Abstract
Movement covariates, such as electromyographic or kinematic activity, have been proposed as candidates for the neural representation of hand control. However, it remains unclear how these movement covariates are reflected in electroencephalographic (EEG) activity during different stages of grasping movements. In this exploratory study, we simultaneously acquired EEG, kinematic and electromyographic recordings of human subjects performing 33 types of grasps, yielding the largest such dataset to date. We observed that EEG activity reflected different movement covariates in different stages of grasping. During the pre-shaping stage, centro-parietal EEG in the lower beta frequency band reflected the object’s shape and size, whereas during the finalization and holding stages, contralateral parietal EEG in the mu frequency band reflected muscle activity. These findings contribute to the understanding of the temporal organization of neural grasping patterns, and could inform the design of noninvasive neuroprosthetics and brain-computer interfaces with more natural control.
Highlights
The pathway between the brain and the hand, which enables the motor control of reaching and grasping movements, has been of interest to scientists for many decades[1,2,3,4,5,6,7]
Knowledge is still lacking about how the neural mechanisms behind the neural decoders of distinct grasping movements are represented in electroencephalography (EEG), and how these EEG representations are related to the behavioral response described by covariates of movements such as those that result from muscle or kinematic activity
To gain a better understanding of the mechanisms that the brain uses to conduct goal-directed movements, researchers seek and evaluate representational models[25] that can capture differences between movements by comparing behavioral movement features with neural patterns[26,27,28,29]. Such models can be used to address the relation between the movement patterns encoded in specific brain regions, and the extent to which the neural representation of the movement is reflected in the patterns of different movement covariates
Summary
The pathway between the brain and the hand, which enables the motor control of reaching and grasping movements, has been of interest to scientists for many decades[1,2,3,4,5,6,7]. The findings of previous studies have revealed differences in the EEG neural correlates of different movements of the same arm/hand (e.g., supination/pronation, opening/closing)[48], as well as among three grasp types: power, pincer and intermediate grasps[21,49] It is still unclear whether different brain areas and frequency bands are involved in different stages of the grasping movement, and which covariates of the grasping movement are encoded in these brain patterns. We believe that exploratory approaches in the case of broad research questions are as relevant as the confirmatory approaches for specific, narrowed down questions[50,51] In this exploratory study, we chose to investigate the similarity in human grasping movements between EEG representations and their associated movement covariates, in three stages of the grasping movement: hand pre-shaping, reach of the final grasping position and holding. We conducted this study at a group level, and applied representational similarity analysis (RSA)[52,53,54] to investigate the similarities among the effects of the neural, behavioral (muscle and kinematic) representations and categorical models at different stages of grasping movements
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