The vertebrate visual system is characterized by multiple pathways originating from the retina that innervate different target nuclei in the brain. In addition to the extensively investigated retino geniculate-cortical pathway, many other retinal afferent pathways have been described that mediate visuomotor behaviors and other non-perceptual visual functions. One longstanding hypothesis about the significance of these multiple, parallel pathways postulates that specific aspects of visual information encoded by the retina are sorted out in these different pathways and that their retinorecipient target nuclei mediate different aspects of visual function. Recently, a direct retinal projection that terminates in the large, serotonergic dorsal raphe nucleus (DRN) of the midbrain has been demonstrated in a variety of mammalian species. Serotonin is one of the oldest and most extensive neurochemical systems in the CNS and is involved in a broad range of physiological, behavioral, and cognitive functions. The DRN contains the vast majority of brainstem serotonergic neurons that send efferent axons to widespread regions of the forebrain. We believe that the retinal-DRN pathway is associated with a “non-image forming” subsystem of retinal afferents that terminate in regions involved in such functions as circadian rhythms neuroendocrine, reproductive, and arousal-related physiological and behavioral processes.

Katherine V. Fite  Interface Between Visual and Serotonin Systems   Our previous research indicates that the retinal-DRN projection is larger in diurnal than in nocturnal species, suggesting that it may play an important role in animals that are highly visual and active primarily during the daylight hours. A primary goal of ongoing research in my laboratory is to understand the neuroanatomical organization and functional significance of this unusual retinal pathway in mammals using a variety of techniques that include single-unit electrophysiological, immunohistochemical, electron microscopic, and confocal microscopic analyses to determine how light stimulation may influence the activity of neurons in the DRN over the diurnal cycle and during experimentally controlled visual stimulation.

Previously, we have shown that efferent projections from different subdivisions of the dorsal raphe nucleus terminate in a number of structures in the central visual system including the superior colliculus, lateral geniculate nucleus, and visual cortex. This direct retinal-DRN pathway, appears to represent an important interface between visual and serotonergic systems, yet at the present time, little is known about how photic stimulation may affect serotonergic neurons. Recently, we have shown that light stimulation has differential effects on c-Fos expression in the DRN depending upon time of day, and actually may supress c-Fos and affect serotonin levels in the DRN over the diurnal cycle using quantitative, immunocytochemical techniques. At present, we are investigating the newly discovered "melanopsin" ganglion cell in rodent retinas to determine whether it also communicates with the DRN. The effects of light on the serotonin system may underlie the well-established effects of light therapy in alleviating the symptoms of seasonal affective disorder and perhaps other forms of depression as well. Our research is providing valuable new information about how environmental light and visual stimulation can directly influence the DRN, which is the largest serotonergic nucleus in the brainstem of mammals, and can enhance our understanding of the organization and functional significance of this unusual sensory pathway.

Selected Publications:

Anderson, D. R., K. V. Fite, N. Petrovich and J. Hirsch. "Cortical Activation while watching video montage: an fMRI Study (in press, 2005)

Fite, K. V., P. Wu, A. Bellemer.(2005) "Photostimulation alters c-Fos expression in the dorsal raphe nucleus. Brain Research, 1031: 245-252.

Birkett, M. and K. V. Fite. (2005) "Diurnal Variation in serotonin immunoreactivity in the dorsal raphe nucleus, Brain Research, 1034, 180-184.

Janusonis, S., Fite, K. V., and Bengston, L. (2003) Subdivisions of the dorsal raphe nucleus projecting to the lateral geniculate nucleus and primary visual cortex of the Mongolian gerbil. Neuroreport, 14: 459-462

Fite, K. V., Birkett, M., Smith, A., Janusonis S. and McLaughlin S. (2003) Retinal ganglion cells projecting to the dorsal raphe and lateral geniculate complex in Mongolian gerbils. Brain Research, 973: 146-150.

Fite, K.V., and Janusonis, S. (2002) Optic afferents to the parabrachial nucleus. Brain Research, 943: 9-14.

Fite, K.V. and Janusonis, S. (2001) Retinal projection to the dorsal raphe nucleus in the Chilean degus (Octodon degus). Brain Res. 85: 139-145.

Li, Z and Fite, K. V. (2001) GABAergic visual pathways in the frog Rana pipiens. Visual Neuroscience, 18: 457-464.

Janusonis, S. and Fite, K. V. (2001) Diurnal variation of c-Fos expression in subdivisions of the dorsal raphe nucleus of the Mongolian gerbil (Meriones unguiculatus) J. Comp. Neurol., 440: 31-42.

Janusonis, S., Fite, K.V., Foote, W. (1999) Topographic organization of serotonergic dorsal raphe neurons projecting to the superior colliculus in the Mongolian gerbil (Meriones unguiculatus). J. Comp Neurol. 413(2): 342-355. MEDLINE

Fite, K.V., Janusonis, S., Foote, W. and Bengston, L. (1999) Retinal afferents to the dorsal raphe nucleus in rats and Mongolian gerbils. J. Comp Neurol. 414(4): 469-484. MEDLINE

Li, Z. and Fite, K.V. (1998) Distribution of GABA-like immunoreactive neurons and fibers in the central visual nuclei and retina of frog, Rana pipiens. Vis Neurosci, 15:995-1006. MEDLINE

Fite, K.V., Blaustein, A., Bengston, L. and Hewitt, H. (1998) Evidence suggesting retinal light damage in Rana cascadae, a declining amphibian species. Copeia, 4:906-914.

Montgomery, N.M., Tyler, C.J. and Fite, K.V. (1998) Organization of retinal axons within the optic chiasm and the innervation of multiple central nervous system targets. J. Comp Neurol, 402:222-237. MEDLINE

Janusonis, S. and Fite, K. V. (1997) NMDAR1-like immunoreactive fibers appear in the ipsilateral optic tract during optic nerve regeration in Rana pipiens. Neurosci Lett, 236:1-4. MEDLINE

Aller, M. I. , Janusonis, S. Fite, K. and Fernandex-Lopez, A. (1997) Distribution of the GABA-A receptor complex b2/3 subunits in the brain of the frog, Rana Pipiens. Neurosci Lett, 225:65-68. MEDLINEFite, K.V.,

Li, Z., Fite, K.V., Montgomery N.M and Wang, S. R. (1996) Single unit responses to visual, whole-field stimulation in the pretectum of Rana pipiens. Neurosci Lett, 218(3):193-197. MEDLINE

Basil, J.A., Kamil, A.C., Balda, R.P. and Fite, K.V. (1996) Differences in hippocampal volume among food storing corvids. Brain Behavior and Evolution, 30:156-165.

Montgomery, N.M., Fite, K.V. and Li, Z. (1995) Segregation of optic axons based on central target: The medial optic tract in Rana pipiens. Neurosci Lett, 195:199-202.

Tyler, C.J., Fite, K.V., and DeVries, G.J. (1995). Distribution of GAD-like immunoreactivity in the retina and central visual system of Rana pipiens. J. Comp. Neurol. 353:439-450.

Fite, K.V., Bengston, L., and Cousins, F. (1994) Drusen-like deposits in the outer retina of Japanese quail. Exp Eye Res, 59(4):417-424. MEDLINE

Fite, K.V., Bengston, L. and Donaghey, B. (1993) Experimental light damage increases lipofuscin in the retinal pigment epithelium of Japanese quail (Coturnix coturnix japonica). Exp Eye Res, 57(4):449-460. MEDLINE

BIOGRAPHICAL INFORMATION

Education:

Ph.D. - Brown University, 1969, Experimental Psychology

M.S. - Brown University, 1967, Experimental Psychology

B.S. - Florida State University, 1963, Psychology (Honors)

Professional Positions:

Assistant Professor, University of Massachusetts Amherst, 1970-1974

Associate Professor, University of Massachusetts Amherst, 1975-1980

Visiting Associate Professor, SUNY Stony Brook, 1976-1977

Professor, University of Massachusetts Amherst, 2981-present

Director, Sensory Systems Program, Integrative Biology and Neuroscience, National Science Foundation, 1991-1992

Director, Neuroscience and Behavior Program, University of Massachusetts Amherst 1994-2001

Honors and Awards:

NIH Predoctoral Fellowship, 1964-1968

NIH Postdoctoral Fellowship, 1968-1970

NIH Research Career Development Award, 1977-1982

US-China Distinguished Exchange Scholar, National Academy of Sciences Award, 1988-1989

Research Faculty Fellowship Award, University of Massachusetts, 1988-1989

Founding Editor, VISUAL NEUROSCIENCE, 1986-1991

Elected Officer, Association of Neuroscience Departments and Programs, 1998-2000

Citations:

American Men and Women of Science

Who's Who in American Women

Who’s Who in the World

Who’s Who in Science and Technology

Professional Memberships:

Society for Neuroscience

Association of Neuroscience Programs and Departments (Elected officer: l998-2000)

International Brain Research Organization (IBRO)

Massachusetts Society for Medical Research

American Association for the Advancement of Science

Research and Scholarly Interests:

Visual Neuroscience and Comparative Neuroanatomy: Neuroanatomical, neurophysiological, and behavioral correlates of vision; comparative functional anatomy of retina and subcortical visual pathways; interface between visual and serotonin systems and the role of light stimulation in mood and affective responses.

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