Investigating the role of the Extrastriate Body Area in motor planning - an explorative TMS-study

There*s debate on the function fulfilled by the extrastriate body area (EBA).
It has been suggested that EBA*s function is to process structural limb and
body information for (Downing et al., 2001), but that it is not, as suggested
by others, directly involved in higher-level cognitive functions concerned with
for example motor control, action understanding and identity recognition (for a
review see Downing and Peelen, in press). This information, according to
Downing and colleagues, is made explicit by other brain areas, based on the
information about a bodies shape provided by EBA. We propose that, with respect
to motor control, EBA provides a visual representation of a body posture
suitable to achieve an actions goal, which is used by the fronto-parietal motor
network to evoke a motor plan towards that particular goal posture.

Here, we want to investigate the role of EBA in planning and control of
goal-directed actions using transcranial magnetic stimulation (TMS) and
investigate whether EBA plays a crucial role in planning of goal-directed
action by providing an early visual representation of the desired goal-state.
Therefore we want to show that stimulation of EBA modulates overt motor
behaviour.

experimental within-subject design with healthy volunteers.

We plan to use single-pulse TMS over three brain regions (EBA, intraparietal
sulcus (IPS), vertex). We will assess effects of TMS behaviourally, we plan to
use a regular intensity (120 V/m).

TMS is not painful, especially not at the low intensities used in the present
study. However, TMS may lead to feelings of discomfort from the stimulation of
the scalp and associated nerves and muscles. The volunteers are requested to
come to the Donders Institute for four sessions. In the first session
participants undergo structural and functional MRI and we will establish their
active motor threshold for TMS. The next three sessions will be TMS sessions
(one for each stimulation site) separated at least by a week from each other.