Spatial and Spectral Changes in Cortical Surface Potentials during Pinching versus Thumb and Index Finger Flexion

Electrocorticographic (ECoG) signals provide high-fidelity representations of sensorimotor cortex activation during contralateral hand movements. Understanding the relationship between independent and coordinated finger movements along with their corresponding ECoG signals is crucial for precise brain mapping and neural prosthetic development. We analyzed subdural ECoG signals from three adult epilepsy patients with subdural electrode arrays implanted for seizure foci identification. Patients performed a cue-based task consisting of thumb flexion, index finger flexion or a pinching movement of both fingers together. Broadband power changes were estimated using principal component analysis of the power spectrum. All patients showed significant increases in broadband power during each movement compared to rest. We created topological maps for each movement type on brain renderings and quantified spatial overlap between movement types using a resampling metric. Pinching exhibited the highest spatial overlap with index flexion, followed by superimposed index and thumb flexion, with the least overlap observed for thumb flexion alone. This analysis provides practical insights into the complex overlap of finger representations in the motor cortex during various movement types, and may help guide more nuanced approaches to brain-computer interfaces and neural prosthetics. SIGNIFICANCE STATEMENTThis study measured brain activity actively during finger movement and found that pinching movements show higher cortical overlap with index finger flexion and uniquely engage parietal regions, advancing our understanding of motor control hierarchy and sensorimotor integration, while suggesting improvements for more naturalistic brain-computer interfaces through prioritized index finger decoding and integration of parietal lobe measurements.