Decomposing Motor Lateralization in the MID Task
Poster No:
1700
Submission Type:
Abstract Submission
Authors:
Chen Zheng1, Tianye Jia1
Institutions:
1Fudan University, Shanghai, Shanghai
First Author:
Co-Author:
Introduction:
Although voluntary movements have traditionally been attributed to the contralateral motor cortices, significant evidence shows the involvement of ipsilateral cortices (Bundy, 2019). However, the precise role of both hemispheres in motor control remains unclear.
Methods:
Longitudinal fMRI and behavioral data from the IMAGEN project were utilized, including right-handed participants at their ages 14 (baseline, n=1540), 19 (follow-up 2, n=1062), and 24 (follow-up 3, n=856) (Schumann 2010). Participants respond to left/right cues by pressing the button with the corresponding hand in a modified Monetary Incentive Delay (MID) task (Knutson, 2001). The first-level analysis was conducted, specifying phases (anticipation, pressing, feedback) and conditions (big/small/no win). Regions of interest (ROIs) were defined as intersections of areas exhibiting significant activation (pFWE < 0.05) across conditions and ages in the primary motor cortices (Fig. 1a). The mean activation during anticipation and its correlation with task performance were subsequently calculated.Based on our results and the hence proposed hypothesis that both cortices may share a latent signal irrespective of the hand used, we decomposed the signals of both hemispheres into a bilaterally shared and a lateralized latent signal favoring the contralateral hemisphere using multiple linear regression (MLR), i.e., the high contralateral activation could be understood as an add-up of both latent signals, whereas the low ipsilateral activation was due to a cancellation of both signals. The consistency of this decomposition was then evaluated across different conditions. Also, MLR was employed to determine the voxel-wise contribution to each latent component.
Results:
Contralateral activation exhibited a negative correlation with reaction time (RT), whereas ipsilateral activation showed a positive correlation (Fig. 1b). Activation for one hand predicted RT for both hands, and activation in one condition anticipated RT across conditions, showing a consistent inter-conditon and inter-hand effect, which could be explained by strong correlations between activations (Fig. 1c). To explain the positive correlations between activations, which demonstrated contradictory roles in motor control, we proposed a decomposition model, effectively breaking activations into a bilaterally shared latent signal and a lateralized latent signal, which demonstrated consistently high intra-correlations and low inter-correlations across all conditions (Fig. 2a).While the lateralized signal was negatively correlated with success RT (Fig. 2b), the shared signal showed a strong correlation with success rate, too early rate, too late rate, and overall RT (Fig. 2c). Using MLR, cerebellar regions (Fig. 2d) were found to be significantly associated with the lateralized signals, with the latent signals exhibiting similar correlation patterns with task performance (Fig. 2e-f), with contralateral corticocerebellar projections reversed the polarity of the lateralized results.
Conclusions:
The two hemispheres showed distinct relationships with performance in the MID task. Our decomposition suggests this differentiation may stem from a shared latent signal governing attention and motor initiation, and a lateralized signal controlling motor execution, which was further corroborated by findings in the cerebellum, offering a new perspective on the contralateral control model.
Motor Behavior:
Motor Planning and Execution 1
Perception, Attention and Motor Behavior:
Attention: Auditory/Tactile/Motor 2
Keywords:
Motor
Other - Lateralization
1|2Indicates the priority used for review
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Provide references using APA citation style.
Knutson, B. (2001). Dissociation of reward anticipation and outcome with event-related fMRI. Neuroreport 12(17): 3683-3687.
Schumann, G. (2010). The IMAGEN study: reinforcement-related behaviour in normal brain function and psychopathology. Molecular Psychiatry 15(12): 1128-1139.