The long-term objective of these studies are to better understand the neural control of the pupil. When light is shone in one eye, pupilloconstriction occurs in both eyes and is termed the pupillary light reflex (PLR). With near viewing, convergence and accommodation are accompanied by a pupilloconstriction that is termed the pupillary near response. These pupillary responses are extremely useful to clinicians diagnosing the nature, severity, and extent of brain damage. Furthermore, detailed knowledge of the anatomy and physiology of the subcortical and cortical pathways involved in these pupillary responses is essential if the fledgling field of objective visual field testing using pupillometry (pupil perimetry) is to advance significantly. Unfortunately, there have been few recent studies of the neural control of these pupillary responses. Indeed, to my knowledge, our laboratory is currently only one of two in the world carrying out such up-to-date studies in alert, behaving primates. Therefore, despite the clinical importance of these pupillary responses, the literature is forced to rely on the results of experimental work that was mostly carried out before the advent of modern techniques. Hence, despite our recent extensive studies of the subcortical pupillary pathway in primates, there is still little or no data on the characteristics of the retinal ganglion cells that mediate the PLR, on the influences of the brainstem on the PLR, or on the role of the cerebral cortex in the PLR. To address these issues, we will use electrophysiological, anatomical, and pharmacological techniques in alert, behaving rhesus monkeys. We propose to determine the physiology, morphology, and immunohistochemical characteristics of the retinal ganglion cells that project to the pretectal olivary nucleus, the pretectal nucleus that mediates the PLR. We will characterize the brainstem afferents to this nucleus and the neurotransmitters within it. We will investigate the role of the cerebral cortex in influencing the PLR, we will study the effects of reversible and permanent lesions of striate cortex. In addition, permanent lesions of the dorsal prelunate gyrus will be used to study its involvement in the PLR. We will also use anatomical and electrophysiological techniques to investigate projections from the prelunate gyrus and other extrastriate visual areas to the pretectal olivary nucleus.

National Institute of Health (NIH)
National Eye Institute (NEI)
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Visual Sciences B Study Section (VISB)
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University of Alabama Birmingham
Schools of Optometry/Ophthalmol
United States
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Liao, Hsi-Wen; Ren, Xiaozhi; Peterson, Beth B et al. (2016) Melanopsin-expressing ganglion cells on macaque and human retinas form two morphologically distinct populations. J Comp Neurol 524:2845-72
McDougal, David H; Gamlin, Paul D (2015) Autonomic control of the eye. Compr Physiol 5:439-73
Hannibal, J; Kankipati, L; Strang, C E et al. (2014) Central projections of intrinsically photosensitive retinal ganglion cells in the macaque monkey. J Comp Neurol 522:2231-48
Kozicz, Tamás; Bittencourt, Jackson C; May, Paul J et al. (2011) The Edinger-Westphal nucleus: a historical, structural, and functional perspective on a dichotomous terminology. J Comp Neurol 519:1413-34
Kankipati, Laxmikanth; Girkin, Christopher A; Gamlin, Paul D (2011) The post-illumination pupil response is reduced in glaucoma patients. Invest Ophthalmol Vis Sci 52:2287-92
Kankipati, Laxmikanth; Girkin, Christopher A; Gamlin, Paul D (2010) Post-illumination pupil response in subjects without ocular disease. Invest Ophthalmol Vis Sci 51:2764-9
McDougal, David H; Gamlin, Paul D (2010) The influence of intrinsically-photosensitive retinal ganglion cells on the spectral sensitivity and response dynamics of the human pupillary light reflex. Vision Res 50:72-87
Crook, Joanna D; Peterson, Beth B; Packer, Orin S et al. (2008) The smooth monostratified ganglion cell: evidence for spatial diversity in the Y-cell pathway to the lateral geniculate nucleus and superior colliculus in the macaque monkey. J Neurosci 28:12654-71
Gamlin, Paul D R; McDougal, David H; Pokorny, Joel et al. (2007) Human and macaque pupil responses driven by melanopsin-containing retinal ganglion cells. Vision Res 47:946-54
Gamlin, Paul D R (2006) The pretectum: connections and oculomotor-related roles. Prog Brain Res 151:379-405

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