Functional anatomy of the mental representation of upper extremity movements in healthy subjects

Abstract

1. Differences in the distribution of relative regional cerebral blood flow during motor imagery and execution of a joy-stick movement were investigated in six healthy volunteers with the use of positron emission tomography (PET). Both tasks were compared with a common baseline condition, motor preparation, and with each other. Data were analyzed for individual subjects and for the group, and areas of significant flow differences were related to anatomy by magnetic resonance imaging (MRI). 2. Imagining movements activated a number of frontal and parietal regions: medial and lateral premotor areas, anterior cingulate areas, ventral opercular premotor areas, and parts of superior and inferior parietal areas were all activated bilaterally when compared with preparation to move. 3. Execution of movements compared with imagining movements led to additional activations of the left primary sensorimotor cortex and adjacent areas: dorsal parts of the medial and lateral premotor cortex; adjacent cingulate areas; and rostral parts of the left superior parietal cortex. 4. Functionally distinct rostral and caudal parts of the posterior supplementary motor area (operationally defined as the SMA behind the coronal plane at the level of the anterior commissure) were identified. In the group, the rostral part of posterior SMA was activated by imagining movements, and a more caudoventral part was additionally activated during their execution. A similar dissociation was observed in the cingulate areas. Individual subjects showed that the precise site of these activations varied with the individual anatomy; however, a constant pattern of preferential activation within separate but adjacent gyri of the left hemisphere was preserved. 5. Functionally distinct regions were also observed in the parietal lobe: the caudal part of the superior parietal cortex [medial Brodmann area (BA) 7] was activated by imagining movements compared with preparing to execute them, whereas the more rostral parts of the superior parietal lobe (BA 5), mainly on the left, were additionally activated by execution of the movements. 6. Within the operculum, three functionally distinct areas were observed: rostrally, prefrontal areas (BA 44 and 45) were more active during imagined than executed movements; a ventral premotor area (BA 6) was activated during both imagined and executed movements; and more caudally in the parietal lobe, an area was found that was mainly activated by execution presumably SII. 7. These data suggest that imagined movements can be viewed as a special form of "motor behavior' that, when compared with preparing to move, activate areas associated heretofore with selection of actions and multisensory integration.(ABSTRACT TRUNCATED AT 400 WORDS)

Looking for the agent: an investigation into consciousness of action and self-consciousness in schizophrenic patients

“…These critical issues have been raised in recent PET experiments in normal subjects. Conditions where subjects were intending actions and preparing for execution, mentally simulating actions, or observing actions performed by other people were compared (Decety et al, 1994(Decety et al, , 1997Grafton et al, 1996;Rizzolatti et al, 1996a;Stephan et al, 1995). The outcome of these studies is two-fold: First, there exists a cortical network common to all conditions, to which the inferior parietal lobule (area 40), the ventral premotor area (ventral area 6), and part of SMA contribute; second, motor representations for each individual condition are clearly specified by the activation of cortical zones which do not overlap between conditions.…”

Dynamic patterns make the premotor cortex interested in objects: influence of stimulus and task revealed by fMRI

“…On the other hand, involved in visually guided motor selection and control [6,16,45,62,68], the preSMA is Table 2 Experiment 2: anatomical specification, mean Talairach coordinates and known to project restrictively to the ventral subregions of reaching activation in this area [3,30,66] activated in the absence of the conscious intention, or even CAU, caudate nucleus; other abbreviations as in Table 1.…”

Cortical activations during paced finger-tapping applying visual and auditory pacing stimuli

“…Some authors have identified a ventral premotor area more ventrally than the above described area lying in the opercular cortex [49]. Table 1 Finally, it is possible that a part of vPMC extends into area Interestingly, the cerebellar activation for both visual conditions were located in the right superior cerebellum (main effect analysis for modality) revealed stronger signal (x516, y5248, z5224) while the cerebellar activations increases bilaterally in the vPMC ( Fig.…”

“…A more ventral and rostral part of the between an imagined trigger stimulus and the motor vPMC is also suggested to be involved in the imagination commands. This interpretation is related to findings linking of complex movements [49], preparation of imitated the caudal part of the dPMC to the learning of visual movements [24], or imitation of movements in general conditional tasks both in monkeys and humans [17,33]. [41, 44,45].…”