Mental representations of movements. Brain potentials associated with imagination of hand movements

Abstract

The present study was designed in order to contribute towards the understanding of the physiology of motor imagery. DC potentials were recorded when subjects either imagined or executed a sequence of unilateral or bilateral hand movements. The sequence consisted of hand movements in 4 directions, forwards, backwards, to the right and to the left, and varied from trial to trial. The sequence had been cued by visual targets on a computer screen and had to be memorized before the trial was initiated. Changes of DC potentials between task execution and imagination were localized in central recordings (C3, Cz, C4) with larger amplitudes when executing the task than when imagining to do so. Stimulation of peripheral receptors associated with task execution or a different level of activation of the cortico-motoneural system could account for this finding. The main result of the present study was that with unilateral performance, the side of the performing hand (right, left) had localized effects in recordings over the sensorimotor hand area (C3, C4) which were qualitatively the same with imagination and execution and quantitatively similar (i.e., without significant difference). Performance of the right hand augmented negative DC potentials in C3, performance of the left hand augmented amplitudes in C4. This result is consistent with the assumption that the primary motor cortex is active with motor imagery. Finally, the question has been addressed whether motor imagery may involve the left hemisphere to a larger extent than the execution of the movement. It is shown that a particular contribution of the left hemisphere associated with motor imagery may only show up under strictly controlled conditions.

Memory for pantomimed actions versus actions with real objects

“…Three varieties of action encoding are included because evidence from a variety of methods (hemodynamic imaging, magnetoencephalography, ERPs, single-unit recording) indicate some overlap in the brain areas engaged during execution of an action, motor imagery, and watching someone else perform an action (Beisteiner et al, 1995;Cunnington et al, 1996;Hari et al, 1998;Grafton et al, 1996;Grezes and Decety, 2001;Rizzolatti et al, 1996;Schnitzler et al, 1997). If episodic retrieval involves some degree of recapitulation of study-phase activity, there is thus reason to expect common brain activity when participants retrieve memories with an action element.…”

Electric and magnetic fields of the brain accompanying internal simulation of movement

“…Slow brain potentials (SPs) were recorded when subjects executed motor sequences of either hand or when they imagined to do so [1]. At locations above the MI-hand area (left MI: C3; right MI: C4) amplitudes of SPs systematically varied with the side executing the task: movements by the right hand caused an increase of negative SPs in C3.…”

“…Changes of SPs between these conditions were localized in central recordings (C3, Cz, C4) with larger amplitudes when executing the tasks than when imagining to do so. Proprioceptive and kinaesthetic input with task execution or an enhanced level of activation of the cortico-motoneural system with task execution may account for this difference [1].…”

Motor Facilitation While Observing Hand Actions: Specificity of the Effect and Role of Observer's Orientation

“…Elements of this common circuitry involve the supplementary motor area (SMA), the premotor cortex, the superior temporal sulcus, the inferior frontal cortex (area 45), and the inferior parietal cortex (area 40). More recently, modulation of the activity of the primary motor cortex (M1) during mental imagery (Beisteiner et al 1995;Fadiga et al 1999;Pascual-Leone et al 1993Porro et al 1996;Roth et al 1996) and observation of hands or actions (Fadiga et al 1995;Ganis et al 2000;Hari et al 1998;Nishitani and Hari 2000;Strafella and Paus 2000) has been reported in neurophysiologic studies. One of the techniques that has been used in these studies is transcranial magnetic stimulation (TMS) (Abbruzzese et al 1996;Fadiga et al 1995Fadiga et al , 1999Hashimoto and Rothwell 1999;Ikai et al 1996;Kasai et al 1997;Pascual-Leone et al 1993.…”