Abstract

Interplay between posterior parietal cortex (PPC) and ipsilateral primary motor cortex (M1) is crucial during execution of movements. The purpose of the study was to determine whether functional PPC-M1 connectivity in humans can be modulated by sensorimotor training. Seventeen participants performed a sensorimotor training task that involved tapping the index finger in synchrony to a rhythmic sequence. To explore differences in training modality, one group (n = 8) learned by visual and the other (n = 9) by auditory stimuli. Transcranial magnetic stimulation (TMS) was used to assess PPC-M1 connectivity before and after training, whereas electroencephalography (EEG) was used to assess PPC-M1 connectivity during training. Facilitation from PPC to M1 was quantified using paired-pulse TMS at conditioning-test intervals of 2, 4, 6, and 8 ms by measuring motor-evoked potentials (MEPs). TMS was applied at baseline and at four time points (0, 30, 60, and 180 min) after training. For EEG, task-related power and coherence were calculated for early and late training phases. The conditioned MEP was facilitated at a 2-ms conditioning-test interval before training. However, facilitation was abolished immediately following training, but returned to baseline at subsequent time points. Regional EEG activity and interregional connectivity between PPC and M1 showed an initial increase during early training followed by a significant decrease in the late phases. The findings indicate that parietal-motor interactions are activated during early sensorimotor training when sensory information has to be integrated into a coherent movement plan. Once the sequence is encoded and movements become automatized, PPC-M1 connectivity returns to baseline.

Links

Publisher Full Text

Authors

Karabanov A, Jin SH, Joutsen A, Poston B, Aizen J, Ellenstein A, Hallett M

Institution

Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA. ankenk@drcmr.dk

Source

Journal of neurophysiology 107:11 2012 Jun pg 3190-9

MeSH

Acoustic Stimulation
Adult
Female
Humans
Learning
Male
Motor Cortex
Neural Pathways
Parietal Lobe
Photic Stimulation
Psychomotor Performance
Time Factors
Transcranial Magnetic Stimulation
Young Adult

Pub Type(s)

Journal Article
Research Support, N.I.H., Intramural

Language

eng

PubMed ID

22442568