Representations of Graphomotor Trajectories in the Human Parietal Cortex: Evidence for Controlled Processing and Automatic Performance

Abstract

The aim of this study was to identify the cerebral areas activated during kinematic processing of movement trajectories. We measured regional cerebral blood flow (rCBF) during learning, performance and imagery of right-hand writing in eight right-handed volunteers. Compared with viewing the writing space, increases in rCBF were observed in the left motor, premotor and frontomesial cortex, and in the right anterior cerebellum in all movement conditions, and the increases were related to mean tangential writing velocity. No rCBF increases occurred in these areas during imagery. Early learning of new ideomotor trajectories and deliberately exact writing of letters both induced rCBF increases in the cortex lining the right intraparietal sulcus. In contrast, during fast writing of overlearned trajectories and in the later phase of learning new ideograms the rCBF increased bilaterally in the posterior parietal cortex. Imagery of ideograms that had not been practised previously activated the anterior and posterior parietal areas simultaneously. Our results provide evidence suggesting that the kinematic representations of graphomotor trajectories are multiply represented in the human parietal cortex. It is concluded that different parietal subsystems may subserve attentive sensory movement control and whole-field visuospatial processing during automatic performance.

Neural Substrates of Graphomotor Sequence Learning: A Combined fMRI and Kinematic Study

“…The early learning period was associated with activation of the dorsal and ventral visual streams and the dorsal premotor cortex (Burnod et al 1999;Caminiti and Johnson 1992;Caminiti et al 1996Caminiti et al , 1998Caminiti et al , 1999Lacquaniti et al 1995), and it may reflect the tuning of sensorimotor transformations that map, for example, visuospatial signals into motor commands. The important role of the superior parietal lobule in this graphomotor sequence task is consonant with earlier studies involving graphomotor learning (Seitz et al 1994(Seitz et al , 1997.…”

“…Graphomotor sequence learning involves multiple, interacting networks of neural regions that contribute successively to the formation of multiple representations for graphomotor trajectories (Seitz et al 1994(Seitz et al , 1997. First, the novel sequence of movements is initially mapped to form an internal representation of the sequence, involving cortical processes (including the dorsal and ventral visual streams).…”

“…Prior neuroimaging studies on the short-term learning of handwriting have revealed multiple representations of graphomotor trajectories in parietal cortex (Seitz et al 1997) as well as a successive role of the cerebellum and the premotor cortices in trajectorial learning using PET (Seitz et al 1994). These results are consistent with functional magnetic resonance imaging (fMRI) data obtained during the performance of Japanese kanji ideograms, which has been shown to activate left fronto-parietal networks, including the middle and inferior frontal gyri and pre-and postcentral gyri.…”

Activation of Cortical and Cerebellar Motor Areas during Executed and Imagined Hand Movements: An fMRI Study

“…In our study a very simple hand movement was performed, during which no parietal activation is expected. High activity of the parietal cortex was observed only in motor tasks, which include complex movements coordinated in space, such as graphomotor control (Seitz et al, 1997).…”

Neuronal Modifications During Visuomotor Association Learning Assessed by Electric Brain Tomography

“…Of special interest in this context is the reduced activation in the IPL/SPL in later learning stages. The posterior IPL/SPL is involved in a variety of mental operations, including mental rotation (Jordan et al 2001), imagining motor acts , learning movement trajectories (Seitz et al 1997), controlling self-determined finger movements (Schubert et al 1998), and recognising objects in relation to actions (Faillenot et al 1997). The common feature of the tasks used in these studies is the generation of a mental representation of a visual object and imagined motor acts of grasping, exploring, manipulating or manually constructing the object.…”