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Frans Ottenhoff Tel: 030 -535113
05-12-1991, 08:09 PM
In our department we study the neuro-muscular control of human mandibular
movements during chewing. In one of the projects, subjects make open-close
movements at their natural chewing rate, while food resistance is simulated
by an external computer controlled force, acting on the mandible in a downward
direction during part of the closing phase. The advantage of this method is
that food resistance is under complete control and can be easily
manipulated.

One of the experiments we perform is the so called APPEAR experiment. After
a large number of open-close movements without force, the force appeared.
The subjects did not know during which cycle the force would be present,
but they did know that if the force was applied for the first time, it
would also be present in the following ten cycles.

We observed in the EMG of the closing muscles Additional muscle activity
(AMA), which is required to overcome the external force. In the first cycle
with force, this AMA starts late, i.e. about 130 ms after the onset of the
force. However, in the following cycles this AMA starts already after 25
ms.

We are very interested in literature about this kind of experiments, i.e.
experiments in which knowledge about upcoming disturbances influences the
amplitude and/or the latency of the (long latency) reflexes evoked by these
disturbances.

We hope to receive a lot of suggestions.

With kind regards, Frans Ottenhoff.
__________________________________________________ _____________________
Frans Ottenhoff Telephone +31-30-535113
Dept. Oral Pathophysiology Telefax +31-30-521105
University of Utrecht
Padualaan 14 INTERnet OTTENHOFF@ruumtc.tcu.ruu.nl
3584 CH Utrecht
The Netherlands