Carol Mason

Carol A. Mason, Ph.D.

Professor, Pathology & Cell Biology, Neuroscience, Ophthalmology

Physicians & Surgeons, 14th Floor
Tel +1 212-305-2105

Area of Research

Axon Pathfinding and Synaptogenesis, Synapses and Circuits, Cell Specification and Differentiation


Mammalian brain development; specifically axonal growth cone interactions during pathfinding and during target cell selection and synaptogenesis in visual pathways and cerebellum.


In our studies of axon guidance in the visual pathways, we analyze the behaviors, cellular interactions and molecular directives of retinal axon growth cones during avoidance and crossing of the midline at the optic chiasm.  This system is a model for axon navigation at the CNS midline, and for patterning the binocular projection. We have identified a molecular program of transcription factors and guidance receptors that regulate cell identity and projection of the ipsilateral retinal axon pathway through the optic chiasm.  Current work aims to investigate transcriptional regulators and guidance mechanisms for the contralateral projection, and mechanisms of growth cone interactions with cells of the chiasm midline. 

We have recently addressed whether the programs of gene expression that direct retinal axon decussation at the optic chiasm are relevant to the formation of connections of retinal axons in their first target, the lateral geniculate nucleus.  We now aim to identify molecular regulators of axon-targeting and retinal ganglion cell axon arbor morphogenesis, and to analyze the interplay of molecular factors and neural activity in the targeting and refinement of eye-specific projections 

A genetic model for these studies is the albino.  In both humans and rodents, lack of pigment in the eye leads to visual impairment due to the misrouting of retinal fibers at the optic chiasm to contralateral rather than ipsilateral targets.  Albinism is caused by diverse genes controlling melanogenesis.  We aim to study how factors in the melanogenic pathway from the retinal pigment epithelium (RPE) affect retinal patterning, and retinal ganglion cell specification and projection fate.


Rebsam, A., Petros, T., Bhansali, P., and Mason, C.A.  2009 Switching retinogeniculate axon laterality leads to normal targeting but abnormal eye-specific segregation that is activity dependent.  J. Neurosci.   29:14855-63.

Petros, T., Shresta, B., and Mason, C.A.  (2009) Specificity and sufficiency of EphB1 in driving the ipsilateral retinal projection.  J. Neurosci. 29: 3463-3474.

Petros TJ, Rebsam A, Mason C. 2008  Retinal axon growth at the optic chiasm: To cross or not to cross.  Ann. Rev. Neurosci. 31: 295-315.

Lee, R., Petros, T., and Mason, C.A.  (2008) Zic2 regulates retinal ganglion cell axon avoidance of ephrinB2 through inducing expression of the guidance receptor EphB1.  J. Neurosci. 28: 5910-19.

Williams, S.E., Grumet ,M., Colman, D., Henkemeyer, M., Mason, C.A.,and Sakurai, T. (2006) A role for Nr-CAM in the patterning of binocular visual pathways. Neuron 50:535-47.

Herrera, E., Marcus, R., Li, S.,Williams, S.E., Erskine, L., Lai, E.,and Mason, C.A. (2004). Foxd1 is required for normal development of the optic chiasm. Development 131:5727-39.

Williams,S.E., Mann, F., Sakurai, T., Erskine, L.,Wei, A., Rossi, D.J., Gale,N., Holt, C.E., Mason, C.A., and Henkemeyer, M. (2003) Ephrin-B2 andEphB1 mediate retinal axon divergence at the optic chiasm. Neuron 39:919-935.

Herrera, E., Brown, L, Aruga, J., Rachel, R.A., Dolen, G., Mikoshiba,K., Brown, S. and Mason, C.A. (2003) Zic2 patterns binocular vision byspecifying the uncrossed retinal projection. Cell 114: 545-557.