Influence of touching an object on corticospinal excitability during motor imagery

• Published in: Experimental brain research 2009-07, Vol.196 (4), p.529-535
• Main Authors: Mizuguchi, Nobuaki, Sakamoto, Masanori, Muraoka, Tetsuro, Kanosue, Kazuyuki
• Format: Article
• Language: English
• Subjects: Adult; Afferent Pathways - physiology; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Brain Mapping; Electrodes; Electroencephalography; Evoked Potentials, Motor - physiology; Evoked Potentials, Somatosensory - physiology; Fingers - innervation; Fingers - physiology; Fundamental and applied biological sciences. Psychology; Humans; Imagination - physiology; Male; Mechanoreceptors - physiology; Median Nerve - physiology; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Motor Cortex - physiology; Movement - physiology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Neural Conduction - physiology; Neural Pathways - physiology; Neurology; Neuropsychological Tests; Neurosciences; Psychomotor Performance - physiology; Pyramidal Tracts - physiology; Research Article; Somatosensory Cortex - physiology; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Touch - physiology; Touch Perception - physiology; Transcranial Magnetic Stimulation; Vertebrates: nervous system and sense organs; Young Adult
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-009-1875-5

We investigated whether corticospinal excitability during the imagery of an action involving an external object was influenced by actually touching the object. Corticospinal excitability was assessed by monitoring motor evoked potentials (MEPs) in the first dorsal interosseous muscle following transcranial magnetic stimulation over the motor cortex during imagery of squeezing a ball--with or without passively holding the ball. The MEPs amplitude during imagery when the ball was held was larger than that when the ball was not held. The MEPs amplitude was not modulated just by holding the ball. In the same experimental condition, the somatosensory evoked potentials (SEPs) in response to the stimulation of median nerve were not modulated by motor imagery or by holding the ball. These results suggest that the corticospinal excitability during imagery of squeezing a ball is enhanced with the real touch of the ball, and the enhancement would be caused by some changes along the corticospinal pathway itself and not by the change in responsiveness along the afferent pathway to the primary somatosensory cortex.