Dacey, Dennis, Ph.D.
It is now well accepted that the vertebrate retina contains on
the order of 50-60 distinct neural cell types. Why does the retina, situated at the earliest stage of the visual process, require
so many cell types? One hypothesis is that the photoreceptor responses to light are channelled into a number of parallel
signal pathways that separately encode various aspects of a visual image and play different roles in visual perception. In
the retina each of these visual pathways would be composed of a set of interneurons linked to an output neuron, the ganglion cell,
whose axon projects to a target in the brain. To test this hypothesis we are attempting to identify each of the retinal
ganglion cell types and their associated interneurons. Work in the lab has recently focused on the retina of the human and
macaque monkey. In the primate we know that some ganglion cell types receive excitatory input from red, green, or blue cone
photoreceptors and therefore show color selective light responses; other ganglion cell types are excited equally by all of the
cone types and are non-color selective. The neural organization that gives rise to these distinct signal pathways is
unknown. To approach the problem we are using intracellular recording and staining in in vitro preparation of the macaque
retina to identify the color-coding light responses of morphologically identified ganglion cell
Dacey, D.M., and Brace, S. (1992) A coupled network for parasol but not midget ganglion cells in
the primate retina. Visual Neuroscience 9: 279-290.
Dacey, D.M., and Petersen, M. (1992) Dendritic field size
and morphology of midget parasol ganglion cells of the human retina. Proc. Natl. Acad Sci. USA. 89:
Milam, A.H., Dacey, D.M., and Dizhoor, A.M. (1993) Recovering immunoreactivity in mammalian cone bipolar
cells. Visual Neuroscience 10: 1-12.
Dacey, D.M. (1993) Morphology of a small-field bistratified ganglion cell
type in the macaque and human retina. Visual Neuroscience 10: 1081-1098.
Dacey, D.M. (1993) The mosaic of midget
ganglion cells in the human retina. The Journal of Neuroscience 13:5334-5355.
Dacey, D.M., and Lee, B.B.
(1994) The blue-ON opponent pathway in primate retina originates from a distinct bistratified ganglion cell type.
Nature 367: 731-735.
Dacey DM, Peterson BB, Robinson FR, Gamlin PD (2003) Fireworks in the primate retina: in vitro
photodynamics reveals diverse LGN-projecting ganglion cell types. Neuron 37(1):15-27
Lee BB, Dacey DM, Smith VC, Pokorny J (2003)
Dynamics of sensitivity regulation in primate outer retina: the horizontal cell network. Journal of Vision 3:513-26
Packer OS (2003) Colour coding in the primate retina: diverse cell types and cone-specific circuitry. Current Opinion in Neurobiology
Diller LC, Packer OS, Verweij J, McMahon MJ, Williams DR, Dacey DM (2004) L- and M-cone contributions to the midget and
parasol ganglion cell receptive fields of macaque monkey retina. Journal of Neuroscience 24(5):1079-1088
McMahon MJ, Packer OS,
Dacey DM (2004) The classical receptive field surround of primate parasol ganglion cells is mediated primarily by a non-GABAergic
pathway. Journal of Neuroscience, 24(15):3736-3745.
Dacey DM, Liao H-W, Peterson BB, McDougal DH, Robinson FR, Smith VC, Pokorny J,
Yau K-W, Gamlin PD (2005) Melanopsin-expressing ganglion cells in primate retina project to the LGN and signal both color and
irradiance. Nature 433:749-754.
Packer, OS, Dacey DM (2005) Synergistic center-surround receptive field model of monkey H1 horizontal
cells. Journal of Vision, 5(11): 1038-1054.
Gamlin PD, McDougal DH, Smith VC, Dacey DM, Pokorny J, Yau K-W. Human and macaque pupil
responses driven by intrinsically photoreceptive retinal ganglion cells. Submitted.