Functional Specialisation and Effective Connectivity in Cerebral Motor Cortices: An fMRI Study on Seven Right Handed Female Subjects
- Author:
Ahmad Nazlim Yusoff
;
Mazlyfarina Mohamad
;
Aini Ismafairus Abd Hamid
;
Wan Ahmad Kamil Wan Abdullah
;
Mohd Harith Hashim
;
Nurul Zafirah Zulkifli
- Publication Type:Journal Article
- From:Malaysian Journal of Medicine and Health Sciences
2010;6(2):71-92
- CountryMalaysia
- Language:English
-
Abstract:
Objective: This study investigates functional specialisation in, and effective connectivity between the precentral gyrus (PCG) and supplementary motor area (SMA) in seven right handed female subjects. Methods: Unimanual (UNIright and UNIleft) and bimanual (BIM) self-paced tapping of hand fingers were performed by the subjects to activate PCG and SMA. Brain activations and effective connectivity were analysed using statistical parametric mapping (SPM), dynamic causal modeling (DCM) and Bayesian model selection (BMS) and were reported based on group fixed (FFX) and random (RFX) effects analyses. Results: Group results showed that the observed brain activation for UNIright and UNIleft fulfill contralateral behavior of motor coordination with a larger activation area for UNIright. The activation for BIM occurs in both hemispheres with BIMright showing higher extent of activation as compared to BIMleft. Region of interest (ROI) analyses reveal that the number of activated voxel (NOV) and percentage of signal change (PSC) on average is higher in PCG than SMA for all tapping conditions. However, comparing between hemispheres for both UNI and BIM, higher PSC is observed in the right PCG and the left SMA. DCM and BMS results indicate that most subjects prefer PCG as the intrinsic input for UNIright and UNIleft. The input was later found to be bi-directionally connected to SMA for UNIright.The bi-directional model was then used for BIM in the left and right hemispheres. The model was in favour of six out of seven subjects. DCM results for BIM indicate the existance of interhemispheric connectivity between the right and left hemisphere PCG. Conclusion: The findings strongly support the existence of functional specialisation and integration i.e. effective connectivity in human brain during finger tapping and can be used as baselines in determining the probable motor coordination pathways and their connection strength in a population of subjects
