Stimulation of Patterned Neuronal Cultures by a Magnetic Field

Take a patterned coverslip with a neuronal ring culture within a culture plate containing an extracellular recording solution.

These cells are preincubated with a calcium-sensitive fluorescent dye to measure intracellular calcium levels.

Place the plate on a fluorescence microscope stage.

Position the circular magnetic coil connected to a magnetic stimulator concentrically at a suitable distance above the culture to ensure optimal stimulation.

Using the magnetic stimulator, apply high voltage and current through the coil to generate a time-varying magnetic field.

This magnetic field induces an electric field in the neurons, generating an action potential.

Upon reaching the nerve terminal, the action potential activates the voltage-gated calcium channels, allowing calcium influx into the cell and neurotransmitter release at the synapse.

This release facilitates signal transmission to the neighboring neurons through synaptic connections.

Due to the calcium ion influx, these ions bind to the intracellular calcium-sensitive dye, increasing fluorescence indicative of neuronal activity.

To begin magnetic stimulation, position a neuronal culture, grown in a circular shape pattern, under the microscope. Stimulate the culture using a standard circular magnetic stimulation coil and a supporting stimulator, which are commercially available.

To stimulate the cultures with non-standard magnetic field intensities, connect a custom-made magnetic stimulation coil to the custom-built stimulator. Then, with an aid of a laser pointer, align the center of the culture to the center of the coil to ensure successful stimulation.

Adjust the coil position so that it remains approximately five millimeters above the center of the culture. Once the stimulation coil is properly positioned, load the stimulator to a potential of up to five kilovolts. Then, using a high-current, high-voltage switch, discharge the high voltage and current through the stimulation coil to generate a magnetic pulse that stimulates the activity of the cultured neurons.