Neural Correlates Of Vibrotactile Frequency And Spatial Pattern Discrimination

Tactile perception relies on both temporal (frequency) and spatial (amplitude) dimensions of tactile stimuli. Meanwhile, there exist widespread interactions between tactile perception and perception of stimuli of other sensory modalities. Our study is to explore the neural mechanisms during the discrimination of different tactile information and their interactions with other perception channels by using EEG and fMRI techniques.In the current study, vibrotactile stimuli were used, which included both frequency and spatial (shape) domain information. In the EEG experiment, subjects performed the vibrotactile frequency or spatial pattern discrimination tasks in a delay-match-to-sample paradigm. We found:1) P200component during the first tactile stimulus period shows significant amplitude differences between the two tasks, indicating the attention on different dimensions of stimuli;2) the memory maintenance of the frequency and spatial pattern information may be related to the Late Positive Component(LPC);3) the comparison and decision-making of tactile information in the two tasks may be indicated by the Late Component(LC).In our fMRI experiment, with a similar paradigm and vibrotactile stimuli created by an fMRI compatible vibrotactile stimulator, subjects wearing eye masks performed the two tasks. We observed significant activation in primary visual cortex in the spatial pattern discrimination task but not in the vibrotactile frequency discrimination task. Along with the specific EEG component, this finding reveals that visual cortex is involved in the maintenance of tactile spatial pattern, suggesting the interaction between the visual and tactile channels when memorizing the spatial pattern of tactile information.Generally, for the first time, we used EEG and fMRI to investigate the neural mechanisms underlying the tactile working memory in two stimulus domains: frequency and spatial pattern, and found EPRs related to the neural process of coding, maintaining and decision-making in the tactile DMS task. The fMRI results further indicated the primary visual cortex might be involved in the maintenance of spatial pattern(shape) but not frequency information during the delay task.