Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA.
Photonics Center, Boston University, 8 Saint Mary's Street, Boston, MA, 02215, USA.
Sci Rep. 2022 Aug 20;12(1):14196. doi: 10.1038/s41598-022-18139-2.
Infrared (IR) neuromodulation (INM) has been demonstrated as a novel modulation modality of neuronal excitability. However, the effects of pulsed IR light on synaptic transmission have not been investigated systematically. In this report, the IR light (2 μm) is used to directly modulate evoked synaptic transmission at the crayfish opener neuromuscular junction. The extracellularly recorded terminal action potentials (tAPs) and evoked excitatory postsynaptic currents (EPSCs) modulated by localized IR light illumination (500 ms, 3-13 mW) aimed at the synapses are analyzed. The impact of a single IR light pulse on the presynaptic Ca influx is monitored with Ca indicators. The EPSC amplitude is enhanced, and its rising phase is accelerated under relatively low IR light power levels and localized temperature rises. Increasing the IR light power reversibly suppresses and eventually blocks the EPSCs. Meanwhile, the synaptic delay, tAP amplitude, and presynaptic Ca influx decrease monotonously with higher IR light power. It is demonstrated for the first time that IR light illumination has bidirectional effects on evoked synaptic transmission. These results highlight the efficacy and flexibility of using pulsed IR light to directly control synaptic transmission and advance our understanding of INM of neural networks.
红外（IR）神经调节（INM）已被证明是一种新的神经元兴奋性调节方式。然而，脉冲 IR 光对突触传递的影响尚未被系统地研究。在本报告中，使用 2μm 的 IR 光直接调制螯虾开口神经肌肉接点处的诱发突触传递。分析了针对突触的局部 IR 光照射（500ms，3-13mW）调制的终端动作电位（tAP）和诱发的兴奋性突触后电流（EPSC）。用 Ca 指示剂监测单个 IR 光脉冲对突触前 Ca 内流的影响。在相对较低的 IR 光功率水平和局部温升下，EPSC 幅度增强，上升相加快。增加 IR 光功率可可逆地抑制并最终阻断 EPSC。同时，随着 IR 光功率的增加，突触延迟、tAP 幅度和突触前 Ca 内流单调下降。首次证明，IR 光照射对诱发的突触传递具有双向作用。这些结果突出了使用脉冲 IR 光直接控制突触传递的有效性和灵活性，并增进了我们对神经网络 INM 的理解。
