Cd. Mackinnon et al., CONTRIBUTIONS OF THE MESIAL FRONTAL-CORTEX TO THE PREMOVEMENT POTENTIALS ASSOCIATED WITH INTERMITTENT HAND MOVEMENTS IN HUMANS, Human brain mapping, 4(1), 1996, pp. 1-22
Citations number
79
Categorie Soggetti
Neurosciences,"Radiology,Nuclear Medicine & Medical Imaging
Two premovement potentials, the bereitschaftspotential (BP) and negati
ve slope (NS'), can be recorded prior to the execution of self-paced h
and movements using back-averaging of scalp electrical recordings. The
contributions of the contralateral and ipsilateral primary motor cort
ex (M1) and the mesial dorsal frontal cortex (MFC) to the generation o
f the potentials were examined by simultaneously collecting positron e
mission tomography (PET) scans and scalp recorded electrical activity
for dipole source analysis in eight right-handed normal subjects. Subj
ects performed simple unilateral thumb-finger opposition movements int
ermittently with an average inter-movement interval of 7.4 s. PET was
also collected for the same movement performed repetitively with inter
-movement intervals of 0.5 s such that finger movements were nearly co
ntinuous. PET studies of the intermittent movement revealed marked act
ivation of the MFC in the region of the rostral supplementary motor ar
ea (SMA) and cingulate motor area, contralateral sensorimotor cortex a
nd no activation of the ipsilateral sensorimotor cortex. When the same
movements were performed in a continuous repetitive manner, PET revea
led strong contralateral sensorimotor and caudal MFC activation, and n
o ipsilateral sensorimotor or rostral MFC activation. Dipole source so
lutions of the back-averaged potentials for the intermittent movements
were analyzed by testing dipole vectors placed into the regions of PE
T activation. The premovement potentials were dominated by dipoles in
the region of the MFC, with minimal contribution from either the contr
alateral or ipsilateral MI. Activation in the region of the contralate
ral M1 began near the onset of muscle activity. The orientation and ti
ming of the MFC dipoles were consistent with both the BP and NS' poten
tials originating from neurons in the rostral SMA and dorsal tier of t
he cingulate sulcus and were appropriate for MFC activity to contribut
e to both the preparation for movement and the descending activation o
f spinal motor networks. (C) 1996 Wiley-Liss, Inc.