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PubMed Central
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Comparing information about arm movement
direction in single channels of local and epicortical field potentials
from monkey and human motor cortex.
Mehring C, Nawrot MP, de Oliveira SC, Vaadia E, Schulze-Bonhage A, Aertsen A, Ball T.
Institute
for Biology I, Hauptstr. 1, Albert-Ludwigs-University, 79104 Freiburg,
Germany; Berstein Center for Computational Neuroscience,
Albert-Ludwigs-University, 79104 Freiburg, Germany.
Cortical
field potentials have been used for decades in neurophysiological
studies to probe spatio-temporal activity patterns of local populations
of neurons. Recently, however, interest in these signals was spurred as
they were proposed as potential control signals for neuronal motor
prostheses, i.e., for devices fit to record and decode brain activity
to restore motor functions in paralyzed patients. Little is known,
however, about the functional significance of these cortical field
potentials. Here we compared information about arm movement direction
in two types of movement related cortical field potentials, obtained
during a four direction center-out arm reaching paradigm: local field
potentials (LFPs) recorded with intracortical micro-electrodes from
monkey motor cortex, and epicortical field potentials (EFPs) recorded
with macro-electrode arrays subdurally implanted on the surface of the
human cerebral cortex. While monkey LFPs showed a typical sequence of
positive and negative potential peaks, an initial negative peak was the
most salient feature of human EFPs. Individual contralateral LFPs from
the monkey motor cortex carried approximately twice as much decoded
information (DI) about arm movement direction (median 0.27bit) as did
individual EFPs from the contralateral hand/arm area of primary motor
cortex in humans (median 0.12bit). This relation was similar to the
relation between median peak signal-to-noise ratios for directional
modulation of movement related potentials (MRPs) of both types of
signals. We discuss possible reasons for the observed differences,
amongst them epi- vs. intracortical recording and the different
electrode dimensions used to measure EFPs and LFPs.
PMID: 16310349 [PubMed - as supplied by publisher]
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