觉模态之间进行区分，但更倾向于报告感觉到振动而不是 ICMS。
ICMS 诱发的感知潜伏期比机械刺激的潜伏期慢。然而，潜伏期的差异很小，尤其是当刺激强度匹配时，这意味着基于 ICMS 的感觉反馈足够快，可以在神经假体应用中有效。
