[Abstract Title]. - Society for Neuroscience

correlated (r=+0.59). In contrast, the correlation between indoor and outdoor COMR was not
significant, although it was in the predicted direction (r=+0.21, p=0.36). One factor that may
dissociate indoor and outdoor COMR is the fact that the range of gaze positions was controlled
experimentally indoors, but determined spontaneously (and idiosyncratically) by each subject
while outdoors. The results suggest that, despite there being many factors that determine whether
or not the head is moved during each specific saccade, there are consistent head movement
tendencies that influence subject performance across very different behavioral contexts.
Disclosures: Z.C. Thumser, None; J.S. Stahl , None.
Poster
263. Eye Movements: Eye and Head Control
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 263.3/DD3
Topic: D.06.c. Eye and head control
Support: NIH Grant EY014263
Title: Sources of input to the central mesencephalic reticular formation in macaque monkeys
Authors: *S. WARREN 1 , L. ZHOU 1 , P. J. MAY 2 ;
1 Dept Anat., 2 Dept Anatomy, Ophthalmology & Neurol., Univ. Mississippi Med. Ctr., Jackson,
MS
Abstract: The central mesencephalic reticular formation (cMRF) is a region of the primate
midbrain where electrical stimulation elicits horizontal saccadic eye movements and recordings
show activity related to the eye and head components of gaze. We previously demonstrated that
the superior colliculus (SC) provides an intense input to the cMRF that terminates on cells
projecting back to the SC. The cMRF also provides downstream projections to raphe interpositus
(RIP), the paramedian pontine reticular formation (PPRF), medullary reticular formation (MdRF)
and cervical spinal cord. In the present study, we sought to identify the sources of input to the
cMRF, by injecting retrograde tracers into this structure in M. fascicularis monkeys. In the
diencephalon, labeled neurons were observed in the zona incerta (ZI) and the rostral interstitial
nucleus of the medial longitudinal fasciculus (riMLF), ipsilaterally. In the midbrain, we found
that the tectoreticular projection showed injection site specific differences: the upper sublamina
of the intermediate gray layer (SGI) was preferentially labeled from lateral cMRF injections, but
injections that also included the medial cMRF labeled cells throughout SGI. Based on the known
SGI projections, the medial and lateral cMRF appear to receive inputs from SGI sublaminae that
are more head and eye related, respectively. The main source of midbrain input to the cMRF