Correlations between histology and neuronal activity recorded by microelectrodes implanted chronically in the...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Intracortical microelectrodes are crucial for neural recording.
• Long-term stability of neural recordings is often limited by tissue response.
• Understanding the relationship between tissue histology and signal quality is vital.

Purpose of the Study:

• To quantify the relationship between neuronal activity and surrounding tissue histology.
• To investigate how radial distance and time affect this relationship.
• To identify factors influencing the long-term functionality of microelectrode arrays.

Main Methods:

• Implanted 'Utah'-type microelectrode arrays in cats' sensorimotor cortex for 275-364 days.
• Used immunohistochemistry to stain for neuronal (NeuN) and astrocyte (GFAP) markers.
• Applied Pearson's correlation to analyze relationships between histology and recorded neural signals (action potential amplitude and signal-to-noise ratio).

Main Results:

• Signal-to-noise ratio (S/N) correlated with neuron density up to 140 μm, while action potential (AP) amplitude correlated within 80 μm.
• AP amplitude-histology correlations were strongest early post-implantation; S/N-neuron density correlation was strongest near sacrifice.
• S/N showed no significant correlation with glial scarring (GFAP density), unlike AP amplitude.

Conclusions:

• There is an evolving interaction between tissue changes and microelectrode electrical properties.
• Ongoing neuron loss and tissue scarring significantly impact long-term microelectrode functionality.
• Mitigating these tissue responses is key to improving chronic neural recording stability.