The activity of mirror neurons in macaque ventral premotor cortex (PMv) and primary motor cortex (M1) is modulated by the observation of another's movements. This modulation could underpin well documented changes in EEG/MEG activity indicating the existence of a mirror neuron system in humans. Because the local field potential (LFP) represents an important link between macaque single neuron and human noninvasive studies, we focused on mirror properties of intracortical LFPs recorded in the PMv and M1 hand regions in two macaques while they reached, grasped and held different objects, or observed the same actions performed by an experimenter. Upper limb EMGs were recorded to control for covert muscle activity during observation.The movement-related potential (MRP), investigated as intracortical low-frequency LFP activity (<9 Hz), was modulated in both M1 and PMv, not only during action execution but also during action observation. Moreover, the temporal LFP modulations during execution and observation were highly correlated in both cortical areas. Beta power in both PMv and M1 was clearly modulated in both conditions. Although the MRP was detected only during dynamic periods of the task (reach/grasp/release), beta decreased during dynamic and increased during static periods (hold).Comparison of LFPs for different grasps provided evidence for partially nonoverlapping networks being active during execution and observation, which might be related to different inputs to motor areas during these conditions. We found substantial information about grasp in the MRP corroborating its suitability for brain-machine interfaces, although information about grasp was generally low during action observation.
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http://dx.doi.org/10.1523/JNEUROSCI.5137-14.2015 | DOI Listing |
Neuroscience
January 2025
Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne Australia. Electronic address:
Transcranial alternating current stimulation (tACS) modulates brain oscillations and corticomotor plasticity. We examined the effects of four tACS frequencies (20 Hz, 40 Hz, 60 Hz, and 80 Hz) on motor cortex (M1) excitability and motor performance. In a randomised crossover design, 12 adults received 20-minute tACS sessions, with Sham as control.
View Article and Find Full Text PDFJ Physiol
December 2024
Department of Neuroscience and Movement Science, University of Fribourg, Fribourg, Switzerland.
The human cortical inhibitory system is known to play a vital role for normal brain development, function, and plasticity. GABA is the most prominent inhibitory neurotransmitter in the CNS and is a key regulator not only for motor control and motor learning, but also for cognitive processes. With ageing and many neurodegenerative pathologies, a decline in GABAergic function in several cortical regions together with a reduced ability to task-specifically modulate and increase inhibition in the primary motor cortex has been observed.
View Article and Find Full Text PDFNeuroscience
December 2024
The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, FL, USA; Department of Neurological Surgery, University of Miami Miller School of Medicine, FL, USA; Department of Biomedical Engineering, University of Miami, FL, USA. Electronic address:
The optimal stimulation frequency for inducing neuromodulatory effects remains unclear. The purpose of our study was to investigate the effect of neuromuscular electrical stimulation (NMES) with different frequencies on cortical and spinal excitability. Thirteen able-bodied individuals participated in the experiment involving NMES: (i) low-frequency at 25 Hz, (ii) high-frequency at 100 Hz, and (iii) mixed-frequency at 25 and 100 Hz switched every one second.
View Article and Find Full Text PDFNeuroscience
January 2025
Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
The most characteristic feature of the human electroencephalogram is the peak alpha frequency (PAF). While PAF has been proposed as a biomarker in several diseases and disorders, the disease mechanisms modulating PAF, as well as its physiological substrates, remain elusive. This has partly been due to challenges related to experimental manipulation and invasive procedures in human neuroscience, as well as the scarcity of animal models where PAF is consistently present in resting-state.
View Article and Find Full Text PDFBMJ Open Sport Exerc Med
December 2024
School of Psychology, College of Health and Education, Murdoch University, Murdoch, Western Australia, Australia.
Objectives: Following anterior cruciate ligament reconstruction (ACLR), maladaptive changes occur in the motor cortex representation of the quadriceps, evidenced by increases in intracortical inhibition and facilitation. The primary objective of this proof-of-concept study was to determine if anodal transcranial direct current stimulation (tDCS) can alter quadriceps intracortical inhibition and facilitation in an early-ACLR population after 6 weeks of application during exercise.
Methods: We performed a randomised, triple-blind controlled trial for proof of concept comparing anodal-tDCS to sham-tDCS following ACLR.
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