Existence in the nucleus incertus of the cat of horizontal eye movement-
related neurons projecting to the cerebellar flocculus.
CHERON, GUY, SVEN SAUSSEZ, NICO GERRITS, AND EMILE GODAUX.
Laboratory of Neurosciences, University of Mons-Hainaut, Belgium;
Department of Anatomy, Erasmus University of Rotterdam, The Netherlands.
APStracts 2:0187N, 1995.
Summary and Conclusions
Properties of nucleus incertus (NIC) neurons projecting to the cerebellar
flocculus were studied in alert cats by using chronic unit and eye movement
recording and antidromic activation. Projection of these neurons onto the
flocculus was verified with retrograde transport of horseradish peroxidase
(HRP) after injections in the flocculus. Bipolar stimulation electrodes were
implanted into the middle zone of each flocculus because this zone is known to
be involved in the control of horizontal eye movements.The dorsomedial aspect
of the pontine tegmentum was explored with microelectrodes during stimulation
of both flocculi. The majority of neurons antidromically activated from the
flocculus were found in the caudal part of the NIC. Out of the 69 neurons
activated from the flocculus, 44 were classified as burst-tonic (BT) neurons;
34 discharged in relation with horizontal movements of the eye, 10 in relation
with vertical movements. Out of the 14 remaining neurons, 6 were not related
to eye movements and 8 were classified as burst neurons. The BT-neurons of the
NIC displayed a great sensitivity to both horizontal eye position and
horizontal eye velocity. This study demonstrates the presence of a new group
of horizontal eye movement related BT-neurons situated in the NIC. The fact
that they project to the horizontal floccular zone emphasizes the importance
of the functional specialization of the different Purkinje cell zones.
Received 3 April 1995; accepted in final form 5 June 1995.
APS Manuscript Number J216-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.