Images from the Shatz Lab
Pseudocolor representation of three class I MHC mRNA subtypes (red, H2-D; green, Qa-1; blue, T22) expressed in P40 mouse brain.Huh, G. S., Boulanger, L. M., Du, H., Riquelme, P. A., Brotz, T. M., and Shatz, C. J. (2000). Functional requirement for class I MHC in CNS development and plasticity. Science 290: 2155-2159.
High-magnification view of the involvement of RGCs in waves. Each colored dot is the cell body of a single RGC that is involved in a wave during a calcium imaging experiment (they are roughly 10 microns in diameter). Each active cell has been given a false color to represent the magnitude of the change in fluorescence when it is active. Cells that are red/white are very active, while blue/green cells are not. (Fluorescence changes are due to calcium entry into the cell body caused by wave activity.)
Wong, R.O.L., A. Chernjavsky, S.J Smith and C.J. Shatz (1995) Early functional neural networks in the developing retina. Nature 374: 716-718.
The following two slides show eye-segregation in the LGN. Axons of RGCs from both eyes project to the LGN. Initially, the areas in the LGN occupied by axons from each eye overlap, but the overlapping area grows smaller over development until the connections coming from the retinal ganglion cell axons in each eye occupy completely separate areas. Overlapping inputs are shown as yellow; red represents the inputs from ganglion cells in one eye, while green represents the inputs from the other eye. The completely segregated projections of each eye into the adult layers are shown as pure red and pure green zones.
Penn, A.A., Riquelme, P.A., Feller, M.B., and Shatz, C.J. (1998) Competition in retinogeniculate patterning driven by spontaneous activity. Science 279: 2108-2112.
The first slide shows development of eye segregation in the
ferret LGN. When the ferret is born (post-natal day 0, P0),
there are large areas of overlap in the connections made by
ganglion cells axons coming from the right and left eyes
(yellow) in a cross-section of each LGN. By P10, there is
complete segregation (red, green). Thus, the adult pattern
of connectivity between eye and brain is not present
initially, and only emerges gradually. This is a nice
demonstration of the fact that the baby's brain is not just
a miniature version of the adult brain.
The segregation of eye input into the LGN layers is completely disrupted by blocking wave activity in the eye (waves are blocked using a drug called epibatidine). The presence of the large yellow areas show that there are still large areas of overlapping projections, as compared with normal development (saline &endash; i.e., no drug blocking the waves) where these same areas are red and green (corresponding to the segregated eye input forming the adult layers). Thus, blocking spontaneous activity early in development prevents the formation of the adult pattern of connections between eye and brain.
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A single retinal ganglion cell filled with a
fluorescent dye. You can see dendrites (where the
RGC receives inputs from other nerve cells in the
retina) that surround the cell body, and the long,
smooth axon that extends down and slightly right,
sending information onwards to the LGN.
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Another view of a retinal ganglion cell, this time filled with horseradish peroxidase. |
| Ramoa, A.S., G. Campbell and C.J. Shatz, 1988. Dendritic growth and remodelling of cat retinal ganclion cells during fetal and postnatal development. J. Neurosci. 8:4239-4261. |
Unpublished, M. Kliot and C.J. Shatz. |
A high magnification view of eye segregation in the LGN, which reminds all of us of a Monet painting.
Penn, A.A., Riquelme, P.A., Feller, M.B., and Shatz, C.J. (1998) Competition in retinogeniculate patterning driven by spontaneous activity. Science 279: 2108-2112.