Poster #: 100
Wednesday, Sep 9, 2015
MMN distributed sources – evidence from human intracranial recordings
1Institute of Cellular Biology and Neuroscience, CONICET - University of Buenos Aires, Buenos Aires, Argentina
2University of Cambridge, Cambridge, United Kingdom
3National University of La Plata, Argentina
4CONICET - University of Buenos Aires, Buenos Aires, Argentina
5University of Cambridge, United Kingdom
In order to investigate MMN sources we recorded electrocorticography (ECoG) and/or Stereo-electroencephalography (SEEG) in 14 patient candidates for epilepsy surgery, covering temporal, parietal, occipital and frontal cortices.
We used three paradigms to evoke MMN potential.
1- An auditory MMN paradigm (Näätänen et al. 2004), alternating standard tones with deviant tones. Performed by 13 patients.
2- Four series of 5 complex tones (Bekinschtein et al, 2009). Two using the same 5 sounds and two with the final sound swapped. Performed by 6 patients.
3- A modification of the previous paradigm (Chennu et al 2013), where sequences were either monaural or interaural. Performed by 7 patients.
Channels with epileptic activity or noise were discarded, and a total of 683 channels were analyzed. Local average reference was used to improve signal from local sources compared to distant ones. MMN potentials were analyzed with paired t-test (p<0.01 for a least 25ms).
The greatest amplitude MMN was located in the left Heschl gyrus, however no electrodes were recorded from the right Heschl gyrus for comparison. Furthermore, we found most consistent activations located in right hemisphere in the superior temporal gyrus, middle temporal gyrus, anterior central gyrus, inferior frontal gyrus, and superior parietal lobule. In the left hemisphere activations were located in superior temporal gyrus, middle temporal gyrus, anterior central gyrus, inferior frontal gyrus, middle frontal gyrus and superior frontal gyrus.
These results reveal that MMN sources, evoked by different paradigms and found in different patients, are consistently distributed in a fronto-temporo-parietal network