Trans-Spinal Direct Current Stimulation of a Rat's Spinal Motoneuron
Transcription
To place the trans-spinal direct current stimulation electrodes, place a saline-soaked sponge on the dorsal side of the TH-12 vertebra, and use fine manipulation to press the sponge with an active trans-spinal direct current stimulation electrode. Then, mount a custom-pulled microelectrode onto the micromanipulator, allowing a 1 to 2-micron stepping movement and stereotaxic calibration, and drive a micropipette tip into a selected patch in the PR at a 15 to 20-degree medial-lateral angle.
To record the motor neuron membrane and firing properties, in the bridge mode of the intracellular amplifier, stimulate the respective nerve branches to identify the motor neuron on the basis of the all-or-nothing appearance of the antidromic action potential.
In the discontinuous current clamp mode of the intracellular amplifier with a current switch rate mode of 4 to 8 kilohertz, use a 0.5-millisecond intracellular depolarizing current pulses to evoke an orthodromic action potential in a motor neuron.
To calculate the cell input resistance, stimulate a motor neuron with 40 short 100-millisecond pulses of hyperpolarizing 1 nanoamp current. To determine the rheobase value as the minimum amplitude of the depolarizing current required to elicit a single spike, stimulate a motor neuron with 50-millisecond square wave pulses at increasing amplitudes.
Then, inject 500-millisecond square wave pulses of depolarizing current at increasing amplitudes in 0.122 nanoamp steps to evoke rhythmic discharges of motor neurons. For trans-spinal direct current stimulation, start the polarization procedures by trans-spinal application of direct current, while maintaining a stable penetration of the motor neuron.
