Dipole Source Localisation and fMRI
of Simultaneously Recorded Data
Applied to Somatosensory Categorisation


Sebastian Thees, Felix Blankenburg, Birol Taskin, Gabriel Curio and Arno Villringer

In this recent work human brain activity at high spatiotemporal resolution was recorded noninvasivly, using simultaneously EEG and fMRI. Brain activity was imaged while the subjects performed a bimodal categorisation of a somatosensory stimulation (a so called choice reaction task, CRT). They had to decide whether a single puls stimulation of the left whrist had a low or high amplitude. To seperate activity related to categorisation, a control-experiment was performed. Here the subjects only had to confirm the stimulation (a so called simple reaction task, SRT).
choice reaction task simple reaction task

fMRI and dipole source localisation showed consistent activations of the contralateral primary and secondary cortex, the SMA and the posterior ACC in the medial wall and the anterior poles of the insulae.
For the choice reaction task 3D-animated views of the activations at these sites in fMRI and dipole source localisation and the time courses of the respective dipol- moments are given below (images and animations were computed using AMIRA):

 

 

Brain activity of the choice reaction task, resolved by fMRI and dipole source analysis.
show activation at:
select the qualitiy / size of animation

Dipole-moments time courses for the two tasks of the dipole shown in the animation above. The dipole moment strength is a measure for brain activity.