Subregions of human MT complex revealed by comparative MEG and direct electrocorticographic recordings.

Abstract

OBJECTIVE:

To locate the visual motion complex (MT+) and study its response properties in an epilepsy surgery patient.

METHODS:

A 17-year-old epilepsy patient underwent invasive monitoring with subdural electrodes in the right temporo-parieto-occipital area. MT+ was investigated by cortical electric stimulation and by epicortical visual evoked potentials time-locked to motion onset of sinusoidal gratings (motion VEP). Motion-related visual evoked magnetic field (motion VEF) was also recorded before the electrode implantation to complement the invasive recording.

RESULTS:

Motion VEPs revealed two subregions within MT+, generating early and late potentials respectively. The early activity with a peak around 130 ms was localized at a single electrode situated immediately caudal to the initial portion of the ascending limb of the superior temporal sulcus (AL-STS). The late activity, peaking at 242-274 ms, was located ventro-rostrally over three electrodes. Among the four electrodes with motion VEPs, cortical stimulation at the most caudal pair elicited motion-in-depth perception involving the whole visual field. In addition to two subregions revealed on the gyral crown, magnetoencephalography (MEG) demonstrated another subregion with a late motion VEF in AL-STS immediately rostral to the electrode with the early motion VEP.

CONCLUSIONS:

In combination with MEG recording, the present invasive exploration demonstrated human MT+ in a focal area of the temporo-parieto-occipital junction and delineated possible three subregions as indicated by the different latencies and distributions of the motion VEP/VEFs.

SIGNIFICANCE:

Comparative MEG and direct electrocorticographic recordings delineated possible subregions within the human MT complex.

• Authors: R Matsumoto, A Ikeda, T Nagamine, M Matsuhashi, S Ohara, J Yamamoto, K Toma, N Mikuni, J Takahashi, S Miyamoto, H Fukuyama, H Shibasaki
• Journal: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology (Clin Neurophysiol) Vol. 115 Issue 9 Pg. 2056-65 (Sep 2004) ISSN: 1388-2457 [Print] Netherlands
• PMID: 15294208 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adolescent
• Electric Stimulation
• Electrodes, Implanted
• Electroencephalography
• Epilepsy, Complex Partial (physiopathology)
• Evoked Potentials, Visual (physiology)
• Humans
• Magnetoencephalography
• Male
• Motion Perception (physiology)
• Parietal Lobe (physiology)
• Subdural Space
• Temporal Lobe (physiology)
• Visual Cortex (physiology)