Cerebral structures participating in motor preparation in humans: a positron emission tomography study

Abstract

1. Using positron emission tomography and measurement of regional cerebral blood flow (rCBF) as an index of cerebral activity we investigated the central processing of motor preparation in 13 healthy volunteers. 2. We used a motor reaction time paradigm with visual cues as preparatory and response signals. A preparatory stimulus (PS) provided either full, partial, or no information regarding two variables of a forthcoming right finger movement: finger type (index or little finger) and movement direction (abduction or elevation). After a variable delay period, a response stimulus (RS) prompted the movement. A condition was also tested in which the subject could freely select any of the four possible movements during the preparation period ("free" condition). The timing of events was designed to emphasize the motor preparation phase over the motor execution component during the scanning time of 1 min. 3. Distinct preparatory processes, which depended on the information contained in the PS, were demonstrated by significant differences in reaction time between conditions. The reaction time was shorter in the "full" and free conditions, intermediate in the two partial information conditions ("finger" and "direction"), and longer when no preparatory information was available ("none" condition). Conversely, movement time and movement amplitude were similar between conditions, establishing the constancy of the motor executive output. 4. In comparison with a "rest" condition, which had matched visual inputs, the different conditions of motor preparation were associated with increased rCBF in a common set of cerebral regions: the contralateral frontal cortex (sensorimotor, premotor, cingulate, and supplementary motor cortex), the contralateral parietal association cortex (anterior and posterior regions), the ipsilateral cerebellum, the contralateral basal ganglia, and the thalamus. This observation substantiates the participation of those cerebral structures in the preparation for movement. Furthermore, the similarity of the activated areas among the different conditions compared with the rest condition suggests a single anatomic substrate for motor preparation, independent of the movement information context. 5. Differing amounts of movement information contained in the PS affected rCBF changes in some cerebral regions. In particular, the rCBF in the anterior parietal cortex (Brodmann's area 40) was significantly larger in each of the full, finger, and direction conditions, individually, compared with the none condition. This observation supports the hypothesis that the anterior parietal association cortex plays a major role in the use of visual instructions contained in the PS for partial or complete preparation to perform a motor act. On the other hand, the posterior parietal association cortex (Brodmann's area 7) was more activated in the finger, direction, and none conditions than in the full condition. This increased activity with restricted advance information suggests that the posterior region of the parietal corte...

Imaging a cognitive model of apraxia: The neural substrate of gesture‐specific cognitive processes

“…Moreover, a modular organization of internal models of tool manipulation has been recently reported in the cerebellum using fMRI [Imamizu et al, 2003], extending the predictions of the MOSAIC computational model [Haruno et al, 2001;Wolpert and Kawato, 1998] from to the "motor" to the "cognitive" cerebellum. In the present study, we suggest that the vermian cerebellar activation associated with the innervatory pattern stage merely reflects its contribution to movement regulation [Deiber et al, 1996;Jueptner et al, 1996;Kitazawa, 2002] and integration of simple movements into more complex ones [Ramnani et al, 2001;Thach, 1998] during actual movement production. Rothi et al [1991Rothi et al [ , 1997b incorporated in their model the proposal presented by Roy and Square [1985] of a core conceptual, or action semantic, system that involves three kinds of knowledge: knowledge of the functions that tools and objects may serve, knowledge of actions independent of tools, and knowledge about the organization of single actions into sequences.…”

“…Notwithstanding, increased cerebellar activation was reported during movement imagination [Decety et al, 1994;Jueptner et al, 1997], preparation [Deiber et al, 1996;Krams et al, 1998], and observation with the aim to imitate [Grèzes et al, , 1999, although the highest activations are usually found during actual movement execution [Deiber et al, 1996;Jueptner et al, 1997;Krams et al, 1998]. Cerebellum plays also a significant role in the early phases of acquisition and planning of motor sequences [Doyon et al, 2002], and is known to participate in a wide variety of cognitive and emotional processes [e.g., see Marien et al, 2001;Middleton and Strick, 1998;Rapoport et al, 2000;Salman, 2002].…”

The contribution of the right supra-marginal gyrus to sequence learning in eye movements

“…Neural activity in the SMG has previously been shown to be important for the preparation of limb movements, even when they are not actually executed (Deiber, Ibanez, Sadato & Hallet, 1996;Deiber, Ibanez, Honda, Sadato, Raman & Hallett 1998;Krams, Rushworth, Deiber, Frackowiak & Passingham, 1998).…”

Parieto-frontal gamma band activity during the perceptual emergence of speech forms

“…The specific signification of increased gamma band activities observed in the supramarginal gyrus is less clear. The supramarginal gyrus has been associated with temporary storage of phonological material (Paulesu, Frith and Frackowiak, 1993;Cohen et al, 1997;Jonides et al, 1998;Honey, Bullmore and Sharma, 2000), phonological judgements (Romero, Walsh and Papagno, 2006), motor preparation (Deiber et al, 1996), and motor attention (Rushworth, Krams and Passingham, 2001). The present study cannot disambiguate the specific contribution of the supramarginal gyrus to these processes.…”