Investigating directed influences between activated brain areas in a motor-response task using fMRI

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Functional Neuroimaging

Background:

• Functional neuroimaging excels at localizing cognitive processes.
• Understanding functional interactions between brain regions is vital for a comprehensive grasp of brain function.

Purpose of the Study:

• To apply vector autoregressive modeling with Granger causality to analyze directed connectivity in an event-related fMRI study.
• To investigate causal influence between auditory cortex, supplementary motor area (SMA), and primary motor cortex in a simple auditory-motor paradigm.

Main Methods:

• Utilized vector autoregressive modeling within the Granger causality framework.
• Analyzed directed connectivity using temporal information from brain region time series in a standard event-related fMRI study.
• Employed a simple auditory-motor task involving auditory commands and hand presses.

Main Results:

• Granger causality demonstrated influence from the bilateral auditory cortex and SMA on the left motor cortex in 9 out of 11 subjects.
• Influence from the bilateral auditory cortex and SMA to the right motor cortex was observed in 5 and 6 subjects, respectively.
• The SMA showed Granger causality from the right and left auditory cortex in 7 and 8 subjects, respectively.

Conclusions:

• Granger causality is a valuable tool for exploring effective brain connectivity, even under suboptimal fMRI conditions (TR of 2440 ms).
• Optimizing scanning parameters for temporal resolution is expected to further enhance the potential of Granger causality analysis in neuroimaging.