Selective Activation of Cortical Columns Using Multichannel Magnetic Stimulation With a Bent Flat Microwire Array

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Cortical neural prostheses aim to restore sensory functions but require precise neural targeting.
• Current electrical stimulation methods using intracortical electrodes lack spatial resolution.
• Magnetic stimulation offers potential for selective neural activation, avoiding off-target effects.

Purpose of the Study:

• To develop and evaluate a novel bent flat microwire array for precise cortical stimulation.
• To compare the spatial resolution of magnetic stimulation using different bent wire array designs.
• To demonstrate the effectiveness of bent microwire arrays for selective activation of cortical columns.

Main Methods:

• Developed a computational model to assess magnetic stimulation resolution with 280 and 530 μm tip spacings.
• Fabricated bent flat microwire arrays for experimental validation.
• Utilized calcium imaging (GCaMP6s) in mouse brain slices to assess cortical activation patterns.

Main Results:

• Bent wire arrays produced spatially discrete cortical activations at low stimulus amplitudes.
• 280 μm spacing led to interference at high amplitudes, causing merged or asymmetric activations.
• 340 μm spacing in 4-channel arrays avoided interference, yielding clearer activation patterns than conventional electrodes.

Conclusions:

• Bent wire array design significantly influences the spatial resolution and strength of multichannel magnetic stimulation.
• Novel bent microwire arrays enhance stimulation selectivity in the brain.
• These findings support the development of more effective cortical neural prostheses.