Humans, as foveate creatures, continuously examine their environment through a series of gaze changes involving saccadic eye movements and, in many cases, quick accompanying head movements. Normal visual perception requires that these movements be accurate and precisely coordinated. Consequently, neurological disorders that interfere with gaze are quite debilitating, often producing symptoms that result in the initial clinical visit. Our long-term goal is to analyze the circuitry underlying gaze. The central mesencephalic reticular formation (cMRF) represents the major midbrain target of the superior colliculus (SCol), and is believed to provide input to brainstem visual motor structures, and the spinal cord, in addition to feeding back upon the SCoI. cMRF stimulation elicits gaze changes, and this region contains several different physiological cell types that fire before saccadic eye movements. However, our knowledge of cMRF connectivity is limited. In this study, a series of dual tracer experiments will be undertaken in macaque monkeys to define cMRF connections with reticulospinal neurons in the medulla, motoneurons in the spinal cord, SCol neurons projecting in the predorsal bundle, and with the paramedian pontine reticular formation (PPRF). These projections will be tested utilizing post-embedding immunohistochemistry to determine whether they are GABAergic (inhibitory). Multiple fluorescent tracer injections will be utilized to determine whether separate neuronal populations provide inputs to the SCol, PPRF, and head movement centers in the medulary reticular formation and cervical cord. In addition, these cMRF neurons will be characterized with respect to their collicular input. Light and electron microscopic analysis of the dual tracer experiments will allow input/output relationships in the cMRF and its targets to be specified at the neuronal level. The results from these experiments will test the hypothesis that the cMRF provides the SCol with separate channels to modulate the eye and head components of gaze. In addition, they will provide an understanding of the cMRF and SCol circuitry at the neuronal level that can help delineate the feasibility of current and future models of gaze generation. Thus, this study will provide a scientific basis for better understanding gaze mechanisms and pathology. ? ?

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY014263-02
Application #
6718988
Study Section
Visual Sciences B Study Section (VISB)
Program Officer
Hunter, Chyren
Project Start
2003-04-01
Project End
2007-02-28
Budget Start
2004-03-01
Budget End
2005-02-28
Support Year
2
Fiscal Year
2004
Total Cost
$288,800
Indirect Cost
Name
University of Mississippi Medical Center
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
928824473
City
Jackson
State
MS
Country
United States
Zip Code
39216
May, Paul J; Basso, Michele A (2018) Connections between the zona incerta and superior colliculus in the monkey and squirrel. Brain Struct Funct 223:371-390
May, Paul J; Warren, Susan; Gamlin, Paul D R et al. (2018) An Anatomic Characterization of the Midbrain Near Response Neurons in the Macaque Monkey. Invest Ophthalmol Vis Sci 59:1486-1502
Bohlen, Martin O; Warren, Susan; May, Paul J (2017) A central mesencephalic reticular formation projection to medial rectus motoneurons supplying singly and multiply innervated extraocular muscle fibers. J Comp Neurol 525:2000-2018
Wang, Niping; Perkins, Eddie; Zhou, Lan et al. (2017) Reticular Formation Connections Underlying Horizontal Gaze: The Central Mesencephalic Reticular Formation (cMRF) as a Conduit for the Collicular Saccade Signal. Front Neuroanat 11:36
Barnerssoi, Miriam; May, Paul J; Horn, Anja K E (2017) GABAergic innervation of the ciliary ganglion in macaque monkeys - A light and electron microscopic study. J Comp Neurol 525:1517-1531
Binda, Paola; Gamlin, Paul D (2017) Renewed Attention on the Pupil Light Reflex. Trends Neurosci 40:455-457
Bohlen, Martin O; Warren, Susan; Mustari, Michael J et al. (2017) Examination of feline extraocular motoneuron pools as a function of muscle fiber innervation type and muscle layer. J Comp Neurol 525:919-935
May, Paul J; Warren, Susan; Bohlen, Martin O et al. (2016) A central mesencephalic reticular formation projection to the Edinger-Westphal nuclei. Brain Struct Funct 221:4073-4089
Costello, M Gabriela; Zhu, Dantong; May, Paul J et al. (2016) Task dependence of decision- and choice-related activity in monkey oculomotor thalamus. J Neurophysiol 115:581-601
Bohlen, Martin O; Warren, Susan; May, Paul J (2016) A central mesencephalic reticular formation projection to the supraoculomotor area in macaque monkeys. Brain Struct Funct 221:2209-29

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