Studying the Coding Profiles of Somatic Stimulation on Cardiac-locked Neuronal Responses in the Rat Spinal Dorsal Horn

My research decodes acupuncture spinal neuromodulation effects of cardiovascular regulation via thoracic spinal stabilized MEA ECG protocol, enabling milliseconds to process and analyze a particle like the SDHN dynamics.

Current experimental challenges involve achieving reliable thoracic spinal stabilization to prevent neuro threats. Optimizing the initiate protocols for neuro stability as well as ensuring millisecond-level MEA ECG synchronization.

[Yun Liu] Our protocol provided a general approach for simultaneously monitoring neural activity and cardiac functions, and by combining the recordings of electrocardiograms and micro-electrodes, erase overcoming low temporal resolution, than calcium imaging.

Our results promote investigation into whether cardiac located spinal neurons drive MI progressing, and if acupoint-specific acupuncture modulation offers therapeutic benefits for myocardial infarction.

[Narrator] To begin, examine a Y-shaped cannula to confirm that it is completely dry. Using spring scissors, make a transverse incision in the trachea of an anesthetized rat. Insert the cannula into the tracheal opening. Secure the tracheal cannula with three zero non-absorbable sutures to prevent air leakage and accidental extubation. Next, insert three electrodes into the rat's skin. Place the positive electrode into the left lower limb, the ground electrode into the right lower limb, and the negative electrode into the right upper limb. Place the rat in a supine position. After disinfecting the skin, perform a thoracotomy to expose the thymus. Then use the tip of a glass dissecting needle to make a small opening in the pericardium. Now insert a silicone catheter with several small holes at its distal end one to two centimeters into the pericardium through the incision. Secure the catheter to the chest wall tissue with BioGlue. Then, perform manual acupuncture at the PC six acupoint using a stimulation parameter of one hertz. Insert acupuncture needles into the PC six accupoints at a depth of approximately three millimeters. Remove the muscles attaching to the head clamp and the straight portion of the long neck muscles to expose the spinous processes of the second thoracic vertebrae. Then displace the semispinalis and spinalis muscles to expose the vertebral arch from T2 to T6. Using rongeurs, remove the spinous process of the T3 vertebrae to expose the T3 spinal cord. For thoracic vertebrae fixation, use a custom spinal clamp to secure the articular processes of T2 and T6. Moisten the surrounding muscles with saline to maintain hydration. Now attach the electrode array to the micro manipulator of a stereotactic instrument. Insert it vertically into the T3 dorsal horn of the spinal cord through the dorsal median sulcus. Then insert the reference electrode into the back muscle. For stimulation, load a micros syringe connected to a silicone catheter having multiple holes with bradykinin solution. Inject four microliters of the solution and induce cardiac nociceptive stimulation. Observe heart rate and neuronal discharge changes in the T3 spinal cord dorsal horn within 30 minutes of injection. Launch the software to import the recorded neural data in .ns6 format. Drag and drop the .ns6 file into the program. Select file and click on save as, then choose the next .nex5 format to generate standardized spike train data. Import the converted .nex5 files into the classification software. Execute the relevant code for filtering and categorizing the signals. Then sort spike waveforms based on waveform characteristics and principle component analysis with threshold parameters set at plus or minus three standard deviations from baseline noise. Analyze the cardiac locked spinal dorsal horn neurons by launching MATLAB. Define the experimental parameters. Click run to execute. Neurons recorded from channel 19, showed dense rhythmic spike trains with a symmetrical correlation pattern and tightly clustered waveform groups on PCA. Neurons from channel 11 split into three distinct firing profiles, each with unique auto correlation features and PCA waveform clusters. Cardiac locked neurons on Channel 17 C and 21 A fired rhythmically with ECG are waves at baseline, but bradykinin disrupted this pattern and introduced new spike clusters between the P and Q waves. MAPC6 restored our wave locked firing, although this rhythmicity declined again post MAPC6. Bradykinin sharply increased the proportion of excited neurons while MAPC6 reduced this response. Conversely, inhibitory neuron proportions dropped with bradykinin but recovered after MAPC6. Chan21a fired in sync with the ECG P wave at baseline, clustered between P and Q waves after bradykinin and relocked to the P wave following MAPC6.