Microelectrode arrays for stimulation of neural slice preparations

Area of Science:

• Neuroscience
• Electrophysiology
• Biomedical Engineering

Background:

• Understanding neural circuit connectivity is crucial for deciphering sensory processing.
• Existing electrode technologies present limitations in high-resolution spatial mapping of neural responses.
• The substantia gelatinosa (SG) plays a key role in pain modulation, but its network organization remains incompletely understood.

Purpose of the Study:

• To develop and utilize a novel planar electrode array for high-resolution neural recordings.
• To investigate the spatial patterns of neural interconnectivity within the rodent spinal cord's substantia gelatinosa.
• To explore the functional organization of SG neurons in response to afferent and direct electrical stimulation.

Main Methods:

• Fabrication of a 6x6 planar array of platinized iridium microelectrodes (10 µm diameter, 100 µm pitch) with reference electrodes.
• Acute preparation of rodent spinal cord slices for ex vivo electrophysiological recordings.
• Whole-cell, tight-seal intracellular recordings from single neurons in the substantia gelatinosa (SG).
• Stimulation of primary afferent fibers and individual electrodes of the array to map neural responses.

Main Results:

• The electrode array enabled low-noise, high-resolution intracellular recordings of neuronal electrical activity.
• Spatial mapping of responses revealed limited interconnectivity among SG neurons surrounding the recorded cell.
• Strong excitatory or inhibitory responses were observed from electrodes oriented longitudinally (rostral-caudal) to the recorded neuron.

Conclusions:

• The developed iridium electrode array is effective for detailed spatial neurophysiological analysis.
• The substantia gelatinosa appears organized into largely independent networks.
• Network organization may be related to sensory modality and specific body region inputs, suggesting functional segregation within the SG.