Cat Retina Data
Point pattern of retinal ganglion cells identified as `on' or `off'. A marked point pattern.
An object of class
representing the point pattern of cell locations.
x Cartesian $x$-coordinate of cell
y Cartesian $y$-coordinate of cell
marks factor with levels 0 or 1
indicating ``off'' and ``on'' cells
ppp.object for details of the format.
W"assle et al (1981), data supplied by Peter Diggle
The data represent a pattern of beta-type ganglion cells in the retina of a cat recorded by W"assle et al. (1981). The window is a rectangle $(0,1) \times (0, .7533)$ mm approximately.
Beta cells are associated with the resolution of fine detail in the cat's visual system. They can be classified anatomically as ``on'' or ``off''. Statistical independence of the ``on''- and ``off''-components would strengthen the claim that there are two separate channels for ``brightness'' and ``darkness'' as postulated by Hering in 1874.
Diggle, P. J. (1986). Displaced amacrine cells in the retina of a rabbit : analysis of a bivariate spatial point pattern. J. Neurosci. Meth. 18, 115--125. Van Lieshout, M.N.M. and Baddeley, A.J. (1999) Indices of dependence between types in multivariate point patterns. Scandinavian Journal of Statistics 26, 511--532.
W"assle, H., Boycott, B. B. & Illing, R.-B. (1981). Morphology and mosaic of on- and off-beta cells in the cat retina and some functional considerations. Proc. Roy. Soc. London Ser. B 212, 177--195.