Cerebral ordening of space and time in the anticipation of events.

The fMRI study is related to previous studies on reaching and grasping. Those
studies addressed visuomotor control in relation to a static environment. This
study will provide information about the perception of a dynamic environment,
needed for making goal-directed movements, in which anticipation plays an
important role. E.g., in order to catch a ball, your brain needs to estimate
*when* that flying object is at a specific location, thus preparing the
commands for the appropriate movements. Novelty in the present design is that
spatial and temporal characteristics can be studied by contrasting conditions
with identical visual stimuli, motor responses and levels of attention.
Moreover, on a philosophical level, the topic is of interest because the clear
distinction between time and space, as we perceive it, is a construct of the
brain itself.

Research questions:
1. Which cerebral regions are involved in space- and time perception: which of
them are specific for either space- or time processing, and which regions are
involved in both.
2. What are the differences in cerebral activation related to event
anticipation and the recall of very recent events: (a) regarding selective
processing of either their spatial or their temporal characteristics, and (b)
regardless which of these two is dealt with.

Design:
In the fMRI study, a block design is used, which has the advantage of a
straight forward *simple* design. Subjects have to watch a monitor screen, on
which a little ball is moving. The ball moves with different speed and along
different curves. At specific moments it stops, which provides the signal for
subject to make a motor response by pushing a button of a response box. Its new
starting point is at (pseudo)random positions on the screen.
- In the control condition (1), subjects always push the same button when the
ball stops.
- In the condition of locating its actual stop-position (2), subjects indicate
such location by pushing a corresponding button.
- In the condition of spatial anticipation (3), subjects push a button that
corresponds to the location where the ball would have touched the bottom of the
screen, if it had followed its trajectory.
- In anticipatory timing (4), subjects indicate when the ball would have
touched the bottom of the screen.
- Similarly, in condition (5), subjects indicate the location from where the
ball started.
- In condition (6), subjects indicate when the ball started its present
trajectory.

For both the spatial and the temporal estimations, subjects choose 1 out of 3
options, which is expressed by pushing 1 of 3 buttons of a responsebox. As to
enable a spatial choice, the bottom of the screen is divided in 3 segments
(left, middle, right). For the temporal conditions, the options short (t < 2s),
in-between (2 < t < 5s) and long (t > 5s) are given. The paradigm implies
identical visual presentation and motor responses, which means a balance
concerning basic visuomotor processing. At the start of each task block, the
instruction is given on the screen. In (pseudo)randomised 30s blocks, the 6
successive conditions constitute a run. By designing 8 runs, each condition is
repeated 8 times. Each run starts and ends with a non-motor condition in which
subjects only attend a central fixation mark.

no specific risks,
burden includes spending time for the study, about 2 hours.