Neurophysiological correlates of tactile width discrimination in humans

Abstract

Tactile information processing requires the integration of sensory, motor, and cognitive information. Width discrimination has been extensively studied in rodents, but not in humans. Here, we describe Electroencephalography (EEG) signals in humans performing a tactile width discrimination task. Comparison of changes in Spectral Power Density during two different periods of the task corresponding to the discrimination of the tactile stimulus and the motor response, revealed the engagement of a complex network associated with the electrodes recording from fronto-temporo-parieto-occipital areas and across multiple frequency bands. Analysis of ratios of higher [Ratio1:(0.5-20Hz)/(0.5-45Hz)] or lower frequencies [Ratio2: (0.5-4.5Hz)/(0.5-9Hz)], also revealed that the periods of tactile discrimination and motor response, were accompanied by changes in these ratios. Further analysis of the tactile discrimination period demonstrated that ratios of frequencies recorded from electrodes located in fronto-parietal regions were correlated to tactile width discrimination performance between subjects, while the dynamics in parietal and occipital electrodes were correlated to the changes in performance within subjects. These results support the notion that a bilateral asymmetrical widespread network is associated with tactile width discrimination.