Abstract
Advances in imaging and recording of neural activities with a single neuron resolution have played a significant role in understanding neurological diseases in the past decade. Conventional methods relying on patch-clamp and electrodes are regarded as invasive, whereas fluorescence-based imaging tools are useful but still suffer from a low signal-to-noise ratio and low sensitivity. Here we developed a novel optical imaging and recording system by employing laser emissions to record the action potentials in single neurons and neuronal networks caused by subtle transients (Ca2+ concentration) in primary neurons in vitro with a subcellular and single-spike resolution. By recording the laser emissions from neurons, we discovered that lasing emissions could be biologically modulated by intracellular activities and extracellular stimulation with >100-fold improvement in detection sensitivity over traditional fluorescence-based measurement. Finally, we showed that ultrasound can wirelessly activate neurons adsorbed with piezoelectric BaTiO3 nanoparticles, in which the neuron laser emissions were modulated by ultrasound. Our findings show that ultrasound stimulation can significantly increase the lasing intensity and neuron network response. This work not only opens the door to laser emission recording of intracellular dynamics in neuronal networks but may provide an ultra-sensitive detection method for brain-on-chip applications, optogenetics, and neuro-analysis.
