Mapping of sheep sensory cortex with a novel microelectrocorticography grid

Area of Science:

• Neuroscience
• Electrophysiology
• Animal Models

Background:

• Microelectrocorticography (µECoG) offers high temporal and spatial resolution for neural recording.
• Understanding cortical organization is crucial for neural information processing.
• The ovine model is suitable for studying sensory cortex function.

Purpose of the Study:

• To evaluate microelectrocorticography (µECoG) for detailed cortical recording of somatosensory evoked potentials (SEPs) in sheep.
• To describe a minimally invasive surgical approach for chronic µECoG implantation.
• To characterize the functional properties and somatotopic organization of the sheep's sensory cortex.

Main Methods:

• Utilized MRI-based 3D brain models for surgical planning.
• Performed a minimally extended craniotomy for dual µECoG grid placement on the somatosensory cortex.
• Conducted acute and chronic recordings of SEPs in an ovine model for up to 16 weeks.

Main Results:

• Identified significant SEP responses in the somatosensory cortex.
• Demonstrated a reliable ipsilateral, somatotopic response pattern (lateral-to-medial) to stimulation of facial areas (nose, lips, chin).
• Found high gamma band activity to be the most spatially specific frequency component of the SEP.

Conclusions:

• The study validates the ipsilateral, somatotopic organization of the sheep sensory cortex.
• The described surgical approach is suitable for chronic µECoG implantation, maintaining sterility.
• This work provides a foundation for future acute and chronic research on the sheep sensory cortex.