研究目的
To develop and test an optrode design using tapered optical fibers combined with a multi-electrode array for more uniform and restricted light delivery in the mouse medial prefrontal cortex, enabling better optical control and electrical readout of neural activity.
研究成果
The engineered TF-based optrode provides more uniform light distribution and better spatial restriction of illumination in the dorso-ventral axis of the mPFC compared to commercial FF-based optrodes. It enables simultaneous optical stimulation and electrical recording with reduced invasiveness and improved control over neural activity, making it suitable for studying prefrontal subdivisions in developing brains. Future work could extend this design to other experimental contexts and improve fabrication techniques.
研究不足
The study is limited to neonatal mice and the mPFC region; applicability to other brain regions or adult animals is not tested. The TF fabrication and assembly require precise alignment, which may be challenging. Potential tissue damage from probe insertion is noted, especially in young mice. Commercial availability and cost of specialized equipment like micromanipulators and lasers may restrict widespread use.
1：Experimental Design and Method Selection:
The study designed an optrode with a tapered optical fiber (TF) coated with metal on one half to emit light from one side, combined with a 16-electrode silicon-based neural probe. Monte-Carlo simulations were used to model light distribution and optimize the TF-probe positioning. In vivo experiments compared the TF-based optrode with a commercial flat-cleaved fiber (FF) optrode in neonatal mice expressing Channelrhodopsin-2 (ChR2) in the medial prefrontal cortex (mPFC).
2：Sample Selection and Data Sources:
Neonatal mice (postnatal day 8-10) were used, with ChR2 expressed in layer 2/3 pyramidal neurons of the mPFC via in utero electroporation. Extracellular electrophysiology data were collected from the mPFC.
3：List of Experimental Equipment and Materials:
Tapered optical fibers (NA=0.22, core/cladding diameters 105/125 μm, taper angle ~4°), silicon-based neural probes with 16 IrOx electrodes, printed circuit board (PCB), UV curable epoxy glue, lasers (473 nm and 594 nm), micromanipulators, multi-channel extracellular amplifier, and software for data acquisition and analysis.
4：22, core/cladding diameters 105/125 μm, taper angle ~4°), silicon-based neural probes with 16 IrOx electrodes, printed circuit board (PCB), UV curable epoxy glue, lasers (473 nm and 594 nm), micromanipulators, multi-channel extracellular amplifier, and software for data acquisition and analysis.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: TFs were fabricated using the heat-and-pull technique and coated with Cr and Au. Neural probes were fabricated using MEMS technologies. The TF was aligned and fixed beside the probe shank using micromanipulators and epoxy. In vivo recordings involved inserting the optrode into the mPFC, delivering light pulses, and recording local field potentials and multi-unit activity. Data were filtered and analyzed for light-induced responses and artifacts.
5：Data Analysis Methods:
Data were band-pass filtered for LFP (1-100 Hz) and MUA (500-9000 Hz). A modulation index was calculated to quantify evoked responses. Monte-Carlo simulations in MATLAB were used to estimate power density distributions.
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