Complexity affects regional cerebral blood flow change during sequential finger movements

Abstract

Brain regions activated with complex sequential finger movements were localized by measuring regional cerebral blood flow (rCBF) with positron emission tomography. Whereas the total number and frequency of finger movements were kept constant, the complexity of auditory cued sequential finger movements of the right hand varied, with sequence length as the independent variable. In four conditions of differing complexity, the bilateral primary sensorimotor area, left ventral premotor cortex, posterior supplementary motor area, right superior part of the cerebellum, and left putamen were consistently and equally activated. This finding suggests an executive role in running sequences, regardless of their length. The right dorsal premotor cortex (Brodmann area 6) and the right precuneus (Brodmann area 7) showed a linear increase of rCBF as sequence complexity increased. This finding is consistent with the hypothesis that these areas function in the storage of motor sequences in spatial working memory and the production of ongoing sequential movement with reference to that of buffered memory. A similar increase in the cerebellar vermis and the left thalamus likewise suggests a role of these subcortical structures in complexity of sequential finger movements. Conversely, the left inferior parietal lobule showed a decrease of rCBF as complexity increased. Because short-term phonological storage is localized to this area, we suggest that the visuospatial working memory system may suppress other systems not in use. Our findings suggest that complex sequential finger movements recruit a discrete set of brain areas, in addition to areas underlying the execution of simple movement sequences.

A Blueprint for Target Motion: fMRI Reveals Perceived Sequential Complexity to Modulate Premotor Cortex

“…This is in line with the finding that even when sequences are performed or learned with the right hand, the right PM appears to play a greater role than its left homologue in sequential production (Seitz and Roland, 1992;Jenkins et al, 1994;Sadato et al, 1996). Based on these and present findings, it could be suggested that there is a right premotor dominance not only in sequential production, but also in perceptual sequential processing.…”

“…Most interestingly for us, all involved brain areas, but particularly premotor areas, have been reported also to underlie the planning and production of motor sequences that follow an external sequential target stimulus, as particularly evident from imaging studies using the serial reaction task paradigm (Gordon et al, 1995;Grafton et al, 1995;Hazeltine et al, 1997;Hikosaka et al, 1998Hikosaka et al, , 1996Honda et al, 1998;Sadato et al, 1996;Sakai et al, 1998;Toni et al, 1998). As expected, the present outcome indicates that an attentively observed sequential signal can be a stimulus sufficient to elicit activations within a brain network closely related to that one that participates in sequential motor behavior.…”

“…Moreover, the right PMv was the only frontal area to be sensitive for all measures of sequential complexity, including behavioral measures and both physical measures, i.e., element number and sequential trend. The key function classically assigned to the lateral PM is the organization of sequential movement under sensory guidance, as indicated from research both in monkeys (Halsband and Passingham, 1985;Halsband et al, 1994;Kettner et al, 1996a,b;Mushiake et al, 1991) and humans (Deiber et al, 1991;Ellermann et al, 1998;Halsband and Freund, 1990;Halsband et al, 1993;Kawashima et al, 1994;Sadato et al, 1996;Van Oostende et al, 1997;Wessel et al, 1997) (for review, see Wise, 1985). Since sensoryguided movements are usually sequential movements, it may not be a mere coincidence that functions relating to both the sensory guidance of movement and the sequential organization of movement are supported within the same cortical structure.…”

“…We take both activations to reflect increasing visuospatial attentional demands. The production of increasingly long sequences of finger movements have yielded responses in the FEF in two recent PET studies (Jenkins et al, 1994;Sadato et al, 1996) and is thus suggested to be engaged in the memory of visuospatially guided motor sequences. Moreover, the FEF were reported to be involved in predictive visual response to a future stimulus (Umeno and Goldberg, 1997), visual stimulus selection (Kodaka et al, 1997), or visuospatial orientation (Scalaidhe et al, 1997;Fujii et al, 1998).…”

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

“…This finding raises and more independent from guidance by the stimulus due the question why the PMC should respond not only to to a learning process. The premotor role in this senpragmatic object properties, but also to dynamic stimulus sorimotor transformation has been indicated by a number features, such as continuously changing patterns in an of imaging studies [11,14,[19][20][21]23,26,42,51,52,67] using abstract figure sequence.…”